Novel NPC three-level photovoltaic grid-connected control method

Abstract

The invention discloses a novel NPC three-level photovoltaic grid-connected control method, which is characterized in that the method is a novel control method combining active filtering and reactivepower compensation with photovoltaic grid-connected power generation. The novel NPC three-level photovoltaic grid-connected control method adopts a quasi proportional resonance controller which does not need coordinate transformation, decoupling control and feedforward compensation, can realize zero steady-state error tracking of an AC signal in a stationary coordinate system, and completes inverter grid-connected control simply and efficiently. The novel NPC three-level photovoltaic grid-connected control method solves the inevitable problems such as complex coordinate transformation, decoupling control and feedforward compensation, realizes the zero steady-state error tracking of the AC signal in the stationary coordinate system, can effectively completes unified control of harmonic suppression and reactive current compensation while simplifying a control algorithm, realizes the functions of reactive power compensation and harmonic suppression on loads, and improves the utilization rate of a photovoltaic grid-connected system.

Description

technical field [0001] The invention belongs to the field of harmonic suppression and reactive power compensation, and in particular relates to a novel NPC three-level photovoltaic grid-connected control method combining active filtering and reactive power compensation with photovoltaic grid-connected power generation. Background technique [0002] Active power filter (APF) is one of the effective measures to solve harmonic and three-phase unbalance problems and improve grid-connected power quality, but its application is greatly limited due to its high price. The inverter main circuit of photovoltaic grid-connected power generation generally adopts a voltage-type full-bridge structure, and its topology, operation mode and control method have many similarities with conventional active filtering and reactive power compensation devices; and in order to maintain the maximum power of solar photovoltaic cells In the output state, its inverter circuit rarely runs at full load, and...

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Problems solved by technology

[0003] The traditional PI controller cannot realize the static error-free tracking of the AC current in the static coordinate system. Some scholars have proposed to establish a mathematical model of the grid-connected inverter in the d-q rotating coordinate system through coordinate transformation, and in the pulse width modulation rectification (PWM ) have been successfully applied in

However, in order to achieve the goal of no steady-state error in harmonic compensation control, conventional PI control must perform coordinate transformation at multiple frequencies, and the complicated calculation limits its practical application

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