王成山,焦冰琦,郭力,原凱(智能電網(wǎng)教育部重點(diǎn)實(shí)驗(yàn)室(天津大學(xué)),天津市300072)
微電網(wǎng)規(guī)劃設(shè)計方法綜述
王成山,焦冰琦,郭力,原凱
(智能電網(wǎng)教育部重點(diǎn)實(shí)驗(yàn)室(天津大學(xué)),天津市300072)
微電網(wǎng)是解決分布式發(fā)電并網(wǎng)和偏遠(yuǎn)地區(qū)或海島供電的有效途徑,具有廣闊的應(yīng)用前景。微電網(wǎng)的建設(shè)需依托有效的規(guī)劃設(shè)計方法,但因可再生能源和儲能裝置的接入,使得微電網(wǎng)規(guī)劃設(shè)計與傳統(tǒng)的電網(wǎng)規(guī)劃方法出現(xiàn)較大區(qū)別。該文從技術(shù)角度闡述了微電網(wǎng)規(guī)劃設(shè)計的關(guān)鍵環(huán)節(jié),分建模方法、求解算法與優(yōu)化軟件3個層面,逐一介紹了該領(lǐng)域的最新進(jìn)展;并重點(diǎn)針對其中的規(guī)劃設(shè)計與運(yùn)行優(yōu)化的耦合性、可靠性計算方法以及主要的設(shè)計軟件進(jìn)行了論述;最后從微電網(wǎng)自身、綜合能源網(wǎng)、與配電網(wǎng)協(xié)調(diào)規(guī)劃等視角,對微電網(wǎng)規(guī)劃設(shè)計方法未來的研究方向進(jìn)行了展望。
微電網(wǎng);規(guī)劃設(shè)計;運(yùn)行優(yōu)化;可靠性;優(yōu)化算法;規(guī)劃設(shè)計軟件
微電網(wǎng)是指由分布式電源、能量轉(zhuǎn)換裝置、負(fù)荷、監(jiān)控和保護(hù)裝置等匯集而成的小型發(fā)配電系統(tǒng),是一個能夠?qū)崿F(xiàn)自我控制和管理的自治系統(tǒng)[1]。微電網(wǎng)可以看作是小型的電力系統(tǒng),它具備完整的發(fā)電和配電功能,可以有效實(shí)現(xiàn)網(wǎng)內(nèi)的能量優(yōu)化。微電網(wǎng)既可應(yīng)用于偏遠(yuǎn)地區(qū)或海島獨(dú)立運(yùn)行,也可接入配電網(wǎng)中并網(wǎng)運(yùn)行,在滿足自身負(fù)荷需求的同時,為配電網(wǎng)提供功率支撐與備用等輔助服務(wù)。
微電網(wǎng)的建設(shè)需要進(jìn)行充分的技術(shù)、經(jīng)濟(jì)和環(huán)境效益分析。技術(shù)可行性分析決定了微電網(wǎng)能否建立,經(jīng)濟(jì)可行性分析則是微電網(wǎng)是否具備建設(shè)和運(yùn)行經(jīng)濟(jì)性的關(guān)鍵,環(huán)境效益分析則是從保護(hù)環(huán)境的角度考慮微電網(wǎng)接入帶來的好處。相對于傳統(tǒng)電網(wǎng),微電網(wǎng)建設(shè)運(yùn)行更為復(fù)雜,需要考慮風(fēng)/光/氣、冷/熱/電等不同形式能源的合理配置與科學(xué)調(diào)度,這使得微電網(wǎng)規(guī)劃設(shè)計的不確定性和復(fù)雜度都顯著增加,尤其是目前微電網(wǎng)還面臨著分布式電源成本高、技術(shù)經(jīng)驗(yàn)不足、標(biāo)準(zhǔn)缺乏、行政政策障礙以及市場機(jī)制不健全等一系列挑戰(zhàn)。只有合理確定微電網(wǎng)結(jié)構(gòu)與容量配置,才能保證微電網(wǎng)以較低的成本取得最大的效益,進(jìn)而達(dá)到示范、推廣的目的。因此,研究和發(fā)展合理可行的微電網(wǎng)規(guī)劃設(shè)計方法[1-14]對保證其順利的建設(shè)與運(yùn)行至關(guān)重要。
