Voltage Control of a Novel Double-Winding Asynchronous Generator with Current Control Voltage Inverter Fu Yu, Ma Weiming, Li Yumei, Wang Dong (Institute of Power Electronics Technology, Naval University of Engineering, Wuhan 430033, China) The electromagnetic compatibility of the system. Its control system consists of two PI voltage controllers and one hysteresis current controller. In order to study its voltage control performance and regulation speed, a mathematical model of the two-winding asynchronous generator and its control system considering magnetic saturation is established. The voltage control performance in dynamic process such as load and sudden change of speed is simulated. The results show that the system has better voltage control performance and response speed.
With the emphasis on renewable energy, the research and development of self-excited asynchronous generators has been accelerated at home and abroad. Cage induction motors have attracted more and more attention due to their outstanding advantages such as simple structure, strong wear resistance, low cost, convenient maintenance and high power density. Conventional self-excited three-phase asynchronous generators provide excitation by shunting capacitors at their outputs, establishing a voltage at the output of the motor. When the load or prime mover speed changes, the output voltage and frequency of the asynchronous generator will change accordingly. The method of synchronous phase modulator is proposed, but the cost and maintenance workload are added. The paper regulates the voltage by controlling the current of the saturated reactor, but the large reactor has the problem of large volume and heavy weight. The transformer performs series compensation on the self-excited asynchronous generator to control the voltage, and the power electronic conversion device will cause distortion of the AC voltage waveform and reduce electromagnetic compatibility.
The novel double-winding asynchronous generator has two sets of windings arranged on the stator. As shown, one set of windings is a power winding, the output end is connected to the self-exciting capacitor and the load; the other set is a control winding, which is connected by a three-phase current. A voltage control loop formed by a voltage-controlled inverter. An electrolytic capacitor is connected to the DC side of the inverter as a voltage source. Since the DC side of the voltage type inverter has no power source connected, the asynchronous generator provides a small amount of active power to compensate the loss of the inverter to maintain the voltage of the DC side capacitor at a constant value. When the motor is running at no load, the self-excited capacitor self-excited to establish the no-load rated voltage; when the motor load is running, the inverter output voltage is adjusted by the controller to provide the required reactive excitation current, so that the terminal voltage is kept constant. There is no direct electrical connection between the two sets of windings, only magnetic coupling, which greatly reduces the influence of the power electronic converter on the power winding and improves the electromagnetic compatibility. 1. In addition, since the number of poles of the power winding and the control winding are the same Therefore, the operating frequency of the power winding and the control winding are also the same. This characteristic makes it possible to determine the frequency of the power winding by the frequency of the control winding and to stabilize the frequency.
For this system, its voltage regulation performance and dynamic response speed are important performance indicators, which need to be studied in detail. Since the self-excited construction voltage of self-excited asynchronous generator is related to the saturation of magnetic circuit, the mathematical model of double-winding asynchronous generator and its control system considering magnetic saturation is established, and the control strategy is analyzed. The voltage control performance in the dynamic process of sudden change of load and speed is simulated. The simulation results show that the system has better voltage control performance and response speed.
Model 1 of the double-winding asynchronous generator 1.1 Mathematical model To simplify the analysis, the coordinate system is selected as the dq0 coordinate of the rotation of the rotor. The mutual inductance between the dq-axis windings and the main magnetic circuit is eliminated by dq transformation, but the mutual leakage inductance between the dq axes is even in the test of Ma Weiming (960) male, professor, academician, Ph.D. And electromagnetic compatibility research in power systems. Hey,
In the case of considering the fundamental component of the air gap magnetic field, it cannot be completely decoupled.
However, these mutual leakage inductance values ​​are very small, ignoring their small error caused by system analysis. Thus, the voltage and flux linkage equations of the power winding, the control winding and the rotor winding can be expressed as the following values: the leakage resistance of the sub-winding, Xm is the excitation reactance, and the subscripts ps and r represent the stator power winding and the stator control winding, respectively. And rotor windings. d, q current and flux linkage.
1.2 Consideration of magnetic circuit saturation The current of the dq axis of each winding is synthesized to obtain the equivalent current, and the saturation parameter (excitation reactance) of the motor can be determined by using the no-load characteristic curve. The saturation magnetization reactance is substituted into the model for calculation to simulate the effect of magnetic circuit saturation.
+idr, synthesize the two to obtain the total combined current and current to determine the excitation reactance Xrn. 2 Control strategy The two-winding asynchronous generator is provided by the current-controlled voltage-type inverter connected to the control winding side to provide the required reactive current. To compensate for the excitation current that changes due to the load.
The control system uses two PI closed-loop controls: one is the closed-loop control of the DC-side voltage of the rectifier bridge load of the power winding; the other is the closed-loop control of the DC-side capacitor voltage of the inverter. The DC side voltage of the generator power winding rectifier bridge load is fed back, compared with the voltage, the error is passed through a PI controller, and its output signal (sq) is used to control the reactive component of the inverter current. If the feedback voltage value is greater than the voltage value, the inverter provides a backward dq axis, 5 read resistance and the n voltage blish regaining the output voltage amplitude of the generator is reduced by m phase Fu Yu, etc.: The voltage control of the new two-winding asynchronous generator with current-controlled voltage inverter requires a leading non-functional amount when the feedback voltage value is less than the voltage value. In addition, the energy that maintains the DC-side capacitor voltage of the inverter to a constant value needs to be provided by the asynchronous generator, so the active component of the inverter current is output by the other PI controller by the DC-side capacitor voltage of the inverter compared with its voltage ( /sd) get.
The unit vector sine waves Va, Vb, and V are obtained by dividing the control winding output voltages Usa, Usb, and Use by their amplitudes Um, and Wa, Wb are sinusoidal waves of phase Va, Vb, and V.
3 Results and analysis In order to study the voltage regulation performance of the system, some dynamic processes were simulated, and the power windings were loaded with rectifier bridges. See Appendix for system parameters. The waveforms of the DC side voltage and the control winding current of the rectifier bridge of the self-excited no-load construction voltage and the inverter suddenly put into operation are given. When the inverter is put into operation at 4.2s, the DC side voltage of the rectifier bridge and the phase current of the control winding will have an impact, but it will soon become stable.
The phase current waveform of the DC link voltage of the rectifier bridge and the power winding when the rated load is suddenly applied and unloaded. At 3s, the load is suddenly loaded to full load, and then 5s is then unloaded to no load. It can be seen that when the sudden load is suddenly applied, the voltage on the DC side of the rectifier bridge is abrupt, and the phase current impact of the power winding is not as good as that of the system. The BumalElecic postal H. Can 4 conclusion that the new double-winding self-excited asynchronous generator can be compared. It can solve the problem of traditional asynchronous generator voltage changing with load and improve system electromagnetic compatibility. In this paper, a mathematical model of a two-winding asynchronous generator and its control system considering magnetic saturation is established. The voltage control performance in the dynamic process of sudden change of load and speed is simulated. The results show that the system has better voltage control performance and response speed.
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