Analysis Of Dynamic Coupling Relationship Power System With OLTC And Research On Voltage Regulation Method

With the rapid development of China's economy and society,the demand ing for electric energy is increasing,the scale of the power grid is expanding,and the voltage stability problem has become an important concern for the stability analysis of power systems.In the face of the increasingly complex status of power systems,in order to ensure the safe and stable operation of the power system,higher requirements are required for the accuracy and reliability of the voltage stability analysis method.In the context of large power grids,the electrical connections between load nodes or regions tend to be complicated.Therefore,when analyzing the voltage stability problems of power systems with complex network topologies and large number of load nodes,the coupling relationship between nodes should be combined.The relationship between voltage stability between nodes is analyzed.In order to quantitatively evaluate the influence of on-load tap changer(OLTC)regulation on system voltage stability,according to the principle of extreme value analysis of nonlinear equations,the necessary conditions for network transmission power limit are derived,and it is proposed that the system sta tic can be accurately evaluated by the impedance modulus margin index for voltage stability.In the nonlinear power system with OLTC,in order to analyze the influence of continuous adjustment of the ratio,this paper corrects the jacobian matrix that can converge the power flow calculation in the initial state based on the Newton-Raphson method for solving the power flow equations.Dynamic equivalent parameters are proposed to account for the load characteristics and the impedance modulus margin of the OLTC voltage regulation effect.The proposed impedance mode margin index can accurately quantify the influence of OLTC coordinated action on voltage stability in different locations in complex systems.It can be used as a rational evaluation basis for the OLTC coordinated action scheme and the ratio adjustment range of the whole network.In order to analyze the coupling relationship between power system nodes and voltage stability under multi-OLTC coordinated action,the static analysis method and dynamic analysis method of coupling relationship between nodes are proposed by extracting the physical meaning of the impedance matrix elements of power system.Based on the system dynamic impedance matrix,a quantitative index of electrical coupling characteristics that can dynamically track the degree of tightness between system nodes is defined.The weak voltage stability nodes and the nodes with large coupling characteristics are the key nodes of system voltage stability analysis.Finally,the effectiveness and correctness of the analysis method are illustrated by the simulation results of IEEE14 node system.In order to reduce the actions of the voltage regulating equipment and improve the voltage regulation efficiency of the power system,a voltage regulation scheme that uses OLTC and dynamic reactive power devices to coordinate and adjust voltage is proposed.In this paper,based on the dynamic equivalence principle,the node selection function of the voltage regulation region with both node voltage stability and voltage amplitude level is designed.By comparing the static analysis method and the dynamic analysis method of the dynamic reactive power compensation device,the rationality of dynamic reactive power configuration according to the impedance mode margin index is determined.Finally,based on the voltage division area division,a coordinated voltage regulation control strategy is proposed,and the correctness of the coordination control strategy is verified in the IEEE30 system.