微電網(wǎng)規(guī)劃設(shè)計中需要計及可再生能源的隨機(jī)性與波動性對微電網(wǎng)安全可靠運(yùn)行產(chǎn)生的影響,這導(dǎo)致了微電網(wǎng)規(guī)劃設(shè)計問題與其運(yùn)行優(yōu)化問題的耦合。同時,微電網(wǎng)中分布式電源類型多樣,系統(tǒng)運(yùn)行方式復(fù)雜。這些特點(diǎn)都使得傳統(tǒng)電網(wǎng)的規(guī)劃方法并不適用于微電網(wǎng),需要“量身定做”微電網(wǎng)的規(guī)劃設(shè)計方法。
國內(nèi)外已有很多學(xué)者針對微電網(wǎng)規(guī)劃設(shè)計方法進(jìn)行了廣泛研究,并從新的應(yīng)用場景、新的建模方法、新的求解算法以及個性化的規(guī)劃設(shè)計軟件開發(fā)等方面不斷完善微電網(wǎng)的規(guī)劃設(shè)計工作。因此,本文針對微電網(wǎng)規(guī)劃設(shè)計問題,從微電網(wǎng)規(guī)劃設(shè)計建模方法、求解算法和軟件等角度,詳細(xì)闡述微電網(wǎng)規(guī)劃設(shè)計技術(shù)的研究現(xiàn)狀,并對未來研究方向進(jìn)行展望。
1.1 可再生能源與負(fù)荷需求分析
實(shí)現(xiàn)微電網(wǎng)合理規(guī)劃設(shè)計的首要任務(wù)是對微電網(wǎng)中可再生能源和負(fù)荷需求的分布特性進(jìn)行分析,主要包括確定性分析[15-40]和不確定性分析[41-51]2種方法。確定性分析主要是指微電網(wǎng)規(guī)劃設(shè)計中所涉及到的風(fēng)、光等資源情況與負(fù)荷需求等信息來源于歷史記錄數(shù)據(jù)。一種典型應(yīng)用即利用風(fēng)速、光照強(qiáng)度與負(fù)荷等信息的全年8 760 h的歷史數(shù)據(jù),對微電網(wǎng)的運(yùn)行情況進(jìn)行序貫分析[15-33]。此外,選取若干典型日[34-40]來代表可再生能源與負(fù)荷的全年變化特性也得到了較多應(yīng)用。這類方法簡單直接,但獲取小時級、半小時級[20]甚至10分鐘級[19]的現(xiàn)場歷史氣象信息的難度較大,特別是對于偏遠(yuǎn)地區(qū)或海島,應(yīng)用研究時有一定的局限性。即使能夠獲得完整的全年歷史信息并對微電網(wǎng)的運(yùn)行情況進(jìn)行分析,這樣得到的結(jié)果也有一定的局限性,并不能全面地反映系統(tǒng)未來所有可能的運(yùn)行情況。
不確定分析主要是基于概率統(tǒng)計理論對可再生能源與負(fù)荷的變化特性進(jìn)行建模。為了考慮氣象信息與負(fù)荷需求的隨機(jī)特性,可采用蒙特卡洛隨機(jī)生產(chǎn)模擬[41-44]、時間序列法[45]或馬爾可夫方法[46-48]形成小時級別的風(fēng)、光及負(fù)荷信息。此外,選取24 h的時間粒度,對可再生能源與負(fù)荷等進(jìn)行多狀態(tài)建模[49-51],既可計及相關(guān)變量的長期變化特性,也可有效降低計算復(fù)雜度,因而相關(guān)方法得到了較多的關(guān)注。
1.2 建模一般化描述
微電網(wǎng)規(guī)劃設(shè)計建模時,需要按照負(fù)荷需求、分布式能源情況,基于各設(shè)備的準(zhǔn)穩(wěn)態(tài)運(yùn)行模型,從技術(shù)、經(jīng)濟(jì)和環(huán)境等不同角度選定合理的優(yōu)化變量、目標(biāo)函數(shù)和約束條件,形成規(guī)劃設(shè)計問題的數(shù)學(xué)描述。一般可以表述為如下的形式:
式中:X表示優(yōu)化向量;fi表示目標(biāo)函數(shù);Ω表示可行解空間;G和H分別表示等式約束和不等式約束構(gòu)成的函數(shù)集合。由于規(guī)劃設(shè)計階段設(shè)計目標(biāo)、分布式電源類型和運(yùn)行特性的差異,不同微電網(wǎng)之間的模型細(xì)節(jié)差別顯著。
一般來講,微電網(wǎng)規(guī)劃設(shè)計的優(yōu)化變量主要包括分布式電源、儲能裝置與冷/熱/電聯(lián)供系統(tǒng)所含設(shè)備等的型號[15,21,26,36,41,46,52-53]、容量[15-17,19-47,50,52-59]和位置[55,58-60]。
