适用于对称故障仿真的特高压柔性直流换流站动态相量建模

Dynamic phasor modeling of VSC-UHVDC converter station suitable for symmetrical fault simulation

随着多项特高压柔性直流工程投运,建立高效而准确的模型用以研究特高压柔性直流换流站运行特性很有必要。为此提出了基于模块化多电平换流器的特高压柔性直流换流站的动态相量解析模型,该模型能准确描述稳态及发生对称故障时特高压柔性直流换流站的动态特性。首先通过研究高低端换流器交直流侧的相互作用关系,重新建立了多换流器与交直流系统的接口模型。然后结合考虑内部谐波特性的换流器模型,建立了特高压柔性直流换流站的动态相量解析模型。通过对已建立动态相量模型中交流侧状态空间方程的修正,进一步扩展了其在交流系统发生对称故障下的适用性。最后基于PSCAD/EMTDC中的电磁暂态仿真模型,验证了所建模型在稳态和故障下的正确性和高效性。

With many voltage source converter ultra-high voltage direct current(VSC-UHVDC) projects put into operation,it is necessary to establish an efficient and accurate model to study the operation characteristics of VSC-UHVDC converter station. A dynamic phasor analytical model of VSC-UHVDC converter station based on modular multilevel converter(MMC) is proposed,which can accurately describe the dynamic characteristics of VSC-UHVDC converter station under steady state and symmetrical fault. Firstly,the interface model between multi-converters and AC/DC system is re-established by studying the interaction between the high and low terminal converters at AC/DC sides. Then,combined with the MMC model considering internal harmonic characteristics,the dynamic phasor analytical model of VSC-UHVDC converter station is established. Through the modification of the AC side state space equation in the established dynamic phasor model,its applicability in the case of symmetrical fault in AC system is further extended. Finally,based on the electromagnetic transient simulation model in PSCAD/EMTDC,the correctness and efficiency of the established model under steady state and fault conditions are verified.