I-shaped commutation method and system for thermal power energy storage

Abstract

The present invention discloses a thermal power energy storage I-shaped commutation method and system, which relates to the field of energy storage commutation technology, including constructing an energy storage unit, boosting the voltage and then converging it to an AC energy storage system; installing an I-shaped commutation unit, connecting the energy storage side rectifier device and the motor side inverter device with a DC bus; configuring the energy storage unit to assist the thermal power unit in frequency regulation, supporting single-stage or combined regulation; and implementing a droop control scheme to maintain system stability and suppress instability during power regulation. The present invention adopts back-to-back I-shaped commutation units to enable flexible access to energy storage. Two sections of energy storage can independently assist a thermal power unit in frequency regulation, or jointly assist a unit in frequency regulation. By controlling the back-to-back I-shaped commutation units, the two sections of energy storage can simultaneously assist two thermal power units in frequency regulation. A droop control scheme is adopted in the energy storage side rectifier device and the motor side inverter device to maintain bus voltage stability and suppress power overshoot and oscillation during AC side power regulation.

Description

Technical Field

[0001] The present invention relates to the technical field of energy storage commutation, in particular to a method and system for I-shaped commutation of thermal power energy storage. Background Art

[0002] In the power supply systems of modern large-scale thermal power plants, traditional designs have long relied on power-frequency transformers to convert and distribute electrical energy. Typically, starting with the 20kV voltage at the generator output, the voltage is reduced through two stages, first to 6kV and then to 400V, with power-frequency transformers used throughout the entire process to process the AC power. However, as the capacity of thermal power plants continues to increase, the capacity of power supply systems has also increased accordingly, and this traditional model has gradually exposed many serious problems.

[0003] First, the increase in high-voltage transformer capacity has led to a sharp increase in short-circuit current in the auxiliary power system. This not only places stricter demands on the short-circuit breaking capacity of high-voltage switches, but also necessitates the use of thicker cables to ensure thermal stability in the auxiliary power system's high-voltage cables during short-circuit conditions, significantly increasing investment costs. Second, traditional power-frequency transformers are inherently bulky. When power plants undergo capacity expansion and retrofits to increase auxiliary power system capacity, they face high costs and lengthy construction periods. During these upgrades, the power plant cannot generate electricity normally, severely impacting operational efficiency. In stark contrast, the application of DC networking in auxiliary power systems offers new hope for resolving these issues. DC networking offers numerous significant advantages. Its larger power supply capacity compared to traditional AC networking can better meet the growing demand for auxiliary power. Furthermore, DC networking eliminates the need to consider phase angle and frequency, enabling interconnection of asynchronous systems and providing greater flexibility in connecting auxiliary loads. The factory load is connected to the DC factory power system through a rectifier device, which not only improves the power conversion efficiency and reduces equipment losses, but also realizes variable frequency drive of the load, simplifies the internal circuit of the load, and effectively reduces the failure rate and equipment cost.

[0004] Based on the above situation, the present invention proposes an I-shaped commutation method and system for thermal power energy storage, aiming to fully utilize the advantages of DC networking, overcome the various disadvantages brought by traditional power frequency transformers, and optimize the performance and improve the efficiency of thermal power energy storage systems to meet the growing needs of modern thermal power plant power systems. Summary of the Invention

[0005] In view of the above-mentioned problems, the present invention is proposed.

[0006] Therefore, the problem to be solved by the present invention is: how to solve the disadvantage of the traditional industrial frequency transformer itself being bulky. When the power plant carries out capacity expansion and transformation in order to obtain a larger plant power system capacity, it faces the dilemma of high transformation costs and long construction period. During the transformation period, the power plant cannot generate electricity normally, which seriously affects the production and operation efficiency of the power plant.

[0007] To solve the above technical problems, the present invention provides the following technical solutions: an I-shaped commutation method for thermal power energy storage, comprising: constructing an energy storage unit, boosting the voltage and then converging it into an AC energy storage system; installing the I-shaped commutation unit, and connecting the energy storage-side rectifier device and the motor-side inverter device with a DC bus; the I-shaped commutation unit includes a back-to-back I-shaped commutation unit, which is divided into an energy storage-side rectifier device and a motor-side inverter device, and the energy storage-side rectifier device and the motor-side inverter device are connected by a DC bus. The DC bus is extended and connected to the load to form a flexible DC networking system; the energy storage unit is configured to assist the thermal power unit in frequency regulation, supporting single-stage or combined regulation; and a droop control scheme is implemented to maintain system stability and suppress instability during power regulation.

