Research On Some Problems Of Generation-network's Optimized Coordination In Power System

The power source is not only one of the main methods for electric power generation, but also the basic guarantee and crucial component of generation sector in the unified strong intelligent power grid. With the increasing of installed capacity of power generators and the intensifying of the interconnection of electrified wire netting, the operating characteristics of power systems are getting so complicated that the mutual influence between large units and power grids has become the one of the most critical technical problems that affects the safety and economical efficiency of power generation. Research on the onsite evaluation about parameters of generators involving in the grid and the method of optimal control for coordinating the plants and grids, as well as the strengthening of the coordination of generators and grids, conduces to the upgrade of security and stability of power systems, the improvement of ability in emergency such as large-scale power supply blackout, which is the foundation of conducting a strong grid.This thesis focuses on the optimization problem about the coordination between generators and grids, and proposes an evaluation index system for primary frequency regulation. The system takes objects, events and times into consideration. The thesis also constructs a control strategy of coordination and optimization for AGC and AVC, both of which are based on event-driven and hierarchical control theory. Furthermore, the thesis raises a coordinating control method for generator excitation. The method is based on the control theory of nonlinear robust and the feedback control of fractional state parameters. Finally, the thesis designs a new loss-of-excitation protection program involving the coordination between the generators and the grids.1) This thesis constructs an onsite evaluation index system for primary frequency regulation of generators based on WAMS system. The system can comprehensively analyze and evaluate the ability of primary frequency regulation from three aspects (objects, events and times). According to the data characteristic, it designs specific algorithms for every index, settle the problem that the critical timing of system frequency saltation is uncertain, and avoid the influence of the electromechanical transient state process on the accuracy of the computation results.2) This thesis constructs a hierarchical control system for AGC and AVC, which is based on event-driven,(The event here can be security, quality or economical efficiency), and designs specific system control strategies and control theories for AGV and AVC. Besides, it makes full use of the stratification structure of coordinated control system and the cross iteration method to achieve the coordinated control of power distribution and network loss optimization.3) Taking the dynamic generator model in excitation system into consideration, this paper takes the variations of excitation circuit and speed regulation side as distractions (magnetic and mechanical disturbances in excitation circuit and calculates in the model, and introduce auxiliary control variable into the speed regulation side to enhance the stability of the generators. As a result, the paper draws a control method about the excitation and governing of generators and the coordinated control of power system stabilizers in speed regulation side.4) Through the analysis on the protection device's behavior in the dynamic process of electric grid, this thesis analyzes coordinating relationship between loss-excitation protection and control of generators and system to guarantee the stability, and thus raises an improvement program for loss-excitation protection, taking the coordination of generators and grids into consideration. This program can meet the requirements of angle and voltage stability as well as the power plants and the grids.