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Electrical storage devices can be very useful in electrified mass transit and in particular in trolleybus lines and tramways. In fact, storage devices are capable of supporting the line voltages of old lines, avoiding the opening of minimum voltage protective relays, especially when the new generation vehicles of greater power circulate. Among electrical storage devices, supercapacitors seem to be...
It is proposed in this paper a methodology to obtain optimal controllers gains for the rotor-side converter of doubly fed induction generators (DFIGs) using a genetic algorithm approach. The main objective is to enhance the operational security and robustness of the power system, by a more effective contribution of the DFIG controllers to the system controllability. To reach this goal, the crow-bar...
In power system, the voltage pulsation and deficiency or surplus of reactive power will have a great effect on the quality of electric power supply. Dynamicly local reactive power compensation is one of the best methods to reduce the power network loss and improve the efficiency of transmission and distribution. Through the effective methods of compensation, we can keep the balance of reactive power...
This paper aims at the application of a half bridge DC-DC converter as a power factor correction (PFC) converter for a permanent magnet brushless DC motor (PMBLDCM) driven air conditioner. This PFC converter is fed from single-phase AC mains through diode bridge rectifier (DBR) and connected to a voltage source inverter (VSI) feeding the PMBLDCM. The proposed PFC half-bridge converter based PMBLDCM...
This paper presents and compares the performance of two controllers namely Fuzzy Logic and Proportional Integral applied to a voltage source inverter/converter operating as an active power filter. The active power filter is operated to compensate harmonics and reactive power generated by the non-linear load and power factor correction simultaneously. This work is performed in order to make an accurate...
In this modern power system the power quality issue is important issue. Problem of power quality is diverse both in nature and also in terms of the power that must consider. In traditional power system FACTS controllers are used to improve power transfer capabilities and stability performance of the power system. This paper presents a case study of mitigation of power quality problems such as voltage...
A three-phase four-wire DSTATCOM (distribution static compensator) based on three-leg VSC (voltage source converter) isolated with a star/hexagon transformer is demonstrated for power quality enhancement in a three-phase four-wire distribution system. The DSTATCOM is controlled to compensate the reactive power, eliminate harmonic currents, balances the load and also to mitigate the neutral current...
This paper deals with a novel configuration of single-phase hybrid active power filter. One of the advantages of the proposed hybrid filter is its adjustable capability to determine voltage rating and current rating of active power stage by selecting appropriate values for its passive filter parameters. Equivalent circuit of proposed hybrid filter has been presented and its filtering characteristic...
In a power system, load varies from one hour to another, reactive power varies accordingly which results into unacceptable voltage variation. This affects the performance of load and other parameters like power loss and power factor. This paper deals with Simulation of 132/11 kV Distribution Sub Station using SVC for voltage enhancement. Load Flow is carried out, considering balanced system during...
This paper presents analysis of time-ratio-controlled autotransformer as a mitigating device for voltage sag disturbance. Control circuit based on load RMS and voltage sag sensing circuit based on peak detection are employed. Commonly dynamic voltage restorer and STATCOM are employed for mitigation of voltage sag. The proposed system has less number of switching devices in comparison to commonly used...
Through analyzing the typical systempsilas characteristic and Ultra-High Voltage(UHV) ac transmission linepsilas characteristic, the strategy by controllable shunt reactor is presented to improve transmission quality in electric networks in this paper. By using MATLAB PSB, simulation model of UHV ac transmission line from Jindongnan to Jingmen was built to study control effects on frequency over voltage,...
Voltage sag caused by induction motor starting is one of the main causes resulting in sensitive equipment dropout. A simulation model of Dynamic voltage restorer (DVR) has been proposed to mitigate voltage sag caused by high-power induction motor starting. The relationship of starting current and voltage sag depth has been discussed in this paper. Based on these analyses, a control strategy, associating...
This paper presents a novel DC link voltage feedforward control to improve the electric drive system tolerance capability to the dc link voltage sag. A uniform mathematic model, comprising the battery packs, voltage source inverter (VSI), permanent magnet synchronous motor (PMSM) is built up in the d-q rotating coordinates rather in three-phase stationary coordinates. In order to study the influence...
Voltage sags/swells have been becoming the main reasons of equipment tripping in industry, dynamic voltage restorer (DVR) is a power custom device that is used to compensate voltage sags/swells in the distribution system to maintain the voltage level at the rated value of sensitive loads, the DVR can inject three-phase voltages whose magnitude and phase angle can be regulated. This paper explores...
Voltage source converter (VSC) is sensitive to the AC unbalanced input voltages under traditional control strategy, and leads to 2nd order DC voltage fluctuation which will be spread from one station to the other through the DC cables. As a result, it appears to be 2nd order power fluctuation and power quality problems, or even leads to system instability. So it is necessary to carry out the research...
A novel dynamic voltage restorer (DVR) with flywheel energy storage system (FESS) is proposed in this paper, which can compensate the deep voltage sag. In order to increase the amount of stored energy, flywheel energy storage array (FESA) is employed. The topology of the system is introduced and the control strategies for the system are analyzed. An optimized discharging control strategy for the parallel...
This paper presents a nonlinear control strategy for unified power quality conditioner(UPQC) with better stability and dynamic performance in comparison with PI control and classical decoupled strategy. The analysis is based on the rotating reference frame, and the nonlinear property of UPQC mode is partly dealt through the exact linearization via feedback. The operation of control circuit has been...
Power quality of AC excited variable speed constant frequency (VSCF) generator, which adopts cycloconverter as exciting device, canpsilat meet the need of power system well because of harmonics in the output voltage of cycloconverter. So, how to reduce harmonics is an important problem for VSCF generator. A new active power filter method named synchronous filter method is presented in this paper,...
For UPQC, when source voltage or load current are unbalance or distort, conventional proportional-integral controller on the p-q-r axis can not eliminate steady-state error. To solve this question, an AC equivalent proportional-integral controller in p-q-r axis was proposed. Its principle of eliminating steady-state error to zero was analyzed and a new control strategy by using of it was presented...
A method of the thyristor rapid switched capacitors is presented in this paper, which breaks through the bondage of the conventional methods. In addition, a novel algorithm of two time reactive power has been presented, with which reactive power can be calculated fast. Meanwhile, with microcomputer synchronous phase lock technology, quick switching without transition can be realized, dynamic reactive...
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