Modeling and Control of an Islanded Campus Microgrid with Coordinated CHP and PV Systems

On-site power generation systems, integrating combined heat and power (CHP) and solar photovoltaics (PVs), could bring significant energy cost savings to the electricity consumers and reduce carbon emissions. This paper presents detailed modeling of an existing gas-turbine-based 5-MVA CHP unit located on a university campus. In addition, integration of a 10-MW solar farm into the campus microgrid is investigated. A virtual synchronous generator (VSG) approach is proposed to control the PV system as a double-stage PV-VSG, which emulates the rotational inertia of a conventional synchronous generator (SG) using only the dc-link capacitor. The coordinated control of the two generation facilities is studied when the microgrid is in islanded mode. The large capacity of the PV farm is leveraged to serve part of the campus baseload demand when sufficient solar power is available, while the CHP is on hot standby. When the grid frequency stabilizes, the CHP will be brought online for load sharing. The underfrequency load shedding (UFLS) is also in place to arrest the potential rapid frequency fall. The simulated campus microgrid system is developed in MATLAB/Simulink to verify the modeling accuracy and control performance.