Chen Yunping

Development of iterative learning control strategy for active power filter

The paper introduces iterative learning control strategy to active power filter (APF). The control strategy can incorporate feedback and feedforward into the controller of APF and it can enhance the tracking speed, simplify the configuration of the controller and obtain a fast and simple algorithm. The strategy with good robustness can realize self-optimizing and self-stabilizing of the system. It is suitable for the hybrid passive filter and APF The simulation and experiment results are given in the paper.

An ANN and wavelet transformation based method for short term load forecast

A new method for short term load forecast based on an artificial neural network (ANN) and wavelet transformation is presented in this paper. The load series is mapped onto some sub-series with wavelet transformation and then the sub-series are forecast by ANN. Weather factors are taken into account in forecasting. After all sub-series of load series are forecast, the whole predicted load series can be composed or reconstructed. In addition, a new BP algorithm is proposed to speed up the training process and improve the convergence of the ANN. All experimental results show the correctness of the principles proposed and the feasibility of the algorithm.

A live-line measurement method to parameters of high voltage cable lines with mutual inductance based on GPS

The theoretical calculation method with formulae and the conventional measurement method of zero-sequence self-and mutual-impedance of high voltage cable lines are reviewed. Then the principles and mathematical models of zero-sequence parameter live-line measurement method of cable lines with mutual inductance based on GPS (Global Positioning System) technology are presented together with key techniques, hardware structure and software algorithm of the measurement system. Finally, field measurement results with the three different methods are given. Theoretical analysis and field measurement results prove that this new live-line method proposed in the paper is correct, effective and efficient.

Application of models of the wind energy conversion system to wind power dynamic analysis

Due to stochastic variation of the wind energy, the wind power connected to the grid is stochastic. As a result, the voltage of the grid, particularly near a wind farm, fluctuates. According to the characteristics of the wind energy conversion system (WECS), a program including the models of the WECS was developed. The dynamic performances of the startup, shutdown, and running processes of the WECS and the front of the gust could be simulated and investigated. In this paper, a typical WECS connected to a large system (infinite bus) was simulated, and the relationships of the short circuit capacity (SCC) with the wind power penetration were investigated. The results showed that the SCC was one of important factors to affect the wind power penetration. The bigger SCC of the network at the WECS connection, the larger the wind power penetration. There was a maximum penetration level of the wind power to a given SCC. If the wind power of the WECS had exceeded a limit, the grid voltage fluctuation would have been in excess of the allowable value of the grid; in a severe case, the voltage would have been unstable.

New live line measurement methods of transmission lines' inductance parameters based on GPS

This paper firstly reviews the incremental method of live line measurement of parameters of transmission lines with mutual inductance. Then, based on GPS technology and differential equations, new live line measurement methods are proposed. The principles and mathematical models of the new methods are explained in detail. Data processing method using least square method is introduced. RTDS simulation results are provided. Finally, an example of live line measuring two 330 kV transmission lines with mutual inductance in Northwest China power network is given. The wiring diagram, measurement methods and measuring results are shown. Results of incremental method and differential equations method are compared. The field measurement results prove that the new methods can meet the need of live line measurement of parameters of transmission lines.

New methods and realization of live line measurement of zero sequence parameters of transmission lines with mutual inductance

Based on GPS technology and differential equations, two new methods of live line measurement of the parameters of transmission lines with mutual inductance are proposed. The principles and mathematical models of the steady differential method and the transient differential method are explained in details. Data processing algorithm by least square method is introduced in the measurement. The hardware structure of the measuring system and digital simulation results are given. Finally, an example of live line measuring 500 kV transmission lines with mutual inductances in Northeast China power network is given. Comparison of results among the steady differential method, the transient differential equation method and the conventional method is also shown. The field measurement results prove that the new methods can meet the needs of live line parameter measurement of transmission lines

Transient analysis of grounding system under lightning stroke using 3D FEM method

The transient behavior of a grounding electrode under lightning stroke is an interesting topic in EMC analysis of a substation environment. This paper uses a novel method, finite element time domain (FETD) method, to solve this problem. In the calculation, skin effect in the grounding electrode is considered, but neglecting the discharge around it. We get some calculation results of electromagnetic field distribution on a simplified model.

Theory and practice of semiconductor lightning eliminator

The paper introduces the structure and function of the semiconductor lightning eliminator (SLE). It is pointed that the SLE can limit the main discharge current and reduce the rate of lightning current rise. Therefore SLE is very suitable for the lightning protection of microelectronic equipment and flammable and explosive facilities.

Shielding effectiveness of shielding cabinet in substation with 3D eddy current FEM calculation

Detail of the electromagnetic shielding effectiveness of shielding cabinets under serious electromagnetic environments in substation, in which control and protective equipment is installed, have not been very clear until now. The authors research is based upon a numerical simulation method-the 3D eddy current edge finite element method. With this novel analysis tool, considering the geometry, material and air window of the cabinet, they have obtained some interesting calculation results, which may be useful for the design of the cabinet.

An application of ANN in scheduling pumped-storage

An artificial neural network (ANN) based optimization method in scheduling pumped-storage is proposed in the paper. Short-term scheduling as well as real-time dispatch of a pumped-storage station is a constrained optimization problem. It becomes more complicated when coordinated with other generation resources. The computation time is often long and the operation conditions may change unpredictably. A fast and practical way is expected. The ANN is used as a signal processing device, which represents mapping functions from input space to output space. Through a training process, multi-layered feedforward and neural networks can be used to approximate the continuous functions with a given accuracy and real-time solution can be achieved. In this paper three layer feedforward ANN and improved BP algorithm are adopted to solve the problem of pumped-storage scheduling. A set of ANN training data are obtained by running an optimization software. The paper describes how to select and organize the input data and how to train the ANN. A work example is presented and a comparison with traditional method is made. It shows that a fast and accurate solution for pumped-storage scheduling can be achieved with ANN.