面向多能互补微网的故障辨识与继电保护算法

Fault Identification Method and Relay Protection Algorithm for Multi-Energy Complementary Microgrid

由于含有多种具有互补特性的分布式电源,多能互补微电网在能源综合利用、供电可靠性和运行经济性方面具有明显的优势。然而与传统配电网相比,各类分布式电源的并入导致微电网拓扑结构和运行方式变得更为复杂,并网和离网运行对应的故障特性存在差异,使得传统继电保护方案难以满足此类微电网保护的要求。针对这一问题,首先围绕传统继电保方案的不足展开讨论,分析微电网网内故障特点,继而提出一种适用于微电网的改进故障辨识算法,以实现对网内故障的快速准确辨识。综合考虑多能互补微网继电保护的需求,结合改进故障辨识算法,将改进电流差动保护与广域自适应电流速断保护相结合,提出一种适用于微电网分布式电源上下游线路的综合继电保护算法,在缩小故障影响范围的基础上,提高保护响应速度并降低保护拒动的概率。最后,利用RT-LAB实时仿真系统构建含风、光、储、微型燃气轮机等分布式电源在内的多能互补微网模型,通过网内模拟不同类型故障,验证了所提故障辨识和继电保算法的有效性。

Multi-energy complementary microgrid has obvious advantages in energy comprehensive utilization,power supply reliability and operational economy due to the multiple complementary power sources connected to the grid.However,compared with conventional distribution network,the incorporation of various types of distributed power sources has made the microgrid topology and operation mode more complicated,and there are some differences in fault characteristics corresponding to gridconnected/islanded operation.Conventional relay protection scheme is difficult to meet the protection requirements of microgrid.Aiming at this problem,this paper firstly discusses the shortcomings of conventional relay protection schemes,analyzes the fault characteristics in microgrid,and proposes an improved fault identification algorithm to achieve fast and accurate fault identification in microgrid.Considering the requirements of relay protection of microgrid,combined with improved fault identification algorithm,an integrated relay protection algorithm is proposed on the basis of an improved current differential protection and adaptive current quick-break protection on the feeder upstream and downstream.The relay protection algorithm not only reduces the scope of fault,but also improves the protection response speed and reduces the probability of protection rejection.Finally,in the RT-LAB real-time simulation system,a multi-energy complementary microgrid model including distributed power sources such as wind turbine,photovoltaic panel,energy storage battery,and micro gas turbine is established,and the simulations are conducted under different fault conditions.The simulation results verify the correctness and effectiveness of the proposed relay protection algorithm.