10MP Uptake and partitioning of amino acids and pepides
Molecular Plant?Volume3?Number6?Pages997–1011?November2010REVIEW ARTICLE Uptake and Partitioning of Amino Acids and Peptides
Mechthild Tegeder a,1and Doris Rentsch b
a School of Biological Sciences,Washington State University,Pullman,WA99164-4236,USA
b Institute of Plant Sciences,University of Bern,Altenbergrain21,3013Bern,Switzerland
ABSTRACT Plant growth,productivity,and seed yield depend on the ef?cient uptake,metabolism,and allocation of nutrients.Nitrogen is an essential macronutrient needed in high amounts.Plants have evolved ef?cient and selective transport systems for nitrogen uptake and transport within the plant to sustain development,growth,and?nally repro-duction.This review summarizes current knowledge on membrane proteins involved in transport of amino acids and pep-tides.A special emphasis was put on their function in planta.We focus on uptake of the organic nitrogen by the root, source-sink partitioning,and import into?oral tissues and seeds.
Key words:Organic nitrogen;amino acid;peptide;transporter;source;sink;root;leaf;?ower;seed;nitrogen uptake; assimilate partitioning.
INTRODUCTION
Nitrogen(N)is quantitatively the most important nutrient for plant development.It is a major constituent of essential com-pounds such as chlorophyll,nucleic acids(DNA and RNA),and amino acids(peptides and proteins),and limited N availability has severe consequences for plant metabolism and growth (Epstein and Bloom,2005).Inadequate N supply,for example, leads to reduced leaf area,chlorophyll content,and photosyn-thetic rate,resulting in lower biomass production and yield of storage compounds(e.g.oil and proteins).Therefore,in sup-port of growth and development,suf?cient N needs to be taken up and allocated to source and sink organs.Plants ac-quire N not only as nitrate and ammonium that are reduced to amino acids in the root or shoot tissue,but also as organic N forms(i.e.amino acids,peptides,and proteins)from the soil (Na¨sholm et al.,2009).N uptake and ef?cient partitioning of amino acids or peptides within the plant require the activity of transporters that transfer the N compounds across cellular membranes.Taken into account that plants are multi-cellular organisms with highly specialized cell types,and that a large variety of N-containing compounds exist,it is not surprising that a large number of N transporters belonging to different families have been identi?ed(Table1;Rentsch et al.,2007). The characterized transport proteins display different sub-strate selectivities and/or af?nities when expressed in heterol-ogous systems such as Saccharomyces cerevisiae mutants and Xenopus laevis oocytes,and their expression is highly regu-lated and shows distinct cellular localization(for detailed descriptions,see Rentsch et al.,2007).This review will focus on organic N uptake and partitioning in the plant,and specif-
ically on amino acid and peptide transporters involved in this process.For transporters of ureides,urea,and other N metab-
olites like peptide conjugates,we refer to recent reviews (Kojima et al.,2006;Rea,2007;Rentsch et al.,2007;Maurel
et al.,2008;Verrier et al.,2008).
Transport studies with isolated membrane vesicles and plant
tissues revealed the presence of multiple transport systems for
amino acids and peptides in plant(e.g.Higgins and Payne,
1982;Weston et al.,1995;Li and Bush,1990,1991;see also
Bush,1999).Using molecular approaches,meanwhile,10dis-
tinct amino acid and two peptide transporter families have
been identi?ed,and the functional properties,organ expres-
sion,and tissue or cellular localization have been described for
some of the family members(Table1;see also Koh et al.,2002;
Wipf et al.,2002;Renne′et al.,2003;Picault et al.,2004; Lubkowitz,2006;Waterworth and Bray,2006;Duy et al.,
2007;Murcha et al.,2007;Rentsch et al.,2007;Tsay et al., 2007).Most of the transporters characterized so far are plasma membrane-localized proteins that import the organic N in co-transport with protons into the plant cell(Rentsch et al.,2007
1To whom correspondence should be addressed.E-mail tegeder@https://www.wendangku.net/doc/1a14566182.html,,
fax+015093353184,tel.+015093357545.
aThe Author2010.Published by the Molecular Plant Shanghai Editorial
Of?ce in association with Oxford University Press on behalf of CSPP and
IPPE,SIBS,CAS.
doi:10.1093/mp/ssq047,Advance Access publication16November2010
Received21June2010;accepted23July2010
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Table 1.Overview of Genes Encoding Transporters for Amino Acids (aa)or Peptides that Have Been Characterized Using Heterologous Expression in Saccharomyces cerevisiae Mutants and/or Xenopus laevis Oocytes,Gene Expression Analyses,and/or Localization (RNA,Protein)Studies.
Functional characterization using heterologous expression systems,expression analyses and/or localization studies Family
Substrate
Gene and publications
ATF (or AAAP)amino acid transporter family (or amino acid/auxin permease)AAP amino acid permease
Neutral aa,Glu
AtAAP1(NAT2),Frommer et al.,1993,Hsu et al.,1993,Boorer et al.,1996,Chang and Bush,1997;AtAAP1-2,Kwart et al.,1993,Hirner et al.,1998;AtAAP1-5,Fischer et al.,1995;AtAAP1-6,Fischer et al.,2002;AtAAP3,Breitkreuz et al.,1999,Okumoto et al.,2004;AtAAP5,Boorer and Fischer,1997;AtAAP6,Rentsch et al.,1996;AtAAP6,8,Okumoto et al.,2002;BnAAP1,2,6,Tilsner et al.,2005;PsAAP1-2,Tegeder et al.,2000,2007;VfAAP1,3,4,Miranda et al.,2001,2003;VfAAP2,a,b,c ,Montamat et al.,1999;PvAAP1,Tan et al.,2008;RcAAP1,Marvier et al.,1998;RcAAP1-2,Bick et al.,1998;RcAAP3,Neelam et al.,1999;NaAAP1-3,Schulze et al.,1999;PtAAP1-14,Couturier et al.,2010a;StAAP1,Koch et al.,2003
LHT ‘lysine/histidine’transporter
Neutral and acidic aa,Lys and His
AtLHT1,Chen and Bush,1997;Hirner et al.,2006;AtLHT2,Lee and Tegeder,2004;AtLHT2,4,5,6,Foster et al.,2008;McLHT (McAAT2),Popova et al.,2003;NsLHT (NsAAP1),Lalanne et al.,1997
ProT proline transporter
Pro,quaternary ammonium compounds
AtProT1-2,Rentsch et al.,1996;AtProT1-3,Grallath et al.,2005;AtProT2,Breitkreuz et al.,1999;AmBet/ProT1-3(AmT1-3),Waditee et al.,2002;BvBet/ProT1,Yamada et al.,2009;HvProT ,Ueda et al.,2001;HvProT2,Fujiwara et al.,2010;LeProT1-3,Schwacke et al.,1999;OsProT ,Igarashi et al.,2000ANT1-like aromatic–neutral aa transporter
Neutral and aromatic aa AtANT1,Chen et al.,2001
GAT c -aminobutyric acid transporter
GABA and related compounds
AtGAT1,AtGAT2,Meyer et al.,2006
APC amino acid-polyamine-choline CAT cationic aa transporter
Neutral and cationic aa
AtCAT1(AtAAT1),Frommer et al.,1995;AtCAT2,3,6,8,Su et al.,2004;AtCAT6,Hammes et al.,2006;McCAT (McAAT1),Popova et al.,2003;PtCAT1-12,Couturier et al.,2010b
BAT bidirectional aa
transporter
Ala,Arg,Glu,Lys
AtBAT1,Du
¨ndar and Bush,2009OEP16or PRAT plastid outer envelope porin of 16kDa (or preprotein and amino acid transport)OEP plastid outer envelope protein
OEP16:aa,amines;OEP24:charged aa,ATP ,phosphate,triosephosphate AtOEP16(1–4),Reinbothe et al.,2004a,Drea et al.,2006,Murcha et al.,2007,Philippar et al.,2007;PsOEP16,Pohlmeyer et al.,1997,Linke et al.,2000;HvOEP16(PTC16),Baldi et al.,1999,Reinbothe et al.,2004a,2004b;PsOEP24,Pohlmeyer et al.,
1998,Ro
¨hl et al.,1999MCF mitochondrial carrier family BAC (mitochondrial)basic
aa carrier
Arg,Lys,Orn,His
AtmBAC1-2,Catoni et al.,2003,Hoyos et al.,2003,Palmieri et al.,2006
DASS divalent anion:Na 1symporter DiT (plastidic)dicarboxylate transport
Exchange Glu/malate
AtDiT2.1,AtDiT2.2,Renne
′et al.,2003PTR/NRT1peptide transporter/nitrate transporter 1PTR1-like peptide
transporter
di-and tripeptides (PTR1-branch and AtPTR3)His,nitrate
AtPTR1,Dietrich et al.,2004;AtPTR2(AtNTR1,AtPTR2B),Frommer et al.,1994,Rentsch et al.,1995,Song et al.,1996,Chiang et al.,2004;AtPTR3,Karim et al.,2005,2007;AtPTR5,Komarova et al.,2008;HaPTR4,Paungfoo-Lonhienne et al.,2009;HvPTR1,West et al.,1998,Waterworth et al.,2000,2005;NaNTR1,Schulze et al.,1999;VfPTR1,Miranda et al.,2003;BnNRT1;2,Zhou et al.,1998
OPT oligopeptide transporter OPT oligopeptide transporter
tetra-and pentapeptides,glutathione (and GS-conjugates)
AtOPT1-9,Koh et al.,2002;AtOPT1,3,4,6,7,8,Stacey et al.,2006;AtOPT4,Osawa et al.,2006;AtOPT6,Cagnac et al.,2004,Pike et al.,2009;BjGT1,Bogs et al.,2003;OsGT1,Zhang et al.,2004
For accession numbers of the speci?c genes,we refer to the Aramemnon database at http://aramemnon.botanik.uni-koeln.de/(Schwacke et al.,2003).
Arabidopsis ,At Arabidopsis thaliana ;mangrove,Am Avicennia marina ;Indian mustard,Bj Brassica juncea ;canola,Bn Brassica napus ;sugar beet,Bv Beta vulgaris ;Ha Hakea actites ;barley,Hv Hordeum vulgare ;tomato,Le Lycopersicon esculentum (=Solanum lycopersicum );ice plant,Mc
Mesembryanthemum crystallinum ;pitcher plant,Na Nepenthes alata ;South American tobacco,Ns Nicotiana sylvestris ;rice,Os Oryza sativa ;pea,Ps Pisum sativum ;popular,Pt Populus trichocarpa ;common bean,Pv Phaseolus vulgaris ;castor bean,Rc Ricinus communis ;potato,St Solanum tuberosum ;Faba bean,Vf Vicia faba .
