柔性直流输电换流站的同步电机模拟特性分析

Analysis of VSC-HVDC Station Characteristic in Synchronous Machine Emulation

简要介绍了柔性直流输电换流站的同步电机模拟控制策略,通过在传统下垂控制中专门加入一阶惯性环节实现了换流站的同步电机模拟。换流站不仅可以实现一次调频的静态特性,还能够模拟同步发电机的转子运动方程。对同步电机模拟控制策略进行了理论分析,指出了各控制参数对换流站特性的影响。通过将频率偏差的积分值加入到换流站的有功功率指令中,换流站可以实现二次调频功能。在PSCAD/EMTDC软件中建立了双端柔性直流输电系统的详细仿真模型,通过2个仿真案例下的多个复杂工况的仿真,验证了换流站在同步电机模拟控制策略下,具有增加系统惯性、提供频率支撑等功能,可以显著提升换流站适应电网复杂工况、安全穿越电网故障的能力。

This paper presents a synchronous generator emulation control（SGEC） strategy for voltage source converter based high voltage direct current（VSC-HVDC） station,where a first-order inertia element is intentionally added to conventional frequency-power droop control to realize primary frequency regulation and simulate rotor motion equation.Impact of control parameters on steady-state and dynamic characteristics of the converter station are theoretically analyzed.In addition,secondary frequency regulation is achieved by modulating scheduled power of VSC station with integral element on frequency deviation from nominal value.Detailed time-domain simulation results in PSCAD/EMTDC environment demonstrate that VSC-HVDC station with the proposed control strategy can operate as a virtual synchronous generator with system inertia enhancement,grid frequency support and fault ride through capability.