摘要
随着新能源发电占比的不断提高,特高压直流输电系统的送端电网强度变弱,送端交流系统可能存在电压质量较差的问题。为提高送端弱交流系统的电压质量,基于大规模风电接入的特高压混合级联直流系统,提出了滤波器与模块化多电平换流器(modular multilevel converter,MMC)协调参与送端电网调压的无功协调控制策略。分别分析了该级联直流系统的运行特性、滤波器的无功控制原理以及MMC在不同运行工况下影响其无功支撑能力的因素。针对MMC在过载的运行工况下对弱交流系统无功支撑能力较弱的问题,提出了一种MMC直流电压自适应控制策略,根据MMC传输的有功功率调整其直流电压,以扩大MMC的无功功率极限。仿真算例表明,所提无功协调控制策略能够有效支撑送端弱交流系统的电压,提高送端交流系统的电压质量。
With the continued increase of the proportion of renewable energy generation,the strength of the sending power grid in UHVDC transmission system is weakened and poor voltage quality might exist in AC system at the sending end.To improve the voltage quality of the weak AC system located at the sending end,based on the hybrid cascaded UHVDC system with grid-connected large-scale wind power,a reactive power coordinated control strategy,in which the filter and the modular multilevel converter(abbr.MMC)were coordinately participated into the voltage regulation of power grid sending end,was proposed.The operating characteristic of this cascaded DC system,the principle of reactive power control of the filter and the factors impacting the reactive power supporting ability of MMC under different operating condition were respectively analyzed.In allusion to the insufficient reactive power supporting capacity of MMC for weak AC system under the overloaded operating condition,an adaptive DC voltage control strategy for MMC,which could adjust DC voltage of MMC according to the active power transmitted by MMC to expand the reactive power limit of MMC,was put forward.Results of simulation example show that the proposed reactive power coordinated control strategy can effectively support the voltage of weak AC system located at the sending end and the voltage quality of the AC system can be also improved.
作者
李昊
仝义
赵成勇
王志冰
迟永宁
LI Hao;TONG Yi;ZHAO Chengyong;WANG Zhibing;CHI Yongning(State Key Laboratory for Alternate Electrical Power System with Renewable Energy Sources(North China Electric Power University),Changping District,Beijing 102206,China;China Electric Power Research Institute,Haidian District,Beijing 100192,China)
出处
《现代电力》
北大核心
2023年第2期210-218,共9页
Modern Electric Power