設(shè)備安裝位置將會影響到系統(tǒng)短路電流的大小、節(jié)點(diǎn)的電壓分布等,合理的安裝位置有助于改善網(wǎng)絡(luò)電壓水平,減小系統(tǒng)網(wǎng)損。此外,光伏陣列的傾斜角[54]、風(fēng)機(jī)輪轂高度[27,54]、調(diào)度策略類型[19]、微電網(wǎng)中聯(lián)絡(luò)開關(guān)的位置[51,59]等也可作為待決策的變量??紤]到實(shí)際的工程應(yīng)用條件及一些技術(shù)的限制,文獻(xiàn)中提及的大多數(shù)優(yōu)化變量基本都是離散變量,如風(fēng)機(jī)的類型、臺數(shù),柴油機(jī)組的臺數(shù),電池組的并聯(lián)數(shù)(串聯(lián)數(shù)由其所連接換流器的直流側(cè)電壓確定)等。
微電網(wǎng)規(guī)劃設(shè)計的目標(biāo)可以是系統(tǒng)總成本的最小化[16-17,20,22,24-29,31,34-35,37-42,44-47,54,59]、投資凈收益的最大化[15,30,36-37]、污染物排放的最小化[26,31,35,40,46]、系統(tǒng)供電可靠性的最大化[20,26,41,54,58]、系統(tǒng)網(wǎng)損的最小化[55,58,60]、燃料消耗量的最小化[52]、平準(zhǔn)化能量成本(單位電能成本)的最小化[19,22,43,50,54]等目標(biāo)中的單個[15-18,21-25,27-28,30][36-39,42-45,49-52,59-60]或者多個[20,26,29,31,34-35,40][41,46,54-55,58]。對微電網(wǎng)進(jìn)行經(jīng)濟(jì)性分析時,資金投入主要包括分布式電源、儲能、控制器[23]等的初始投資成本、運(yùn)行維護(hù)成本、設(shè)備更換成本、燃料成本、排污懲罰[25,50]、停電懲罰[16,22,28,50,59]、并網(wǎng)運(yùn)行時的購電成本[15-16]等;項(xiàng)目收益主要來自賣電[16,36]、節(jié)能減排效益[15,30]、改善可靠性效益[15,30]、政策補(bǔ)貼[39]、延緩電網(wǎng)投資[30]及資產(chǎn)處置過程中產(chǎn)生的殘值[50]等。由于微電網(wǎng)規(guī)劃設(shè)計周期時間較長,有時需要長達(dá)數(shù)十年,因此微電網(wǎng)經(jīng)濟(jì)性分析過程中通常會計及利率和通脹率等對規(guī)劃年現(xiàn)金流的影響,以使各方案具有經(jīng)濟(jì)可比性。微電網(wǎng)的環(huán)境效益分析[26,31,34-35,40,46,54]主要是對以石油等化石燃料為發(fā)電來源的機(jī)組在運(yùn)行過程排放的污染物進(jìn)行統(tǒng)計,關(guān)注的焦點(diǎn)主要為CO2對環(huán)境的影響。微電網(wǎng)的技術(shù)分析主要為供電可靠性的計算,后續(xù)章節(jié)將對該問題詳細(xì)闡述。
由于微電網(wǎng)的規(guī)劃設(shè)計需要考慮系統(tǒng)運(yùn)行優(yōu)化策略的影響,因而在制定約束條件時,通常需計及系統(tǒng)運(yùn)行策略中所考慮的約束條件。此外,還需考慮規(guī)劃設(shè)計問題本身的一些約束。約束條件主要有:微電網(wǎng)功率(電、冷、熱)平衡約束[34];潮流約束[41,51,58-60]、熱穩(wěn)定約束[51,58]、電壓約束[51,58,60]、聯(lián)絡(luò)線功率約束[16,23,44];設(shè)備運(yùn)行約束[20-32,34-40,42-46],如設(shè)備出力上下限限制、爬坡率限制、運(yùn)行時間限制、儲能存儲容量約束等;監(jiān)管約束,包括能源利用率約束[19,49]、最大碳排放量限制[30,39,47]等;資金約束,主要指系統(tǒng)總投資的最大值約束[19],投資回收期約束等;優(yōu)化變量取值范圍約束,這里主要考慮相關(guān)設(shè)備的安裝面積及臺數(shù)的限制,對應(yīng)公式(1)中的Ω;系統(tǒng)長期可靠性約束[15-17,19,21-22,24-26,29-31,38,44-47]、旋轉(zhuǎn)備用約束[16,37,52];其他約束,如光伏安裝角度約束[28]、風(fēng)光互補(bǔ)特性約束[16]、聯(lián)絡(luò)線功率波動約束[16]等。
