Dichen Liu
Wuhan University
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Publication
Featured researches published by Dichen Liu.
ieee pes asia-pacific power and energy engineering conference | 2009
Bo Wang; Dichen Liu; Xiong Li
GPS-based synchronous phasor measurement technology is a powerful tool for the security and reliable operation of the inter-connected electric power system. This paper presents an ACO-based approach to optimize the phasor measurement unit (PMU) placement problem. The pheromone trail persistence coefficient adaptive adjustment mechanism and stochastic perturbing progress are introduced into the ant colony system(ACS), in case the algorithm entering the stagnation behavior and getting stuck at local minima. The improved algorithm outperforms the ACS in obtaining global optimal solution and convergence speed, when applied to optimizing the PMU placement problem. A graph-theoretic procedure based on depth first search is adopted to analyze system observability. Simulation results in optimizing a provincial 46-bus system PMU placement problem show that the improved ACS algorithm is effective.
conference on industrial electronics and applications | 2007
Jie Dang; Dichen Liu; Xiaolu Bai; Yuanxin Xiong
This paper develops a simplified dynamic phasors model for TCSC. The existent dynamic phasors models are accurate and suitable for transient simulation. Note that the order of dynamic phasors model is typically higher than the order of the original time-domain equation, so a further simplification, first based on the participation factors of state variables, then based on the coefficients comparison between Fourier series and dynamic phasors, is discussed in this paper. The distinguishing feature of the proposed model is the important harmonic characteristics are analyzed while the order of this model is still controlled to a real second-order state-space equation. Validation of the model is done by comparing simulation results of the proposed model and time-domain model. The results show that this model has excellent tracking behavior, good stability and more valuable for transient simulation and control design.
conference on industrial electronics and applications | 2009
Li Xiong; Dichen Liu; Bo Wang; Ping Wu; Jie Zhao; Xi Shi
The large capacity nuclear power plants have been widely constructed in recent years to cope with social economic development and electrical energy demands. Consequently, it is necessary to be aware of nuclear power plant (NPP) dynamic characteristics in order to study the transient and midterm dynamic process of power system. Due to lacking suitable NPP model which is described the detail characteristics of the Nuclear Power Unit in the power system simulation, at first, the paper presents functional description of nuclear power plant. Then a detailed pressurized water reactor (PWR) plant overall model for medium-term and long-term power system transient stability is proposed based on PSASP through user-defined modeling program. In the end, dynamic response characteristics of pressurized water reactor is presented. The simulation results are obtained.
conference on industrial electronics and applications | 2007
X. W. Du; Dichen Liu; Yuan Li
This paper introduces a mixed digital/analog testing system for relay protection of power system, which creatively integrates digital simulation and analog testing in one system. The system accepts almost all kinds of power fault data including actual fault data, simulation data and imaginary data and possesses powerful fault analysis function based on accurate basal value calculation using the modified-DFT algorithm. The digital simulation software for relay protection is embedded in the upper-computer of the system, which provides an open, expandable experimental platform for users. A closed-loop configuration and a novel modified algorithm using wavelet neural network (WNN) are applied in the lower-amplifying part of the system, which reduces the non-linear distortion of the output waveform of analog protection test greatly. A prototype of the proposed instrumentation system has already been put into practical operation and the good effects obtained have revealed its practicability and effectiveness.
ieee international conference on power system technology | 2006
Qingfen Liao; Dichen Liu; L. M. Ying; X. Cui; Yuan Li; W. T. He
The parameter identification based on Hopfield neural network (HNN) was applied to a static excitation system. The applicable algorithm of the identification method was given in detail. Nine-parameter excitation system was studied. The HNN of twenty neurons were designed in order to identify these parameters. Finally model validation was performed. Numerical simulation results testify that this method has high precision and quick convergence. The method can be implemented with electronic circuit, so it will benefit the on-line parameter identification of the excitation system and will have significance to any system that can be described by state space model.
ieee pes asia-pacific power and energy engineering conference | 2010
Suxuan Guo; Dichen Liu
This paper presents a three-phase 2N+1 level transformer less cascaded pulse width modulation (PWM) static synchronous compensator (STATCOM) that intended for installation on industrial and utility power distribution systems. Based on voltage oriented control (VOC), this paper proposes a control algorithm that devotes itself not only to meet the reactive power compensation but also to voltage balance of isolated and floating dc capacitors of each H-bridge converter. Based on the relationship of reactive power and active power for each H-bridge converter, the proposed control system is detailed, and the simulation results also demonstrate the validation of proposed control strategy.
