CN-121983934-A - Three-phase grid-connected system based on lithium battery and super capacitor hybrid energy storage complementation

Abstract

The invention discloses a hybrid energy storage complementary three-phase grid-connected system based on a lithium battery and a super capacitor. The three-phase bridge grid-connected inverter comprises a hybrid energy storage system unit, a control unit of a bidirectional energy storage circuit, a three-phase bridge grid-connected inverter and a control unit of the three-phase bridge grid-connected inverter, wherein the hybrid energy storage system unit comprises a lithium battery energy storage unit and a super capacitor energy storage unit, the lithium battery energy storage unit and the super capacitor energy storage unit are respectively connected with a direct current bus through a bidirectional DC/DC converter, the control unit of the bidirectional energy storage circuit is used for obtaining reference power which is needed to be provided by the lithium battery and the super capacitor respectively through power distribution, a reference power signal is used as an input signal, a control signal of a switching device is formed through signal processing and conversion, and then the energy storage equipment is charged and discharged according to the reference power, and the three-phase bridge grid-connected inverter and the control unit of the three-phase bridge grid-connected inverter are used for controlling the three-phase bridge inverter through PWM pulse signals. The invention can improve the stability and reliability of the power grid and reduce the running cost of the power system.

Inventors

• Wang Yiao
• LI WEIMIN
• DENG LIMING
• JIANG LAN
• QU KUN
• ZHENG XUEQI

Assignees

• 中冶华天南京电气工程技术有限公司
• 中冶华天工程技术有限公司
• 中冶华天南京工程技术有限公司

Dates

Publication Date

20260505

Application Date

20251215

Claims (6)

1. 1. The hybrid energy storage complementary three-phase grid-connected system based on the lithium battery and the super capacitor is characterized by comprising a hybrid energy storage system unit, a control unit of a bidirectional energy storage circuit, a three-phase bridge type grid-connected inverter and a control unit of the three-phase bridge type grid-connected inverter, wherein the hybrid energy storage system unit comprises the lithium battery energy storage unit and the super capacitor energy storage unit, and the lithium battery energy storage unit and the super capacitor energy storage unit are respectively connected with a direct current bus through a bidirectional DC/DC converter; The control unit of the bidirectional energy storage circuit is used for obtaining reference power which is needed to be provided by the lithium battery and the super capacitor through power distribution, taking a reference power signal as an input signal, and forming a control signal of the switching device through signal processing and conversion, so that the energy storage device is charged and discharged according to the reference power; The three-phase bridge grid-connected inverter and the control unit thereof are used for controlling the three-phase bridge inverter through PWM pulse signals.
2. 2. The hybrid energy storage complementary three-phase grid-connected system based on the lithium battery and the super capacitor according to claim 1, wherein the charging and discharging of the energy storage converter of the hybrid energy storage system unit are independent of each other and do not interfere with each other, and the hybrid energy storage complementary three-phase grid-connected system is switched between a boost working mode and a buck working mode according to the energy flow direction of the energy storage device.
3. 3. The hybrid energy storage complementary three-phase grid-connected system based on lithium batteries and super capacitors according to claim 2, wherein when the bidirectional DC/DC converter is operated in a boost mode, the lithium batteries and the super capacitors discharge, and energy flows from the energy storage device into the bus.
4. 4. The hybrid energy storage complementary three-phase grid-connected system based on lithium batteries and super capacitors according to claim 2, wherein when the bidirectional DC/DC converter works in buck mode, the lithium batteries and the super capacitors are charged, and energy flows from the bus to the energy storage device.
5. 5. The hybrid energy storage complementary three-phase grid-connected system based on the lithium battery and the super capacitor as claimed in claim 1, wherein the control strategy of the energy storage battery and the super capacitor is to obtain a reference current by dividing the reference power by the battery/capacitor voltage, then the reference current is controlled by a current loop in a closed loop manner, a duty ratio is generated by a limiting link, and then a pulse signal is generated by a PWM module to control the bidirectional DCDC circuit.
6. 6. The three-phase grid-connected system based on hybrid energy storage complementation of a lithium battery and a super capacitor as claimed in claim 1, wherein the three-phase bridge grid-connected inverter and the control unit thereof comprise an outer ring which is a DC bus voltage outer ring, so that the actual voltage is different from a reference given voltage value, the difference value is passed through a first PI controller to generate a reference inductance current, and then passed through a second PI controller, namely a current inner ring to generate a PWM pulse signal, thereby controlling the three-phase bridge inverter.

