Local-coordinated voltage optimal control strategy of integrated PV and ESS system in distribution networks with π-type network simplification

Abstract

With the increasing penetration of distributed photovoltaics (PVs) in distribution networks (DNs), the voltage violation and PV absorption difficulty have become great challenges for the security operation of DNs. In this context, the integrated photovoltaic and energy storage system (PESS) plays an increasingly important role in enhancing the DNs operational security and economy with its capability of flexible power regulation and energy transfer. Considering the incomplete online measurement of DNs, this paper proposes a local-coordinated voltage optimal control strategy that combines local optimization and real-time coordinated control. Firstly, a new π-type network simplification method is proposed, which is less demanding on the measurement device and doesn't add new virtual nodes for the convenience of modeling. Then the local rolling optimization model for PESS is established based on simplified network to solve the optimal local instruction, which only uses the measurement data of local node and the slack bus rather than global measurement. Next, a real-time coordinated voltage control method based on network loss sensitivity is proposed to eliminate voltage violation caused by random fluctuations of PV and load power. Finally, the IEEE 33-bus system and modified 123-bus system are used to verify the effectiveness and accuracy of the proposed voltage optimal control strategy, which is also compared with centralized optimization method with global measurement. The simulation results indicate that the proposed control strategy can effectively solve the voltage violation and improve the system operation economy, especially only relying on partial measurement.