1.3 規(guī)劃設(shè)計與運(yùn)行優(yōu)化的耦合性
為了計及微電網(wǎng)規(guī)劃設(shè)計與運(yùn)行優(yōu)化的耦合特性,一種途徑是直接將規(guī)劃設(shè)計問題與運(yùn)行優(yōu)化問題聯(lián)立建模[35],即優(yōu)化變量中除了包含與規(guī)劃設(shè)計相關(guān)的分布式電源的類型與容量等變量,還涵蓋與運(yùn)行優(yōu)化相關(guān)的優(yōu)化變量,如各設(shè)備的優(yōu)化出力等。另外一種是建立兩階段的建模方法[34,53-54],典型流程[34]如圖1所示。該模型可以實(shí)現(xiàn)外層設(shè)備類型、容量優(yōu)化模塊和內(nèi)層運(yùn)行策略優(yōu)化模塊的交互優(yōu)化;將前一種方法中的聯(lián)立模型分解為2個子優(yōu)化問題,實(shí)現(xiàn)了求解問題的降維。
1.4 微電網(wǎng)可靠性
微電網(wǎng)可靠性評估是微電網(wǎng)規(guī)劃設(shè)計中的重要環(huán)節(jié)。由于微電網(wǎng)集成了發(fā)、配、用電的整個過程,可以綜合考慮各個環(huán)節(jié)的系統(tǒng)可靠性指標(biāo)。
發(fā)電環(huán)節(jié)[61]主要傾向于發(fā)電容量的充裕度評估,可靠性指標(biāo)主要有缺供電時間期望(loss of load expectation)、缺供能量期望(loss of energy expectation)等,而配用電環(huán)節(jié)[62]可借鑒傳統(tǒng)配電網(wǎng)的可靠性評價指標(biāo)的制定方式。類似于配電網(wǎng)的可靠性評估方法,微電網(wǎng)的供電可靠性計算可采用蒙特卡洛模擬法[17,43,45,48-49,59]和解析法[15-17,19-21,24-31,43,49-50,63]。由于可再生能源的接入,風(fēng)機(jī)等分布式電源的供電能力既取決于設(shè)備自身的故障率[45,61],也受到風(fēng)速等資源隨機(jī)波動性的影響[45]。而蓄電池的供電可靠性除受設(shè)備自身的故障水平影響外,還受SOC時序性的制約[50]。而像柴油機(jī)等設(shè)備的供電性能雖沒有明顯的時序性,但系統(tǒng)控制策略對其有一定的約束[26,46]。這些新特點(diǎn)使得微電網(wǎng)的供電可靠性方法較常規(guī)的計算方法有所差別。
圖1 一種典型的2層優(yōu)化模型Fig.1 Optimization model typical2 layer
應(yīng)用蒙特卡洛法計算微電網(wǎng)供電可靠性時,需要重復(fù)抽樣可再生能源[17,43,45,48-49]、負(fù)荷[45,48-49]、設(shè)備[45,49,59]等的狀態(tài),并對相應(yīng)的狀態(tài)依序進(jìn)行可靠性分析,直至蒙特卡洛法終止條件滿足,最終給出微電網(wǎng)可靠性的期望水平。該方法的計算復(fù)雜性不依賴于系統(tǒng)的規(guī)模,不過為了得到高計算精度,需要消耗大量時間;若要考慮項(xiàng)目周期內(nèi)負(fù)荷的增長情況,該方法的實(shí)用性將受到很大程度的限制。而現(xiàn)有的解析求解方法主要分3類:一是基于確定性風(fēng)光數(shù)據(jù),序貫仿真計算系統(tǒng)全年或典型運(yùn)行場景下的供電可靠性指標(biāo)[15-17,19-21,24-31];二是建立系統(tǒng)可靠性指標(biāo)的解析表達(dá)式[43,63],顯式求解得到;三是考慮風(fēng)光負(fù)荷等多狀態(tài)建模環(huán)境下的可靠性計算方法[49-50]。由于多狀態(tài)模型計及了風(fēng)光負(fù)荷等的隨機(jī)性且模型準(zhǔn)確、計算時間可接受,使其在微電網(wǎng)可靠性計算上也得到了廣泛研究。該方法在應(yīng)用時,主要通過將分布式電源、儲能系統(tǒng)等的運(yùn)行狀態(tài)離散化,以枚舉系統(tǒng)整體的運(yùn)行方式,進(jìn)而確定其長期的可靠性水平。
