Impacts of distributed generation on the protection system of distribution network | |
| Author | Se Samnang |
| Call Number | AIT RSPR no.ET-18-10 |
| Subject(s) | Distributed generation of electric power--Equipment and supplies Electric power distribution--Protection |
| Note | A research study submitted in partial fulfillment of the requirements for the degree of Master of Engineering in Energy |
| Publisher | Asian Institute of Technology |
| Abstract | The penetration of distributed generators introduces coordination issues to power system protection. In a distributed generation connected distribution network, power flow becomes bi‐directional. Conventional overcurrent and earth fault protection schemes are made vulnerable. Adding distributed generation could cause protection blinding, sympathetic tripping, and miscoordination in conventional overcurrent protection. This research will investigate three methods including sequence networks model, time current-voltage characteristic and point of common coupling protection to minimize the loss of coordination. First, we evaluate the coordination by modeling a distribution system with sequence networks for different types of faults and different kinds of interconnection transformer to analyze the effectiveness of overcurrent protection relay. Second, timecurrent and time-voltage characteristics is used to minimize the recloser operation time to its minimum. Lastly, the point of common coupling protection scheme is utilized to prevent unwanted islanding and maintain proper operation of the recloser. The power system is modeled with the Digsilent PowerFactory program. The results illustrate that the loss of coordination can be mitigated by using sequence components to identify faults by using existing conventional overcurrent relay with static setting. In conventional distribution network, only phase overcurrent relay and ground overcurrent relay are used. Negative sequence overcurrent relay is the most effective to detect phase to phase fault and single to ground fault with grounded interconnection transformer. Negative sequence overcurrent relay is used as a main protection function in this study. The analysis shows that the problem of loss of coordination between the fuse and the recloser can be mitigated by the coordinated use of phase overcurrent relay, ground overcurrent relay and negative sequence overcurrent relay, in the detection of asymmetric and symmetric faults. The effective utilization of the relays depends on the various factors viz., network configuration, fault location, type of interconnection transformer, type of DGs and levels of integration. Using time-voltage-current characteristics based scheme, recloser operation time can be reduced to its minimum and the fuse can be saved in all the cases except when the recloser operating time is already at the minimum. The downside being that this scheme can be used with only a microprocessor relay. Hence, by adopting this scheme, the investment on the communication or fault current limiter can be avoided, but the voltage input signal from the voltage transformer is needed. Thus, by making use of the time-voltage-current characteristics based scheme and microprocessor relays, most of the conventional protection infrastructure can be retained and the investment toward the modernization be minimized. |
| Year | 2018 |
| Corresponding Series Added Entry | Asian Institute of Technology. Research studies project report ; no. ET-18-10 |
| Type | Research Study Project Report (RSPR) |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Energy and Climate Change (Former title: Department of Energy, Environment, and Climate Change (DEECC)) |
| Academic Program/FoS | Energy Technology (ET) |
| Chairperson(s) | Weerakorn Ongsakul; |
| Examination Committee(s) | Singh, Jai Govind;Loc Thai Nguyen ; |
| Scholarship Donor(s) | Electricite Du Cambodge (EDC);Asian Institute of Technology Fellowship ; |
| Degree | Research Studies Project Report (M.Eng.) - Asian Institute of Technology, 2018 |