Development of simple determination method for available interconnection capacity of PV considering voltage stability

In Japan, the growing adoption of photovoltaic (PV) systems has led to power quality issues (e.g. voltage drops) caused by lower voltage stability in distribution lines (6.6 kV). However, the current PV interconnection limit is determined mainly by the thermal capacity. To address this limitation, we propose a novel evaluation method that incorporates the voltage stability to assess the PV hosting capacity (PVHC). Using the proposed method, we quantitatively analysed the effects of thicker power lines on the PVHC, and discovered that an increased line capacity does not always enhance the PVHC owing to its impact on the voltage stability. Furthermore, we developed a simplified evaluation approach that efficiently determines the PVHC under the constraints of the voltage stability, thermal capacity, and voltage limits. This method allows distribution system operators to quickly identify distribution lines that critically require detailed investigation, thereby minimising the manpower and computational effort required to maintain the system. Therefore, the proposed approach provides a practical solution for optimising PV integration and stabilising the system, thus supporting the shift to renewable energy.