基于附加有功信号的VSC-MTDC系统平衡控制策略

Strategy of balanced control based on additional active power signal for VSC-MTDC system

对基于电压源型换流器的多端直流输电(VSC-MTDC)系统的协调控制策略进行了分析研究,提出了基于附加有功功率信号的平衡控制策略,具有不需要站间通信和模式切换的优点。对VSC-MTDC系统各换流站传输功率与其直流电压之间的关系进行分析,由并联型接线方式的VSC-MTDC系统结构推导了各换流站直流电压正常及极限工作范围,结合定有功功率换流站的改进有功功率-直流电压特性曲线,计及换流站可调容量裕度,给出了有功功率附加信号的计算方法,并分析了在正常运行及直流电压控制站故障时采用附加有功信号的定功率换流站维持有功功率平衡及直流电压稳定的工作原理。在电磁暂态仿真软件PSCAD/EMTDC中进行仿真验证,结果表明在直流电压控制站扰动情况下,所提出的控制方法可以维持系统有功功率平衡及直流电压的稳定。

The coordinated control strategy of VSC-MTDC（Voltage-Source Converter based Multi-Terminal Direct Current） is analyzed and the strategy of balanced control based on the additional active power signal is proposed,which does not need the inter-station communication and mode switching. For each converter station,the relationship between transmission power and DC voltage is studied and the normal and limited scopes of DC voltage are derived based on the structure of VSC-MTDC system in the parallel wiring mode.Combined with the improved active power-DC voltage characteristic curve of the converter station with constant active power,the method for calculating the additional active power signal is given,which considers the adjustable capacity margin of converter station. The working principles of converter station with constant active power are analyzed,which apply the additional active power signal to maintain the balanced active power and stable DC voltage in normal operation and when the DC voltage control station is faulty.Simulation is performed with PSCAD / EMTDC software and the results show that the proposed control method maintains the balanced system active power and stable DC voltage during the disturbance of DC voltage control station.