Papers by Keyword: Power System

Abstract: Using the principle of wavelet transform in the aspect of signal singularity detection analyzes and detects the electric power system fault signal. Then we extract signal feature near the fault moment and sent the feature vectors into the neural network. The simulation results fully prove the effectiveness and superiority of combining wavelet transform and neural network in electric power system fault recognition.

Abstract: The historical data of wide area measurement system (WAMS) contains the daily record of the number of oscillations. The phenomenon, which the number of these oscillations suddenly increases at a certain frequency, indicates that the risk of weak damping oscillation with this frequency will increase. In other words, the statistical characteristics of these oscillations can reflect the system stability level. In this paper, the formulation of the small signal analysis including power disturbance on the power grid is given firstly. Then the relationship between the oscillation probability and damping ratio is obtained theoretically. Finally, a case study is carried out based on a 10-machine 39-bus power system. Simulation results verify the validity of the expression of oscillation amplitude of tie-line active power and the relationship between the oscillation probability and damping ratio. These theoretical results can be used to guide the power operator to assess the damping level of the power grid based on the daily number of oscillations recored by WAMS.

Abstract: A method for fast search of dangerous lines in power flow transferring was put forward. Search the equal-phase parallel lines of the overload line by graph theory and voltage phasor angle. Search the shortest path between the end nodes of the overload line which went through the equal-phase parallel lines. The lines on the paths belonged to the power flow transferring line set, where the lines with high active power flow distribution coefficient were dangerous lines in power flow transferring. The method is more targeted in the search for power flow transferring path. It will not leave out dangerous lines for only looking for the shortest line between the two nodes of the overload line, and it wil not select the redundant lines for searching the K shortest paths between the two nodes of the overload line. This method is simple and accurate with little calculation. The method is verified by simulation analysis based on IEEE 39 and IEEE 118 bus system.

Abstract: A real-time dispatch (RTD) model for wind power incorporated power system aimed at maximizing wind power utilization and minimizing fuel cost is proposed in this paper. To cope with the prematurity and local convergence of conventional particle swarm optimization (PSO) algorithm, a novel adaptive chaos quantum-behaved particle swarm optimization (ACQPSO) algorithm is put forward. The adaptive inertia weight and chaotic perturbation mechanism are employed to improve the particle’s search efficiency. Numerical simulation on a 10 unit system with a wind farm demonstrates that the proposed model can maximize wind power utilization while ensuring the safe and economic operation of the power system. The proposed ACQPSO algorithm is of good convergence quality and the computation speed can meet the requirement of RTD.

Abstract: Power system stabilizer in a power system is a closed-loop controller. The conventional participation factor method just considers the effect of PSS input signal. When the system stress is heavier, it may give misleading results. Based on the participation factor of modal analysis, an integrative participation factor is proposed to determine the optimum PSS location. The integrative participation factor takes into account both the input and control effect of PSS controllers. The case studied in 2-area 4-generator power system power system confirms that the integrative participation factor is more reasonable and effective than the participation factor method.

Abstract: With the rapid development of the grid scale, there are huge data generated in grid, which include many sample data, alarm data used for real-time monitor and analysis, the traditional dispatching system can’t meet the demands of big capacity storage very well. In recent years, big data technology develop very fast, among it the distributed column-oriented database system is rising gradually with the vigorous development of cloud computing. Considering the character of power data, this paper studies how to use distributed column-oriented database system in power application for storing massive increasing data. The paper design massive data storage structure of power data, design software frame and deployment of massive power data storage. Through experiment it is feasible for distributed column-oriented database to be applied in EMS system through experiment.

Abstract: A harmony search algorithm with opposition-based learning techniques (HS-OBL) to solve power system economic load dispatch has been presented. The proposed algorithm integrates the opposition-based learning operation with the improvisation process to prevent the HS-OBL algorithm from being trapped into the local optimum effectively. Besides, a new adjusting strategy is designed to dynamic adjust pitch adjusting rate (PAR) and harmony memory consideration rate (HMCR), which is to further improve the performance of algorithm. The HS-OBL is employed to solve 6 units and 13 units power system, the numerical results indicate that the HS-OBL has perform much better than harmony search(HS) algorithm and other improved algorithms that reported in recent literature.

Abstract: This paper proposes a reduction in the deficit of electricity in the energy system in Tajikistan, by optimizing the operating conditions of hydroelectric power plants of the power system. The paper reveals the application of the method of Lagrange multipliers for the solution of the optimum distribution of power between hydroelectricity power grids corresponding to the minimum water flow.

Abstract: The technology of VSC-HVDC transmission has a high degree of flexibility and controllability.This paper researches the control strategy of VSC-HVDC and the operating principle of the wind turbine, which can effectively enhance the stability of power system in the region of wind farms, improve the long-distance transmission capacity of wind power and stabilize the voltage level of public connection point.

Abstract: In the view of the safe and stable operation of power system in the extreme environments, the status and the role of two typical provincial power systems in China were analyzed. Combined with the spatial and temporal distribution characteristics of this total solar eclipse in July 22, the operations of the two provincial power systems in different regions during the total solar eclipse were compared. The main impacts of the development process of the total solar eclipse on power systems were analyzed. At last, combined the development trend of the extreme environments in the world, how to reduce the running risk of power system in the extreme environments by the crisis dispatch was explored.