Zonghe Gao

Design of intelligent dispatch systems network analysis software

Smart grid is the ideal solution for future power system. As the nerve center of smart grid, the intelligent dispatch systems represent the intelligence characteristics. The network analysis section is foundation to achieve intelligent dispatch. In traditional dispatch systems, the network analysis software (NAS) are divided by module functions and shows information respectively, which result that the conclusions are relatively separate. The operator did not get computed information from integrated entity. The useful information cannot share to other advanced applications, which weaken the foundation action of NAS. This paper present the NAS design of the functions and construction based on intelligent dispatch systems. The software layout regard the service as guiding and function as components to meet the requirements of network analysis, which reach the purpose of full-featured, flexible and convenient. At same time, it takes advantages of the intelligent scheduling system with a unified platform, and enhances information exchange and data sharing with other advanced applications. The other requirements and development of NAS in intelligent dispatch systems are also discussed in the paper.

Research on real-time control strategy of tie-lines in UHV interconnected power grid

Researches on UHV power transmission have been carried out more than forty years. It aims to improve the transmitting capability of power grid and realize the long-distance large power transmission and system interconnection. In China, the successful commissioning of UHV pilot projects makes it possible to optimally dispose electric power resources on a large scale, to effectively control the short-circuit current in the areas of high electric density, and to solve the dynamic stability problem in long chained power grid. On the background of UHV networking, the system frequency will be more stable, but even micro fluctuation of system frequency can cause the power flow of UHV tie-line to be changed. Started from instructing the relationship between active power of tie-line and system frequency, this paper researches on the primary cause of why tie-line flow changes and analyzes the principle how it changes. Then new control strategies for tie-line flow control on the background of UHV networking are especially presented, which provides some reference to Three-Hua synchronous UHV power grid, which connects North China, East China and Central China grids.

Research and development of multivariable coordinated automatic voltage control system for Guizhou power grid

Reactive power and voltage control is the important technical means to improve the voltage quality and reduce the active loss of power grid. It is hard to regulate the voltage and reactive power of Guizhou power grid by manual operation. In this paper, adopting to the successful experiences in automatic voltage control (AVC) system of several power companies in Europe and China, a new decomposition and coordination method is presented for multivariable coordinated control between generators, shunt capacitors, shunt reactors and adjustable reactive loads. Firstly, the method utilizes the primal-dual interior point algorithm to solve an large-scale discrete and mixing optimal reactive power flow (ROPF) calculation, which gives an optimal voltage profile of the whole power grid; Then the method utilizes the extended coordinated secondary voltage control to optimize the regional reactive power distribution with discrete and mixing variables coordination based on the local balance of reactive power, whilst satisfying the optimal voltage profile. The substation of district power network is equivalent to the adjustable reactive loads with coordination between provincial and district AVC systems. The paper also presents a new method of main and auxiliary dual instructions, which is used to control the plant voltage by master station. The newly developed AVC system has been put into practical operation in Guizhou power grid, and the results show that the AVC system is remarkably effective.

The control strategies and assessment methods for transmission interface power flow based on hierarchical and divisional dispatch mode

Due to the rapid development of China power source construction, the generation and load in regional power grids are gradually imbalanced, which highlights the contradiction between power source and network distribution and causes the security constraints problems. The paper first presents a divisional control modeling method which significantly reduces the complexity of the flow control. Then, an automatic hierarchical interface control strategy is proposed based on the divisional dispatch mode, which achieves the multi-target and hydro-thermal coordination. In addition, the paper also designs a series of indexes which used to evaluate the control performance for transmission interface control. These indexes provide a basis for decision making on real-time power control. The proposed control strategies and assessment methods have been put into operation in actual power grids. The results are proved to be feasible and effective.

A multi-objective coordinated control method for AGC

By dividing the global area into several control areas, a multi-objective coordinated AGC control method is introduced in this paper. The main control areas objective is the ACE of global area. The sub-areas maintain the power flow of transmission lines among areas at scheduled interchange and cooperate with the main area in emergency. AGC system based on the addressed method can realize multi-objective coordinated control conveniently. The proposed method has been implemented in several provincial power grids in China and proved efficient.