Unbalance voltage compensation and control method based on virtual synchronous machine

Abstract

The invention discloses an unbalance voltage compensation and control method based on a virtual synchronous machine. According to the method, the power calculating method on the basis of notch filter is adopted, the problems that a first order low pass filter is low in responding speed and stability and cannot eliminate secondary harmonic caused by unbalance load can be eliminated, the calculated total active power and reactive power serves as the feedback input of droop control, and part of produced unbalance voltage is suppressed by the proportional integral and the resonance control method; meanwhile, an unbalance voltage compensation controller is adopted to eliminate the unbalance quantity. The unbalance voltage can be compensated, the fine equalizing current balance of parallelly-connected multiple machines can be maintained, the method can be widely applied to micro grid inverter control on the unbalance loaded condition so as to maintain the output voltage balance during off-grid operation, and parallelly-connected operation of multiple machines is allowed.

Description

technical field [0001] The invention relates to an unbalanced voltage compensation control method, in particular to an unbalanced voltage compensation control method based on a virtual synchronous machine. Background technique [0002] In recent years, virtual synchronous generator technology, as a new power generation mode of microgrid inverter, has received a lot of attention from scholars. The microgrid inverter using virtual synchronous generator technology is called virtual synchronous generator. The virtual synchronous generator (Virtual Synchronous Generator, VSG) needs to operate in two modes, grid-connected and islanded parallel operation. [0003] There are a large number of unbalanced loads in the microgrid. These unbalanced loads will seriously affect the quality of the output voltage supply of the VSG, cause the output voltage to be unbalanced, and cause problems such as overvoltage of electrical equipment. In order to achieve a good output voltage power suppl...

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Problems solved by technology

[0005] Entitled "Autonomous voltage unbalance compensation in an Islanded Droop-controlled microgrid", Savaghebi M, Jalilian A, Vasquez J C, et al, "IEEE Transactions on Industrial Electronics", 2013, 60(4), 1390-1402 ("applied to Unbalanced Voltage Automatic Compensator for Droop Control Microgrid Island Mode", "IEEE Transactions-Journal of Industrial Electronics", 2013, Vol. 60, No. 4, pp. 1390-1402); this paper proposes a resonant voltage controller To compensate the unbalanced voltage, but because the unbalanced voltage drop on the virtual impedance is not considered, the compensation effect is poor

[0006] Titled "Voltage unbalance and harmonics compensation for islanded microgrid inverters", Liu Q, Tao Y, Liu X, et al, "Power Electronics IET", 2014, 7(5), 1055-1063 ("Islanded microgrid inverters voltage unbalance and harmonic compensation control", "IET Engineering Technology Society - Power Electronics Journal", 2014, Vol. Unbalanced, but its control bandwidth is narrow, and the compensation effect is poor when the frequency of the microgrid system changes

[0007] Titled "A method of three-phase balancing in microgrid by photovoltaic generation system", Hojo M, Iwase Y, Funabashi T, et al, "Power Electronics and Motion Control Conference2008.EPE-PEMC", 2008, 13th.IEEE, 2008 , 2487-2491 ("Three-phase Balance Control Strategy in Photovoltaic Power Generation Micro-grid System", "The Thirteenth International Conference on Power Electronics and Motion Control", Issue 13, 2008, pp. 2487-2491); However, under severe conditions, the injection of negative sequence current will cause the microgrid inverter to overcurrent and cause shutdown

[0008] To sum up, none of the existing technologies can solve the problem of ensuring a good balance of the output voltage and ensuring the parallel balance of the inverters during island operation in the microgrid inverter parallel operation system with unbalanced loads. flow problem

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