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and references therein).To date,only a few transporters me-diating intracellular transport or amino acid export have been
described (Catoni et al.,2003;Hoyos et al.,2003;Renne
′et al.,2003;Palmieri et al.,2006;Du
¨ndar and Bush,2009).Although the physiological importance of amino acid and peptide trans-porters is still poorly understood (Lalonde et al.,2003;Liu and Bush,2006;Rentsch et al.,2007),some progress demonstrating the role of transporter function in N uptake from the soil and movement of organic N within the plant was achieved in re-cent years (see Table 2).
ACQUISITION OF ORGANIC NITROGEN FROM THE SOIL
Soils contain both inorganic (nitrate and ammonium)and or-ganic N,though concentrations and availability vary in differ-ent soil types.As summarized in a recent review by Na
¨sholm et al.(2009),inorganic N is predominant in cropland,while concentrations of dissolved organic N may exceed inorganic N forms by a factor of 10,as found in soils of boreal forests.In addition,in a variety of other ecosystems,organic N levels
can be high (Lipson and Na
¨sholm,2001;Jones et al.,2005;Na
¨sholm et al.,2009).In fact,depending on the soil type,con-centrations of free amino acids in soil solutions were reported
similar to those of ammonium or nitrate (Na
¨sholm et al.,2009).Not all of the organic N in these soils may be bio-available,and although peptides and proteins can be directly utilized by the plant (see below)or are a source for amino acid production,plants face extensive competition with microorganisms for the organic N (Jones et al.,2005).Therefore,the importance of organic N uptake for N nutrition and plant performance in different ecosystems is still a topic of debate.
Uptake studies have shown that plants are generally able to acquire amino acids from the rhizosphere (Lipson and
Na
¨sholm,2001and references therein),although its impor-tance for N nutrition may vary depending on the soil and plant species.For root uptake of amino acids,high-and low-af?nity transport systems have been predicted and,indeed,respective transporters were identi?ed in Arabidopsis .AtAAP1belongs to the amino acid permease (AAP)family of moderate af?nity systems that transports glutamate and neutral amino acids in-to plant cells (Fischer et al.,2002).In roots,AtAAP1is expressed in epidermis cells including root hairs and in root tips (Lee et al.,2007).By analyzing ataap1mutants,it was discovered that AtAAP1is essential for uptake of neutral amino acids and glutamate,consistent with its substrate selectivity deter-mined in heterologous expression systems (Figure 1;Fischer et al.,2002;Lee et al.,2007).Svennerstam et al.(2008)showed that AtAAP5,another member of the AAP family that is expressed in all root tissues (Birnbaum et al.,2003),functions in acquisition of the cationic amino acids L-lysine and L-arginine.
Other amino acid transporters that play a role in N uptake from the soil are the LHTs,lysine-histidine-like transporters.AtLHT1was described by Chen and Bush (1997)as a lysine and histidine selective transporter,whereas other studies showed that AtLHT1and AtLHT2transfer preferentially neu-tral and acidic amino acids across plasma membranes with high af?nity (Lee and Tegeder,2004;Hirner et al.,2006).According to the Arabidopsis root expression map (Brady et al.,2007),AtLHT1transcripts are found in the root cap,epidermis,and cortex.Chen and Bush (1997)also showed expression of the transporter at the root surface in seedlings,whereas AtLHT1-promoter-GUS studies revealed expression in roots only in the lateral root cap,in addition to leaf mesophyll (Hirner et al.,2006).Nonetheless,while localization of AtLHT1expression needs to be clari?ed,AtLHT1was shown to be re-sponsible for the uptake of neutral and acidic amino acids into
Table 2.Amino Acid and Peptide Transporters with Demonstrated Function In Planta Using Knockout and/or Overexpressing Lines.Function in plants Family Gene,role or effects in transgenic plants and publications
AAP
AtAAP1,root uptake,seed loading,Lee et al.,2007,Sanders et al.,2009;AtAAP5,root uptake,Svennerstam et al.,2008;AtAAP6,phloem amino acid content,Hunt et al.,2010;AtAAP8,seed development,Schmidt et al.,2007;StAAP1,long-distance transport,Koch
et al.,2003;VfAAP1,seed size,seed protein,vegetative biomass,Rolletschek et al.,2005,Go ¨tz et al.,2007,Weigelt et al.,2008LHT AtLHT1,uptake in root and leaf mesophyll cells,Hirner et al.,2006,Svennerstam et al.,2007,2008
ProT AtProT2,uptake into roots,Lehmann and Rentsch,unpublished;HvProT ,growth,tissue proline levels,Ueda et al.,2008ANT AtANT1,phloem amino acids content,Hunt et al.,2006CAT AtCAT6,sink supply,Hammes et al.,2006
OEP AtOEP16,role in deetiolation and NADPH:protochlorophyllide oxidoreductase A import (Pollmann et al.,2007),but not con?rmed by
other studies (Philippar et al.,2007;Pudelski et al.,2009)DASS AtDiT2.1,glutamate/malate exchange,Renne
′et al.,2003PTR AtPTR1,5,root uptake,biomass,N content,uptake in pollen,Komarova et al.,2008;AtPTR2,?owering,seed development,Song et al.,
1997;AtPTR3,seed germination on salt,pathogen defense,Karim et al.,2005,2007
OPT
AtOPT3,seed development (Stacey et al.,2002),however,phenotype is due to a function of AtOPT3in iron nutrition e.g.by transporting a peptide/modi?ed peptide Fe chelator or Fe chelator complex (Stacey et al.,2008)
Arabidopsis ,At Arabidopsis thaliana ;barley,Hv Hordeum vulgare ;potato,St Solanum tuberosum ;Faba bean,Vf Vicia faba .
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roots as well as into mesophyll cells (Hirner et al.,2006;Svennerstam et al.,2007).Double mutants of AtLHT1and AtAAP5showed a strong reduction in amino acid acquisition when these were supplied with low concentrations (10l M)of amino acids,suggesting that the transporters are important for uptake of neutral and acidic (AtLHT1),and basic (AtAAP5)amino acids when their levels in the rhizosphere are low (Svennerstam et al.,2008).AtAAP1,on the other hand,might play a role in uptake at higher concentrations of amino acids (Lee et al.,2007).
Members of the ProT family were shown to transport the compatible solutes proline and glycine betaine in heterol-ogous expression systems (Rentsch et al.,1996;Breitkreuz et al.,1999;Schwacke et al.,1999;Ueda et al.,2001;Waditee et al.,2002;Grallath et al.,2005;Yamada et al.,2009;Fujiwara et al.,2010;Lehmann et al.,2010).Consistent with this selectivity and AtProT2expression in the root epidermis and cortex,as well as with higher expression of AtProT2under water stress (Rentsch et al.,1996;Grallath et al.,2005),uptake of glycine betaine was reduced in atprot2knockout mutants,especially in salt-treated plants (Lehmann and Rentsch,unpub-lished).This indicates that Arabidopsis may take up compatible solutes from the environment as a strategy to adjust to water stress,as shown for bacteria (Sleator and Hill,2002).A similar
mechanism might also exist in Acacia senegal (Ra
¨sa ¨nen et al.,2004).Furthermore,AtProT1and AtProT2overexpression lines,and atprot2knockout mutants showed increased and re-duced sensitivity to external proline,respectively.Yet,pheno-
typic differences or altered proline levels could not be detected in atprot2plants (and atprot1atprot2atprot3triple knockouts),indicating compensation by other transporters or adjustment of proline metabolism (Lehmann and Rentsch,un-published).Constitutive overexpression of the barely HvProT1in Arabidopsis plants showed that changes in proline transport led to feedback on proline metabolism,resulting in altered proline content and biomass production (Ueda et al.,2008).Similarly,root-cap-speci?c expression of HvProT affected root growth and proline levels (Ueda et al.,2008).However,these effects are most likely due to altered distribution of proline within the plant and not altered uptake.
Further,expression data suggest that additional amino acid transporters are expressed in roots (see,e.g.Birnbaum et al.,2003;Brady et al.,2007),but their function in N uptake and partitioning remains to be resolved.In addition,nutrient forms and concentrations,as well as environmental stresses,might change requirements for organic N transporters in dif-ferent tissues and organs,and may lead to tight and rapid reg-ulation of transporter expression.It has,for example,been shown that amino acid and peptide transporter gene expres-sion is in?uenced by N as well as by abiotic and biotic stresses (Rentsch et al.,1996;Karim et al.,2005,2007;Liu and Bush,2006;Tegeder et al.,2007).Thus,the contribution of individual transporters in N uptake and allocation will not be static,but may change according to the prevailing conditions.
Studies investigating the role of the di-and tripeptide trans-porters AtPTR1and AtPTR5provided evidence that the uptake and utilization of organic N are not restricted to amino acids,but that dipeptides may also be used as N source (Komarova et al.,2008).Both AtPTR1and AtPTR5mediate low-selective transport of di-and tripeptides with high af?nity in heterol-ogous expression systems and are localized at the plasma membrane (Rentsch et al.,1995;Dietrich et al.,2004;Komarova et al.,2008).Whereas AtPTR1is expressed in the vas-cular tissue throughout the plant,in all cells of the root tip and in cotyledons,AtPTR5expression is found predominantly in pollen and developing ovules (Dietrich et al.,2004;Komarova et al.,2008).Growth studies with seedlings of atptr1mutants and p 35S-AtPTR5overexpressing lines on media containing dipeptides resolved that AtPTRs can mediate dipeptide uptake into roots (Komarova et al.,2008).Atptr1seedlings showed re-duced total N levels and reduced shoot growth.Consistent with this ?nding,seedlings of p 35S-AtPTR5lines displayed en-hanced shoot growth and increased N content.AtPTR5func-tion in import of peptides was further established in growth experiments with toxic peptides,leading to growth inhibition in the overexpressing lines (Komarova et al.,2008).
Until recently,soil protein was not considered as a direct N source for plants,but was described to be accessible only after conversion by proteolytic activities of soil microorganisms or through symbiotic mycorrhizal fungi that provide the plant with N after protein degradation.Paungfoo-Lonhienne et al.(2008)now showed that both the cluster root-producing heath-land plant Hakea actites and Arabidopsis can utilize protein
as
Figure 1.Model of Amino Acid (aa)and Peptide (pep)Transporters with Demonstrated Function in Arabidopsis .
(A)Root uptake.
(B)Xylem–phloem transfer.
(C)Import into mesophyll cells (mc).(D)Seed loading.
(E)Function of transporters in phloem loading has not been shown up to date,but potential candidates have been identi?ed based on expression or localization studies (see text).CH 2O,carbohydrates.
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a N source.Generally,two mechanisms were suggested.First, proteolytic enzymes are released by the plants followed by transporter-mediated root uptake of peptides or amino acids.Alternatively,intact proteins might enter the root hairs through endocytosis(Paungfoo-Lonhienne et al.,2008).The mechanisms of uptake and the contribution of protein utiliza-tion to plant N nutrition need to be explored in future studies that also have to consider plant–microorganism competition for N.
