| In recent years,with the continuous development of China’s AC-DC hybrid power grid,the requirements for safe and stable operation of power systems at all levels have gradually increased in various regions.More and more regions are gradually adopting large-capacity synchronous condensers to provide reactive support for the system and improve the safety and stability of grid operation.The large-capacity synchronous condenser can emit or absorb reactive power within a certain range,forming mutual influence and compensation with the reactive voltage characteristics of UHV lines.In this paper,the corresponding research and analysis of the operation and application of large-capacity synchronous condenser in UHV DC receiving power grid is carried out.The grid-connected operation mode of large-capacity synchronous condenser is researched,and it is coordinated and optimized with other reactive power equipment in the power grid.Give full play to the large-capacity synchronous condenser’s reactive power control capability to ensure the optimization of the comprehensive operation benefits of the power grid,to further analyze the impact of the large-capacity synchronous condenser on the provincial grid’s reactive voltage.The main research work done in this article is as follows:Firstly,the related algorithms involved in reactive power optimization of power systems are analyzed: two basic algorithms commonly used in power system state estimation are analyzed.Analyze the characteristics of the mathematical model for reactive power optimization of power systems,and explain the general composition of the mathematical model for reactive power optimization and the general solution of the optimization model.According to the characteristics of the variables in the actual power grid,some optimization improvements are made to the reactive power optimization processing method.Secondly,a mathematical model of nonlinear reactive power optimization with a large-capacity synchronous condenser is constructed.The objective function is active power loss and voltage qualification rate.Since the main purpose of the large-capacity synchronous condenser is to adjust the dynamic system voltage when the DC line is blocked,in order to ensure the stability of the UHV DC receiving end grid and enhance the resistance of the UHV DC to the continuous commutation failure,sufficient reactive power margin needs to be reserved in the vicinity of the converter station,so consider adding the reactive power margin of the local power grid to the objective function of reactive power optimization.Based on the steady-state and dynamic correlation analysis of voltage-reactive power,the steady-state reactive power optimization algorithm and the eigenvalue analysis method of dynamic small-interference stability are used to select the peripheral units that adjust the synchronous condenser to form the corresponding local power grid.There is a strong correlation between the generator set and the synchronous condenser in the local power grid.When calculating the reactive power margin,the surrounding area centered on the converter station is no longer considered one by one,but the reactive power margin of the local power grid centered on the synchronous condenser is directly calculated.A solution algorithm for reactive power optimization model was established.According to the different characteristics of the optimization variables,different algorithms were used to alternately process the continuous and discrete variables to be completed to complete the reactive power optimization calculation process.Finally,using Henan Power Grid as an example,according to the optimization model and optimization algorithm established in the article,simulate the operation performance of provincial AVC and write an optimization program to calculate.Verifies the feasibility and practicability of the reactive power optimization model with large-capacity synchronous condenser described in this paper. |
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