New-energy power generation system friendly to power grid and flexible to extend

Abstract

The invention discloses a new-energy power generation system friendly to power grid and flexible to extend. The power generation system is composed of no less than one power generation unit, and each power generation unit is internally provided with a DC bus and the DC bus has constant voltage; photovoltaic power generation is firstly transmitted to the DC bus via a photovoltaic controller; wind power generation is firstly transmitted to the DC bus via a wind energy converter; when the power generation system is used for grid-connected power generation, an energy-storage device can be equipped, and when the power generation system is used for off-grid power supply, a battery energy storage device needs to be equipped; a frequency converter has DC input and AC output, the DC side is connected with the DC bus, and the motor is controlled to operate in a variable frequency and speed regulation mode; the motor is connected with a synchronous generator via a coupler, the synchronous generator is driven to generate power, and photovoltaic power generation and wind power generation are accessed to the power grid via the synchronous generator; the DC bus can also be connected onto a grid-connected inverter whose rated power is 10% to 30% of that of a power generator or a two-way converter; and the two-way converter can transmit power of the power grid to the DC bus, and is matched with the power grid for peak regulation and frequency modulation.

Description

technical field [0001] The present invention relates to a photovoltaic, wind power and energy storage combined power generation system, specifically, a large-scale photovoltaic, wind power and energy storage power station that adopts synchronous generators to connect to the grid and a combined power generation system that includes photovoltaic, wind power, Energy storage off-grid power supply system. Background technique [0002] At present, photovoltaic power generation is connected to the grid through photovoltaic inverters, which are limited by the withstand voltage, switching frequency and power level of power electronic devices. The maximum rated power of a single photovoltaic inverter of mainstream manufacturers is 500kW, and the output voltage level of photovoltaic inverters For 270 or 315V, it needs to be connected to 10kV or 35kV power grid through a step-up transformer. [0003] The output of photovoltaic and wind power generation is random and intermittent. At th...

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Problems solved by technology

[0005] Some MW-level off-grid power supply systems adopt micro-grid architecture to realize large-scale solar-storage complementary off-grid power stations, rely on bidirectional converters as voltage sources to establish power grids, and operate photovoltaic and wind power in parallel with the grid. The maximum rated power of a single bidirectional converter of a mainstream manufacturer is 500kW, and it needs to be operated in parallel on the AC side to reach a capacity above the MW level. Moreover, the control strategy is complex, the overload capacity is poor, and resonance is prone to occur. Usually, transformer isolation is required After being connected to the power grid after voltage, excitation inrush current will be generated when the transformer is switched on, which will easily lead to overcurrent protection. In addition, when the inverter or energy storage converter is used as the voltage source for power supply, it does not have the general adaptability of the generator to the load.

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