Novel topological-structure multifunctional single-phase grid-connected inversion system and method

Abstract

The invention provides a novel topological-structure multifunctional single-phase grid-connected inversion system and method. The system comprises a photovoltaic direct-current power source, a first capacitor, a second capacitor, a photovoltaic panel end capacitor, a switching tube parallel capacitor, a first inductor, a coupling inductance primary-side self-inductor, a coupling inductance secondary-side self-inductor, a coupling inductance mutual inductor, a diode, a first switching tube, a second switching tube and a single-phase alternating-current power distribution network. According to the system, an inductance value of the coupling inductance primary-side self-inductor and an inductance value of the coupling inductance mutual inductor are equal, so that switching ripples of a grid-connected current are eliminated; and since a cathode of the photovoltaic direct-current power source, a cathode of the photovoltaic panel end capacitor, a cathode of the switching tube parallel capacitor, a source of the first switching tube and a cathode of the second capacitor are connected with a neutral line of the alternating-current power distribution network, a common-mode leakage current is eliminated. According to the method, decoupling of photovoltaic cell panel output power and alternating-current-side grid-connected power can be realized just by regulating switching frequency, andpower fluctuation of doubled grid frequency at a direct-current side can be effectively suppressed.

Description

technical field [0001] The invention relates to the technical field of power electronic conversion, in particular to a multifunctional single-phase grid-connected inverter system and method with a new topology. Background technique [0002] Single-phase non-isolated photovoltaic inverters have the advantages of small size, low cost, and high efficiency, and are widely used in small and medium power distributed photovoltaic power generation grid connection. At present, many different types of single-phase non-isolated photovoltaic grid-connected inverter topologies have been proposed, such as single-phase full-bridge, single-phase half-bridge, and neutral-point clamped. However, due to the lack of transformer isolation, single-phase photovoltaic grid-connected inverters generally have the problem of common-mode leakage current, which affects the efficiency of the inverter, and even generates electromagnetic interference, which endangers personal safety. The power fluctuation...

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Problems solved by technology

Filters suitable for grid-connected inverters mainly include L-type and LCL-type filters. L-type filters do not have resonance peaks, but have low ripple attenuation capabilities, and usually require a larger inductance value to meet filtering requirements; while LCL-type The filter has strong filtering ability, but there are resonance peaks. Although the resonance peak can be suppressed by the active damping strategy, it increases the complexity of the control strategy

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