Direct power control method for inhibiting voltage fluctuation of DC-side bus of photovoltaic grid-connected inverter

Abstract

The invention discloses a direct power control method for inhibiting voltage fluctuation of a DC-side bus of a photovoltaic grid-connected inverter, and belongs to the technical field of converter control. The method comprises the steps of establishing a photovoltaic power generation system, determining instantaneous active components v<alpha> and i<alpha> and instantaneous reactive components v<beta> and i<beta> of a power grid, realizing the maximum power point tracking of a photovoltaic array by adopting a fixed-step perturbation and observation method, determining the disturbance power Pswith a short wavy line thereon by a disturbance observer through a correction link; respectively taking output signals [nu]<^>P and [nu]<^>Q of two PI controllers as the input of a feedforward decoupling controller to construct a feedforward decoupling model, obtaining voltage control signals e<alpha> and e<beta> by combining the output uP and uQ of the feedforward decoupling system based on voltage v<alpha> and v<beta> of the power grid, and carrying out [alpha][beta] / abc conversion on the voltage control signals e<alpha> and e<beta> to obtain an SPWM control signal e<a, b, c> of the inverter. According to the invention, the feedforward disturbance is introduced into the voltage outer loop, and the zero steady-state error tracking of the DC bus voltage can be ensured by adopting a simpleproportional controller; it does not need to obtain phase information of the power grid voltage and does not need to perform synchronous rotation coordinate transformation, so that the stability problem caused by the use of a phase-looked loop (PLL) is avoided.

Description

technical field [0001] The invention belongs to the technical field of converter control, and in particular relates to a direct power control method for suppressing voltage fluctuations of a DC side busbar of a photovoltaic grid-connected inverter. Background technique [0002] With the rapid development of renewable energy technologies such as wind power and solar power generation, the control of photovoltaic grid-connected inverters has become a research hotspot. As an interface device between renewable energy and the grid, the control performance of the inverter directly affects the grid-connected power quality and grid-connected efficiency. [0003] The photovoltaic inverter is in the state of grid-connected operation, and the DC side bus voltage is easily affected by active power fluctuations. In order to realize sinusoidal inverter, the DC bus voltage must be controlled within a reasonable range and kept relatively stable. If the DC bus voltage is too high, it will t...

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Problems solved by technology

However, this method uses a proportional resonant controller in the inner loop, which needs to convert the power reference into a corresponding current reference, and then control the current, which increases the computational burden of the system

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