Abstract:
Extreme natural conditions often cause the collapse of the island microgrid which needs to be restored by the black start. However, the black start is affected by a large number of inductive load due to the particularity of the island microgrid load. In order to improve the efficiency of the black start of island microgrid, this paper proposed a black start optimization strategy of island microgrid based on virtual active load. First, a black start power startup sequence optimization model was proposed and the entropy weight method was used to evaluate the black start ability of different DGs. Then, a load recovery optimization model was proposed with the maximum load recovery amount and the maximum load recovery importance as the goals and solved by the PSO algorithm. Next, the path recovery optimization model of DG and load was proposed. The model was solved by Prim algorithm of minimum spanning tree. In addition, a virtual active load construction method was proposed. In the black start process, the inductive load and the parallel compensation capacitor are considered equivalent to the active load, thereby improving the black start success rate. Finally, the simplified 19-node microgrid structure was used as the test system for simulation verification. The simulation results show that, compared with the traditional optimization of black start strategy, the proposed method increased the load recovery by 46.8% during the black start process and at the same time, took the load importance into consideration. Furthermore, the total path restoration time was reduced by 8.8%. In addition, according to the proposed virtual active load construction method, the simulation results show that when the reactive power provided by the parallel capacitor was sufficient, the impact of the inductive load on the system voltage could be significantly reduced during the black start process.
