The Principle And Realization Of Hierarchical Region Protective System Of Power System

Relay protection, as the first line of defence of power system, is the key of the safe operation of the system. With the continually enlargement of the scale of local power grid connection and the increasingly complexity of operation mode, as well as the introduction of competition in power market, power systems frequently operate under extreme conditions, leading to serious security problems. On the other hand, the connotation of protection is expanding and the protecting coordination becomes more and more difficult. This thesis aims at studying some practical problems by virtue of the project of the electric power company of Henan province-- The research of hierarchical region protective system. It brings forward a hierarchical region protective system which is used to protect the key tie lines of power systems. The accomplishements of this thesis will be used in the engineering practice.Firstly, on the basis of thorough reading, the developing history and researching actuality of high voltage transmission line protection are presented in this thesis, showing the questions in traditional protecting device, which cause outgrowth of wide-area protection. After that, the latest survey of research of wide area protection is presented, including some implemented examples of wide-area protection. Then some deficiencies of existing wide area protection system are indicated.The cascaded tripping of protections is the immediate cause of blackouts. Therefore, the thesis analyzes the deep reasons of the cascaded tripping of protective relaying system, including the maloperation of backup protection, the hidden fault and protection tripping caused by overload. Besides, it also introduces some primary countermeasures presented.Based on this analysis, the thesis presents a hierarchical region protective system which is suitable for protecting the key transmission line of energy convergence. This system is implemented by virtue of synthesis decision based on multiple information of power grid. This system can cooperate with traditional main and backup protections, further strengthening the first line of defense of power systems. The hierarchical structure and working process has been detailedly introduced. Among them, the theory of zero and negative sequence directional elements used for fault location has also been expatiated, and a theory based on synthesis fault phase selection of sequential components and impedance measurement has been put forward. Various faults are simulated with EMTP to validate the proposed system, especially the system response under the scenarios of complex faults within and out of the area, and the results are satisfactory.Region protective system can identify the power transferring caused by removal of faults, and during this transient state process the power swing of the system may be arisen. The damage of three phase fault in the power swing is the most serious, and also the most difficult to recognize. This thesis brings forward a kind of fast-identifying method of symmetrical fault that may occur during power swings based on the cross-blocking scheme and power change rate. As an integral-type criterion, the performance of this scheme has high stability. The results of simulation tests show that this method has high reliability and speed.According to the theory of region protection, with the industrial computer of APCI5000 adopted as the platform, the prototype of region protective system has been developed. This thesis detailedly introduced the hard structure and the software design of this prototype. Then, the dynamic simulation system has been constructed in line with the transmission lines of three substations in Luoyang, Henan, and various tests have been strictly carried out. All of those proved the favorable capability of the system.In the last part of the thesis, the primary scheme of the integration of protection and stability control system is presented. With the analysis of operation conditions of power grid, the coordination between protection and preventive control, protection and emergency control have been emphasized. In concrete coordination strategy, several researching clews has been arisen, e.g., self adaptive inverse time characteristics to remove fault, overload recognization based on network topology, control strategy based on network topology, using operating mode of power network to optimize protective function. The thesis can be the foundation of above aspects being about to be launched.