Description

Three-phase grid-connected system based on lithium battery and super capacitor hybrid energy storage complementation Technical Field The invention relates to a hybrid energy storage complementary three-phase grid-connected system based on a lithium battery and a super capacitor. Background Along with popularization and application of the intelligent power grid and large-scale access of new energy power generation to the power grid, the important effect of the energy storage technology is increasingly obvious, and the application range of the intelligent power grid relates to various links of power generation, power transmission, power transformation, power distribution and power utilization. The energy storage technology has various types, and the technical characteristics such as capacity, power, response time and the like and the related economic characteristics are different. The energy storage technology mainly comprises pumped storage, compressed air storage, various battery storage, superconducting magnetic storage, flywheel storage, super capacitor storage and the like. Pumped storage is the most mature energy storage technology of the large power grid at present, and the application of the technology is over 100 years, but the problems of geographical position limitation and insufficient circulation efficiency (about 75%) exist. Lithium battery energy storage has the advantages of higher energy density, higher cycle efficiency and being substantially free of geographical limitations, but also suffers from low power density. The super capacitor energy storage has high power density, can be charged and discharged with high power, has quick response time, and is suitable for coping with voltage sag and instantaneous power failure, improving the electric energy quality of users, inhibiting low-frequency oscillation of an electric power system, improving the stability of the electric power system and the like. But supercapacitor energy storage suffers from lower energy density. There is therefore a need for energy storage technology that combines lithium batteries and supercapacitors for application to an ac power grid. Disclosure of Invention In order to overcome the defects, the invention aims to provide a hybrid energy storage complementary three-phase grid-connected system based on a lithium battery and a super capacitor. In order to achieve the aim, the three-phase grid-connected system based on hybrid energy storage complementation of the lithium battery and the super capacitor comprises a hybrid energy storage system unit, a control unit of a bidirectional energy storage circuit, a three-phase bridge grid-connected inverter and a control unit of the three-phase bridge grid-connected inverter, wherein the hybrid energy storage system unit comprises a lithium battery energy storage unit and a super capacitor energy storage unit, and the lithium battery energy storage unit and the super capacitor energy storage unit are respectively connected with a direct current bus through a bidirectional DC/DC converter; The control unit of the bidirectional energy storage circuit is used for obtaining reference power which is needed to be provided by the lithium battery and the super capacitor through power distribution, taking a reference power signal as an input signal, and forming a control signal of the switching device through signal processing and conversion, so that the energy storage device is charged and discharged according to the reference power; The three-phase bridge grid-connected inverter and the control unit thereof are used for controlling the three-phase bridge inverter through PWM pulse signals. Further, the charging and discharging of the energy storage converter of the hybrid energy storage system unit are independent of each other and do not interfere with each other, and the boost working mode and the buck working mode are switched according to the energy flow direction of the energy storage device. Further, when the bi-directional DC/DC converter is operating in boost mode, the lithium battery and super capacitor discharge and energy flows from the energy storage device into the bus. Further, when the bi-directional DC/DC converter is operated in buck mode, the lithium battery and the super capacitor are charged and energy flows from the bus to the energy storage device. Further, the control strategy of the energy storage battery and the super capacitor is to divide the reference power by the battery/capacitor voltage to obtain the reference current, then the reference current is subjected to closed loop control by a current loop, the duty ratio is generated by an amplitude limiting link, and then a pulse signal is generated by a PWM module to control the bidirectional DCDC circuit. Further, the three-phase bridge grid-connected inverter and the control unit thereof comprise an outer ring which is a direct-current bus voltage outer ring, so that the actual voltage is different from a refe