多风电场柔直并网调频的组合控制策略  

Combined Control Strategy for Frequency Regulation of Multi-wind Farms Connected to Multi-terminal Flexible DC

作　　者：郎燕生 杨东冀 杨晓楠 温渤婴[2] 赵昆 LANG Yanshcng;YANG Dongji;YANG Xiaonan;WEN Boying;ZHAO Kun(China Electric Power Research Institute,Haidian District,Beijing 100192,China;College of Information and Electrical Engineering,China Agricultural University,Haidian District,Beijing 100083,China)

机构地区：[1]中国电力科学研究院有限公司,北京市海淀区100192 [2]中国农业大学信息与电气工程学院,北京市海淀区100083

出　　处：《电网技术》2019年第12期4468-4477,共10页Power System Technology

基　　金：北京市科委重大科技成果转化落地培育项目“柔直电网汇集新能源接入交流电网调度技术研究”(Z161100004816025);国家电网公司科技项目“张家口可再生能源示范区重大科技示范工程运维关键技术研究”(52130A17005H)~~

摘　　要：大规模多个风电场通过多端柔性直流系统向受端交流电网供电,会解耦风电场和交流电网的频率联系。并且对于含有多个换流站的柔直系统,直流电压控制更为复杂。针对多端直流系统参与交流电网调频以及换流站故障时协调直流电压稳定运行的问题,提出一种不依靠通信的汇集风电多端柔直系统的变下垂组合控制策略。首先,对于连接交流电网的受端换流站(grid side VSC,GSVSC)采用改进虚拟同步机(VSG)电压变下垂策略,该策略一方面可以通过变下垂控制改善直流系统的电压质量;另一方面根据受端电网频率波动幅度不同,可以有选择地为交流电网频率提供惯性响应。其次针对传统电压下垂不适用于含风电场的柔性直流系统的问题,对连接风电场的换流站(wind farm VSC,WFVSC)采用改进电压–频率下垂控制策略。对风电场采用变调频因子惯量控制实时改变出力,根据不同风速下风机改变出力的能力不同,在改进惯量控制中引入转速调频能力因子防止转速越限。最后,在PSCAD/EMTDC仿真软件上进行仿真分析,验证所提控制策略的正确性和有效性。A large number of wind farms supplying power to AC power through multi-terminal flexible DC system will decouple the frequency relationship between the wind farms and the AC grid. DC voltage control is more complicated when there are many wind farms connected to flexible DC systems. In this paper, a combined control strategy is proposed with the multi-terminal DC system participating in frequency regulation of the AC grid and coordinating stability of DC voltage at converter station failure. Firstly, the grid side VSC(GSVSC) connected to the AC grid adopts an improved virtual synchronous generator(VSG) variable droop strategy, cooperating improved variable droop control to respond to DC voltage fluctuations. It can selectively provide inertial response to AC grid frequency according to frequency fluctuations. Secondly, for the problem that traditional voltage drop control is not suitable to the flexible DC system with wind farms, the improved voltage-frequency droop control strategy is applied to the VSCs connected to the wind farms(WFVSCs). The wind farms use frequency regulation factor inertia control to change the output in real time according to wind speed. Finally, simulation analysis is carried out on PSCAD/EMTDC to verify correctness and effectiveness of the proposed control strategy.

关 键 词：多端柔性直流 双馈感应发电机 虚拟同步机 变下垂控制 调频因子 组合控制 

分 类 号：TM721[电气工程—电力系统及自动化]