CN-122000965-A - Modularized multi-level converter energy storage integrated device and energy interaction method thereof

CN122000965ACN 122000965 ACN122000965 ACN 122000965ACN-122000965-A

Abstract

The invention provides a modular multilevel converter energy storage integrated device and an energy interaction method thereof, wherein the device comprises a modular multilevel converter MMC and an energy storage branch; the energy storage branch is connected in parallel with upper and lower bridge arm inductors of each phase of the MMC, and is used for storing the energy of the MMC or releasing the stored energy to the MMC by taking the bridge arm inductors as media. According to the invention, energy exchange between the MMC and the energy storage branch can be realized by connecting the energy storage branch at two ends of the MMC bridge arm inductor, the engineering implementation is simple, the transformation cost is extremely low, and the energy storage upgrading method is suitable for upgrading the operated MMC transformer substation. The energy storage branch circuit is physically isolated from the MMC main circuit and can be arranged in an independent cabin body with special fire-fighting facilities. The problem that faults such as battery thermal runaway directly affect expensive main converter equipment is thoroughly avoided, and the safety and reliability of the whole energy storage integrated system are greatly improved.

Inventors

QI LIANGBO
XU BIN
ZHANG SHENG
ZHOU WANDI
GAO CHONG
LIU LEI
ZHANG FEI

Assignees

国家电网有限公司
中国电力科学研究院有限公司
国网新疆电力有限公司电力科学研究院

Dates

Publication Date: 20260508
Application Date: 20251217

Claims (11)

1. The modular multilevel converter energy storage integrated device is characterized by comprising a modular multilevel converter MMC and an energy storage branch; the energy storage branch is connected in parallel with upper and lower bridge arm inductors of each phase of the MMC, and is used for storing the energy of the MMC or releasing the stored energy to the MMC by taking the bridge arm inductors as media.
2. The apparatus of claim 1, wherein the energy storage branch comprises a DC/AC converter and an energy storage unit connected.
3. The apparatus of claim 2, wherein the energy storage unit comprises a battery or a super capacitor.
4. An energy interaction method of a modular multilevel converter energy storage integrated device is characterized by comprising the following steps: Acquiring electrical parameters of an MMC and an energy storage branch in the modular multi-level converter energy storage integrated device; Inputting the electrical parameters into a preset current set value calculation formula to obtain the current set values of bridge arms of each phase of MMC and the access current set values of the energy storage branch converters; performing energy interaction on the MMC and the energy storage branch based on the set value of the bridge arm current of each phase of the MMC and the set value of the access current of the energy storage branch converter; Wherein the device is a modular multilevel converter energy storage integrated device according to any of claims 1-3.
5. The method of claim 4, wherein the electrical parameters comprise: The power control method comprises the steps of an MMC alternating current side power reference value, an MMC direct current side power reference value, grid fundamental wave angular frequency, the times of injected high-frequency harmonic waves, an MMC bridge arm series inductance value, phase angles of alternating current output by each phase of the MMC and phase angles of energy storage branch current.
6. The method of claim 5, wherein said inputting the electrical parameter into a pre-constructed current setpoint calculation formula to obtain an MMC phase leg current setpoint and an energy storage limb converter access current setpoint comprises: Calculating a direct current circulation given value, an MMC phase fundamental wave alternating current circulation amplitude given value and an energy storage branch reference power based on the MMC alternating current side power reference value and the MMC direct current side power reference value; The direct current circulation given value, the MMC each phase fundamental wave alternating current circulation amplitude given value, the energy storage branch reference power, the power grid fundamental wave angular frequency, the times of injected high-frequency harmonic waves, the MMC bridge arm serial inductance value, the phase angle of the MMC each phase output alternating current and the phase angle of the energy storage branch current are input into the current given value calculation to obtain MMC each phase bridge arm current given value and the energy storage branch converter access current given value.
7. The method of claim 6, wherein the current set point calculation is represented by: wherein, P es is the reference power of the energy storage branch, Is the current amplitude of the inductance of the x-phase bridge arm of the MMC, The current amplitude is accessed to an x-phase bridge arm of the energy storage branch current converter, omega is the fundamental wave angular frequency of a power grid, t is a time variable, h is the times of injected high-frequency harmonic waves, L s is the series inductance value of the MMC bridge arm, For the given value of the current of the x-phase bridge arm of the energy storage branch current converter, theta x is the phase angle of the x-phase output alternating current of the MMC, ψ e is the phase angle of the energy storage branch current, X-phase bridge arm of MMC the current set point is given by the current, For a given value of the direct current circulation, X-phase fundamental wave alternating current for MMC the circulation amplitude is given value.
8. The method of claim 4, wherein the energy interacting the MMC with the energy storage leg based on the MMC phase leg current setpoint and the energy storage leg converter access current setpoint comprises: based on the current set values of bridge arms of each phase of the MMC, generating an MMC trigger signal through current closed-loop control of the MMC; Based on the given value of the access current of the energy storage branch current converter, generating an energy storage branch current converter trigger signal through the current closed-loop control of the DC/AC converter in the energy storage branch; based on the MMC trigger signal and the energy storage branch current converter trigger signal, high-frequency circulation is excited on a bridge arm inductor of the MMC so as to perform energy interaction between the MMC and the energy storage branch.
9. The energy interaction system of the modularized multi-level converter energy storage integrated device is characterized by comprising an acquisition module, a calculation module and an input module; the acquisition module is used for acquiring the electrical parameters of the MMC and the energy storage branch in the modular multi-level converter energy storage integrated device; the calculation module is used for inputting the electrical parameters into a preset current set value calculation formula to obtain the current set values of the bridge arms of each phase of MMC and the current set value accessed by the energy storage branch converter; the input module is used for inputting the given value of the current of each phase bridge arm of the MMC and the given value of the access current of the energy storage branch current converter into the device to perform energy interaction between the MMC and the energy storage branch; Wherein the device is a modular multilevel converter energy storage integrated device according to any of claims 1-3.
10. The electronic equipment is characterized by comprising at least one processor and a memory, wherein the memory and the processor are connected through a bus; The memory is used for storing one or more programs; an energy interaction method of a modular multilevel converter energy storage integrated device according to any of claims 4 to 8, when said one or more programs are executed by said at least one processor.
11. A readable storage medium, having stored thereon an execution program, which when executed, implements a method of energy interaction of a modular multilevel converter energy storage integrated device according to any of claims 4 to 8.

