柔性直流配電網(wǎng)保護(hù)技術(shù)研究
發(fā)布時間：2018-12-13 12:27
【摘要】：當(dāng)前國內(nèi)外學(xué)者對柔性直流配電網(wǎng)的研究剛開始起步,柔性直流配電網(wǎng)的應(yīng)用仍受限于缺乏關(guān)鍵技術(shù)、運(yùn)行經(jīng)驗(yàn)以及相關(guān)標(biāo)準(zhǔn)。本文以應(yīng)用于城市的柔性直流配電網(wǎng)為研究對象,采用理論分析與PSCAD/EMTDC仿真驗(yàn)證相結(jié)合的方法,系統(tǒng)的分析了柔性直流配電網(wǎng)的系統(tǒng)架構(gòu)和控制策略,研究了系統(tǒng)的接地方式和故障特性,并提出了一種新的繼電保護(hù)方案。本文首先分析了應(yīng)用于柔性直流配電系統(tǒng)的關(guān)鍵設(shè)備如整流器、逆變器、直流變壓器,直流斷路器,以及分布式電源光伏發(fā)電和風(fēng)力發(fā)電并網(wǎng)的模型。提出了一種柔性直流配電系統(tǒng)的啟動控制策略,以避免啟動過程中過流對電力電子器件造成損害。提出了一種保護(hù)系統(tǒng)與控制系統(tǒng)的協(xié)調(diào)策略,以確保故障被隔離后,非故障區(qū)域能夠正常運(yùn)行。其次,在研究了直流不平衡電壓恢復(fù)的理論的基礎(chǔ)上分析了聯(lián)接變壓器的接地方式對換流器交流側(cè)不同位置單相接地故障和直流側(cè)單極接地故障的影響。與以往分析方法不同,為了提高系統(tǒng)運(yùn)行可靠性,在分析系統(tǒng)故障時,考慮了IGBT不閉鎖的情況。并討論了在實(shí)際應(yīng)用中如何確保IGBT運(yùn)行在不閉鎖狀態(tài)下。分析結(jié)果表明,接地方式對系統(tǒng)的故障過程和故障恢復(fù)過程有很大影響。分析方法和結(jié)論為柔性直流配網(wǎng)的接地方式選取、保護(hù)方案配置提供了參考。在此基礎(chǔ)上確立了柔性直流配電系統(tǒng)的接地系統(tǒng)配置。第三,在特定的接地方式下,在不閉鎖換流站的前提下研究了該系統(tǒng)中壓直流側(cè)發(fā)生極間短路和單極接地短路故障時的故障特性,并分析了故障對其他區(qū)域的影響以及故障點(diǎn)過渡電阻的大小可能對故障特性產(chǎn)生的影響。第四,提出了一種新的繼電保護(hù)方案。針對會產(chǎn)生過流并危害電力電子裝置的極間短路故障和小電阻接地故障,設(shè)計(jì)了通過比較相鄰保護(hù)安裝處測得的線路電流狀態(tài)值來判別故障區(qū)間的主保護(hù)。針對系統(tǒng)可能出現(xiàn)的大電阻接地故障情況,設(shè)計(jì)了以電壓不平衡量作為啟動判據(jù),通過比較任何相鄰保護(hù)安裝處測得的不平衡電流狀態(tài)值來實(shí)現(xiàn)故障定位和故障隔離的后備保護(hù)。針對可能出現(xiàn)的保護(hù)拒動或通信裝置失靈現(xiàn)象設(shè)計(jì)了第一級遠(yuǎn)后備保護(hù)和第二級遠(yuǎn)后備保護(hù),各級保護(hù)通過時間上的配合來避免同時動作。最后,對本文所做的研究進(jìn)行了總結(jié)。
[Abstract]:At present, the domestic and foreign scholars have just begun to study the flexible DC distribution network, the application of the flexible DC distribution network is still limited by the lack of key technology, operation experience and related standards. In this paper, the flexible DC distribution network applied in cities is taken as the research object, and the system architecture and control strategy of the flexible DC distribution network are systematically analyzed by combining theoretical analysis with PSCAD/EMTDC simulation. The grounding mode and fault characteristics of the system are studied, and a new relay protection scheme is proposed. In this paper, the models of the key equipment used in the flexible DC distribution system such as rectifier, inverter, DC transformer, DC circuit breaker, distributed power generation and wind power generation are analyzed. A startup control strategy for flexible DC distribution system is proposed to avoid overcurrent damage to power electronic devices during startup. A coordination strategy between the protection system and the control system is proposed to ensure the normal operation of the non-fault area after the fault is isolated. Secondly, based on the research of the theory of DC unbalanced voltage recovery, the influence of the grounding mode of the transformer on the single-phase grounding fault of AC side and single-pole grounding fault of DC side is analyzed. In order to improve the operational reliability of the system, the condition that IGBT is not locked is considered in the analysis of the system fault, which is different from the previous analysis methods. How to ensure that IGBT runs without locking in practical application is discussed. The analysis results show that the grounding mode has great influence on the fault process and fault recovery process of the system. The analysis methods and conclusions provide a reference for the selection of the grounding mode and the configuration of the protection scheme for the flexible DC distribution network. On this basis, the grounding system configuration of flexible DC distribution system is established. Thirdly, the fault characteristics of interpole short-circuit and single-pole earthing short-circuit in the voltage DC side of the system are studied under the special grounding mode and without locking the converter station. The influence of fault on other regions and the influence of the size of fault point transition resistance on the fault characteristics are analyzed. Fourth, a new relay protection scheme is proposed. In view of the inter-pole short circuit fault and the small resistance grounding fault which will cause over-current and harm to power electronic devices, the main protection in fault zone is determined by comparing the current state values of the line measured at the adjacent protection installation. The voltage unbalance is used as the starting criterion for the possible grounding fault of large resistance in the system. The back-up protection for fault location and fault isolation is realized by comparing the unbalanced current state values measured at any adjacent protection installation. The first stage remote backup protection and the second stage remote backup protection are designed in view of the possible failure of protection or communication device. All levels of protection avoid simultaneous action through the cooperation of time. Finally, the research done in this paper is summarized.
