System for thermal power frequency modulation by combining super capacitor energy storage with lithium battery energy storage

Abstract

The invention discloses a system for thermal power frequency modulation by combining super capacitor energy storage with lithium battery energy storage. The system comprises an energy storage system.The energy storage system is composed of a lithium iron phosphate battery, a super capacitor, a first PCS circuit, a second PCS circuit, a DC/DC converter and a medium-voltage transformer. The super capacitor, the second PCS circuit and the DC/DC converter constitute super capacitor energy storage of the system, and the lithium iron phosphate battery and the first PCS circuit constitute lithium battery energy storage of the system. The system has the beneficial effect that high-power charging and discharging can be achieved and high-power long-time charging and discharging can also be achieved. The super capacitor unit responds to a low-power frequency modulation instruction of a power grid to protect the battery energy storage subsystem, so that the lithium battery energy storage system can be charged and discharged at high power and at low rate, the service life of the system is prolonged, and the economy of the system is improved. The hybrid energy storage system can reduce the output fluctuation of a unit and improve the adjustment precision of a frequency modulation stable area.

Description

technical field [0001] The invention relates to a thermal power frequency modulation system, in particular to a thermal power frequency modulation system in which supercapacitors are combined with lithium battery energy storage, and belongs to the technical field of thermal power frequency modulation. Background technique [0002] At present, the calculation rules of the thermal power frequency regulation system take the frequency regulation mileage of the power generation unit as the transaction target, and the most important one is the frequency regulation performance index K composed of the three technical indicators of the power generation unit’s response to the AGC control command’s adjustment rate, response time and adjustment accuracy. [0003] The current energy storage participates in the AGC frequency regulation of the power grid. The AGC scheduling command of the power grid is sent to the thermal power unit, and the energy storage system simultaneously obtains the ...

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Problems solved by technology

[0004] The advantage of lithium battery is that it has a high energy storage density, which can realize large-capacity energy storage. The disadvantage is that the power density is low, and it is difficult to realize continuous and rapid discharge of large current. The advantage of super capacitor is that it has a large power density and fast charging and discharging speed. , It is less affected by temperature, and the charge-discharge cycle life can reach more than 100,000 times. However, the energy storage density of supercapacitors is lower than that of lithium batteries, so when working alone, it may not be able to meet the command requirements.

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