VARIABLE-STEP-LENGTH, FIXED-SPEED AND LIMIT-DERATING POWER MPPT DISTURBANCE METHOD

摘要

A variable-step-length, fixed-speed and limit-derating power MPPT disturbance method, which involves: calculating a power derating coefficient α by comparing the amount of power change generated by the previous disturbance with a power variation calculated according to a power derating rate issued by an upper computer, and calculating, in real time and by means of the power-voltage relationship of a photovoltaic assembly, the relationship between the next disturbance voltage step length and the power derating coefficient and between same and the previous actual voltage change step length; giving the next voltage disturbance reference value by combining a current voltage measurement value; and when the difference between actual power and expected power is less than a certain set value, using fixed-step-length disturbance to reduce the power oscillation caused by disturbance and improve the disturbance precision. The method of the present invention can implement real-time step length calculation in a simple manner, thereby achieving fast and accurate power change requirements.