青海—西藏±400kV直流联网工程的控制保护策略优化

Optimization of Control and Protection Strategies for Qinghai-Tibet ±400 kV HVDC Project

针对青海—西藏±400kV直流联网工程"大直流、弱系统"的特点,其直流控制保护系统作出了针对性的策略优化:采用低直流电压起停极策略,降低了直流起停过程对西藏中部电网的冲击;采用与静止无功补偿装置(SVC)协调的无功控制策略,抑制了投切滤波器时的电压波动;采用基于直流电压阶跃的功率转移方法,解决了直流系统在低于280kV运行时的功率补偿问题。此外,还提出通过连续功率调节实现与安全稳定控制装置的配合,修正线路低电压保护判据,以及线路保护重启动策略的优化等措施。仿真试验及试运行情况表明,上述优化措施行之有效。

Based on the characteristics of high-voltage direct-current （HVDtS） system teecimg into a weak AC systein, optimization of the DC control and protection systems of Qinghai Tibet ± 400 kV HVDC project has been developed. The strategy of low DC voltage start and stop sequence is used to decrease the impact of impulse on the Tibet grid. The reactive power control strategy coordinated with static var compensator （SVC） is used to restrain the voltage fluctuation while connecting or disconnecting filters. The power transfer method based on DC voltage step is used to solve the power compensation problem when DC voltage is below 280 kV. Cooperation with stability control equipment by continuous power modulation, fixed criterion of DC line under--voltage protection and restart logic optimization are also proposed by continuous power regulation. Simulation and practical results indicate that the proposed optimizations are effective.