Abstract:

Although distributed photovoltaics (DPVs) are increasingly being integrated into power grids, the problems of daytime overvoltage and nighttime low voltage in the distribution the network persist, which affect network economy. To overcome this problem, a two-stage optimization operation strategy involving DPVs and energy storage systems (ESSs) was proposed. In the first stage of the strategy, the position and amount of charge and discharge of the ESSs were determined by calculating the voltage sensitivity of the node and the adjustable photovoltaic reactive power node. Next, the optimization operation model was established. The model minimizes the sum of dispatching cost of ESSs, power exchange cost, and network loss cost. The constraints of the study include the distribution network, node voltage, state of charge (SOC) of ESSs, and adjustable reactive power capacity of photovoltaic inverters. In this model, particle swarm optimization was used to devise the daily scheduling output strategy of DPVs and ESSs. Finally, the effectiveness of the proposed method was verified using a 31-node actual distribution network. The simulation results revealed that the proposed strategy can effectively solve the voltage violation problem through the cooperative dispatching of DPVs and ESSs. Thus, the operating cost of the distribution network can be optimized while ensuring voltage safety.

Key words: distributed photovoltaic, voltage violation, energy storage system, reactive power control, operation optimization