Research On Distribution System Reliability And Its Partial Improvement

The fundamental task for power system is to supply power to customers economically and reliably, i.e., security, economy and reliability are the ultimate requisition for power systems. With the development of city economy and improvement of people's life quality, there is a growing requisition for power quality. Therefore, it is necessary for us to evaluate the reliability of power systems and propose corresponding programming. As is known, distribution network is directly connected to customer, it would affect the power quality greatly. It is estimated that eighty percents of outages in power system are caused by distribution network. Thus it is of great importance to evaluate the reliability of power system and improve the level of reliability.In this thesis, the algorithm of reliability and strategy for improving reliability are studied based on a great many domestic and overseas references.Firstly, Status of reliability study and basic of distribution network are introduced.Secondly, according to the structure and operational characteristic of distribution network, based on interval numbers algorithm, a kind of simplified block algorithm is proposed in the precondition of lack of original data. Meanwhile, an algorithm of interval power flow and load curtailment model are brought forward considering the restriction of load transfer.Thirdly, the distribution network is divided into various parts using the partition method. Then a partial/area improvement method for reliability of distribution system is put forward considering the reality of distribution network. Meanwhile, risk evaluation theory is discussed in details and risk index of every divided part is calculated to find out weak areas of the system. Through the calculation, it can be concluded that rebuilding of weak areas would not only lower the operational risk, but also improve the reliability of distribution system as a whole.Finally, the bus 6 system of IEEE-RBTS is emulated, and the reliability index of load bus, various indexes of system and partial risk index are calculated to find out the best partial improvement method. Compared the pre-improving risk index with post-improving one, it is obvious that the partial improvement method proposed in this paper has better effectiveness and rationality.