Power compensation method for unbalanced direct power control of voltage controlled grid-connected inverter
A power compensation and inverter technology, which is applied in the directions of reducing the asymmetry of the multiphase network, adjusting/eliminating/compensating the reactive power, eliminating/reducing the asymmetry of the polyphase network, etc. Limiting system control bandwidth and other issues
Inactive Publication Date: 2012-10-31
ZHEJIANG UNIV
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Problems solved by technology
Although the positive and negative sequence currents of the VSC are expressed as direct currents in the positive and negative synchronous speed coordinate systems respectively, two PIs can be used to track without static error, but this control needs to extract the positive and negative sequence currents in the control inner loop. components, which will greatly limit the control bandwidth of the system and affect the dynamic and stable response of the system
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[0028] The present invention will be further described below in conjunction with the accompanying drawings, and the purpose and effect of the present invention will become more obvious.
[0029] figure 2 The invention proposes a power compensation method for direct power control of a voltage-type grid-connected inverter (GC-VSI) under the condition of grid voltage asymmetry. Taking a 2kW VSC as an example, the structure of the VSC main circuit is as follows: image 3 As shown, a three-phase fully-controlled bridge 1 composed of grid 14 , line inductance 2 , line resistance 12 , IGBT switch tube 19 and its driver (or IPM module), DC bus capacitor 20 and DC link equivalent power supply 4 is included. The control loop includes: a control chip, a three-phase voltage Hall sensor 5 , a three-phase current Hall sensor 6 , and a single-phase voltage Hall sensor 3 . The control chip usually adopts DSP (such as TI's TMS320LF2812, etc.), and the control process implemented in the DSP ...
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The invention discloses a power compensation method for unbalanced direct power control of a voltage controlled grid-connected inverter, which is suitable for direct power control (the conventional direct power control) without synchronous speed rotational coordinate transformation. The method comprises the following steps of extracting negative sequence voltage signals and positive sequence current signals by collecting voltage and current signals of a three-phase electric network; and computing compensation items of active and reactive power according to selected control targets. In the method of the invention, the compensation items of active and reactive power are injected in the power reference signals of the conventional direct power control according to required control targets so as to respectively eliminate negative sequence current, double frequency fluctuation of the active power and double frequency fluctuation of the reactive power in the electric network, caused by unbalanced voltage in the electric network, and fit different application situations. The invention has the advantages of enhancing the capabilities of control and uninterrupted operation of the voltage controlled grid-connected inverter when the electric network is in an unbalanced fault.
Description
technical field [0001] The invention relates to a voltage-type inverter PWM control technology in the field of power electronics, in particular to a power compensation method for a voltage-type grid-connected inverter to enhance direct power control under the condition of grid voltage asymmetry. Background technique [0002] With its excellent input and output characteristics, voltage-type PWM inverters are widely used in wind power generation, photovoltaic power generation and other new energy generation, as well as high-voltage direct current transmission and other fields. Vector control (VC) and direct power control (DPC) are the main control strategies of voltage source PWM inverter. The research on the direct power control of the voltage source PWM inverter under normal power grid conditions has been relatively complete. However, since the areas rich in wind energy and solar energy are mostly remote and far away from the core large power grid, the power grid is relativ...
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IPC IPC(8): H02J3/18H02J3/38H02J3/26
CPCY02E40/32Y02E40/50Y02E40/30
Inventor 孙丹尚磊章玮方攸同
Owner ZHEJIANG UNIV