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This paper proposed a new control approach for power quality compensation using Unified Power Quality Conditioner (UPQC). This approach has capability of power flow control as well as power quality compensation, too. In the UPQC control, Series Active Filter (SAF) is controlled by dqo approach for voltage sag, swell, unbalance, interruption and harmonic compensation. Also, Parallel Active Filter (PAF)...
When grid voltage is nonsinusoidal, the detection current based on the instantaneous reactive power theory has error. After analyzing the current detection error, a improved n current detection algorithm based on the instantaneous reactive power theory is proposed. The detection current is accurate by the improved current detection algorithm, and the complexity of the algorithm is no significant increase.
Based on PSCAD/EMTDC, the authors build a harmonic analysis model for a bi-pole dual 12-pulse ±1000kV Ultra-High Voltage Direct Current (UHVDC) converter and the interconnected AC system. The control strategy for UHVDC employs the current margin control from CIGRE HVDC Benchmark. The AC system includes the equipments above 500kV and the equivalent circuit under 500kV. The harmonic interaction of DC...
A method that can be used in the calculation of harmonic of MEDC transmission system is described in this paper. This is based on the advanced switching function model of MIDC converters in the DC side and the network topology in the AC side of MIDC. In this method, both the effect of the harmonic interaction between the AC and DC system and the harmonic transfer among subsystems of MIDC are considered...
This paper presents a voltage swell compensator based on a switched autotransformer by random hysteresis voltage control. The advantage of this compensator is that it uses only one controlled switch per phase with no energy storages. Also the control scheme purposed here distributes the harmonic spectrum of the load voltage and reduces its total harmonic distortion (THD). Different voltage swell events...
In view of the difficult interoperations, information sharing and barely reused among existing power quality software and systems, this paper presents a power quality aided service platform which by using multi-agent technology can dynamically compose basic web services to implement advanced power quality aided service functions and meet the rapidly changing business demands flexibly. The aid service...
This paper presents a new type of Hybrid Active Power Filter Device structure, which is based on Double DSP Control with TMS320F2812 as the chip, and combines the active power filter and passive power filters with higher filtering of 5 times, 7 times, etc. In the paper, it introduces the design and realization of the program, and demonstrates the detection and compensation method of the main circuit...
This paper presents a voltage sag compensator based on a switched autotransformer by random hysteresis voltage control. The advantage of this compensator is that it uses only one controlled switch per phase with no energy storages. Also the control scheme purposed here distributes the harmonic spectrum of the load voltage and reduces its total harmonic distortion (THD). Different voltage sag events...
A novel single-phase inverter source based on advanced modulation wave reconstruction pulse width modulation (AMWR-PWM) technology is proposed. The causes of the harmonic production and the impact of balanced and unbalanced systems on the characteristics of the inverter source are analyzed in detail. As a result, a novel method of harmonic elimination of the PWM is presented. The novel PWM technique...
Switching power supply of low voltage and high current based on power electronic technology is widely applied in some industry fields, especially in electroplating, welding and heating. Harmonics in high-power switching supply pollute power system heavily, which must be suppressed effectively. On basis of analyzing harmonic current of switching supply that the output technical specification is 60V/500A,...
Based on current simulation studies of traction power supply system (TPSS), a united simulation model of high-speed Electric Multiple Unit (EMU) and traction power network is built by Matlab/simulink to analyze the characteristic of harmonics while the locomotive is under different work conditions and different output capacities, proving the validity of the model. On the basis of the united model,...
The stability of HVDC system is under the influence of the strength of AC system, which is reflected as the AC and DC short-circuit ratio(SCR) on the converter stations. In this paper, a simulation study is carried out on the sending end of a certain HVDC system that has been put into operation under different SCR, using PSCAD/EMTDC. The simulation indicates that with the reduction of SCR, the recovery...
The harmonic detection of active power filter is a very crucial part. This paper proposed a fast harmonic detection method based on improved iterative DFT. The main features of this method are that 1) the computational complexity of iterative DFT is much lower than that of DFT, 2) it can be used to detect only specific harmonic components, 3) the harmonic current can be directly obtained without low-pass...
Harmonic detection is an important issue for the performance of active power filter (APF), which should provide harmonic current or reactive current accurately and rapidly. At the same time, the detection algorithm is desired to be simple. An improved FBD method combining the generalized inregrator (GI) is proposed. Generalized integrator is used to provide the phase information of the positive sequence...
Two kinds of different arrangements on harmonic-suppressed winding with LC filters is studied in this paper, based on the principle of CRT with simplex control winding. According to the analysis of Equivalent circuit of three-winding transformer, the effect of harmonic-suppressed is optimum when harmonic-suppressed winding is placed between control winding and work winding.The Simulation model of...
The passive control method that apply the passive power filter (PPF) to suppress negative effect of the Thyristor Switched Capacitor (TSC) is given in this paper, in order to improve zero-crossing voltage detection algorithm of controller of TSC. The study aims to suppress transient surge of reactive power induced by the TSC to a point of common coupling (PCC) of the power distribution system. In...
A novel main circuit topology of current quality compensator is proposed in this paper, which is composed of PWM rectifier and cascade H bridge inverter. The three phase inverters are decoupling controlled. PWM rectifier is adopted to maintain the dc-bus voltage stably for the device, the later inverter is composed of cascade H-bridges. The inverter side is controlled by carrier phase shifting and...
At present, the One-Cycle Control of Active Power Filter has two serious problems. One is that this method can just compensate the harmonic and reactive power at the same time, which can not be eliminated separately. The other is that the tracking current will be affected and have huge error when the mains voltage appears distortion. So, through the hard work, in this paper, we adopt the method to...
Microgrid is an effective form of the DGs (distributed generation) integration on distributed network. Through the coordination by energy storage and control devices, microgrid can restrain the negative influence by the DG output fluctuation on the distributed network and buffer the impact of EV charging load effetely. The harmful effect which EV Chargers bring on the microgrid is their nonlinearity...
In order to solve the power quality problem of negative-sequence and harmonic currents in high-speed railway traction systems, a novel power quality compensator is proposed, which is constituted by railway static power conditioner (RPC), two thyristor-controlled reactors and two thyristor-controlled 3rd filters. The RPC contains two converters which are connected back-to-back by sharing the DC link...
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