含电压源换流器的交直流混合电网潮流统一表达与可行解求取  

Unified Power Flow Expressions and Algorithm to Obtain Feasible Solution for Hybrid AC/DC Grids Incorporating VSCs

作　　者：柴润泽 窦竟铭 张保会[1] 

机构地区：[1]电力设备电气绝缘国家重点实验室(西安交通大学),陕西省西安市710049

出　　处：《中国电机工程学报》2016年第5期1260-1268,共9页Proceedings of the CSEE

基　　金：电力设备电气绝缘国家重点实验室自主研究课题(EIPE14111)~~

摘　　要：通常计算含电压源换流器(voltage source converter,VSC)的并联型直流电网与交流电网共同组成的交直流混合电力系统的潮流,按照VSC换流站的控制方式列写对应的电网潮流方程,将有多种表达形式,不便于控制方式切换时潮流的统一求解。该文建立任意控制方式下VSC换流站交、直流两侧变量关系的3个统一表达式,控制方式切换仅改变表达式中的某些系数值,使得混合电网的统一潮流表达模型不变,仅其对应的雅克比元素值改变。提出了基于牛拉法的潮流求解算法,发生电源、负荷方式变化后,首先通过调度计划切换换流站控制方式自动获得可行解。若切换后仍无可行解,则采用约束潮流方法修正指令值,最终自动求取可行解。在交直流混合电网进行诸如N-1安全校验潮流计算、连续潮流计算需要控制方式切换时,该文表达和方法将大大提升计算效率。以含7端VSC直流电网的交直流混合电网为算例,验证了表达与求解的高效性和有效性。As a hybrid AC/DC system consists of paralleled DC grids, there are different power flow expressions according to the control modes of VSCs. However, switching control makes these traditional expressions complicated. This paper proposed three unified expressions for the relationship between the AC and DC sides of the VSC station with an arbitrary control mode. When the DC control mode is switching, we only have to change some coefficients in the unified expressions and in the Jacobian Matrix, so the dimensionality and structure of the AC/DC grids power flow models can stay the same. Based on the Newton method, the power flow algorithm was designed to solve this model. When disturbance occurs, the algorithm may find the practical solution by switching the DC control mode according to the scheduling. Once these switches do not work, revising the references of AC/DC grids according to the constrained load flow method can obtain a feasible solution automatically. For the N-1 security verification or the continuation power flow, where the hybrid AC/DC grid power flow need to be calculated again and again with the DC control switching, the proposed expressions and algorithm can dramatically raise efficiency. Finally, the power flow results of the hybrid AC/DC case with a 7 terminals DC grid demonstrate that the model and algorithm are valid and efficient.

关 键 词：电压源换流器 直流电网 交直流混合电网 统一表达 潮流求解 

分 类 号：TM712[电气工程—电力系统及自动化]