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The fundamental theory and control methods of Active Power Factor Correction (short for APFC) are introduced in this paper. It analyzes and studies the APFC based on the three-phase rectifier. In addition, the simulation model is built on the MATLAB and the results are shown in this paper. The results show that the grids-side input current wave is changed with a sine wave, has the same phase with...
SVPWM can improve the using efficiency of dc voltage much, and its control principle is so simple that it can be easily realized on microcomputer. If it is introduced into the VSC-HVDC which powers to passive network, it will have good performance. This paper firstly introduces the principle of VSC HVDC and the SVPWM technology, then discusses how to realize the SVPWM technology on microcomputer and...
Taking the unified power flow controller as an example, this paper states the applying foreground of flexibility AC transmission system technology in distribution systems, which comprise wind power generators. As for the impacts of the wind power on the power systems, this paper indicates the deficits of the unified power flow controller, proposes the idea that integrating the energy storage system...
Micro-grid technology can integrate the advantages of distributed generation power system, to provide users with quality and reliable electricity. This paper designs the photovoltaic system which is short for PV based on the energy storage structure which not only analyses the energy flow direction of the charging and discharging circuit, but also designs the control strategy of charging and discharging...
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)...
This paper presents the possible improvements of voltage quality in connection of a wind farm to transmission network using VSC-HVDC (Voltage source converter high voltage direct current) link. For a 80 MW wind farm consisting of 40 individual 2 MW doubly fed induction generators, the main influence of voltage fluctuation caused by the wind farm integration is analyzed. The use of a reactive controller...
The paper researches the impacts on the voltage of distribution network after grid connected of distributed generation mainly. First, the paper establishes the DG, distribution network and load model, proposes the algorithm of the simplified voltage superposition theorem, and confirms the accuracy of this algorithm. Then according to the varieties of capacity and location and power factor of DG, and...
Aiming at regional power grid whose power supply is a substation that connects the upper and lower grid, REI (Radial Equivalent Independent) equivalent is applied to voltage and reactive power optimization control, and varying-intercept linear regression method is proposed to obtain equivalent parameters according to local data taking into account the difficulty of getting the upper grid operating...
As the output power of the photovoltaic (PV) cell changes with the insolation , PV cell temperature and cell voltage changing. It is necessary to control the operating point to draw the maximum power of the PV cell in order to increase system efficiency. In this paper, two-level single phase PV grid-connected system is designed, which mainly includes PV cell, BOOST circuit, inverter, filter and the...
This paper presents an on-line equivalent algorithm for power system based on phasor measurement unit. The method considers the changes of the system parameters and load level, which overcome parameters rift problem and the shortage of traditional two points power flow method that supposing the parameters are fixed after a small disturbance. On this basis, voltage stability and Alert margin are proposed,...
Abstract-Voltage breakdown is one of the most failure mechanisms to IGBT. High voltage can generate high electric field at PN junction of IGBT which withstands high voltage blocking. High electric field can bring avalanche phenomenon if this voltage is too high to make PN junction avalanche breakdown. Avalanche breakdown can make current rising dramatically and destroy the IGBT device lastly. This...
This paper presents a procedure for allocating reactive power using artificial neural network (ANN). Artificial neural network is trained based on data from Y-bus matrix. Training and testing of this ANN network have been done with five bus test system. Back propagation learning has been utilized to train the ANN. A numerical example on allocating reactive power using a feed forward back propagation...
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...
It is very important for the ±800kV UHVDC transmission project to study the overvoltage protection and insulation coordination of the converter stations because of its importance in the power grid. The paper studies the DC transient overvoltage of the converter station in the Nuozhadu-Guangdong ±800kV UHVDC transmission project by using the PSCAD simulation program. The simulation results show that...
In this paper, an adaptive fuzzy MPPT controller is designed with FPGA, the design of fuzzy controller and adaptive control theory is described in detail, and it is discussed that how to implement adaptive fuzzy MPPT control with FPGA, and finally The solar storage control system is built with the controller, the experiment proved that the controller using this method can adjust the parameter according...
Based on the discuss and the analyse of the domestic and international study of self excitation over voltage and switching over voltage in 1000kV ultra high voltage long distance transmission line, the main point of the study of these problems is proposed . The first point is the precise production condition of the self excitation over voltage. Besides, the possibility of simultaneity and superposition...
The functions, tasks and operation flow of energy management system are planned for the supervisory control platform sited in lab microgrid. The mathematical formulation on economical dispatching and optimal operation is presented in detail. The control strategy combined central control and local control is put forward for microgrid operation and validated through the microgrid PSCAD model. The results...
The paper discusses the characteristic of single phase fault in Petersen-coil-grounded distribution grid, analyzes the zero sequence voltage and currents of the Petersen-coil, fault point, fault feeder and sound feeders. Adaptive Petersen-coil is applied to help detecting and extinguishing the single earth fault. And the paper studies characteristic of the derivatives of the zero sequence currents...
The low-voltage ride-through (LVRT) capability of a MW-Level variable speed wind turbine with a direct-driven permanent magnet synchronous generator (PMSG) is a hot topic these days. To prevent over-rated dc-link dynamic voltage, a novel dc-link voltage control scheme is proposed. In this paper comparing with traditional control method, the generator-side converter uses a doubly closed loop namely...
In this paper the soft turn-on of NPT IGBT under Active Voltage Control (AVC) is presented. The AVC technique is able to control the IGBT switching trajectory according to a pre-defined reference signal generated by a FPGA chip. By applying a special designed reference signal at turn-on, the IGBT turn-on current overshoot and diode recovery can be optimized. Experiments of soft turn-on with different...
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