Operational Strategy of a DC Inverter Heat Pump System Considering PV Power Fluctuation and Demand-Side Load Characteristics

With the increase in application of solar PV systems, it is of great significance to develop and investigate direct current (DC)-powered equipment in buildings with flexible operational strategies. A promising piece of building equipment integrated in PV-powered buildings, DC inverter heat pump systems often operate with strategies either focused on the power supply side or on the building demand side. In this regard, the aim of this study was to investigate the operational strategy of a DC inverter heat pump system for application in an office building with a PV power system. Firstly, the PV power fluctuation and demand-side load characteristics were analyzed. Then, a series of heat transfer and heat pump system models were developed. A reference building model was developed for simulating the performance of the system. A control logic of the DC inverter heat pump was proposed with a certain level of flexibility and capability considering both the characteristics of the PV power generation and the demand-side heating load. MATLAB/Simulink 2021 software was used for simulation. The simulation results show that the DC inverter heat pump is able to regulate its own power according to the change signal of the bus voltage such that the DC distribution network can achieve power balance and thus provide enough energy for a room. This study can provide a reference for developing flexible operational strategies for DC inverter heat pump systems. The proposed strategy can also help to improve the systems' performance when they are applied in buildings with distributed PV systems.