ROLE OF TRANSPORTERS IN XYLEM–PHLOEM TRANSFER AND PHLOEM LOADING OF AMINO ACIDS AND PEPTIDES
Xylem–Phloem Transfer
Depending on the plant species,environmental conditions, and diurnal rhythm,amino acid assimilation might occur in roots and/or leaves(Coruzzi,2003).Amino acids that are syn-thesized in roots or that are taken up directly from the soil are mainly translocated in the xylem to the shoot.Since transpira-tion is highest in photosynthetically active leaves,a relatively high amount of root-derived amino acids is transported to leaves.Here,amino acids are imported into the mesophyll cells,such as by AtLHT1(Hirner et al.,2006),where they are utilized(e.g.for proteins involved in carbon(C)assimilation) or transiently stored in the form of vegetative storage proteins (Staswick,1994;Klauer et al.,1996)and as amino acids in vacuoles(Tilsner et al.,2005).Alternatively,the amino acids are directly transferred into the leaf phloem for redistribution to?ower,fruit,and seed sinks(Lalonde et al.,2003).Addition-ally,transfer of amino acids from the xylem to the phloem occurs along the long-distance transport pathway for direct N delivery to growing sinks(Pate et al.,1977).The importance of these transfer processes for N distribution within the plant has been nicely demonstrated in physiological studies(Pate et al.,1975,1977,1980;Pate,1980;van Bel,1984;Atkins, 2000),and localization of amino acid transporter AtAAP2in the phloem along the transport highway revealed that xy-lem–phloem transfer requires active loading(Figure1;Hirner et al.,1998;Zhang and Tegeder,unpublished).This work fur-ther proved that AtAAP2-function in phloem loading of amino acids along the transport path is essential,because mutants with reduced transporter activity displayed reduced N supply to seed sinks,resulting in decreased total N and protein levels (Zhang and Tegeder,unpublished).
While not directly involved in phloem loading,AtAAP6has been hypothesized to play a role in xylem–phloem transfer due to its localization to the leaf xylem parenchyma(Okumoto et al.,2002).This is supported by a recent study by Hunt et al. (2010)showing that the amino acid content of sieve elements is reduced in ataap6plants.The ataap6mutants displayed no obvious phenotypic changes,but slight increases in the rosette width and seed size could be measured,potentially caused by changes in N allocations to the different organs.Phloem Loading
While a majority of root-synthesized amino acids is partitioned
to the shoot,amino acids also have to be loaded into the
phloem to supply the growing part of the root with N.Micro-
array expression pro?les of different root cell types(Brady
et al.,2007)together with expression analyses or promoter
GUS studies suggest that Arabidopsis AtAAP2(Hirner et al., 1998),AtAAP3(Okumoto et al.,2004),AtProT1(Rentsch
et al.,1996),AtCAT6(Hammes et al.,2006),and AtCAT9(Su
et al.,2004)might be involved in this process(Figure1).How-
ever,mutant analyses to con?rm the transporter function in
phloem loading in roots are not available at this time.
Export of organic N from the leaves is a major contributor to
sink N-requirements(Hocking et al.,1984;Peoples and Dalling, 1988).As stated above,amino acids might be delivered to the
leaves from the root.However,amino acids are also synthesized
in leaves by reduction of inorganic N(delivered via the xylem),
and may also originate from photorespiration and hydrolysis
of leaf protein(Gan and Amasino,1995,1997;Buchanan-Wollaston,1997;Rachmilevitch et al.,2004).These processes oc-
cur in different cellular compartments,and to move the organic
N compounds across sub-cellular membranes and release these
?nally for distribution to the phloem,transporters are needed. However,only a very small number has been characterized,in-
cluding the AtDiT2and OEP transporters in the chloroplast membranes,and the mitochondrial AtmBAC1and2carriers
(see Tables1and2for references).In addition,proteome stud-
ies localized other organic N transporters to different cellular compartments,but their function still needs to be elucidated
(see Rentsch et al.,2007for details).
In order to be exported out of the leaf,amino acids and pep-
tides are loaded into the phloem of minor veins.Dependent on
the presence of functional plasmodesmata,phloem loading
might be symplastically,or apoplastically as in the case of most
crop plants and Arabidopsis(Turgeon and Wolf,2009).In apo-
plastic loading,the organic N is released into the cell wall space
followed by active uptake into thesieve element–companion cell
complex of the phloem(Riens et al.,1991;Winter et al.,1992;
Lohaus et al.,1994,1995;Ortiz-Lopez et al.,2000;Delrot et al.,
2001;Williams and Miller,2001;Lalonde et al.,2003).The mech-
anisms of ef?ux into the apoplast are still unknown,but recent
studies suggest the bidirectional amino acid transporter AtBAT1
may play a role in this process(Du¨ndar and Bush,2009).In addi-
tion,GDU(glutamine dumper)proteins might regulate amino
acid export by activating non-selective amino acid carriers(Pilot
et al.,2004;Pratelli and Pilot,2006;Pratelli et al.,2010).
Over the last decade,the signi?cance of sucrose transport-
ers in active phloem loading of C assimilates in leaves has been
studied in detail and was established for a number of plant
species(Tegeder et al.,in press;Lalonde et al.,2003;Sauer, 2007).In contrast,transporter function in import of N assimi-
lates into the leaf veins has not been demonstrated up to now (Lalonde et al.,2003;Tegeder and Weber,2006;Rentsch et al., 2007).While little is known about the molecular mechanism of
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phloem loading with organic N,some evidence of the impor-tance of source-located N transport processes for sink N levels has been obtained from potato plants,in which a leaf amino acid permease (StAAP1,tissue-speci?c localization unknown)was down-regulated,leading to a reduction in the free amino acid pool in tubers (Koch et al.,2003).Further,legume AAP transporters were identi?ed that are expressed in the leaf phloem,but their function remains to be investigated (Tegeder et al.,2007;Tan et al.,2008).In addition,Arabidopsis AtAAP5may import amino acids into the phloem,since it is expressed in leaves (Fischer et al.,1995)and most probably in companion cells (Brady et al.,2007;Zhang et al.,2008).Current knowledge suggests that AAPs are the primary amino acid phloem loaders in plants;however,members of other transporter families might also function in source-sink partitioning of amino acids as indicated by their expression in leaves (Tou?ghi et al.,2005)and localization to companion cells (Brady et al.,2007).This includes transporters for neutral amino acids AtCAT6(Hammes et al.,2006)and AtCAT9(Su et al.,2004),as well as AtProT1that transports proline and compatible solutes (Rentsch et al.,1996;Grallath et al.,2005).Expression of AtCAT6and AtProT2in leaves is up-regulated un-der abiotic stress conditions (Rentsch et al.,1996;Kilian et al.,2007)when cellular levels of compatible solutes,including proline,are high.While atcat6and atcat9mutants remain to be analyzed with respect to their function in phloem transport,atprot1and atprot2plants failed to display a phenotype under standard growth conditions and water stress when compared to wild-type (Lehmann and Rentsch,unpublished).Further,ANT1might be involved directly or indirectly in phloem load-ing,since ant1mutants showed an increase in phloem amino acid content (Hunt et al.,2006).
Organic N partitioned to seeds is partly obtained from remo-bilization of leaf proteins stored during vegetative growth (Staswick,1994;Tilsner et al.,2005).Further,breakdown of proteins and redistribution of N is highly up-regulated during some developmental phases such as leaf senescence and seed germination (Lim et al.,2007).Peptides are products of prote-olysis in addition to amino acids,and transporters most prob-ably play a role in loading the peptides into the phloem.In fact,the di-and tripeptide transporter AtPTR1was localized to the phloem in Arabidopsis (Dietrich et al.,2004).However,when analyzing AtPTR1function,no obvious phenotypic dif-ferences could be found,for example,during senescence or germination (Komarova and Rentsch,unpublished).AtPTR1function might be compensated by other peptide transporters,or proteolysis to amino acids occurred in the mutant followed by increased sink translocation of amino acids.
IMPORTANCE OF AMINO ACID AND PEPTIDE TRANSPORTER FUNCTION IN SINK SUPPLY
During reproductive growth,?owers and seeds represent the major N sink,and the delivery of organic N to sink occurs in the
phloem.In general,a broad spectrum of amino acids is found in the phloem,but levels of single amino acids vary depending on the species,diurnal rhythm,and environmental conditions (Riens et al.,1991;Lam et al.,1995;Hunt et al.,2006,2010).Glutamine,glutamate,aspartate,and asparagine are often the dominant N forms in the phloem.Total amino acid concen-trations might range from 40to 500mM (Riens et al.,1991;Bu
¨ssis and Heineke,1998;Lohaus and Moellers,2000;Hunt et al.,2006,2010)and in the case of Brassica napus ,they might be as high as 650mM (Tilsner et al.,2005).On the other hand,levels of peptides have never been determined,but it is expected that the composition and concentrations might be quite variable.Phloem unloading of assimilates into sinks is generally predicted to be symplastically,since plasmodesmata are present that allow cell-to-cell movement of the organic N (Patrick,1990).In addition,transport proteins might move the N across membranes of the different sink tissues and cell layers,depending on the need for retrieval of organic N leaking into the apoplast and the extent of symplastic versus apoplastic pathways (Patrick,1990;Lalonde et al.,2003).
