Research On Safety Stability Analysis And Measure Of The Islanded Power Grid Of Guangxi Some Power Grid

Isolated network is referred to as islanded power grid. It usually refers to the small-capacity power grid which is independent of a large power grid. When the entire islanded power grid only has a generator, it is called the single generator with islanded power grid in power system. The most important characteristic of this operation mode is that the strategy of system safety steady operation converted from the load control to the frequency control and speed regulating system of generator set has a good static characteristics, satisfactory stability and dynamic response. Thus the system automatically keep grid frequency stabilizing within the scope of the request when the load change.This paper analyzes the model of the generator, transmission line, load and other major components and its parameters have an influence on the frequency characteristics of isolated grid. On this basis, the paper researchs safety stability analysis and measure of the isolated grid operation by dynamic simulation algorithm. When the active power supply exceeds demand in power grid, power system frequency will rise. when the active power falls short of demand, power system frequency will reduce. The corresponding measure is high frequency unit cut and under frequency load shedding. Because electrical power system is nonlinear, complexity and huge, it cause mutual coupling between the various measures. So, In order to ensure the coordinated operation of the generator and local networks, we must set the appropriate parameters of various devices.Take the Guangxi some220kV power system islanded power grid as the example, the paper elaborated that the whole planning and practice process of security and stability operations. This process include that design of isolated power system operation mode, analysis stability of voltage and frequency in isolated network, discussion about the voltage and the frequency stability technology when the isolated grid is under steady operation, power load management and control and operation control strategy of power generation units. Two suggestions are proposed. Firstly, in order to enhance the power supply reliability of important urban power loads, we must ensure that the stability of isolated power grid supported by a stand-alone generator. Important generators should have the function of self-start and support isolated power grid. Important city should implement the plan and the construction of the security power source. At the same time,emergency power supply planning for the major cities should be carried out. Secondly, in order to avoid isolated power grid operation mode, we should strengthen power grid construction, build a strong intelligence electrical network and maximize the effect of the operating personnel to ensure that the grid can have a security, stable and economic operation.