【學(xué)位授予單位】：華北電力大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TM721.1
[Abstract]:At present, the domestic and foreign scholars have just begun to study the flexible DC distribution network, the application of the flexible DC distribution network is still limited by the lack of key technology, operation experience and related standards. In this paper, the flexible DC distribution network applied in cities is taken as the research object, and the system architecture and control strategy of the flexible DC distribution network are systematically analyzed by combining theoretical analysis with PSCAD/EMTDC simulation. The grounding mode and fault characteristics of the system are studied, and a new relay protection scheme is proposed. In this paper, the models of the key equipment used in the flexible DC distribution system such as rectifier, inverter, DC transformer, DC circuit breaker, distributed power generation and wind power generation are analyzed. A startup control strategy for flexible DC distribution system is proposed to avoid overcurrent damage to power electronic devices during startup. A coordination strategy between the protection system and the control system is proposed to ensure the normal operation of the non-fault area after the fault is isolated. Secondly, based on the research of the theory of DC unbalanced voltage recovery, the influence of the grounding mode of the transformer on the single-phase grounding fault of AC side and single-pole grounding fault of DC side is analyzed. In order to improve the operational reliability of the system, the condition that IGBT is not locked is considered in the analysis of the system fault, which is different from the previous analysis methods. How to ensure that IGBT runs without locking in practical application is discussed. The analysis results show that the grounding mode has great influence on the fault process and fault recovery process of the system. The analysis methods and conclusions provide a reference for the selection of the grounding mode and the configuration of the protection scheme for the flexible DC distribution network. On this basis, the grounding system configuration of flexible DC distribution system is established. Thirdly, the fault characteristics of interpole short-circuit and single-pole earthing short-circuit in the voltage DC side of the system are studied under the special grounding mode and without locking the converter station. The influence of fault on other regions and the influence of the size of fault point transition resistance on the fault characteristics are analyzed. Fourth, a new relay protection scheme is proposed. In view of the inter-pole short circuit fault and the small resistance grounding fault which will cause over-current and harm to power electronic devices, the main protection in fault zone is determined by comparing the current state values of the line measured at the adjacent protection installation. The voltage unbalance is used as the starting criterion for the possible grounding fault of large resistance in the system. The back-up protection for fault location and fault isolation is realized by comparing the unbalanced current state values measured at any adjacent protection installation. The first stage remote backup protection and the second stage remote backup protection are designed in view of the possible failure of protection or communication device. All levels of protection avoid simultaneous action through the cooperation of time. Finally, the research done in this paper is summarized.
【學(xué)位授予單位】：華北電力大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TM721.1
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