Research On Islanding Algorithm Of Wide Area Protection And Control System For Distribution Network With DGs

With the development of renewable energy resource, distributed generation (DG) has become an important form of electrical source. More and more DGs are connected into the power distribution system and run in the network. This brings a great change to the network configuration and its operation mode. As a result, this leads to a big challenge for the traditional protection and control system. At present, Standards for interconnecting DG with electric power systems mostly are based on the principle that the DG shouldn't bring influence upon the normal operation performance for the utility protection and control system. For example, it's demanded that the DG shouldn't actively participate in the voltage regulation. And for another instance, in case of a fault in the distribution system, it's demanded that the DG be quitted from the system to insure the right operations of the protection devices. In this way, in one hand, it guarantees the security of the system; on the other hand, it also brings damage to the normal operation of the DG. DG sacrifices the interest of the power supplier since it brings negative affection to the development of the distribution generation technology.This thesis is focused on effective protection and control of distribution network with DGs. Firstly, the influence on traditional protection and control system of distribution networks as DGs connect into is analyzed. The existing protection and control method for DG is also generalized. Then, a new idea of wide area protection and control system for distributed generation is proposed. Utilizing the real time data from multi sampling points in area distribution network, it can solve a good many problems in traditional protection and control system on principle. The function principle and its achieving method of this system are then studied in detail. After that, the thesis focuses on the islanding emergency control function, which is an important one in the protection and control system. A new idea of dynamic islanding is presented. The islanding principle, strategy and algorithm are introduced in detail. Finally, the achieving method of islanding algorithm is discussed. The data structure, parameter extraction and mathematical manipulation referred to in this algorithm are introduced. Some cases are presented to analyze the feasibility of the algorithm.The wide area protection and control system for distributed generation and the islanding algorithm in this thesis will not only farthest explore the benefits of distributed generation system, but also avoid its negative influences upon the security of the power system at the same time, thus guarantee the power system more efficient and reliable operation.