Import into Flower Tissue
Transport of N to newly developing ?owers is a signi?cant de-terminant for ?ower set,growth,and abortion,and it is essen-tial for proper development of male and female gametophytes,?nally resulting in successful seed production (Pate,1980;Gifford et al.,1984;Patrick and Stoddard,2010).Much of our current knowledge on organic N trans-porter function in ?owers is based on expression and localiza-tion studies.In Arabidopsis ,expression of speci?c AAP ,CAT ,GAT ,LHT ,ProT ,PTR ,and OPT transporters has been localized to basic ?oral structures,including peduncle,pedicel,sepal,petals,and developing anthers and pistils (Figure 2;Frommer et al.,1995;Okumoto et al.,2002;Dietrich et al.,2004;Su et al.,2004;Grallath et al.,2005;Hammes et al.,2006;Hirner et al.,2006;Meyer et al.,2006;Stacey et al.,2006;Foster et al.,2008),suggesting a role in N supply for ?ower establishment.An-other set of transporters,especially members of the LHT family,seem to function in delivery of organic N for gametophyte de-velopment and successful fertilization (Foster et al.,2008).The male gametophytes or pollen grains are symplastically isolated from the surrounding sporophytic tissue including the tape-tum that is facing the anther locule in which the microspores reside (Goldberg et al.,1993;Pacini,1997).The tapetum takes up amino acids and presumably peptides,and releases these into the locule solution for pollen nourishment (Echlin,1971;Scott,1993).AtLHT2and AtLHT4expression was local-ized to the tapetum,supporting their role in amino acid trans-fer to the pollen grains (Lee and Tegeder 2004;Foster et al.,2008).In Arabidopsis ,uptake of amino acids and peptides into the pollen seems to be mediated by AtLHT1,AtLHT2,AtLHT4(NsAAP/LHT in Nicotiana sylvestris ),and AtProT1(LeProT1in tomato),AtOPT1,and AtPTR5,respectively (Chen and Bush,1997;Lalanne et al.,1997;Schwacke et al.,1999;Koh et al.,2002;Foster et al.,2008;Komarova et al.,2008;Lehmann
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and Rentsch,unpublished).However,although AtProT1is highly expressed in mature as well as in geminating pollen,no change in pollen amino acid content was found in atprot1mutants (Lehmann and Rentsch,unpublished).During pollen germination,minor differences in levels of glutamate (re-duced)and arginine (elevated)were detected in atprot1lines,but pollen germination and transmission of the AtProT1alleles to the off-springs were not altered compared to wild-type (Lehmann and Rentsch,unpublished).On the other hand,in vitro germination analysis of atptr5mutants and lines overex-pressing AtPTR5demonstrated that this transporter is involved in peptide uptake into germinating pollen (Komarova et al.,2008).Further,AtLHT5is expressed in germinating pollen dur-ing growth through the pistil to the ovary and into the ovule,pointing to a function in amino acid uptake for pollen tube elongation for successful fertilization (Foster et al.,2008).In addition,AtLHT5and AtLHT6expression was found in the transmitting tract of the pistil,the route of pollen tube growth to ovules for release of the sperm cells.The role of the trans-porters might be two-fold;they may accumulate amino acids to guarantee N supply of the pollen tube but also to provide the building blocks for transmitting tissue-speci?c proteins functioning in attraction of pollen tubes and acceleration of their growth (Wang et al.,1993;Cheung et al.,1995;Cheung,1996).AtPTR1expression is present in the style and stigma (Dietrich et al.,2004)and might have similar function with re-spect to peptide supply for initial tube elongation and directed growth.Finally,strong expression of AtPTR5in ovules is pre-dicted to be important for ovule development (Komarova et al.,2008).Several of the OPT s are expressed in different parts
of ?owers,indicating that also larger peptides might contrib-ute to N supply of these sinks (see Stacey et al.,2006).For ex-ample,of the functionally characterized oligopeptide transporters,namely AtOPT1and OPT4-7,AtOPT1is expressed along the septum of the ovary and in mature and germinating pollen,whereas AtOPT6-GUS activity was detected in ovules (Koh et al.,2002;Osawa et al.,2006;Stacey et al.,2006;Pike et al.,2009).Further,OPT1,4,6,and OPT7-GUS staining was found in the funiculi (Stacey et al.,2006).
Overall,expression and localization studies indicate that a broad spectrum of organic N transporters is needed for nour-ishment of ?oral tissues,and that their expression is highly reg-ulated during ?ower development.Tissue and cell-speci?c localization further strengthen the importance of N assimilate transporters in successful sexual reproduction.Although a number of transporters have already been identi?ed in ?ow-ers,publically available expression data (see Tou?ghi et al.,2005;Bock et al.,2006;https://www.wendangku.net/doc/1a14566182.html,/geo/)suggest that a far larger number of amino acid and peptide transport-ers is present to support one of the most important phases dur-ing the lifecycle of a plant.
Seed Loading
In seeds,phloem unloading into the seed coat occurs symplasti-cally (Patrick,1990).However,since the ?lial parts of the seeds (endosperm and embryo)are largely symplastically isolated,or-ganic N is released from the maternal seed coat (testa)into the seed apoplast,followed by uptake into ?lial cells (Weber et al.,1998,2005;Tegeder and Weber,2006;Zhang et al.,2007).In endospermic seeds such as Arabidopsis seeds,the testa and en-dosperm surround the embryo.Assimilates are released from the testa by a yet unknown transport protein,pass through the en-dosperm,and are then taken up by the embryo.In non-endospermic seeds like those of legumes,the endosperm is de-graded during seed development.Cotyledons or embryos are enclosed by the testa and are able to import assimilates imme-diately after release from the maternal tissue.Following uptake,organic N compounds imported into the embryo are utilized for development,biosynthesis of storage compounds (e.g.oil and protein),or they are stored as proteins in the embryo.
Schmidt et al.(2007)detected expression of AtAAP8in young seeds 2–5d post fertilization.Ataap8mutant analyses revealed a reduction in seeds per silique by 50%,demonstrat-ing that AtAAP8is essential for seed development.While it was suggested that AtAAP8plays an important role in uptake of amino acids into the endosperm during early embryogen-esis (Schmidt et al.,2007),AtAAP1and AtCAT6from Arabidop-sis as well as the legume PsAAP1and PvAAP1most probably play a role in import of amino acids into the embryo (Figure 1;Hirner et al.,1998;Tegeder et al.,2000;Okumoto et al.,2002;Hammes et al.,2006;Tegeder et al.,2007;Tan et al.,2008).These transporters are expressed in the outer epidermal cell layer of the embryo/cotyledons,the entry cell layer for as-similate import into the seeds.In pea (Pisum sativum )and Faba bean (Vicia faba ),the epidermal cells are transfer
cells
Figure 2.Model of Amino Acid and Peptide Transporter Function in Gametophyte Development and Fertilization in Arabidopsis Flow-ers.
The model is mostly based on expression and localization studies (see text).dan,developing anthers;es,embryo sac;lo,anther loc-ulus;msp,microspores;man,maturing anther;pg,pollen grain;pgp,germinating pollen grain;pt,pollen tubes;se,septum epider-mis;ta,tapetum;tt,pistil transmitting tissue.
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characterized by cell-wall in-growth allowing insertion of an increased number of transporters into the enlarged plasma membrane and subsequent high assimilate uptake (Gunning and Pate,1974;Of?er et al.,1989,2003;Weber et al.,1998).In contrast to the restricted expression of common bean (Pha-seolus vulgaris )PvAAP1in the epidermis,and of pea PsAAP1and Arabidopsis AtAAP1that are expressed in the epidermis cells as well as in the storage parenchyma of cotyledons (Tegeder et al.,2000;Tan et al.,2008;Sanders et al.,2009),VfAAP1expression is found only throughout the storage pa-renchyma of Faba bean cotyledons (Miranda et al.,2001,2003).This suggests species-dependent roles of the AAP1transporters or that an additional transporter might exist in the cotyledon epidermis of Faba bean.Within the storage tis-sue,transporters might be needed for amino acid retrieval from the apoplast or for reallocation within the cotyledons (Miranda et al.,2003).Expression of several seed amino acid transporters precedes storage protein synthesis,supporting their role in amino acid uptake for seed development as well as in storage compound accumulation (Hirner et al.,1998;Miranda et al.,2001,2003;Tegeder et al.,2007).Besides var-iation in spatial and developmental regulation of seed trans-porters,species-dependent differences can also be found in the regulation of expression by N.While amides up-regulate PsAAP1,PsAAP2,and AtAAP1expression (Liu and Bush,2006and references within;Tegeder et al.,2007),Vicia faba VfAAP1expression is down-regulated by glutamine (Miranda et al.,2001).Nevertheless,transporters localized in the epider-mis of the embryo or in transfer cells of cotyledons seem to be regulated by N concentrations in the phloem and ?nally in the seed apoplast.This is in agreement with studies performed in Brassica napus ,suggesting that phloem amino acid concentra-tions are regulating N loading into the seed (Lohaus and Moellers,2000;Tilsner et al.,2005).
So far,only one transporter,AtAAP1,has been shown to be essential for embryo loading with amino acids (Sanders et al.,2009).It was demonstrated that AtAAP1-mediated uptake of amino acids by the embryo is limiting for seed protein synthe-sis.However,not only N import into seeds was affected,but also seed yield,which was strongly decreased due to decreased silique set (Sanders et al.,2009).While source leaf amino acid levels are also changed in ataap1mutants,it is unknown whether changes in source metabolism,assimilate partition-ing,and/or phloem assimilate (amino acid)concentrations,re-spectively,affect sink set.It has,however,been hypothesized that the phloem sap C:N ratio is important for ?ower and fruit development in Arabidopsis (Corbesier et al.,2002).Although knock-out of AtAAP1is affecting seed N and protein content,gene expression studies demonstrate that its function in N seed loading is at least to some extent compensated by amino acid and peptide transporters (Sanders et al.,2009),speci?cally AtCAT6(Hammes et al.,2006)and AtPTR1(Dietrich et al.,2004;Komarova et al.,2008).
The importance of transporters for seed N nutrition was fur-ther demonstrated in studies using plants overexpressing amino acid transporters.When expressing Faba bean VfAAP1in Vicia narbonensis and pea under control of an embryo (stor-age parenchyma)-speci?c promoter,Rolletschek et al.(2005)found that uptake of amino acids was increased.In addition,seed size,weight,and protein content were elevated in the transgenic plants.However,overall seed yield was not changed in the pea plants when grown in the greenhouse or in the ?eld (Rolleschek et al.,2005;Weigelt et al.,2008).This suggests that increased activity of sink-located N transporters positively affects sink strength and N uptake rather than in?u-encing sink numbers.Besides phloem assimilate content (see above),transporter function in source leaves and N loading in-to the phloem might be a limiting step for sink development (see Tilsner et al.,2005).Nevertheless,in the V.narbonensis plants overexpressing VfAAP1,the increase in sink strength positively feedback-regulates N uptake,C ?xation,and N
and C assimilate partitioning to sinks (Go
¨tz et al.,2007).Little is known about the importance of peptide phloem transport and seed loading for seed development and storage product accumulation.The peptide transporter AtPTR2is expressed during seed development,but also in other organs of Arabidopsis plants (Rentsch et al.,1995;Song et al.,1996).When repressing AtPTR2using an antisense approach under control of a constitutive promoter,seed development was par-tially arrested and the fewer seeds were bigger (Song et al.,1997).While the exact role of AtPTR2in this process is not re-solved yet,it,however,supports the importance of peptide transport processes for seed growth.Analysis of mutants of AtOPT3,a putative oligopeptide transporter expressed in the vascular tissue and seed,demonstrated the importance of AtOPT3for embryo development (Stacey et al.,2002).How-ever,more recent work resolved that AtOPT3is involved in iron nutrition rather than being a conventional oligopeptide trans-porter (Stacey et al.,2008).Other transporters that are expressed in seeds and might function in uptake of peptides are Arabidopsis AtPTR1and AtPTR5(Dietrich et al.,2004;Komarova et al.,2008;Sanders et al.,2009),and Faba bean VfPTR1(Miranda et al.,2003).VfPTR1displays a highly com-plex spatial and temporal expression pattern by being mainly expressed in the epidermis at early stages of cotyledon devel-opment,and at later stages in cells surrounding the vascula-ture (Miranda et al.,2003).This expression pattern suggests that there is a switch from VfPTR1function in uptake of pep-tides from the seed apoplast to transport function within the embryo.In addition,when compared to amino acid trans-porter VfAAP1(see above),induction of VfPTR1expression occurs at later stages of seed development (Miranda et al.,2003).Large fractions of sink N including peptides are obtained from hydrolysis of proteins,which is especially high during leaf senescence and seed germination (Wittenbach et al.,1984;Staswick,1994;Good et al.,2004;Lim et al.,2007).Leaf senescence takes place when seed maturation occurs,and it was speculated that the substrates for VfPTR1might derive from this process (Miranda et al.,2003).Along the same line,during barley seed germination,HvPTR1seems
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to be responsible for transport of peptides remobilized from endosperm proteins(West et al.,1998).
