Grid Connection Studies for PV Power Plant in Medium Voltage Distribution Network

Grid connection studies are among the key requirements of detailed feasibility study for grid connected PV power plant. This paper presents design of 10 MWp PV power plant for Kikuletwa Renewable Energy Center located at Kilimanjaro region in Tanzania. Results from the designed PV plant and distribution network data are applied to perform detailed grid interconnection studies in order to evaluate technical performance of the plant as per standards and the current national grid code in Tanzania. The PV plant and existing Medium voltage distribution network are modelled in Electrical Transient Analysis Program (ETAP) software. Then, load flow, short circuit, power quality and stability analysis studies are performed. Results of the studies are applied to evaluate technical feasibility of interconnecting the designed 10 MW PV plant to the distribution network. The study demonstrate relationship between sizing of large scale PV power plant and grid interconnection studies. It is confirmed that load flow, bus voltages, short circuit currents and transient stability of the system are within the required national grid code and standards limits. Interconnection of PV power plant has enabled injection of 4.38 MW into the main grid and improvement of voltage profile of several feeders in the distribution network by 2%-4%. It is recommended to install harmonic filter at PV power plant substation bus bar in order to reduce the Total Harmonic Distortion (THD) to less than or equal to 5% as required by standards.