1.5 其他建??紤]
根據(jù)所采用的可再生能源與負(fù)荷需求分析的不同方法,結(jié)合前述的規(guī)劃設(shè)計模型,可進(jìn)一步建立微電網(wǎng)的確定性規(guī)劃設(shè)計模型或不確定性規(guī)劃設(shè)計模型。確定性建模方法[15-40]即采用歷史全年小時級(或更短)數(shù)據(jù)或者典型運(yùn)行場景進(jìn)行優(yōu)化,優(yōu)化結(jié)果受限于所采用數(shù)據(jù)的完整性與真實(shí)性;而不確定性建模方法[17,41-47,54]則充分計及了微電網(wǎng)規(guī)劃期內(nèi)可能的運(yùn)行場景,使得優(yōu)化結(jié)果具有更強(qiáng)的魯棒性。其中機(jī)會約束規(guī)劃[17,43,46]是比較常用的建模方法,已應(yīng)用于獨(dú)立微電網(wǎng)系統(tǒng)中分布式電源的選址定容問題[46]。
此外,為了研究分布式電源的投資時機(jī)與運(yùn)行靈活性問題,實(shí)物期權(quán)分析法也得到一定的應(yīng)用[64-66]。而為了研究極端氣象條件對微電網(wǎng)規(guī)劃設(shè)計的影響,極值理論[56]和貝葉斯方法[57]也應(yīng)用到氣象變化的周期性與極端氣象災(zāi)害對微電網(wǎng)規(guī)劃影響的研究中。
表1 微電網(wǎng)規(guī)劃設(shè)計常用求解算法Table 1 Common solving algorithms used in planning and design of microgrids
微電網(wǎng)規(guī)劃設(shè)計問題既含有設(shè)備選型與選址等離散變量,也含有設(shè)備出力等連續(xù)變量;既可只考慮單目標(biāo)優(yōu)化,也可進(jìn)行多目標(biāo)優(yōu)化;約束條件中既有線性約束,也有非線性約束;所面對的是一個不確定環(huán)境,既存在可再生能源的隨機(jī)波動性,也面臨電價、燃料價格、設(shè)備投資價格的易變性。因此,微電網(wǎng)規(guī)劃設(shè)計本質(zhì)上是多場景、多目標(biāo)、非線性、混合整數(shù)、不確定性綜合規(guī)劃問題。而為求解微電網(wǎng)規(guī)劃設(shè)計問題,枚舉法[16-17,21,23,38,52]、混合整數(shù)規(guī)劃方法[34-35,37,44,59],啟發(fā)式算法[20,22,24-31,36,39-42,45-47,55,58,60]和混合算法[15,19,34,51,54]等都分別進(jìn)行了應(yīng)用研究。枚舉法,顧名思義就是窮舉所有可能的優(yōu)化變量組合。當(dāng)組合數(shù)目較少時,該方法簡單高效,能確保找到全局最優(yōu)解;但若變量個數(shù)較多、求解空間大,則組合數(shù)目將呈現(xiàn)指數(shù)式增長,極其耗費(fèi)時間。數(shù)學(xué)規(guī)劃方法對目標(biāo)函數(shù)和約束條件有較嚴(yán)格的要求,微電網(wǎng)規(guī)劃設(shè)計問題的復(fù)雜性限制了它的應(yīng)用空間。不過通過適當(dāng)?shù)哪P秃喕?,將微電網(wǎng)規(guī)劃設(shè)計問題列寫為混合整數(shù)規(guī)劃模型(mixed integer linear programming,MILP),則可采用相關(guān)的成熟算法進(jìn)行求解。但模型的簡化意味著丟失了部分可能有用的信息,從而失去尋找最優(yōu)解的機(jī)會。而啟發(fā)式算法通常不依賴于具體的應(yīng)用問題,建模方式相對寬松,能夠方便處理信息的不確定性,因此在微電網(wǎng)的規(guī)劃設(shè)計中應(yīng)用較為廣泛。但該方法并不能保證找到最優(yōu)解,且求解效率較低。為了更直觀地展示微電網(wǎng)規(guī)劃設(shè)計問題的求解算法,表1中給出了文獻(xiàn)中常用到的優(yōu)化算法。
