Inverter reliability-constrained Volt/Var optimization control of distribution network with high-level PV-storage generation

The involvement of renewable energy inverters in regulating the reactive voltage of the distribution network is an efficient approach to enhance the operational security and reliability of high-penetration renewable energy distribution networks. Nonetheless, the reactive power assistance offered by renewable energy inverters leads to an elevation in the maximum junction temperature of photovoltaic inverters and intensifies temperature fluctuations, which will subsequently impact the reliable and secure operation of both the inverters and the distribution network. In order to address this issue, this paper introduces a control strategy for optimizing reactive power and voltage in photovoltaic-storage (PV-storage) distribution networks with significant penetration, taking into account the constraint of IGBT junction temperature. Firstly, the IGBT junction temperature is calculated by the CatBoost algorithm, which improves the efficiency of IGBT junction temperature calculation and avoids the dependence of the traditional junction temperature algorithm on IGBT thermal model parameters. Then, a multi-objective reactive power optimization model of an active distribution network considering IGBT junction temperature constraint is established. The maximum output power of PV-storage power supply under IGBT junction temperature constraint is solved by dichotomy, so the transformation from IGBT junction temperature constraint to output apparent power second-order cone constraint is realized. Finally, the efficiency of the suggested approach is validated using the IEEE 33-bus typical distribution system. At the same time, the setting principle of IGBT junction temperature limit of PV-storage power supply considering the network loss of distribution network and the reliability of PV-storage power supply is proposed.