Maximization of PV Size for Its Limitation in MEA Grid Code by Considering Overvoltage and Increased Active Power Loss Criteria

A photovoltaic (PV) limitation in Thailand grid code has been based only on an average light load to protect the reverse power flow caused by PV systems installed into a LV distribution grid. However, injecting PV power during the light load occurrence can cause overvoltage and increased active power loss impacts on the distribution system. The objective of this paper is to determine the maximum PV size used to set the installation limit in Thailand grid code. The system voltages and the active power loss are used to be constraints of the optimization problem. A Direct Search method is employed and developed on the DIgSILENT PowerFactory program. The simulated system is constructed from typical data of Thailand distribution grids, while the load flow calculation is carried out on the average light load condition of Metropolitan Electricity. Thailand's PV installed capacity from 2014 to 2018 (Until June) Authority (MEA), Thailand. Three simulation cases are studied: (1) PV installed at the beginning of the line, (2) PV installed at the middle of the line, and (3) PV installed at the end of the line. The results show that when a PV system with an appropriate size is installed, its impacts will be mitigated, and that the PV size can be the highest if its location is at the beginning of the line. Since the simulated system is typically constructed, the results and analyses can be applied broadly and imposed on the MEA's grid code.