基于换相面积的CSCC-HVDC输电特性研究

Transmission characteristics of CSCC-HVDC based on commutation area

受端电网的直流接入能力是高压直流输电系统规划和运行的关键问题之一。从可控电容换相换流器接入弱交流受端电网对换相失败的影响出发,在对可控电容换相换流器基本原理和拓扑结构进行分析的基础上,建立了可控电容换相换流器的稳态数学模型。为更接近工程实践和提升控制精度,考虑了高压直流控制系统的响应特性,并研究了以换相电压时间面积为控制目标的含可控电容换相换流器的响应控制策略。针对短路故障引起的换相失败,提出了利用限压器-并联间隙组合保护装置的故障恢复策略以缩短电容换相换流器的故障恢复时间。最后基于PSCAD/EMTDC平台,通过仿真验证并和其他方案的对比研究证明了上述控制策略对于降低弱受端逆变站换相失败风险和故障恢复的有效性。

DC access capability of the receiving power grid is one of the key issues in the planning and operation of the HVDC transmission system. Starting from the influence of the controllable capacitor commutating converter connected to the weak AC receiving power grid on the commutation failure, based on the analysis of the basic principle and topology of the controllable capacitor commutating converter, a steady-state mathematical model of the controllable capacitor commutating converter is established. In order to get closer to engineering practice and improve control precision, the response characteristics of the DC control system are considered, and the response control strategy of the controllable capacitor commutated converter with the commutation voltage time area as the control target is studied. For the commutation failure caused by short circuit fault, a fault recovery strategy using a MOV-parallel gap combination protection device is proposed to shorten the fault recovery time of the capacitive commutated converter during the fault. Finally, based on the PSCAD/EMTDC platform, the simulation verification and comparison with other schemes prove that the above control strategy is effective in reducing the risk of commutation failure and fault recovery of weak receiving end network.