Ma Shiying

PMU placement based on power system characteristics

We present a novel method for placing PMU in power systems based on power system intrinsic characteristics. In the method power system was first analyzed for find out the major or critical interchanges and major load areas, major control systems, critical equipments and power plants in the power system. The overall PMU facilities should provide comprehensive information of line flows, bus conditions, and control actions for power system dispatcher. Then based on coherent characteristics of rotor angles as well as bus voltages, placement of PMU is optimized. All potentially critical-modes, critical bus-clusters and generators are identified by transient stability evaluation and small signal stability analysis, and then PMU are assigned to those critical buses or power plants. The effectiveness of the proposed approach is verified with a real large-scale power system. PMU placement scheme is being implemented in Northwest China power grid. The proposed approach can also be used to different sized power systems. As the power systems become more populated by PMU, the proposed novel method is a useful and convenient tool for systematic installation of PMU around the network, which may assist system planners in deciding on the location of new PMU installments for better dynamic monitoring and control.

Mechanism Research of Short-Term Large-Disturbance Voltage Stability

The right understanding of mechanism of short-term large-disturbance voltage stability is very important for further research of voltage stability. In this paper, the actuality of voltage instability research are summarized, the concepts of voltage stability and voltage collapse are expounded. The influence of load on short-term large-disturbance voltage stability is analyzed on a simple power system. The results show that the dynamic characters of load must be considered in analysis of short-term large-disturbance voltage stability. Through research of voltage stability and voltage collapse, a new mechanism of short-term large-disturbance voltage instability is presented from the engineering point of view. In the end, some solution measures preventing short-term large-disturbance voltage instability are given.

Study on relationship between inter-area oscillation damping and operating conditions in power systems

Inter-area oscillation problem is an important subject in power system stability and control research. This paper focuses on the influence of network operating conditions on inter-area oscillation damping. Since concerned study lacks enough theoretical analysis, the general rule has not been revealed. Using theoretical deduction, the relationship between electromechanical oscillation damping and rotor angle difference under general cases in two-generator interconnected power system is illuminated. Accordingly, the complex inter-area oscillation damping characteristics in real complex power system is theoretically explained. The moving trend of inter-area oscillation damping with the change of inter-area transfer power is determined by the comparison of damping per inertia of generators in equivalent two-generator interconnected system. Three illustrative examples are proposed to verify the validity of the theoretical analysis.

Study on frequency and voltage regulation strategy of thermal power generating units in wind power uniting thermal power outgoing system

In order to make full use of the voltage and frequency regulating ability of thermal generator in wind-thermal-bundled power delivery system, taking Jiuquan wind-thermal-bundled system as an example, the study on strategies of voltage and frequency regulating is carried out. The characteristics and typical structure of the boiler turbine coordinated control system (CCS) of modern large-scale thermal power units are analyzed, the simulation model of the CCS control mode based on boiler following (CBF) which has wide in-situ application is built. Based on the analysis and the CCS simulation model, the frequency regulation characteristic of thermal power units is studied in the case of disconnection fault occurrence in regional grid. The optimization strategies for the frequency regulation of thermal power generating units are given. The basic types and characteristics of the excitation system in large thermal power generating units are analyzed and the simulation model of self-shunt excitation system is built. On the basis of analysis and simulation model above, the thermal power unit voltage regulation strategies are studied under wind turbine generators group tripping accident.

Research on the DC access grid security and stability analysis

This article research on the DC access grid security and stability analysis. It combed the stability and security of electrified weak link, revealing the power grid dynamic characteristics of evolution mechanism. It study and formulation of reservoir in the power grid security and stability control strategy of DC power transmission system, the access of power grids in Tibet, AC / DC hybrid power grid by the end of security and stability control measures. The conclusion of the study, for reservoirs in AC DC hybrid power grid by the end of the safe and stable operation and control measures for reference to make the reasonable.

Energy research of grid scheduling saving electric power

The power system network loss control problem is not only within the region of optimal control problem, but also the area, upper and lower control coordination and cooperation between regional problem. Various network loss how to control and reduce should become great importance problem to current power grid operation department. This paper study of domestic network loss control domain research, summarizes network loss control classification method based on high voltage power system, put forward power loss control methods, to explore in-depth research network loss control method. Analysis and comparison, and verified by calculation example, in order to realize the grid loss control and put forward some measures and suggestions.

Real-Time Control Techniques Research of Low-Frequency Oscillation in Large-Scale Power System Based on WAMS and EMS

With real-time data from WAMS and EMS, the paper proposes a kind of comprehensive dynamic stability prevention and control method including low-frequency vibration monitoring, oscillation source search and dynamic stability control strategy. This method on one hand observes multiple oscillation modes and damping characteristics that may be existing in the power grid on line from EMS and through real-time small signal stability analysis, combining the sensitivity analysis, dynamic stability control aided decision for every kind of mode is generated. On the other hand, data from WAMS and online Prony calculating method are used to fast detect the occurrence of low frequency oscillation. Once it occurs, oscillation propagation way will be tracked by the algorithm based on transient energy function and dynamic hybrid simulation to identify possible initial oscillation point. Oscillation pattern matching calculations start to choose the feasible real-time auxiliary control strategy from the matching small disturbance mode. In ideal condition, initial point position and oscillation inhibit quell measures will be showed which provides online automatic monitoring method for preventing dynamic instability of power grid. The method gets practical application in Henan interconnected power grid.

Influencing Factor Analysis and Simulation of Resonance Mechanism Low-Frequency Oscillation

The enhancement of structure and the access of various kind of new energy in power grid do not reduce the risk of the occurrence of low frequency oscillation. It’s very important to analyze the influencing factors of low frequency oscillation theoretically in view of low frequency monitoring and analysis. In order to analyze the all kinds of factors of resonance frequency oscillation that caused by continuous cycle small disturbance, this article deduces response characteristics of forced power oscillation from mathematics. Its influencing factors is analyzed from the frequency, amplitude, phase three key elements and electrical disturbances propagation, meanwhile this paper points out the corresponding relationship between the various factors and actual disturbance. Finally the correctness of the analytical results is verified using 3-machine 9-bus system.