基于虚拟电阻的P-V下垂系数计算方法

现有研究有很多针对多端柔性直流下垂系数的计算方法,但是鲜有基于虚拟电阻的下垂系数计算方法.参考I-V下垂控制策略,提出了一种基于虚拟电阻的P-V下垂控制策略.首先,在放射型直流电网中,分析了换流站直流端口电压与公共母线电压之间的关系.通过设置虚拟电阻得出换流站桥臂电压和直流端口电压的关系,并根据P-V下垂控制策略,推导...

A Method for Calculating P-V Droop Coefficients Based on Virtual Resistance

Many studies about multi-terminal VSC systems are concentrated on calculating droop control coefficients. However, few methods have been used to obtain the coefficients applying the virtual resistance. According to the I-V droop control, a new P-V droop control method based on virtual resistance is proposed. Firstly, the relationship between the voltage on the DC side of VSC stations and the voltage of the common bus is analyzed in a radial DC system. Then, the relationship between VSC arm voltage and the DC voltage is obtained by imposing a virtual resistance. Considering the P-V droop equation, the method for calculating coefficients is given. Thereafter, the calculation limitations of the proposed method in extreme operating conditions are analyzed, and the resolvent is proposed which improves the control strategy. Finally, three types of control strategies, i.e., the ratio droop control, the adaptive droop control and the droop control based on virtual resistance, are simulated on a six-terminal radial VSC system. Simulation results show that, the proposed method has the advantages of smaller deviation of dc-side voltage and reasonable power distribution.