Piecewise Linear Power Flow Algorithm of DC Distribution Networks Considering Automatic Adjustment of VSC Control Strategy

Voltage source converter (VSC)-based DC distribution networks (DCDNs) can automatically adjust the control strategy of overloaded VSCs to adapt to the variation in renewable energy power, but it brings difficulties to the steady-state performance analysis of DCDNs. This paper presents a piecewise linear power flow (PLPF) algorithm to estimate the joint effect of power disturbance and VSC control strategy adjustment on steady-state performance. Firstly, according to the VSC power balance, the critical point of the VSC hitting the capacity limit is directly determined, and the power variations in each node before VSC control strategy adjustment are obtained. Then, the linear power flow is revised considering the VSC control strategy adjustment. Inversion of the block Jacobian matrix is used to improve the calculation speed of linear power flow revision. Finally, linear power flow calculation is performed in each stage, and the steady-state performance is obtained by using the superposition method. Simulation results show that the proposed PLPF model can estimate the steady-state performance faster and more simply.