為了便于實(shí)際微電網(wǎng)規(guī)劃設(shè)計的應(yīng)用研究,已涌現(xiàn)出多種微電網(wǎng)規(guī)劃設(shè)計軟件,例如:HOMER[21]、DER-CAM[35]、PDMG[26,34,46]等軟件。
美國National Renewable Energy Laboratory開發(fā)的HOMER,以微電網(wǎng)全壽命周期成本最低為優(yōu)化目標(biāo),利用枚舉法可確定微電網(wǎng)中分布式電源的最優(yōu)容量配置、微電網(wǎng)與電網(wǎng)的最優(yōu)交換功率上限以及相應(yīng)的運(yùn)行計劃等;并提供了靈敏度分析功能,方便用戶考慮設(shè)備單價、電價等的不確定性;同時支持氣象與負(fù)荷的歷史小時級數(shù)據(jù)和月均值2種方式,采用序貫分析法對微電網(wǎng)的配置進(jìn)行全年的運(yùn)行分析。
美國Lawrence Berkeley National Laboratory開發(fā)的DER-CAM,主要面向含冷/熱/電聯(lián)供系統(tǒng)的聯(lián)網(wǎng)型微電網(wǎng)的規(guī)劃設(shè)計應(yīng)用。該軟件能夠以微電網(wǎng)年供能成本最低為優(yōu)化目標(biāo),以污染物排放最低為目標(biāo)或約束,進(jìn)行微電網(wǎng)優(yōu)化規(guī)劃設(shè)計,確定微電網(wǎng)中分布式能源最優(yōu)的容量組合以及相應(yīng)的運(yùn)行計劃?;诮o定的典型運(yùn)行場景,采用混合整數(shù)規(guī)劃的建模方式,對系統(tǒng)進(jìn)行運(yùn)行優(yōu)化。
天津大學(xué)開發(fā)的PDMG軟件提供了微電網(wǎng)的確定性規(guī)劃和隨機(jī)機(jī)會約束規(guī)劃2種模型;采用兩階段的建??蚣?,能滿足設(shè)備選型與定容,單目標(biāo)優(yōu)化與多目標(biāo)優(yōu)化;考慮負(fù)荷增長、設(shè)備故障率,靈活實(shí)用的運(yùn)行控制策略等多方面的應(yīng)用需求。該軟件主要的特點(diǎn)包括:1)除確定型規(guī)劃設(shè)計方法外,還能夠在規(guī)劃中計及不確定因素的影響,采用隨機(jī)機(jī)會約束規(guī)劃方法合理制定微電網(wǎng)系統(tǒng)中各類設(shè)備的最優(yōu)類型與最優(yōu)容量;2)在規(guī)劃設(shè)計時除了提供一些給定的典型微電網(wǎng)運(yùn)行優(yōu)化控制策略,還允許用戶自定義控制策略,控制策略更加多樣化;3)評價目標(biāo)充分考慮了系統(tǒng)污染物排放和負(fù)荷滿足度的影響,將傳統(tǒng)的單目標(biāo)優(yōu)化問題改進(jìn)為多目標(biāo)優(yōu)化問題,不再僅僅偏重于經(jīng)濟(jì)性分析;4)具有多方案對比、方案權(quán)重分析、后評估分析等功能,能夠?qū)x擇的多目標(biāo)優(yōu)化結(jié)果進(jìn)行綜合評估和對比分析,得到切合實(shí)際工程需要的優(yōu)化規(guī)劃方案。
此外,文獻(xiàn)[6,8]中還介紹了Hybrids、RETScreen、H2RES、HOGA等軟件,各有所長,具體介紹可參見相關(guān)文獻(xiàn),受篇幅限制,這里不再贅述。
目前針對微電網(wǎng)規(guī)劃設(shè)計的研究已有很多,但仍有許多關(guān)鍵技術(shù)還需繼續(xù)深入和系統(tǒng)化研究。
