不同调度模式下VSC-MTDC系统的协调控制策略

Coordinated Control Strategy of VSC-MTDC System Under Different Power Dispatching Modes

针对电力系统3种调度模式对直流电网实时的潮流分布要求,在多端柔性直流输电(voltage source converter multiterminal direct current,VSC-MTDC)系统中设计了相应的协调控制策略,通过改变下垂系数的值和切换控制模式,以满足直流电网中的潮流分布。为避免控制模式的频繁切换,在受端换流站控制器中加入了滞环比较器。通过在PSCAD/EMTDC仿真软件中搭建的四端柔性直流输电系统,对直流电网处在不同的调度模式下分别进行仿真,结果表明,与定下垂系数的控制方式相比,该协调控制策略可以满足电力系统调度对潮流实时的分布要求,直流电网的输电灵活性得到提高。

Aiming at the real-time power flow distribution requirement of DC power system in three kinds of dispatching modes, this paper designs a coordinated control strategy for voltage source converter multi-terminal direct current （VSC- MTDC） system, which can change the value of droop coefficient and switch control mode to meet the DC power flow distribution. In order to avoid frequent switching of the control mode, a hysteresis comparator is added to the controller of the receiving end converter station. In the end, this paper constructs a four-terminal VSC-MTDC mode in PSCAD/EMTDC, and simulates the DC grid in different scheduling modes. The results show that, compared with the traditional control method with constant droop coefficient, this coordinated control strategy can meet the real-time power flow distribution requirements of the power system, and the transmission flexibility of the DC power grid is improved.