基于全控阻容模块的电网换相换流器方案设计及机理分析

Scheme Design and Mechanism Analysis of Line Commutated Converter Based on Fully Controlled Resistance-capacitance Module

为提高电网换相换流器(line commutated converter high voltage direct current,LCC-HVDC)在严重故障情况下抵御换相失败的能力,提出了一种基于全控阻容子模块(fully controlled resistance-capacitance sub-module,FCRM)的电网换相换流器拓扑方案,通过提供换相电压支撑,限制故障电流,提高了系统抵御换相失败的能力。首先提出FCRM的基本结构和工作模式,分析基于FCRM的电网换相换流器抵御换相失败的作用原理,然后研究故障态FCRM的作用机理和开关器件电气应力。通过对阻尼电阻能量耗散进行计算,提出阻尼电阻的设计原则。PSCAD/EMTDC仿真结果表明,在严重故障下,FCRM电压电流应力满足器件要求,基于FCRM的电网换相换流器可以快速完成换相,增强系统的换相失败免疫能力。

In order to improve the ability of the line commutated converter high voltage direct current(LCC-HVDC)to withstand commutation failures under severe fault conditions,this paper proposes a fully controlled resistance-capacitance sub-module(FCRM)line commutation converter topology scheme to improve the system's ability to resist commutation failures by providing commutation voltage support and limiting the fault current.The article first proposes the basic structure and the working mode of the FCRM,analyzes the functional principle of the line commutated commutation converter based on the FCRM to resist commutation failures,and studies the functional mechanism of the faulty FCRM and the electrical stress of the switching devices.By calculating the energy dissipation of the damping resistor,the design principle of the damping resistor is proposed.The PSCAD/EMTDC simulation results show that under severe faults,the FCRM voltage and current stress meets the device requirements,and that the line commutated commutation converter based on the FCRM can quickly complete the commutation and enhance the system's immunity to the commutation failures.