Research On Automatic Voltage Control Of Multi-zone Power Grid Based On External Network Equivalent

The modern power system has gradually changed to a complex and large-scale structure.Because large power grid has many parameters and massive data,it is difficult to control the power grid by a single control strategy,nowadays the management mode adopted at home and abroad is to divide the large power grid into multi-area power grids to coordinate and control,the regions are relatively independent and interrelated.With the development of the large-scale power grid,the user's demand for power quality is also getting higher and higher.Therefore,the stability of voltage/reactive power is one of the most important issues in the power industry that needs to be studied and solved for a long time.Therefore,the stability of voltage/reactive power is one of the most important issues in the power industry that needs to be studied and solved for a long time.In order to get all buses'voltage in the power grid qualified and the reasonable distribution of reactive power,the correct voltage/reactive power control strategy is needed.This paper takes the offshore oil platform group power grid and the land multi-area transmission network as the research object.The two different systems are equal to the external network,with the principle of the voltage qualification priority and the basic reactive power balance as the principle,the corresponding target function is set up,and the different AVC control strategy based on the external network equivalent is adopted.The main contents of this paper are as follows:(1)Based on the power grid partition theory,the common static equivalent method,Ward equivalent method,is derived and its limitations are analyzed.In order to reduce the equivalent error caused by load change and overcome the disadvantages of the traditional Ward equivalence,a modified Ward equivalent method based on least square estimation is used in this paper.(2)Several traditional voltage/reactive power regulation methods and their usage scenarios are introduced.Two new continuous reactive power regulating devices and a method of voltage regulation based on sensitivity are introduced,and their voltage regulation characteristics are analyzed.(3)In view of the characteristics and different working conditions of the offshore oil platform,based on the local conditions,and build the equivalent modeling of other platforms,a AVC strategy based on the hybrid reactive power compensation is proposed.(4)The AVC optimization idea of multi-area power grid based on Ward is designed,and the equivalent method of this paper is used in the multi-area power grid.According to the characteristics of land power transmission network,the AVC optimization strategy based on genetic algorithm is adopted to solve the research grid.In order to verify this method,we use partitioned IEEE118 node system to test,and compare the three traditional equivalent methods with the equivalent method in this paper.The simulation results show that the hybrid AVC strategy can suppress the rapid transient voltage fluctuation,and keep the voltage stable,release the dynamic reactive power of STATCOM at the steady state in the steady state,maintain its fast reactive power compensation ability,and get the rapid and economical automatic voltage controling of the offshore platform group power grid.The test of IEEE118 transmission system shows that compared with other traditional schemes,The result of improved Ward equivalence is closest to the reference value.The AVC strategy of this paper can effectively optimize operation index and improve voltage stability.