CONCLUSIONS
Since the cloning of the?rst amino acid and peptide transport-ers in the1990s,considerable progress was made in the molecular identi?cation of organic N transporters,and in un-derstanding their substrate selectivity and expression in differ-ent organs.Nevertheless,we have just described the‘tip of the iceberg’.Still,very little is known about the tissue-speci?c and cellular localization of the transporters,let alone their regula-tion and physiological role in planta.The lack of knowledge is even more evident with respect to essential intracellular trans-port and export processes.While the major challenge of assigning functions to transporter genes remains,the rela-tively few studies addressing the role of N transporters provide strong evidence for their importance in organic N uptake, source-sink translocation,and sink loading for plant growth, development,and productivity.The studies also established tight interactions between transport and metabolism,and suggest that transporters are key regulators for speci?c phys-iological processes.Continued efforts are needed to reveal the role of transport systems in the distribution of organic N to speci?c tissues,cells,and compartments,to elucidate the inter-related networks and potential signals,and to understand cross-talk of transport and metabolism in response to the en-vironment.Discoveries might be made on how to improve plant N transport and thereby N use ef?ciency,and how to ma-nipulate distribution of organic N to maintain or increase plant performance even in challenging environments such as N lim-iting conditions.
FUNDING
Research in M.T.’s laboratory was supported by the US National Science Foundation(IOS0135344and IOS0448506)and by the Agricultural and Food Research Initiative Competitive Grant no. 2010-65115-20382from the USDA National Institute of Food and Agriculture.Work in D.R.’s laboratory was supported by grants from the Swiss National Science Foundation3100A0–107507and 31003A_127340,and EU Marie Curie Research Training Network ‘VaTEP-Vacuolar Transport Equipment for Growth Regulation of Plants’(MRTN-CT-2006-035833).
No con?ict of interest declared.
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智能电网调度控制系统现状与技术 黄炜舜
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[1] AWARD BIOS设置图解教程 一、进入AWARD BIOS设置和基本选项 开启计算机或重新启动计算机后，在屏幕显示“Waiting……”时，按下“Del”键就可以进入CMOS的设置界面（图 1）。要注意的是，如果按得太晚，计算机将会启动系统，这时只有重新启动计算机了。大家可在开机后立刻按住Delete键直到进入CMOS。进入后，你可以用方向键移动光标选择CMOS设置界面上的选项，然后按Enter进入副选单，用ESC键来返回父菜单，用PAGE UP和PAGE DOWN键来选择具体选项，F10键保留并退出BIOS设置。 图 1 STANDARD CMOS SETUP（标准CMOS设定） 用来设定日期、时间、软硬盘规格、工作类型以及显示器类型 BIOS FEATURES SETUP(BIOS功能设定)
智能电网调度控制系统现状与技术展望
智能电网调度控制系统现状与技术展望 发表时间：2019-06-18T10:17:36.507Z 来源：《中国建筑知识仓库》2019年01期作者： 1李玲君 2赵振华[导读] 现阶段，各行各业及人们对电能的需求量呈逐年递增的趋势，如果未做好电网调度工作将会出现供电不平衡的情况，为此电力企业需要充分重视电网调度工作，调度情况对电力系统正常运行有较大的影响，为了最大程度地保证电力系统安全运行电力企业需要对一些先进的技术进行合理应用。在科学技术不断发展下，智能电网建设目标得以实现，智能电网调度控制系统是智能电网建设中的关键环节，下 面笔者对其现状及技术展望分别进行分析。 一、智能电网调度控制系统技术的应用现状 将智能电网调度控制系统应用于实际电网的运行过程中，能够以较为安全的方式满足特大电网对调度控制的需求。具体来说，这一目标是通过建立分布式的实时数据库、大电网的统一建模以及远程控制实时图形的浏览技术来实现的。此外，由于这一系统技术的应用攻克了协调控制多级调度业务的告警问题，不仅解决了电网运行在线安全预警的技术难题，还对智能电网调度控制系统在电网中的应用现状进行了具体分析。 1.1多级调度业务告警问题 对于特大电网的多级调度中心系统来说，将全网运行所产生的实时数据信息内容实现共享和协同作用，是提高其可观测性的重要技术应用内容。相关研究人员应按照国际、国家以及多领域行业的运行标准，开发出分布式的实时数据库、特大电网的统一建模。这样一来，该系统所具备的相关技术就可以为电网调控业务的处理以及标准一体化D5000平台的建设提供支撑。在此过程中，优先要解决的问题是对特大电网中多个控制中心进行资源共享。 1.2多级调度协调故障控制 利用智能电网调度控制系统技术，能够实现多级调度协同业务的实时监控、安全控制以及电网智能告警。具体来说，智能电网调度控制系统技术的应用，将国家电网500kV以上的电网故障实现了全网的联动实时告警。这一内容的实现，是智能电网调度控制系统技术，解决了特大电网多级调度协调控制和电网故障联合处理难题的前提下进行的。 1.3多级调度中心的协同运行 在协同运行方面，智能电网调度控制系统技术的应用，能够反映出特大电网实时运行的工况、事件故障的触发情况以及多级调度互动的安全动态预警，这就在很大程度上提高了特大电网系统的运行安全。智能电网调度控制技术具体是通过评估电网实时状态，来解决其过程中存在的运行时间长、多重连锁故障的预警处置问题。以下几点即为该技术突破的最主要内容：第一点，技术的应用，将国、网、省三级调度业务内容实现了联合互动。此外，还为其运行提供了动态预警的保护功能。在跨区域、大规模的电网系统中，成功地建立起了数据信息资源的在线共享平台。这就意味着其的应用，具体解决了特大电网系统的运行过程中，多级调度协同计算的难题和快速对运行数据进行动态预警分析的难题。第二点，此技术的应用还为电网运行，提供了在线小干扰稳定分析和低频振荡预警相结合的综合分析功能。这就意味着对电网运行过程中的低频振荡问题实现了在线监测，在很大程度上提高了电网运行计算的精准性和分析工作的实际效率。第三点，此技术应用还综合考虑了电网运行过程中的开机方式、电压使用技术水平以及负荷的均匀分布等问题。 二、技术展望 尽管我国智能电网调度控制系统在技术上已经取得了很大进步，并在实际应用中取得了显著成效，但由于特大电网对于安全运行、新能源消纳提出了新的发展要求，又随着市场化改革步伐的加快和网络技术的发展，网络安全形势受到严重威胁，这样就对电网调度控制提出新要求，为解决这一问题就需要对智能电网调度控制系统技术进行深层研究。 2.1可信计算与安全免疫技术 随着我国科学技术的不断发展，智能电网调度控制系统已经逐步趋于成熟，无论是从安全性、智能性以及自控性来说都有了较为完善的系统，同时其在电网运行安全管理过程中也发挥着重要的作用。但是从安全管理角度来说仅靠技术的发展是不够的，还需要在原有技术的基础上进行安全管理的完善，进一步确保系统运行状态的平稳性。所以在未来智能电网调度控制的过程中需要对安全管理与系统构建技术进行有机的融合。在现阶段电网调度安全运行过程中信息技术的发展受到了网络信息攻击能力和传播能力的冲击，这对其自身的发展来说既是机遇也是一种挑战，如何能够在意识形态以及技术形态上对其进行进一步的创新显得尤为重要。除此之外在地区电网可信计算和安全免疫技术的发展过程中可以采用国外先进技术与我国实际运行状况相结合的方式，在实际运用过程中对其技术进行改进。 2.2短期电力市场的多级多时段优化技术 我国电力市场的发展经历了几次大起大落，却一直达不到欧美电力市场水平。尽管我国智能电网调度控制系统已经加入了能够支持现阶段电力市场所需要的先进模块，省级以上的调度控制系统也可以满足电力市场运行需求，但这项技术并没有得到实际应用，又由于缺乏一定的市场规则，导致这项技术在实际电力市场中的运行受到了一定阻碍。 2.3运行方式自描述及动态解析技术 电力网络调控技术以及电网调度运行的关键技术指的是电力网络的运行方式以及时机电网的调配。从现阶段我国电网的运行方式来看主要还是以年月日等时间模式运行的，这些运行方式的技术特征都较为相同，在运行管理过程中相关技术人员要根据标准的运行规范进行操作，避免操作不当引起的调度安全问题，在电网调度的科学配置过程中技术人员必须根据技术继续拧动态解析和运行方式的自描述。在电网的运行调控过程中需要对其技术进行不断的改进，并对电网阅读能力进行不断的提升，在促进电力网络动态识别能力以及运行解析方式的同时加强电网调度的安全性。从目前我国电网调度技术的发展状况来看，其不仅在电网控制调度技术方面有了极大的提升，同时可再生资源的随机性方面也变得更为优越。因此在后续发展过程中相关技术人员可以结合新兴的技术以及我国的实际发展国情进行相应的创造和调整，从而有效促进电网调度的自描述技术，加强其运行的有序性与高效性。