(1)微電網(wǎng)自身的規(guī)劃設(shè)計研究?,F(xiàn)有的成果在考慮分布式電源選址、可再生能源的長期波動性、負(fù)荷需求的增長、設(shè)備全壽命周期內(nèi)的經(jīng)濟(jì)性、社會效益等方面的研究還相對簡單,全面系統(tǒng)科學(xué)的規(guī)劃設(shè)計方法亟待建立。這里主要包括微電網(wǎng)結(jié)構(gòu)的設(shè)計方法[11-13,58],計及可再生能源、負(fù)荷、市場信息等各種不確定因素[67]的技術(shù)、經(jīng)濟(jì)與環(huán)境效益綜合評價方法與求解算法,更加通用化的規(guī)劃軟件等。此外,多個微電網(wǎng)的聯(lián)合規(guī)劃運(yùn)行尚缺乏有效的模型與方法;微電網(wǎng)內(nèi)部的停電損失分析也有待研究;以可靠性為中心的微電網(wǎng)規(guī)劃設(shè)計仍需深入。
(2)針對含冷熱電聯(lián)供系統(tǒng)微電網(wǎng)的規(guī)劃設(shè)計。含冷熱電聯(lián)供系統(tǒng)的微電網(wǎng)在滿足用戶電能需求的同時,還能滿足用戶熱能的需求,此時的微電網(wǎng)實(shí)際上是一個能源網(wǎng)。對于這種具有綜合能源網(wǎng)特征的微電網(wǎng),其不同結(jié)構(gòu)對應(yīng)的最佳冷熱電配比與不同能流之間的耦合特性尚缺乏詳盡的分析?,F(xiàn)有的分析方法主要適用于確定性環(huán)境[34],如何建立不確定環(huán)境下的規(guī)劃設(shè)計方法尚需論證。
(3)配電網(wǎng)與微電網(wǎng)協(xié)調(diào)規(guī)劃。隨著風(fēng)、光、生物質(zhì)等可再生能源不斷以微電網(wǎng)的形式接入電網(wǎng)中,配電網(wǎng)自身的規(guī)劃及擴(kuò)展規(guī)劃也需要考慮微電網(wǎng)接入的影響[5,41,51,55,68-69]。因而,如何建立合理實(shí)用的含微電網(wǎng)配電系統(tǒng)的綜合性能評價體系和綜合規(guī)劃理論仍需要進(jìn)行深入的探討和研究。
(4)儲能系統(tǒng)經(jīng)濟(jì)性分析與規(guī)劃。無論在并網(wǎng)還是離網(wǎng)環(huán)境中,儲能系統(tǒng)都可擔(dān)當(dāng)多種角色。在市場環(huán)境下,儲能系統(tǒng)不同角色的長期經(jīng)濟(jì)性分析以及壽命對其經(jīng)濟(jì)性的影響尚缺乏合理論證?,F(xiàn)有的微電網(wǎng)規(guī)劃設(shè)計方法中,通常假定儲能壽命不受其運(yùn)行狀態(tài)的影響,或者雖然受影響,但儲能系統(tǒng)更換成本不變。這些假定往往夸大了儲能壽命或限制了儲能的投資;如何化解這些矛盾,更加真實(shí)的反映儲能的經(jīng)濟(jì)性,值得深入的研究。
(5)交直流混合微電網(wǎng)[70]規(guī)劃設(shè)計。現(xiàn)有的研究主要集中在交流微電網(wǎng)規(guī)劃設(shè)計方法的探討上,有效的交直流混合微電網(wǎng)的規(guī)劃設(shè)計方法尚屬空白。
本文從技術(shù)角度綜述了近年來國內(nèi)外學(xué)者在微電網(wǎng)規(guī)劃設(shè)計方法研究方面的最新成果。從微電網(wǎng)規(guī)劃設(shè)計方法的主要內(nèi)容出發(fā),闡述了現(xiàn)有微電網(wǎng)規(guī)劃設(shè)計研究中涉及到的建模方法、求解算法與相關(guān)軟件,并對未來可能的研究方向進(jìn)行了展望。隨著微電網(wǎng)規(guī)劃設(shè)計方法的不斷深入和完善,微電網(wǎng)必將在實(shí)際應(yīng)用中發(fā)揮更大的價值。
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(編輯:張媛媛)
Review of Methods of Planning and Design of Microgrids
WANG Chengshan,JIAO Bingqi,GUO Li,YUAN Kai
