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Through analyzing the principle of unified power quality conditioner (UPQC), taking the left series-right parallel structure as example, the relationship of energy flow is analyzed. The power demand formulas of series side and parallel side are demonstrated and derived on this basis of minimum energy method. The selected principle of main circuit capacity is determined. Finally, experimental results...
This paper designed a double close loop control system based on current and voltage. As the system instable in some cases, the traditional PI regulator can not regulate the system more precisely. To make a more stable and better control effect, it should be improved by using Neural Network Control to get a feedback adaptive control system of PWM rectifier in order to achieve better results.
Adaptive focusing particle swarm optimization (AFPSO) based on the balance characteristic between global search and local search of particle swarm optimization was an adaptive swarm intelligence optimization algorithm with preferable ability of global search and search rate. AFPSO was proposed to optimize the reactive power optimization. Based on optimal control principle, AFPSO applied for optimal...
Multi-segment Primary Permanent Magnet Linear Synchronous Motor (MP-PMLSM) drives is investigated in this study for vertical linear transportation applications such as a ropeless elevator. The optimization model of MP-PMLSM is established for various considerations of force ripple, driving force, weight and cost. Single primary unit length and the number of primary units are newly chosen as important...
When it is in the wet season and the load is low, reactive power surplus and voltage rise are caused by high-efficiency power generation of small hydropower and load reduction in Linjiang region, Baishan city, JiLin province. These problems, which exist in the power grid, are systematically analyzed in this paper. The solution measures are proposed including generator in leading power factor on operation,...
Considering a large number of negative sequence and harmonic currents caused by V/V traction structure and locomotive load, a reasonable structure of RPC (Railway Static Power Conditioner) was discussed to improve the power quality. The electrical characteristics of V/V traction structure and the negative sequence compensation principle were analyzed. And a method was proposed to obtain the reference...
This paper presents a digital controlled distributed converter system with a switched-mode boost type PWM rectifier and several bidirectional buck/boost dc/dc converters for battery charge and discharge system using digital signal controller (DSC). The rectifier can implement bidirectional power flow, sinusoidal current control and unit power factor in grid side. The system is able to control power...
On the basis of analyzing the maximum short circuit current flowing through the converter valve under different short circuit conditions, the authors propose a method of calculating the short circuit impedance. In addition, on the basis of taking the restrictions which have great influence on the short circuit impedance of the converter transformer into account, the authors point out that the short...
In this paper, a novel control method for the three-leg based three-phase to two-phase matrix converter is proposed. The instantaneous two input line voltages are used to synthesize the desired output voltages, which can get sinusoidal input currents with unity power factor and two-phase sinusoidal output voltages with 90° angle shift. The biggest voltage transfer ratio can reach 0.866. A double-sided...
The vector control strategy for double-fed induction motor fed by back-to-Back dual three-level converter was studied in this paper. The accurate observer and effective control of the stator flux for double-fed induction motor has significant sense to the performance improvement of vector control system. In the thesis, two one-stage low-pass filters are adopted instead of the pure integrator in the...
At present, the fuzzy control method is a more advanced and reasonable control method. This paper adopts the fuzzy control method of UPFC parallel voltage control and series power modulation to solve the active and reactive power flow control effectively, so that the transmission lines can transmit more power with smaller loss.
A high performance rectifier with a novel structural and wide speed range for direct-drive wind energy system has been investigated and design. The utilization rate and efficiency of low wind are critical focus for wind energy system, in the form of ultimate output dc voltage as the optimum object, a traditional full-bridge PWM rectifier and a boost circuit for the direct-drive permanent magnet synchronous...
This paper introduced the control strategy of back-to-back full-scale PWM converter in direct-driven wind power system with PMSG (Permanent Magnetic Synchronous Generator). A simulation model has been built to demonstrate the maximum wind energy capture, DC voltage stability and decouping control of active and reactive power. In addition, the dynamic responses of system parameters during typical voltage...
In the recent years, there has been a growing interest in the design of high-pressure sodium lamp electronic ballast. Two measures are proposed to improve the power factor of high-pressure sodium lamp electronic ballasts from the definition of harmonic and power factor. And the basic principle of active power factor correction is also discussed in this paper. The active power factor correction circuit...
This paper presents a new decomposition and coordination algorithm based on Ward equivalent to solve distributed reactive-power optimization problem in multi-area power system. At first, multi-area interconnected power system is partitioned into master and slaver areas, boundary buses are defined as different bus types respectively corresponding to different areas, and hence the transfer method of...
Distributed Generation (DG) can bring support to distribution system, meanwhile, it bring unbalancedness in power source, load and line. Traditional load flow algorithms are not applicable to the weakly meshed distribution system with DGs. First, this paper present a direct algorithm based on BIBC matrix and BCBV matrix. With some improvement it is applicable to unbalanced and weakly meshed system...
In this paper, an improved Tabu search method is proposed and applied to reactive power optimization planning in power systems. The improvement is done mainly by changing the way that the initial value is generated, and by adding sensitivity analysis and expert knowledge to Tabu search process. The minimum sum of active power loss and the cost of reactive equipment are used as the objective function...
This paper introduces present situation of power grid synchronization parallel operation, and analyzes the principle and characteristics of back-to-back commutation mode and VSC-HVDC. Back-to-back VSC-HVDC is proposed in this paper, which can be used in the power grid synchronization parallel operation. Its working principle is that the difference of frequency and voltage can be regulated by means...
This paper is involved in reactive power optimization. The combining strategy of genetic algorithm and particle swarm algorithm is proposed for the optimization problem of reactive power in this paper. It is necessary that the initial individuals are feasible ones, and good individuals are chosen as the initial particles in the combining strategy. The numerical examples of IEEE-6 and IEEE-30 power...
In the assumption that all load nodes are installed reactive power compensation device, injecting a variety of disturbances to the grid, through the application of improved ant colony algorithm, we can obtain the optimal control sequence under disturbance, that is current switching reactive power compensation device node location. Comparing control sequences under the various perturbations, with circulation...
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