Method for suppressing transient drop of DC voltage of photovoltaic inverter

Abstract

The invention discloses a method for suppressing a transient drop of DC voltage of a photovoltaic inverter. The method comprises the steps of (1) calculating differential Udc-d of DC voltage Udc of aninverter in each control period; (2) summing the differential Udc-d of the DC voltage and the DC voltage Udc, producing a difference between the sum and a reference value Udc<*> of the DC voltage toobtain an error of the DC voltage, and obtaining output Udc-out of an outer DC voltage loop through a DC voltage PI controller according to the error of the DC voltage; (3) adding DC all-feedforward iffd to the output Udc-out of the outer DC voltage loop to obtain a reference value i1<*> of an inner current loop; (4) subtracting a current sampling value i1 from the reference value i1<*> of the inner current loop to obtain a current error value, and obtaining controlled quantity of the control period through an inner current loop PI controller according to the current error value; and (5) modulating the controlled quantity to obtain PWM pulses of various switch tubes. According to the method, the transient drop of the DC voltage can be greatly suppressed and the response is fast.

Description

technical field [0001] The invention relates to the field of photovoltaic power generation, in particular to a method for suppressing transient drop of DC voltage of a photovoltaic inverter. Background technique [0002] With the deterioration of the natural environment and the depletion of fossil energy, renewable energy power generation technology has received more and more attention. Among them, due to the inexhaustible characteristics of solar energy and the advantages of clean and pollution-free photovoltaic power generation, photovoltaic power generation technology has been widely used. Photovoltaic power generation is a technology that uses the photovoltaic effect of photovoltaic panels to directly convert solar energy into electrical energy. The photovoltaic panels emit direct current, which needs to be converted into alternating current through a grid-connected inverter. [0003] see figure 1 , the common three-phase grid-connected inverter adopts three-level topo...

AI Technical Summary

Problems solved by technology

However, the control of the voltage loop is related to the tracking of the maximum power point. Changing the response speed of the voltage loop will cause the DC voltage to oscillate near the maximum power point, and the speed of the outer loop is limited by the inner loop of the current, so the response speed cannot be increased too much and cannot be effectively suppressed. Transient dips in DC voltage

Images