A frequency division control method and control system for a variable speed wind turbine

Abstract

The invention discloses a fractional frequency control method and system of a variable-speed wind power turbine. The method comprises the steps that a voltage signal and an electric current signal ofa power generator of the variable-speed wind power turbine are collected, and the electromagnetic torque output by the power generator is worked out; rotation speed information of the variable-speed wind power turbine is collected; according to the electromagnetic torque and the rotation speed information, based on inertia data of the variable-speed wind power turbine, the pneumatic torque estimator is worked out; the difference value between the pneumatic torque estimator and the theoretical optimal controlling torque is calculated, the torque controlling torque is built through a low pass filter according to the difference value, and finally, the torque controlling set value is obtained. The system comprises a voltage sensor, an electric current sensor, a rotation speed sensor, an electromagnetic torque calculating system, a pneumatic torque estimator calculating system, the low pass filter, a torque additional value building system and a torque controlling set value calculating system. According to the fractional frequency control method and system, the power grid friendly target that the smooth output power fluctuates on the power grid sensitive power section is considered, andmeanwhile, electric energy production is improved.

Description

technical field [0001] The invention relates to the technical field of new energy power generation, in particular to a frequency division control method and control system for variable speed wind turbines. Background technique [0002] Below the rated wind speed, most variable-speed wind turbines control the speed through optimal torque control (OTC, optimal torque control) to realize the maximum power tracking in the variable-speed operation section of the fan, that is, let the speed of the unit track the changing wind speed, so that the tip speed ratio of the unit is at best. Due to the huge inertia of large-scale wind turbines, the time constant of speed tracking under this control method is large, making it difficult for the speed of the unit to track the changing wind speed during the dynamic process, resulting in the deviation of the tip speed ratio of the unit from the optimal value and loss of power generation. But the advantage is that the torque fluctuation and po...

AI Technical Summary

Problems solved by technology

[0003] The core of this improved optimal torque control is how to determine the appropriate torque added value. In the existing technical research, the torque added value is constructed through the proportional quantity of the unit speed differential or the estimated amount of the aerodynamic torque, resulting in The torque control amount is too sensitive to changes in wind speed or rotation speed, especially when the wind speed fluctuates frequently, the output power of the unit fluctuates greatly, causing adverse effects on the power grid, which does not meet the grid-friendly grid-connected requirements

In order to smooth power fluctuations, some technologies use energy storage devices or reduce power through pitch control. The former will increase the cost of the system, while the latter will lose power generation, which conflicts with the economic goal of increasing power generation.

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