特高压直流分层接入系统换相失败预防控制参数优化

Parameter Optimization of Commutation Failure Prevention and Control of UHVDC Hierarchical Connection to AC Grid System

为解决直流分层接入系统中换相失败预防控制并不能较好地抑制非故障层面换流阀发生换相失败的问题，提出了一种改进的控制策略。该策略对换相失败预防控制逻辑进行了优化，修正了电压变化幅值系数、控制增益、自保持环节时间常数和两个电压层面预防控制协同程度等相关参数。使用基于ADPSS的机电一电磁混合仿真软件在实际规划电网中进行了仿真验证，结果表明，改进的控制策略可有效抑制分层接入方式的特高压直流输电系统逆变侧因为一个交流电网故障对另一个无交流故障电网所连接的阀组运行的影响，保证无交流故障的阀组可稳定运行，不会发生换相失败，具有较高的工程应用价值。

In order to solve the problem that commutation failure prevention and control of UHVDC hierarchical con- nection to AC grid system cannot perfectly suppress the converter valve commutation failure on a non-fault level, we proposed an improved control strategy. Several parameters of commutation failure prevention and control were optimized. Meanwhile,we revised the following main parameters in the control logic： amplitude coefficient, voltage change control gain, self maintaining link time constant and prevention and control synergy degree of two voltage levels. By using the ADPSS electromechanical-electromagnetic hybrid simulation software, we simulated the actual power grid data. The re- suits show that the improved control strategy can effectively suppress the UHVDC system inverter＇s commutation failure on both voltage levels, for one non-fault level is caused by another with fault of AC network, which has great value in en- gineering application.