Method for improving photovoltaic power generation low-voltage ride-through capability

Abstract

The invention discloses a method for improving photovoltaic low-voltage ride-through capability. The method comprises the following steps: 1) establishing a photovoltaic L-type inverter mathematical model; 2) carrying out Park transformation on the mathematical model in the step 1) to obtain a two-dimensional voltage equation; 3) simplifying the voltage equation in the step 2); 4) taking the d-axis and q-axis cross coupling item in the step 3) as current control feedforward compensation; 5) discretizing the feedforward compensation item in the step 4) to obtain d-axis and q-axis prediction equations at the moment k + 1; 6) expressing the output control quantity at the moment k as a prediction equation; 7) substituting the output control quantity at the k moment in the step 6) into the prediction equation in the step 5) to obtain new d-axis and q-axis prediction equations; 8) obtaining a k + 2 moment prediction model according to the prediction equation in the step 7) when the control increment at the k moment is 0; 9) setting an objective function according to the photovoltaic low-voltage penetration working condition; 10) setting two current control modes of normal / voltage drop. Model prediction is adopted in photovoltaic inverter control, and the low-voltage ride-through capacity is improved.

Description

technical field [0001] The invention belongs to the technical field of photovoltaic power generation, and in particular relates to a method for improving low-voltage ride-through capability of photovoltaic power generation. Background technique [0002] With the continuous increase of grid capacity, the large-scale access of new energy generation such as photovoltaics will inevitably affect the stability of the power system. Photovoltaics are connected to the grid through the inverter device. When a voltage drop accident occurs on the grid side, the power electronic components used in the inverter device will be damaged. Therefore, it is necessary to carry out research on improving the low voltage ride-through capability of photovoltaic power generation. [0003] In order to enable photovoltaic power plants to have low-voltage ride-through capability, the current mainstream method is to improve the inverter control algorithm. Photovoltaic inverter control adopts PI control...

AI Technical Summary

Problems solved by technology

Photovoltaic inverter control adopts PI control. Traditional PI control cannot realize static-difference adjustment and does not have the ability to quickly track voltage.

[0004] As a new control strategy, model predictive control has been widely concerned in the field of photovoltaic grid-connected inverter control because of its fast dynamic response capability, simultaneous control of multiple targets, and good output characteristics. problem, which requires a higher-performance processor, which undoubtedly increases the cost and is not conducive to the promotion of the control algorithm

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