BIOS设置图解教程(全)
《BIOS设置图解教程》 BIOS设置图解教程之AMI篇 (目前主板上常见的BIOS主要为AMI与AWARD两个系列，如何辨别BIOS品牌系列请移步，本文详细讲解AMI系列的BIOS设置图解教程，如果你的BIOS为AWARD系列请移步BIOS设置图解教程之Award篇，文中重要的部分已经标红，快速阅读请配合图片查阅红色加速字体即可） 对于很多初学者来说，BIOS设置是一件非常头疼的事情，面对着满屏的E文，实在是无从下手。但是，设置BIOS在高手的眼里，却什么也算不上。 当你看着高手的指尖在键盘上熟练的跳动，而蓝色屏幕里的字符不停的变换，你一定很羡慕，不是吗？ 实际上，BIOS设置并不是特别神秘的事情，但是为什么初学者却会如此头疼呢。根据归纳，总结出了几点原因，希望初学者能够避免被这些因素所左右。 ●听别人说操作BIOS很危险 在这里，笔者不否认操作BIOS有一定的风险，BIOS是Basic Input Output System的缩写，乃基本输入/输出系统的意思，也就是计算机里最基础的引导系统，如果BIOS设置错误，硬件将会不正常工作。 操作BIOS真的很危险吗？ 笔者听到很多朋友都在说，设置BIOS很危险，从一个人接触计算机开始，就被前人在BIOS上蒙上了一层神秘的黑纱。可以说，几乎每一个人都知道设置BIOS是一项非常危险的操作，也正是因为这样，菜鸟们也就不敢轻易尝试。但如果你不去尝试，就永远也不会学到该如何设置。所以，在此笔者建议，再危险的 事情我们也要去尝试，敢于尝试是菜鸟变成高手的必备心理素质。
●一看到全英文界面就没信心 很多菜鸟一看到满屏的英文，就完全没有了设置的信心，根本不愿意仔细去看其中的内容，这样自然也不会去深入研究了。但实际上，BIOS里很多设置项目英语都非常简单，在学校里英语不是特别差的人，都基 本上能领会其大意，实在不懂得也不必去调试，毕竟BIOS里经常修改的也就那么几个项目。所以，当你 进入BIOS之后，千万不要被其中满屏的E文所吓倒，这样才能慢慢的学会调教BIOS。 ●习惯于求助别人帮忙 菜鸟和高手在初期是没有区别的，但是菜鸟在遇到问题的时候，求助于别人帮忙搞定，而高手却喜欢自己去查询资料。设置BIOS也是一样，很多人用过10年电脑，都还不知道怎么在BIOS设置光驱为首个引导设备，导致连操作系统都还不会安装。很显然，10年之后，他仍然是一只菜鸟。而喜欢研究的高手，想必在用电脑半年时间内，就会熟悉安装各种操作系统，调试最基本的BIOS。一点也不夸张的说，笔者在使用电脑三个月之后，就已经知道数十条DOS命令了（笔者从Win 3.1时代使用电脑的）。
Ami bios设置图解教程AMI
AMI Bios 设置全程图解 最新AMI Bios 设置全程图解 花了几个星期的时间终于把这个文章完全写玩了，呵呵。于是迫不及待的传上来！文章很长，看上去有一点累，但是我也是为了所有的读者都能看懂，而且尽量讲的详细一些，（想必这应该是国内目前最完善的Bios教程吧！）希望对你有一点用！ 对于一个热衷于电脑的用户来说，最大的乐趣就是发觉计算机的潜能，了解计算机的一些技术，计算机的Bios设置对于很多初用电脑人的来说很是深奥，甚至一些计算机的老用户还不了解Bios，因为计算机Bi os涉及了很多计算机内部硬件和性能差数设置，对于一般不懂电脑的人来说有一定的危险性，加之一般Bi os里面都是英文，这个对于英语好的人来说没有问题，但是这毕竟是中国，还有很多人对英语并不是很懂，所以很多人不敢轻易涉足！为了把大家的这些疑惑解决，我利用空闲时间把Bios的设置用图文解释给大家看看，希望能给一部分人一些帮助！但是因为个人知识有限，所以可能其中有一些遗漏或者不正确的解释，请大家一起来探讨指正！谢谢各位的支持！ 我找了两种Bios的计算机分别是：华硕的AMI BIOS和升技的AWARD BIOS，这也是目前两种主流的Bios，及算是不同品牌的主板，他们的Bios也是与这两种Bios的功能和设置大同小异，但是一般不同的主板及算是同一品牌的不同型号的主板，他们的Bios又还是有区别的，所以一般不同型号主板的Bios不能通用! 先以华硕的AMI Bios为例，介绍一下AMI Bios的设置： 开启计算机或重新启动计算机后，在屏幕显示如下时，按下“Del”键就可以进入Bios的设置界面 要注意的是，如果按得太晚，计算机将会启动系统，这时只有重新启动计算机了。大家可在开机后立刻按住Delete键直到进入Bios。有些品牌机是按F1进入Bios设置的，这里请大家注意！ 进入后，你可以用方向键移动光标选择Bios设置界面上的选项，然后按Enter进入子菜单，用ESC键来返回主单，用PAGE UP和PAGE DOWN键或上下( ↑↓ )方向键来选择具体选项回车键确认选择，F10键保留并退出Bios设置。 接下来就正式进入Bios的设置了！ 首先我们会看到（如图2） 一．Main(标准设定)
智能电网用户端能源管理系统关键技术与应用
智能电网用户端能源管理系统关键技术与应用 智能电网是当前国际国内新技术和新产业发展热点。国家电网公司正在建 设全国统一的坚强智能电网，其基本特征是电力系统的运营实现信息化、自动化、互动化和市场化，真正实现电能的高效利用。 ?根据智能电网研究框架体系，智能电网建设主要抓住发电、输电、变电、配电、用电和调度六个环节。配用电环节即为电网的用户端，按用户属性来分主 要有三类：建筑楼宇，如宾馆、商场、体育馆、学校、写字楼、政府机关等;工矿企业，如冶金、造纸、轻纺、机械、电子、煤矿等;基础设施，如机场、港口、铁路、公路、水利等。用户端消耗着整个电网80%的电能，抓电网用户端智能 化建设，对用户可靠、安全、节约用电有十分重要意义。用户端环节建设内容 主要为：构建智能用电服务体系;全面推广应用智能电表、智能用电管理终端等智能设备;实现电网与用户的双向互动，提升用户服务质量;建设智能用电小区 和电动汽车充电站。用户端急需解决的研究内容主要包括：先进的表计，智能 楼宇、智能电器、增值服务、客户用电系统、需求侧管理等课题。 ?能源管理系统构架及目标 ?智能电网用户端从用户侧一端来讨论配电和用电系统的智能化和信息化，其 范围指电力公司计费电表出口以下，从电力变压器到用电设备之间，对电能进 行传输、分配、控制、保护和能源管理的所有设备及系统。 ?随着科学技术的发展以及人民物质生活水平的提高，用电设备如电梯、水泵、照明、空调系统、家用电器等越来越多，用电负荷快速增长，设备的能效提高 以及不同设备之间的匹配需要科学的管理，用户端的能源管理因此受到越来越 多的关注。 ?一般的智能电网用户端能源管理系统主要包括三方面的内容：计算机管理系
最全面的AMI BIOS设置图解教程
最全面的AMI BIOS设置图解教程 开机显卡自检测完成后，点击＜DEL键＞即可进入AMI BIOS SETUP设置界面主菜单。 进入了AMI BIOS NEW SETUP UTILITY 设定工具, 屏幕上会显示主菜单。主菜单共提供了十二种设定功能和两种退出选择。用户可通过方向键选择功能项目, 按键可进入子菜单。 默认设置 BIOS setup程序有两种默认的设置：BIOS Setup设置和High Performance Defaults设置。BIOS Setup Defaults设置提供了所有设备和系统的稳定但最小效能的设置。而High Performance Defaults设置提供了最好的系统效能，但有可能导致系统不稳定。 Standard CMOS Features(标准CMOS设定) 使用此菜单可对基本的系统配置进行设定。如时间，日期等。 Advanced BIOS Features( Advanced Chipset Features( Power Management Features( PNP/PCI Configurations Integrated Peripherals PC Health Status Frequency/Voltage Control Set Supervisor Password Set User Password Load High Performance Defaults Load BIOS Setup Defaults Save & Exit Setup Exit Without Saving （不保存退出） 放弃对CMOS的修改，然后退出Setup程序。（保存后退出） 保存对CMOS的修改，然后退出Setup程序。（载入BIOS设定值缺省值） 使用此菜单可以加载主板制造商提供的最小稳定的方式运行设置的一组默认值。（载入高性能缺省值） 使用此菜单可以加载主板制造商提供的为较高的性能优化过的BIOS设定值。（设置用户密码）使用此菜单可以设定用户密码。（设置管理员密码） 使用此菜单可以设定管理员密码。（频率和电压控制） 使用此菜单可以设定管理员/用户密码。（PC基本状态） 此项显示了您PC的当前状态。（整合周边设定） 使用此菜单可以对周边设备进行特别的设定。（PnP/PCI配置） 此项仅在您系统支持PnP/PCI时才有效。电源管理设定) 使用此菜单可以对系统电源管理进行特别的设定。高级芯片组功能设定) 使用此菜单可以修改芯片组寄存器的值，优化系统的性能表现。高级BIOS特性设定) 使用此菜单可对系统的高级特性进行设定。[font=]主菜单 主菜单显示了BIOS所提供的设定项目类别。您可使用方向键( ↑↓ )选择不同的条目。对选定项目的提示信息显示在屏幕的底部。 标准CMOS特性设定 Standard CMOS Features菜单中的项目共分为9个类。每类不包含或包含一个到一个以上的
浅析智能电网通信管理系统建设
