频率紧急控制中动作时延和措施量对低惯量系统控制有效性的影响  

Influence of Action Delay and Amount on the Control Effectiveness of Low Inertia Systems in Frequency Emergency Control

作　　者：李兆伟 方勇杰[1,2] 吴雪莲 李建华 赖业宁 Li Zhaowei;Fang Yongjie;Wu Xuelian;Li Jianhua;Lai Yening(School of Electrical and Electronic Engineering North China Electric Power University,Beijing 102206 China;Nari Group Corporation State Grid Electric Power Research Institute,Nanjing 211106 China;East China Branch of State Grid Corporation of China,Shanghai 200120 China)

机构地区：[1]华北电力大学电气与电子工程学院,北京102206 [2]南瑞集团有限公司(国网电力科学研究院有限公司),南京211106 [3]国家电网有限公司公司华东分部,上海200120

出　　处：《电工技术学报》2024年第17期5394-5405,共12页Transactions of China Electrotechnical Society

基　　金：国家自然科学基金重点项目(61933005);国家电网公司科技项目(5100-202240026A-1-1-ZN)资助。

摘　　要：频率紧急控制是保障电网故障后频率安全的第二道防线,通常由基于事件触发的稳控系统实现,已成为支撑特高压直流安全送电的标配。随着高比例新能源的快速发展,系统调频能力和惯量水平不断下降,电网故障后的频率响应特性出现跌落深度大、速度快的新特征,紧急控制能否有效是关系系统频率安全的关键因素。该文首先建立了计及频率紧急控制的高比例新能源电力系统频率响应模型和传递函数;其次从永久性扰动和短时性扰动两方面,详细分析了系统频率响应特性以及频率紧急控制动作时延和措施量的有效性,并给出了紧急控制有效时新能源接入比例的限值;最后结合实际电网仿真模型开展了时域仿真验证,指出低惯量电力系统短路故障引起的连锁短时性功率扰动将成为频率安全防御的关键和难点。Frequency emergency control(FEC)is the second defense line to ensure frequency safety after power grid failures,usually triggered by event of fault,and has become a standard configuration of ultra-high voltage DC(UHVDC).With the rapid development of high proportion of new energy(NE),the frequency regulation ability and system inertia are continuously decreasing.The frequency response characteristics after power grid faults have some new characteristics of large drop depth and fast speed.The effectiveness of emergency control is a key factor related to the frequency safety.This article first establishes frequency response model and transfer function of a high proportion NE power system considering FEC.To analyze the effectiveness of emergency control,this article focuses on two types of disturbances:permanent power disturbances(PPD)and short-term power disturbances(STPD).PPD are represented by faults such as DC blocking,unit tripping,and NE disconnection;STPD are represented by low voltage ride through(LVRT,without disconnection)of NE or flexible DC,DC commutation failure.According to the derivation,the time-domain expression of the system frequency response considering FEC under PPD can be obtained.FEC may not always solve the transient frequency insecurity risk depending on whether the system deviation reaches the control threshold of under-frequency load shedding(UFLS)or over-frequency generator tripping(OFGT)after FEC.When FEC action delayτ0 is less the time when the frequency reaches its lowest point tm,the maximum frequency deviation will be improved.But excessive emergency control amount can cause the risk of transient high-frequency in the system.When the delay of FEC is greater than the moment when the system's minimum frequency occurs,FEC cannot improve the maximum frequency deviation.For the current technical level,the emergency control delay is considered as 300ms.If a PPD of 30%load capacity occurs,the limit value for NE access is 65%of the load.Under STPD the steady-state frequency deviation is zero

关 键 词：新能源 频率安全 频率紧急控制 低惯量电力系统 短时性功率扰动 新能源低 电压穿越 

分 类 号：TM76[电气工程—电力系统及自动化]