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Three-phase cascade H bridge photovoltaic grid-connected inverter interphase power balance control method

A technology of power balance and control method, applied in photovoltaic power generation, single grid parallel feeding arrangement, output power conversion device, etc., can solve the problems of photovoltaic panel illumination imbalance and grid-connected current distortion.

Active Publication Date: 2016-04-06
HEFEI UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0012] Purpose of the invention: The purpose of the present invention is to propose a three-phase cascaded H-bridge photovoltaic grid-connected inverter phase-to-phase power balance control method to solve the problem of grid-connected current distortion caused by the unbalanced illumination of the photovoltaic panels on the DC side of the inverter. Ensure the stable operation of the inverter

Method used

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  • Three-phase cascade H bridge photovoltaic grid-connected inverter interphase power balance control method
  • Three-phase cascade H bridge photovoltaic grid-connected inverter interphase power balance control method
  • Three-phase cascade H bridge photovoltaic grid-connected inverter interphase power balance control method

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Embodiment 1

[0060] Step 1, total power control

[0061] Step 1.1, sample the DC side voltage of each H-bridge unit in the three phases and filter it with a 100Hz notch filter to obtain the actual value V of the DC side voltage of each H-bridge unit pva1 …V pvaj …V pvan , V pvb1 …V pvbj …V pvbn , V pvc1 …V pvcj …V pvcn , sampling the actual value of the three-phase grid voltage v a , v b , v c and grid current actual value i a i b i c , wherein, j=1~n is n H-bridge units per phase of the inverter. In this embodiment, the actual value of the DC side voltage V of each H-bridge unit pva1 =V pva2 =29V, V pvb1 =V pvb2 =29V, V pvc1 =V pvc2 =29V.

[0062] Step 1.2, by performing MPPT control on the DC side of each H-bridge unit in the three phases, the DC-side voltage command value of each H-bridge unit is obtained Wherein, j=1~n is n H-bridge units per phase of the inverter. In this embodiment, taking two H-bridge units per phase as an example, the photovoltaic panels on...

Embodiment 2

[0095] In this embodiment, taking two H-bridge units per phase as an example, at the initial time t=0s, the H-bridge units in the three phases A, B, and C all work at a rated temperature of 25°C 。 , rated light 1000W / m 2 Under the condition of , the DC side voltage command value of each H-bridge unit is obtained At t=0.04s, the H-bridge unit of phase C maintains the same working conditions at the previous moment, and the light intensity of phase A drops to 400W / m 2 , B-phase light intensity drops to 600W / m 2 , get the DC side voltage command value of each H-bridge unit V pva 1 * = V pva 2 * = 27 V , V pvb 1 * = V pvb 2 ...

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Abstract

The present invention discloses a three-phase cascade H bridge photovoltaic grid-connected inverter interphase power balance control method, and aims to solve a grid-connected current aberration problem caused by unbalanced input power of a direct current side photovoltaic cell panel. The method comprises the following steps: (1) controlling total power control to enable direct current side voltages of various H bridge units to track an MPPT instruction value and obtain a three-phase input active power actual value of a system and a total input active power actual value of an inverter; (2) controlling feedforward decoupling current so as to be capable of implementing independent control of active power and inactive power and simultaneously generating a three-phase original modulation signal of the inverter; and (3) controlling interphase power balance, obtaining an overlapped zero-sequence voltage by a ratio of the three-phase input active power actual value to a three-phase active power instruction value, and modifying a three-phase original modulation wave according to the zero-sequence voltage so as to implement balance control of interphase power. The control method is capable of providing an precise zero-sequence voltage value to suppress power imbalance so as to ensure grid-connected current symmetry, and the control method has the advantages of well-defined physical significance, excellent dynamic performance, easiness in engineering implementation and the like.

Description

technical field [0001] The invention relates to a three-phase cascaded H-bridge photovoltaic grid-connected inverter phase-to-phase power balance control method, belonging to the technical field of power balance control of cascaded photovoltaic grid-connected inverters. Background technique [0002] Photovoltaic grid-connected power generation makes the large-scale utilization of solar energy possible, and has the advantages of wide distribution, sustainable, and pollution-free. Facing the problems of high power generation cost and improving system efficiency, the cascaded H-bridge multilevel inverter has become a research hotspot due to its modularization, easy expansion, high efficiency, and ability to generate high-quality grid-connected current and voltage. , and can be used as a photovoltaic panel for an independent DC source, which just solves the shortcoming that this topology requires a large number of DC sources, and can easily realize the independent MPPT function,...

Claims

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Application Information

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IPC IPC(8): H02M7/5387H02J3/38
CPCH02J3/383H02M7/53873Y02E10/56
Inventor 王付胜杨乐张兴
Owner HEFEI UNIV OF TECH
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