Virtual synchronous generator control is considered as an effective solution to optimize the\nfrequency response characteristics of doubly fed induction generator. However, due to the insufficient\ncontrol bandwidth of the original virtual synchronous generator, it has little control effect over the\noscillating components of the power caused by the unbalanced grid voltage. Therefore, long-term\nunbalanced voltage will cause a series of problems, such as distortion of stator and rotor currents, as\nwell as oscillations of power and electromagnetic torque, which seriously affect the power quality\nand the operating performance of the doubly fed induction generator. To solve these problems,\nthe concept of extended power is introduced, and the second-order generalized integrator-based\nresonant controller is used to control the extended power and traditional power. Control targets of\nthe extended power method are discussed and extended, so that the doubly fed induction generator\nsystem using extended power resonant control-based virtual synchronous generator control can\nrealize three different control targets under the unbalanced grid condition. The three control targets\nare: balanced and sinusoidal stator current, sinusoidal stator current and constant active power,\nand sinusoidal stator current and constant reactive power and electromagnetic torque. The three\ncontrol targets can also be flexibly switched according to the real-time requirements of the grid with\nunbalanced voltage. The simulation results verify the effectiveness of the control method.
Loading....