Island microgrid inverter control method of adjustable virtual impedance
A technology of virtual impedance and control method, applied in irreversible DC power input into AC power output, output power conversion device, AC power input into DC power output and other directions, can solve the problem of inability to achieve circulating current suppression, etc. Achieve the effect of improving stability margin and improving dynamic performance
Inactive Publication Date: 2018-04-03
CENT SOUTH UNIV
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However, the virtual impedance in this method is a fixed value. When the line impedance is affected by various factors and the impedance value changes, the fixed virtual impedance obviously cannot achieve the purpose of circulating current suppression.
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[0023] figure 1 is the equivalent circuit diagram of the island microgrid. The main parameters of the system are as follows: the DC side voltage of each inverter is 800V, the peak value of the output voltage of each inverter is controlled to be 311V, and the frequency is 50Hz. The load resistance value is 10Ω and the inductance value is 1mH. The line impedance is R L = 2Ω, X L =5mH. L in LC filter n is the filter inductor, C n is the filter capacitor.
[0024] figure 2 is the overall control block diagram of the inverter control method based on adjustable virtual impedance, namely figure 1 Each inverter corresponds to the control algorithm of the controller. The specific implementation steps are as follows:
[0025] 1) Use the voltage transformer to obtain the A-phase capacitor voltage u of the micro-grid inverter output voltage through the LC filter can , through the phase-locked loop PLL circuit to obtain the reference voltage angular frequency ω n ;
[0026] 2...
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The invention discloses an island microgrid inverter control method of an adjustable virtual impedance. The method comprises the following steps of using a phase-locked loop PLL, inputting an invertercapacitor voltage ucn, and acquiring a reference voltage angular frequency omegan; giving a reference voltage amplitude Un, and through a reference voltage generator, acquiring an inverter capacitorreference voltage ucrefn; according to a difference between a common connection point voltage uac and the inverter capacitor reference voltage urefn, automatically correcting a virtual impedance deltaZvirn so that currents output by a plurality of parallel inverters are equalized; subtracting the feedback inverter capacitor voltage ucn and a voltage uvirn of the virtual impedance from the invertercapacitor reference voltage urefn, and through a PR controller, acquiring a reference current irefn; and subtracting a current in from the reference current irefn, and inputting into PWM modulation via a P controller so as to control the inverters. In the invention, the virtual impedance is accurate and controllable, balance operation without circulation of the parallel inverters is realized, a control algorithm is simple and is easy to realize, and system reliability is increased.
Description
technical field [0001] The invention relates to the technical field of distributed power generation and power electronics, in particular to a control method of an island micro-grid inverter based on adjustable virtual impedance. Background technique [0002] The development of microgrid has been paid more and more attention by various countries, its application has become more and more extensive, and it has become more and more important in the construction of various countries. The microgrid includes distributed power sources. Each power source is connected to the microgrid through the inverter, and the electric energy generated by itself is injected into the microgrid. Therefore, how to control the inverter to ensure the stable operation of the microgrid has become a problem that must be solved. The inverters are connected in parallel with each other, and the characteristics of each module should be as consistent as possible. Their control performance directly affects the ...
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IPC IPC(8): H02M7/48
CPCH02M7/48H02M7/493
Inventor 黎燕樊晓平史向月
Owner CENT SOUTH UNIV