Description

Modularized multi-level converter energy storage integrated device and energy interaction method thereof Technical Field The invention belongs to the technical field of new energy grid connection, and particularly relates to an energy storage integrated device of a modularized multi-level converter and an energy interaction method thereof. Background With the increasing proportion of renewable energy sources in the power grid, the operation of the power grid faces new challenges. The large-scale Energy Storage System (ESS) can provide auxiliary services such as frequency adjustment, power smoothing, energy buffering and the like, and effectively enhances the stability and renewable energy consumption capability of the power grid. At present, the energy storage system integration mode mainly has the following problems that a traditional full-power integration scheme needs to be provided with a high-power converter device which is completely matched with the system capacity, so that the system is high in cost and huge in volume, and an energy storage unit is directly embedded into a Modular Multilevel Converter (MMC) submodule, so that the integration level is improved, but the problems of poor safety, low reliability, great transformation difficulty and the like exist, and particularly, for energy storage elements, such as a lithium battery, which are easy to generate thermal runaway, serious potential safety hazards are brought by placing the energy storage elements in a valve hall of the MMC. In view of the above, there is a need to propose an energy storage scheme applicable to a modular multilevel converter. Disclosure of Invention In order to solve the defects of low energy storage technology efficiency, high cost, poor safety, low reliability, great transformation difficulty and the like of the traditional modularized multi-level converter, the invention provides an energy storage integrated device of the modularized multi-level converter, which comprises an MMC (modular multi-level converter) and an energy storage branch; the energy storage branch is connected in parallel with upper and lower bridge arm inductors of each phase of the MMC, and is used for storing the energy of the MMC or releasing the stored energy to the MMC by taking the bridge arm inductors as media. Preferably, the energy storage branch comprises a DC/AC converter and an energy storage unit which are connected. Preferably, the energy storage unit comprises a battery or a super capacitor. Based on the same inventive concept, the invention also provides an energy interaction method of the modularized multi-level converter energy storage integrated device, which comprises the following steps: Acquiring electrical parameters of an MMC and an energy storage branch in the modular multi-level converter energy storage integrated device; Inputting the electrical parameters into a preset current set value calculation formula to obtain the current set values of bridge arms of each phase of MMC and the access current set values of the energy storage branch converters; performing energy interaction on the MMC and the energy storage branch based on the set value of the bridge arm current of each phase of the MMC and the set value of the access current of the energy storage branch converter; Wherein, the the device is the modularized multi-level converter energy storage integrated device. Preferably, the electrical parameters include: The power control method comprises the steps of an MMC alternating current side power reference value, an MMC direct current side power reference value, grid fundamental wave angular frequency, the times of injected high-frequency harmonic waves, an MMC bridge arm series inductance value, phase angles of alternating current output by each phase of the MMC and phase angles of energy storage branch current. Preferably, the inputting the electrical parameter into a preset current set value calculation formula to obtain a set value of each phase bridge arm current of the MMC and a set value of an access current of the energy storage branch converter includes: Calculating a direct current circulation given value, an MMC phase fundamental wave alternating current circulation amplitude given value and an energy storage branch reference power based on the MMC alternating current side power reference value and the MMC direct current side power reference value; The direct current circulation given value, the MMC each phase fundamental wave alternating current circulation amplitude given value, the energy storage branch reference power, the power grid fundamental wave angular frequency, the times of injected high-frequency harmonic waves, the MMC bridge arm serial inductance value, the phase angle of the MMC each phase output alternating current and the phase angle of the energy storage branch current are input into the current given value calculation to obtain MMC each phase bridge arm current given value and the energy stor