有源配电网继电保护方案研究

发布时间：2018-06-05 21:34

本文选题：有源配电网 + 逆变型分布式电源　；参考：《华北电力大学》2017年硕士论文

【摘要】：全世界范围内能源问题和环境污染问题日益严峻,传统电网的集中发电远距离输电模式又存在着电能损耗大、供电稳定性较差等问题,分布式电源(Distributed Generation,DG)因其清洁、灵活、可调性等优点在配电网中应用越来越广泛。分布式电源的接入改变了配电网的单向电源供电模式,对传统配电网的三段式电流保护产生了影响。本文通过对分布式电源的工作原理进行分析,提出了广泛应用的逆变型分布式电源(Inverter-interfaced Distribution Generation,IIDG)的等值模型。建立了有源配电网的短路故障模型,对分布式电源接入对三段式电流的影响进行定量分析,最终实现有源配电网的继电保护的改进方案,为配电网的可靠运行提供保障。首先,详细介绍了有源配电网的相关概念,并根据按并网方式将分布式电源分为逆变型、同步电机型和异步电机型电源。逆变型电源以良好控制及转换电能的能力得到广泛应用,成为分布式电源最主要的电源形式。逆变型分布式电源的短路电流和逆变器的控制方式有关,对配电网的影响分析更为复杂。分别对不同类型的分布式电源进行了短路电流分析。其次,在我国并网规程对分布式电源低压穿越功能的要求下,为了实现逆变型分布式电源的最优工作效率,通过增加电压跌落门槛值实现输出有功电流的优化,提出了基于无功电流支撑的低电压控制策略。分析了采用该策略时逆变型分布式电源的故障特性,在此基础上建立了含IIDG的配电网短路计算模型。DIGSILENT仿真表明该低电压穿越策略在电压跌落时可实现IIDG的并网运行和最大的有功输出。含IIDG的配电网短路计算模型考虑了低压穿越策略,为大规模分布式电源并网的继电保护方案提供参考。然后,分析了分布式电源接入后对配电网的影响,从DG容量和故障点位置等因素分别对流过保护的电流进行分析比较。利用上文提出的基于低电压穿越策略的IIDG故障等值模型,对有源配电网的瞬时电流速断保护和限时电流速断保护的整定方法进行了改进。针对过电流保护中逆变型分布式电源的短路电流较小不易识别的问题,提出了基于电压加速因子的过电流保护方案。此外,分析讨论了环网运行中过电流保护在近电源端延时过长,不利于系统稳定的问题,提出了故障线路两端保护配合的加速动作保护方案。在高渗透率的有源配电网仿真中证明上述保护方案能解决分布式电源接入后对配电网保护带来的一系列问题。
[Abstract]:The problem of energy and environmental pollution is becoming more and more serious all over the world. The traditional mode of centralized generation and long-distance transmission of power network has many problems, such as large power loss and poor stability of power supply. Distributed Generation (DGG) is characterized by its cleanness and flexibility. Tunability and other advantages are more and more widely used in distribution network. The access of distributed generation changes the unidirectional power supply mode of distribution network and influences the three-segment current protection of traditional distribution network. Based on the analysis of the working principle of distributed power generation, the equivalent model of Inverter-interfaced Distribution Generation (IIDG), which is widely used in inverters, is proposed in this paper. The short-circuit fault model of active distribution network is established, and the influence of distributed power supply access on three-section current is quantitatively analyzed. Finally, the improved scheme of relay protection of active distribution network is realized, which provides a guarantee for the reliable operation of distribution network. Firstly, the concept of active distribution network is introduced in detail, and the distributed power supply is divided into three types: inverter, synchronous motor and asynchronous motor according to the grid-connected mode. Inverter power supply is widely used for its ability to control and convert electric energy. It becomes the main power supply form of distributed power supply. The short circuit current of the inverter is related to the control mode of the inverter, and the analysis of the influence on the distribution network is more complicated. The short circuit current analysis of different types of distributed power supply is carried out. Secondly, under the requirement of the low voltage traversing function of the distributed power supply in our country, in order to realize the optimal working efficiency of the inverter distributed power supply, the output active power current is optimized by increasing the voltage drop threshold. A low voltage control strategy based on reactive current support is proposed. The fault characteristics of inverter distributed power supply with this strategy are analyzed. On this basis, the short circuit calculation model of distribution network with IIDG. DIGSILENT simulation shows that the low voltage traversing strategy can realize the grid-connected operation and the maximum active power output of IIDG when the voltage drops. Low-voltage traversing strategy is considered in the short-circuit calculation model of distribution network with IIDG, which provides a reference for large-scale distributed power generation relay protection scheme. Then, the influence of DG on distribution network is analyzed, and the current of protection is analyzed and compared from DG capacity and fault point location. Using the IIDG fault equivalent model based on low voltage traversing strategy proposed above, the tuning methods of instantaneous current quick break protection and limited time current quick break protection for active distribution network are improved. In order to solve the problem that the short-circuit current of inverter distributed power supply is small and difficult to identify in over-current protection, an overcurrent protection scheme based on voltage acceleration factor is proposed. In addition, this paper analyzes and discusses the problem that the over-current protection delay is too long in the near power source during the operation of the ring network, which is not conducive to the stability of the system, and puts forward the accelerated action protection scheme for the cooperation of the protection at both ends of the fault line. In the simulation of the active distribution network with high permeability, it is proved that the above protection scheme can solve a series of problems caused by the distribution network protection after the distributed power supply is connected.
【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM77

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