浅析智能电网通信管理系统建设 现代电网智能化是电网适应社会发展需求的必然选择，是未来电网发展的重要方向之一。智能电网系统中，通信管理系统无疑占据着举足轻重的重要作用，文章围绕智能电网通信管理系统建设工作有关问题进行探讨，分析了当前我国智能电网通信管理系统的发展现状以及现实需求，并就如何高效科学开展智能电网通信管理系统建设提出建议和对策。 标签：智能电网；通信管理；通信系统；现状；需求；发展策略 引言 现代社会，电能是最主要的能源种类。我国正处于经济高速发展和社会事业空前繁荣阶段，电能需求与日俱增。由此推动了电网建设事业的快速发展。电网建设规模、电力线路里程、运行载荷等逐年上升，给电网运行调度提出了越来越高的要求。信息技术、计算机技术和自动化技术等学科的发展与成熟，为电网运行调度发展创造了良好的理论条件。智能电网已经成为当前电网建设发展的一个重要方向。智能电网是现代化信息技术在电力系统中的一个重要应用。通过对信息技术、网络技术得深入应用，电网在执行各项任务，应对运行过程中的各类问题所表现出来的能力水平获得了极大的提高，工作效率、安全性获得显著增长。作为智能电网的核心环节，通信系统的管理无疑是智能电网应用过程中的重中之重。目前我国智能电网通信系统使用的设备包括光纤通信、微信系统、微博载波系统等多个种类。变电站作为电网输变电环节的中坚力量，受到的影响和发生的变化无疑是十分巨大的。大量现代化技术的出现与投入使用，给智能电网的飞速发展注入了强大活力。智能电网通信随之实现了巨大飞跃。 1 当前我国智能电网通信管理系统发展现状和现实需求 电力产业是我国战略基础产业，事关国计民生。政府一直将电力建设事业作为国家发展建设任务中的关键内容予以高度重视，各级政府都把电网建设纳入各地区、各阶段发展规划之中。这一方面是社会化大生产对电力需求的持续增长造成的，另一方面也是电网建设基础条件日益完善、成熟的结果。与此同时，各地电网建设项目的大规模实施，以及缺乏统一的标准和管理，导致电力企业通信设备、网络设备、管理系统相关的设备和种类差异明显，对于电网整体的运行维护以及调度管理都十分不利。另一方面，关于电网通信系统的深入研究一直在持续，标准化、信息化、自动化、智能化，是当前智能电网通信管理系统的发展重点。 1.1 复杂化程度加深是当前电网通信管理系统的重要特征 通信系统是现代电网的重要组成步伐，在保障电网正常运转，电力企业日常生产顺利进行方面发挥着重要的基础作用。我国电力网络通信系统具有建设时间早、分布范围广、内容繁多、管理分散、流程众多、安全性要求高的特点。电力企业作为现代社会生产体系的重要部门，受信息产业影响重大，越来越多的电力
bios设置图解教程3
附一：BIOS自检响铃含义 一、Award BIOS自检响铃含义： 1短：系统正常启动。恭喜，你的机器没有任何问题。 2短：常规错误，请进入CMOS Setup，重新设置不正确的选项。 1长1短：RAM或主板出错。换一条内存试试，若还是不行，只好更换主板。 1长2短：显示器或显示卡错误。 1长3短：键盘控制器错误。检查主板。 1长9短：主板Flash RAM或EPROM错误，BIOS损坏。换块Flash RAM试试。 不断地响（长声）：内存条未插紧或损坏。重插内存条，若还是不行，只有更换一条内存。不停地响：电源、显示器未和显示卡连接好。检查一下所有的插头。 重复短响：电源有问题。 无声音无显示：电源有问题。 二、AMI BIOS自检响铃含义： 1短：内存刷新失败。更换内存条。 2短：内存ECC较验错误。在CMOS Setup中将内存关于ECC校验的选项设为Disabled就可以解决，不过最根本的解决办法还是更换一条内存。 3短：系统基本内存（第1个64kB）检查失败。换内存。 4短：系统时钟出错。 5短：中央处理器（CPU）错误。 6短：键盘控制器错误。 7短：系统实模式错误，不能切换到保护模式。 8短：显示内存错误。显示内存有问题，更换显卡试试。 9短：ROM BIOS检验和错误。 1长3短：内存错误。内存损坏，更换即可。 1长8短：显示测试错误。显示器数据线没插好或显示卡没插牢。 三、Phoenix BIOS自检响铃含义： 自检响铃自检响铃含义 1短系统启动正常 1短1短2短主板错误 1短1短4短ROM BIOS校验错误 1短2短2短DMA初始化失败 1短3短1短RAM刷新错误 1短3短3短基本内存错误 1短4短2短基本内存校验错误 1短4短4短EISA NMI口错误 3短1短1短从DMA寄存器错误 3短1短3短主中断处理寄存器错误 3短2短4短键盘控制器错误 3短4短2短显示错误 4短2短2短关机错误
从数据流程图导出初始结构图方法模板
从数据流程图导出初始结构图方法 下面分别讨论经过”变换分析”和”事务分析”技术, 导出”变换型”和”事务型”初始结构图的技术。 1．变换分析 根据系统说明书, 能够决定数据流程图中, 哪些是系统的主处理。主处理一般是几股数据流汇合处的处理, 也就是系统的变换中心, 即逻辑输入和逻辑输出之间的处理。 确定逻辑输入——离物理输入端最远的, 但仍可被看作系统输入的那个数据流即为逻辑输入。确定方法是从物理输入端开始, 一步步向系统的中间移动, 直至达到这样一个数据流: 它已不能再被看作为系统的输入, 则其前一个数据流就是系统的逻辑输入。确定逻辑输出——离物理输出端最远的, 但仍可被看作系统输出的那个数据流即为逻辑输出。方法是从物理输出端开始, 一步步向系统的中间反方向移动, 直至达到这样一个数据流: 它已不能再被看作为系统的输出, 则其后一个数据流就是系统的逻辑输出。对系统的每一股输入和输出, 都用上面的方法找出相应的逻辑输入、输出。逻辑输入和逻辑输出之间的加工, 就是系统的主加工。如图4-24所示。
图4-24(a)初始DFD图 图4-24(b)找系统的主加工 2) 设计模块的顶层和第一层 ”顶层模块”也叫主控模块, 其功能是完成整个程序要做的工作。在与主加工对应的位置上画出主模块。系统结构的”顶层”设计后, 下层的结构就按输入、变换、输出等分支来分解。 设计模块结构的第一层: 为逻辑输入设计一个输入模块, 它的功能是向主模块提供数据; 为逻辑输出设计一个输出模块, 它的功能是输出主模块提供的数据; 为主加工设计一个变换模块, 它的功能是将逻辑输入变换成逻辑输出。 第一层模块同顶层主模块之间传送的数据应与数据流程图相对应。这里主模块控制并协调第一层的输入、变换、输出模块的工作。( 3) 设计中、下层模块 由自顶向下、逐步细化的过程, 为每一个上层模块设计下属模块。输入模块的功能是向它的调用模块提供数据, 由两部分组成: 一部分是接受输入数据; 另一部分是将这些数据变换成其调用模块所
智能电网调度控制系统现状与发展探究
智能电网调度控制系统现状与发展探究 发表时间：2019-11-12T09:46:22.597Z 来源：《防护工程》2019年13期作者：田云泉赵文勇王新瑞[导读] 随着改革的不断推进和人民生活水平的提高，客户对电能的使用和消费也在不断提高。 田云泉赵文勇王新瑞 国网山西省电力公司晋城供电公司山西晋城 048000 摘要：随着改革的不断推进和人民生活水平的提高，客户对电能的使用和消费也在不断提高。由于传统电能网络难以顺应现时代的要求，可再生能源发电技术不断进步，人们提出了智能电网，以顺应技术改革和时代发展的潮流。智能电网就是通过在原有基础供电设施的基础上配备现代化的科学技术，例如：信息、计算机技术和计算机通信等等相结合，对电网电力能源进行智能控制，能够达到提高能源效率，减少环境污染，减少电能损耗等环保安全的优势。进而衍生出智能电网调度控制系统对电网进行科学的控制，保证供电的正常运营，从而保障社会市民和企业机构等各方面的用电需求，满足人民生活的需要。 关键词：智能电网；电网调度系统；电网调度系统发展；探究 0引言 智能电网的建立需要使用大量各项设备硬件产品以及现代化的监控系统。主要由电力调度监视系统配合上各变电压监控设备以及图像处理系统等等，搭配传统发电供电系统，实现对电力的调度，优化原有电力系统的输出。就目前智能电网调度系统而言，使用的各个硬件软件必须要有足够高的安全性，能够保证安全使用。而且还采用了新型多核计算机集群控制系统，来提高系统的稳定运行和使其拥有良好的处理能力。采用面向服务的体系结构来进行互联，从而促进电网各方面的联系，进行合理稳定的运输。智能电网调度控制系统能够满足特大电网调度需求，包括大电网统一建模，实时图形远程浏览和分布式实时数据库分析等等，能够保证大电网的对电能的统一分配。 1我国现阶段智能电网的发展状况 我国的智能电网调度系统的发展与研究也是从无到有，经历过学习和自主研究然后根据我国的科学技术的实际发展情况和我国的用电国情相结合，能够建设满足人们生活和社会发展的电力运输。我国改革开放后，国家经济水平和综合国力的高速发展，计算机等方面的科学技术也得到了飞速的发展。向着智能化和信息化不断发展，越来越具有高效性和便捷性。2008年我国电网正式开启智能电网调度系统研究，同一年推出了智能化技术系统基础平台高级应用功能。其后，国家电网电力科学院“时空协调”项目，能够有效地解决我国电网大面积停电的问题。同时现在清华电网调度实验室开发的ems系统等等，基本能够匹配现在社会的电力能源。 2未来智能电网调度控制系统发展要求 在以后的智能电网调度控制系统发展中，应当充分结合当下以及未来的发展趋势，考虑到实用性、智能性和科学环保可持续发展性等等。在合理的维护成本之下，能够很好地兼容行业的标准而且能够有着良好的业务可持续性。再者，还要考虑到未来在此基础上发展扩展，能够有着更加优良的可调控性等。 2.1集群化与服务化 剔除一些传统运用中存在大量问题，严重滞缓的应用程序。应当充分考虑并应用多核机器的处理能力和集群处理的能力，充分发挥好系统和硬件能够发挥的作用，从而减少资源和能源的浪费。当然也可以考虑使用新的技术和信息能使得传统的运用进程多线程化运行，让多机集群的功能分担和负载均衡初衷能够实现。促进和优化调整系统结构，在集群的基础上进行并行处理和冗余备用。全方面、多方位的提高系统的可靠性和充分的处理能力。进行相关平台上所有应用程序的服务化改造和改进，可以根据不同的行业业务性质和接口端口的不同，改造不同的响应模式。在实际应用的基础上进行大胆的思考研究，使其变得更高效、实用、便捷、智能等，提高自己和客户良好的使用指数，进而提高人们的生活水平，减少能源资源的浪费。 2.2优化数据库 目前电网的集群数据库主要是NOSQL数据库，但随着现在科技发展，数据库的快速发展也取得了非常大的进步。在数据库访问中，传统SQL主要是为方便事务处理的原子性设计传统的结构有着很多的缺点，例如解析复杂，效率低下。所以应当及时关注最新数据库优化更新技术，成立相关小组和部门对数据库新型技术的应用，充分发挥优点，弥补传统数据库存在的不足。在未来数据库数据共享方式方面主要存在着几种模式，共享磁盘式或者无共享式，亦或者两者相结合。现阶段中，数据的共享方式存在着很多的弊端。例如切换时间慢，极低的可靠性，处理数据时间长，效率慢等等。在未来应当充考虑关注这些不足，有效地创新相关技术解决存在的问题，可以研究集群式关系的数据库，提高处理效率，优化数据库的应用和使用性能。 2.3实时数据采集的监测 目前的电网在实时数据采集和监测方面也存在着很大的弊端，稳态实时潮流数据并不是严格同一时刻的实测数据，这与现阶段电力数据的传输和实测数据的算法结构有着很大的关系。这对后续电网在线稳定分析会造成很大的不利影响，所以应当充分考虑这方面的因素，解决各个发电站，变电站之间数据传输存在的监测采集问题，解决各个环节数据监测存在的问题，有效地提高数据分析的准确性。 2.4短期电力市场的优化 在我国的电力市场中还是存在着很多的不足的，落后于欧美等发达国家。虽然目前我国的电力市场在当前发展状况和应用都还算是比较完善，省级以上调度控制系统支持了短期电力市场运行的能力，但这都还在算是属于在理论阶段进行试验测算的。没有实际测试验证运行的环境，也没有明确精准的电力市场规则，很是缺乏电力市场实际的运行考验。特别是在众多的多级市场电力空间结构和多时段时间结构之间的相互协调和配合，加深密切合作等方面存在着一些问题，所以在未来的研究中应当根据电力市场的实际发展状况和新技术的使用，不断地优化现有电力市场，对现在电力市场存在的不足进行改革和发展，促进电力市场的健康发展。 3总结 现在国家的高速发展特别是互联网的高速发展，衍生出的智能电网调度控制系统对电力的运输和电网的分布提供了很大的便利。对于人们生活水平的提高也有了很大的帮助，不断改革更新的技术促进的是电力能源资源的合理使用，促进社会的良性发展。本文主要是针对于目前智能电网存在的状况和未来的发展探究进行简要的概述，希望给相关从业人员带来一些帮助。
