Study on hosting capacity criteria other than thermal capacity in distribution network using long-term and geospatial load forecast

In Japan, further expansion of photovoltaic (PV) installation is expected toward carbon neutrality by 2050. To determine the amount of PV that can be added to distribution system without countermeasures, or hosting capacity (HC), the Kansai Transmission and Distribution, Inc. mainly uses the current value; however, voltage violations could occur without overloads. Therefore, this study examined whether voltage violations should be considered as HC criteria in addition to thermal capacity. First, long-term and geospatial load forecasts were conducted for 3,451 distribution lines in Hyogo Prefecture. Second, actual measurements were conducted on the distribution line selected using the load forecasts and specifications of the distribution lines, showing voltage drops due to reactance with the long distribution line and reactive power from PV inverter with fixed power factor. Third, we performed simulation of countermeasures for the voltage violations in the distribution line by power flow analysis and discussed the availability of the long-term and geospatial forecasts in distribution grid planning. Lastly, we estimated that 527 distribution lines would have zero HC by 2050 without countermeasures using the load forecasts. The fact that 25% of them were caused by lower voltage limits indicated its importance as HC criteria in Japan.