(Key Laboratory of Smart Grid of Ministry of Education(Tianjin University),Tianjin 300072,China)
As an effective approach to connect the distributed generation to the grid and to supply energy to remote areas and islands,microgrids present wide application prospect.It’s impossible to build a microgrid without the help of efficient method of planning and design of microgrids.However,the access of renewable energy sources and energy storage system to power system results in a great difference between the planning and design method of microgrid and the one of traditional power system.The paper presents the key steps of planning and design of microgrids on the technique side,reviews the state-of-the-art techniques of planning models,solving algorithms and softwares related to this field,and at the same emphatically discusses the coupling between planning and operation of microgrids,the calculation of reliability and the main planning softwares.Finally,from the perspectives of microgrids themselves,integrated energy network and coordinated planning with distribution system,some proposals on the methods of planning and design of microgrids are proposed.
microgrid;planning and design;operation optimization;reliability;optimization algorithm;planning and design software
TM 715
A
1000-7229(2015)01-0038-08
10.3969/j.issn.1000-7229.2015.01.006
2014-11-03
2014-12-05
王成山(1962),男,博士生導(dǎo)師,主要研究方向?yàn)殡娏ο到y(tǒng)安全性分析、城市電網(wǎng)規(guī)劃和配電系統(tǒng)自動化、分布式發(fā)電;
焦冰琦(1989),男,博士研究生,主要研究方向?yàn)槲㈦娋W(wǎng)規(guī)劃與運(yùn)行;
郭力(1981),男,副教授,主要研究方向?yàn)槲⒕W(wǎng)優(yōu)化規(guī)劃、協(xié)調(diào)控制和高級能量管理;
原凱(1989),男,博士研究生,主要研究方向?yàn)殡娏ο到y(tǒng)穩(wěn)定性仿真與分布式發(fā)電技術(shù)。
國家高技術(shù)研究發(fā)展計劃項(xiàng)目(863項(xiàng)目) (2011AA05A107);國家自然科學(xué)基金國際合作項(xiàng)目(51261130473);高等學(xué)校博士學(xué)科點(diǎn)專項(xiàng)科研基金(20120032130008)資助。