模块图和结构图
结构化设计方法使用的描述方式是系统结构图,也称结构图或控制结构图。它表示了一个系统(或功能模块) 的层次分解关系,模块之间的调用关系,以及模块之间数据流和控制流信息的传递关系,它是描述系统物理结构的主要图表工具。 系统结构图反映的是系统中模块的调用关系和层次关系,谁调用谁,有一个先后次序(时序)关系.所以系统结构图既不同于数据流图,也不同于程序流程图.在系统结构图中的有向线段表示调用时程序的控制从调用模块移到被调用模块,并隐含了当调用结束时控制将交回给调用模块。 如果一个模块有多个下属模块,这些下属模块的左右位置可能与它们的调用次序有关.例如,在用结构化设计方法依据数据流图建立起来的变换型系统结构图中,主模块的所有下属模块按逻辑输入,中心变换,逻辑输出的次序自左向右一字排开,左右位置不是无关紧要的. 系统结构图是对软件系统结构的总体设计的图形显示。在需求分析阶段,已经从系统开发的角度出发,把系统按功能逐次分割成层次结构,使每一部分完成简单的功能且各个部分之间又保持一定的联系,这就是功能设计.在设计阶段,基于这个功能的层次结构把各个部分组合起来成为系统.处理方式设计:确定为实现软件系统的功能需求所必需的算法,评估算法的性能.确定为满足软件系统的性能需求所必需的算法和模块间的控制方式(性能设计).确定外部信号的接收发送形式. 系统功能模块结构图,是什么 1.功能结构图就是按照功能的从属关系画成的图表，图中的每一个框都称为 一个功能模块。功能模块可以根据具体情况分的大一点或小一点，分解得最小功能模块可以是一个程序中的每个处理过程，而较大的功能模块则可能是完成某一个任务的一组程序。 2.功能结构图是对硬件、软件、解决方案等进行解剖，详细描述功能列表的 结构，构成，剖面的从大到小，从粗到细，从上到下等而描绘或画出来的结构图。从概念上讲，上层功能包括(或控制)下层功能，愈上层功能愈笼统，愈下层功能愈具体。功能分解的过程就是一个由抽象到具体、由复杂到简单的过程。图中每一个方框称为一个功能模块。功能模块可以根据
基于智能电网调度系统的调度监控平台探析
基于智能电网调度系统的调度监控平台探析 发表时间：2018-01-28T19:27:24.750Z 来源：《电力设备》2017年第28期作者：李娟吴涛员翠 [导读] 摘要：调度监控平台是智能电网调度系统的重要组成部分，在电网调度系统中发挥着监控、调整、预测等重要功能。 （陕西省电力公司榆林供电公司 719000） 摘要：调度监控平台是智能电网调度系统的重要组成部分，在电网调度系统中发挥着监控、调整、预测等重要功能。本文结合智能电网，对智能电网调度系统中的调度监控平台进行了简要的分析。 关键词：智能电网；调度系统；调度监控平台 1 智能电网调度系统概述 在智能电网中，调度系统犹如它的中枢神经，也是保障电网能够安全、稳定、可靠、经济运行的重要支柱，还是电力系统控制中自动化程度最高的那部分内容。近年来随着我国电网的不断发展，电网的运行管理与需求也在不断提高，这也对电力生产经营过程中的调度系统提出了更高的要求。电力运行调度能够有效实现协调控制一体化、适应调整一体化、流程管理高效化、统筹计划精细化、信息通信网络等发展功能，最终在智能电网中形成自动化、信息化、互动化、分布式、一体化的智能调度决策中心。 智能调度主要是指在各种先进的现代化技术的大力支撑下，在电力企业中实现调度计划、建立模型、实现测量、进行数据分析、做出决策、有效控制与管理生产过程的整个过程。最终将在智能电网中形成具有自动化、适应性强、前瞻性强、优化性强、柔性好、高度的敏锐性等为主要特征的智能化的电力调度。 2 智能调度的优势分析 2.1较强的可观测性 RTU、FTU等这些监测装置都是传统电网中设立的，但是，这些监测装置的设置并不能使相关人员及时了解处于电力系统另一端的用户的实施运行的信息。智能调度则不同，它已经具备了高级智能量测系统，即：AMI，数据共享平台，在这些系统和平台的支撑下，在二测技术的帮助下，能够及时了解用户的用电信息，并以此为基础实现了对全网的需求侧状态的最精确大大估计。可见，智能调度系统具有较强的可观测性。这也帮助智能电网调度中心实现了对整个电网的精确调控。 2.2资源更加可控 发电资源是传统电力系统中的主要可控资源。近年来随着各种可再生能源的大规模接入，在分布式发电的广泛应用环境下，很多发电环节出现了不可控的问题。在智能电网中，可控的资源范围得到扩大，不再局限于发电资源，还包含了储能装置、负荷、电力电子技术基础上的可控输电设备等资源。 2.3运行调控性更加灵活便利 经济性、安全性、电能的质量是对传统电网的调度中衡量的主要目标和控制目标。但是，智能电网调度系统则不通，它将多样化、复杂化特征作为控制的主要目标，电网在保证电力系统供电需求的同时，必须实现能耗的最低排放，保证环保的效果。因此，电网在运行中必须根据实际情况做出调整。 2.4结构功能的开放性更高 电能主要是通过发电、输电、配电、用电等单向流动的程序实现对的，这是传统电网中设计的对电网的调控模式。在设计时也是单纯地将已经具备同一工鞥的软件进行部署的；但是，智能电能这不同于传统的电网，它能够支持那些大接入的规模的、分布式的电源，这样就使得电网的调控模式变得更加复杂了，电网的不同功能模块之间的互操作性更高了，软件的可重用性功能也更高了，系统的开放性也更高了。 3 智能电网调度系统监控平台体系的构架 现代信息技术不断发展、网络技术的迅速普及、云时代和网络时代的到来，为智能电网中的调度系统监控平台提供了新的思路。针对智能电网调度系统的基本特点、电力智能云信息平台应用的可行性，各电力企业应着手构建云计算基础上的智能电网调度系统。平台中将云计算技术、数据服务总线等以系统结构化的方式将分散的数据资源、电网自动化等基础设施进行了整合，最终构建成一套可靠性高、实时性强、准确度高的智能电网调度云计算监控平台。方便系统调度的管理人员能够对系统的组件的运行与使用进行实施监控、按需调整调度等，该平台还专门设立了一个统一的管理监控界面。云计算平台以分布式数据服务总线为核心组件，还包括动态负载均衡及资源调配系统、分布式海量数据存储系统和集成计算引擎三大功能组件。这些功能组件通过分布式数据服务总线构成虚拟层，实现控制信息与数据信息的交换、传输和整合，同时统一管理和调配底层的物理硬件，为各种应用程序被高效稳定地调用和访问提供了保障。 4 智能电网调度系统关键技术的实施 4.1调度数据集成化技术 综合多种数据能够支持电网调度的事故决策时需要利用到电网调度智能监控系统以及事故处理辅助决策系统，常见的几种数据有：①SCADA/EMS稳态数据；②保护数据；③信息管理系统数据，而综合数据的主要基础在于IEC61970系列标准，及松耦合方式下XML自描述的信息交换格式。 4.2智能调度控制技术 电网运行的安全得不到保障时，需要对其灵敏度进行分析，有效的调整电网运行，确保其稳定的运行。而当事故发生时，则需要事先提示，当难以对机组端面存在的过载问题进行调节时，则需要适当的减少负荷。 4.3事故诊断与处理技术 事故诊断以及处理技术主要包含以下几点：①多重复杂故障诊断技术；②错误信息冗余技术；③恢复多目标事故技术。而多重故障诊断技术关键点在于故障区域，通过分组技术展示出电网中动作的信息、保护动作的信息以及诊断故障的信息，同时关联并重组上述相关信息。 5 电网调度智能监控功能的实施 结合信息化技术及自动控制技术的作用，增强电网调度智能监控及防误技术的实际作用效果，优化电网调度智能监控及防误系统的服务功能，可以不断提升电网调度水平。这些技术作用下可以使电网调度具备以下方面的功能：
基于智能电网的AMI系统
基于智能电网的AMI系统 院系： 班级： 姓名： 学号：
摘要：智能电网概念引起当今电力行业最热点的讨论和研究，这也将是电力系统重大的变革趋势及科技创新。作为智能电网中最重要的技术支撑模块，AMI 高级智能量测系统在智能电网中担当着举足轻重的角色，电网中很多智能化功能是由AMI实施和完成的，因此研究AMI系统对智能电网的理解是至关重要的。文章简述了智能电网的概念和组成，AMI高级智能系统的组成和具体内涵，在智能计量中发挥怎样的作用，以及高级量系统AMI的应用前景等。 关键词：智能电网、高级量系统、AMI 引言：高级量测体系( advanced meteringinf rast ructure ,AMI)是智能电网的重要组成部分,也是智能电网与传统电网的主要区别之一。世界各国提出智能电网概念的出发点并不一致。AMI是一个用来测量、收集、储存、分析和运用用户用电信息的完整网络和系统。AMI的建立将彻底改变电力流和信息流单方向流动的现状,为用户和电网的双向全面互动提供平台和技术支持。用户和电网的信息交互,将使用户随时掌握电网的负荷情况和电价信息,从而可以主动参与电网运行;用户侧储能装置和分布式可再生能源的接入将改变配电网的潮流分布,在电价政策的合理引导下减小电网负荷的峰谷差,提高电力设施的利用率。 一、什么是智能电网？ 智能电网作为下一代电网的基本模式，在全球范围内的关注度已迅速升温。智能电网，就是电网的智能化，也被称为“电网 2.0”，它是建立在集成的、高速双向通信网络的基础上，通过先进的传感和测量技术、先进的设备技术、先进的控制方法以及先进的决策支持系统技术的应用，实现电网的可靠、安全、经济、高效、环境友好和使用安全的目标，其主要特征包括自愈、激励和包括用户、抵御攻击、提供满足21世纪用户需求的电能质量、容许各种不同发电形式的接入、启动电力市场以及资产的优化高效运行。 美国电力科学研究院将智能电网定义为：一个由众多自动化的输电和配电系统构成的电力系统，以协调、有效和可靠的方式实现所有的电网运作，具有自愈功能；快速响应电力市场和企业业务需求；具有智能化的通信架构，实现实时、安全和灵活的信息流，为用户提供可靠、经济的电力服务。
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