A general power flow calculation method for power systems with VSC FACTS based on InterPSS and automatic differentiation

This paper presents a general approach to solve the power flow with multiple kinds of VSC FACTS installed in the same power system. Traditional power flow model should be different for each type of VSC FACTS, which will increase the complexity of the calculation as well. However, this paper shows that there are characteristics in common with all FACTS controlled by voltage source converters (VSCs). In power flow calculation, each VSC converter can be equivalent to a controllable voltage source in series with transformer impedance, and thus the power flow model of each kind of VSC FACTS devices can be described by the equations of all the equivalent branches accompanied with the topology of those branches. Based on Newton-Raphson (NR) algorithm theory, a general algorithm framework designed for new power flow calculation considering of multiple types of VSC FACTS has been presented. An open source power system simulation package named InterPSS is extended to realize the generality of the power flow calculation, and automatic differential (AD) technology is utilized to develop a function module to automatically generate the Jacobian matrix so as to avoid manual deduction. The calculation of power flow with VSC FACTS is tested in several IEEE sample systems to validate the correctness and efficiency of the method proposed in this paper.