Application of an Integrated Protection and Control System for Smart Distribution Grid Based on PTN and 4G LTE Communication

The application of an integrated protection and control system for a 10kV smart electricity distribution grid in China Southern Power Grid is presented in this paper. The system can provide current differential protection for 10kV feeders if CBs are installed on the feeders, or fault location function if load switches are installed on the feeders. It also provides a wide area control function for automatic fault isolation and auto-switching function for restoration of power supplies to the healthy part of a feeder after a power system fault is cleared. Both the current differential protection function and the wide area control function can use either Package Transmission communication Network (PTN) of fibre network or 4G LTE (Long Term Evolution) of wireless communication network. In addition, if the topology of electricity distribution network changes, the system can detect the change and automatically send new configuration settings to the affected current differential protection without manually changing the settings. Factory tests have been carried to prove the effectiveness of the system. Compared to the traditional protection and control system for 10kV distribution networks, the system developed can locate and isolate a fault within 900ms (assuming load switch operating time is 700ms), whereas the traditional system has no fault location function, it may take minutes even hours to manually locate a fault, and then restore power supplies. The integrated protection and control system has been installed and commissioned on site recently, and hopefully it will improve the reliability of power supply significantly.