ieee pes asia-pacific power and energy engineering conference | 2009
Xi Shi; Ping Wu; Dichen Liu; Xiong Li; Jie Zhao; Yuanyuan Zhang; Zunlian Zhao
In this paper, we propose a dynamic mathematical model for nuclear power plant (NPP) reactor, and give an implementation in Power System Analysis Software Package (PSASP) through a user-defined program. NPP is modeled with a bipartite model that consists of the neutron dynamics module and thermodynamics module. Through the simulation results of NPP reactor under different disturbances, a conclusion can be drawn that the temperature effect and poisoning effect are crucial to the self-stability of reactor, which is not only the basis of safe operation of the nuclear power plant but also the aim of the designing. The simulation validated the proposed NPP reactor model, and it can be packaged with the other parts of the NPP detailed model in PSASP for further usage in dynamic calculation of the power system. Index Terms—NPP reactor, modeling, self-stability, PSASP. modified and new codes need to be added and debugged carefully via the compute languages which is used for the implementation. In this paper, a reactor model suitable for the high-dynamic analysis was proposed, in which the constant pressure sta- bilized was simplified, and the fuel/coolant temperature ef- fect and poisoning effect were considered to model the true characteristics of reactor more accurately. And we give an implementation of the proposed model in PSASP, a mature and powerful software for steady-state/transient/small-signal stability analysis. Although there is a mature database of models for nearly all electrical devices for PSASP, nuclear unit model is still lacking in the available commercial power system simulation software. And the reactor model can be packaged in the PSASP with the other parts of the NPP models to complete the database. And it can be easily invoked by other researchers for diverse dynamic analysis without modifying the existing program or adding new codes. Based on the program, the basic characteristics of the reactor were studied.
conference on industrial electronics and applications | 2009
Cong Zeng; Dichen Liu; Qingfen Liao
By defining the relationship between regular-sampled PWM and space vector PWM (SVPWM), the implied modulating waves in SVPWM technique is identified in this paper. Then a simulation model of SVPWM controlled three-phase Voltage Source Inverter (VSI) is built under Matlab\Simulink based on the explicit modulating waves. During the simulation, various possibilities of adding a zero-sequence component to the sinusoidal modulating waves are explored and the effects are discussed. It proves that the injection of zero-sequence components results in an extended linear modulation range and high output voltage in PWM inverters.
ieee pes asia pacific power and energy engineering conference | 2014
Xiangyu Han; Jun Liu; Dichen Liu; Qingfen Liao; Jingzhu Hu; Yunlei Yang
The traditional methods used for distribution network planning are challenged because of the access of the stochastic distributed generation. A new distribution network planning model is proposed by converting the distribution network planning with distributed generation into solving the Steiner tree problem. Moreover, in order to solve the problem that the time of calculation multiplied along with the increase in the amount of Steiner nodes, an improved particle swarm optimization algorithm is proposed to solve the Steiner tree Non-deterministic Polynomial problem. In this algorithm the problem of premature convergence is solved by applying a small disturbance to the global optimum and the searching results are more reliable and accurate by improve the search ability for global optimum. Typical results of the proposed algorithm and the traditional algorithm are further illustrated and compared through an actual 54 nodes system to prove the validity of the methods in this paper.
Journal of Applied Mathematics | 2014
Feifei Dong; Dichen Liu; Jun Wu; Fei Tang; Chunli Song; Haolei Wang; Lina Ke; Bingcheng Cen; Wentao Sun; Zhenshan Zhu
Constructing core backbone grid is conducive to strengthen the construction of grid structure and improve the ability of withstanding natural disasters. The survivability index of power grid is made up of four indices, namely, the resistibility, recoverability, security, and connectivity. Based on survivability, a method of constructing core backbone grid with the optimal criteria of the minimal total line length and the largest integrated survivability index is put forward. The biogeography-based optimization (BBO) algorithm is used to search for the core backbone grid. Compared with the traditional algorithms, BBO algorithm shows advantages in fast speed of convergence and high convergence precision. Moreover, the searching results for three kinds of objective functions by BBO algorithm verify the effectiveness of the proposed model of constructing core backbone grid.