基于柔直换流阀的交流电压定量调节方法

Quantitative Regulation Method of AC Voltage Based on Flexible DC Converter Valve

柔性直流无功分量可选择定交流电压控制和定无功控制,换流站现场常采用定无功功率控制。调度可下令通过柔直发出或吸收无功来调节交流电压到目标值,但调度指令一般是交流电压目标值,需要由换流站通过多次无功遥调指令来实现调压,这不仅增加现场操作风险,也给系统引入多次无功和电压小扰动。本文提出一种"两步调压法",第1步测试当前系统短路容量水平,第2步根据当前系统容量水平精确计算无功量,从而能够实现柔性直流换流阀无功控制对交流电压的定量调节。该方法通过两步调压,即可满足精确调压需求,无需对电网系统容量进行实时计算,简便实用。通过PSCAD/EMTDC离线仿真和基于RTDS的控制保护设备硬件在环仿真测试,验证了本方法的有效性。

The flexible DC reactive power component can choose constant AC voltage control and constant reactive power control,and the constant reactive power control is normally adopted in the converter station.The dispatcher may order to emit or absorb the reactive power through the flexible HVDC to regulate the AC voltage to the target value. However,the dispatching instruction is in general AC voltage target value,for which the voltage regulation is achieved by the converter station through multiple reactive power remote adjustment. This not only increases the operation risk at site,but also brings multiple reactive power and small voltage perturbation of the system. In this paper,a kind of Two-step voltage regulation method is proposed. The first step is to test the short circuit capacity level of the system,while,the second step is to calculate the amount of reactive power precisely in accordance with the capacity level of the present system,thus achieving the quantitative regulation of reactive power control of flexible HVDC converter valve to the AC voltage. The method,throughout the two-step voltage regulation,can meet accurate voltage regulation requirement without real time calculation of the capacity of the grid system,and is simple and practical.The effectiveness of the method is verified through PSCAD/EMTDC off line simulation and the in-the-loop simulation test of control & protection equipment hardware based on RTDS.