Voltage source converters (VSCs)-based DC distribution networks (DCDNs) can automatically adjust the control strategy of overloaded VSC to adapt to the variation of renewable energy power, but it brings difficulties to analyze the steady-state performance of DCDNs. A piecewise linear power flow (PLPF) algorithm is proposed to quickly calculate the coupled effect of the power disturbance and VSC control strategy adjustment on steady-state power flow. Firstly, according to the VSC power balance, the critical point of VSC hitting the capacity limit is directly determined and the power variations of each node before VSC control strategy adjustment are obtained. Then, the linear power flow is revised considering the VSC control strategy adjustment. Finally, the linear power flow calculation is performed in each stage before VSC control strategy adjustment, and the steady-state power flow is obtained by using the superposition method. Simulation results show that the proposed PLPF model can directly, quickly, and accurately calculate the steady-state power flow distribution of DCDNs.