[0008] As a preferred solution of the I-shaped commutation method for thermal power energy storage described in the present invention, the construction of the energy storage unit includes constructing A and B section energy storage units to assist in frequency regulation of the two thermal power units, and the energy storage in sections A and B is boosted, and after boosting, the energy is converged to the energy storage sections A and B of the AC boosted voltage.

[0009] As a preferred solution of the I-shaped commutation method for thermal power energy storage described in the present invention, the frequency regulation includes the use of back-to-back I-shaped commutation units to enable flexible access to energy storage, with two sections of energy storage independently assisting a thermal power unit in frequency regulation, or jointly assisting a unit in frequency regulation. By controlling the back-to-back I-shaped commutation units, the two sections of energy storage simultaneously assist two thermal power units in frequency regulation.

[0010] As a preferred solution of the I-shaped commutation method for thermal power energy storage described in the present invention, the droop control scheme includes adopting a droop control scheme in the energy storage side rectifier device and the motor side inverter device to maintain bus voltage stability and improve power stability during AC side power regulation; adopting voltage-current droop control in the energy storage side rectifier device, improving the voltage-current droop control, and entering the impedance error elimination control algorithm; adopting voltage-power droop control in the motor side inverter device, improving the voltage-power droop control, introducing a variable slope droop coefficient, and suppressing the active power overshoot and power oscillation of the motor side inverter device when responding to the frequency adjustment of the thermal power unit. It cannot be restored to a stable value in time.

[0011] As a preferred solution of the I-shaped commutation method for thermal power energy storage of the present invention, the voltage-current droop control includes adopting voltage-current droop control of the energy storage side rectifier device, that is, establishing a voltage-current linear relationship expression expressed as:

[0012] ,

[0013] in, is the current value of the AC side voltage of the i-th energy storage side rectifier device, is the AC side voltage regulation target value of the i-th energy storage side rectifier device, is the output current of the i-th energy storage side rectifier device, is the impedance value of the rectifier device on the i-th energy storage side, that is, the voltage-current droop coefficient; the bus voltage stabilization impedance error elimination control algorithm is adopted, which is expressed as:

[0014] ,

[0015] in, and is the line impedance from the AC side to the neutral grid connection point of the first and second energy storage side rectifier devices, and Output current to the first and second energy storage side rectifier devices.

[0016] As a preferred solution of the I-shaped commutation method for thermal power energy storage described in the present invention, the voltage-power droop control includes adopting voltage-power droop control in the motor-side inverter device, achieving DC voltage static difference regulation through active power regulation, and establishing a voltage-power linear relationship expression expressed as:

[0017] ,

[0018] The variable slope droop coefficient scheme is adopted, and the variable slope droop coefficient is expressed as:

[0019] ,

[0020] in, is the variable slope droop adjustment coefficient, is the power change rate proportional coefficient, is the power change rate; the variable slope droop coefficient is introduced into the voltage-power linear relationship expression, which is expressed as:

[0021] ,

[0022] in, is the real-time value of the DC side voltage of the inverter device on the i-th motor side, is the DC side voltage reference value of the i-th motor side inverter device, is the output power reference value of the inverter device on the i-th motor side, is the actual output power value of the inverter device on the i-th motor side, is the variable slope droop coefficient.

[0023] Another object of the present invention is to provide a system for an I-shaped commutation method for thermal power energy storage, which can solve the I-shaped commutation problem of thermal power energy storage by constructing an I-shaped commutation system for thermal power energy storage.

[0024] In order to solve the above technical problems, the present invention provides the following technical solutions: a thermal power energy storage I-shaped commutation system, comprising a thermal power energy storage segmented grid-connected unit, an energy storage I-shaped commutation unit and a thermal power energy storage segmented boosting unit; the thermal power generator in the thermal power energy storage segmented grid-connected unit is boosted by a main transformer and connected to the power system, and energy storage high-voltage grid-connected busbars A and B are arranged at the outlets of the #1 and #2 generators; the energy storage I-shaped commutation unit is divided into A and B sets of motor-side inverter devices and A and B sets of energy storage-side rectifier devices, the motor-side inverter device and the energy storage-side rectifier device are connected through a DC transmission line, and the DC transmission line is connected to the power system. A DC circuit breaker is arranged on the wiring harness. A droop control scheme is adopted in the energy storage side rectifier device and the motor side inverter device to maintain bus voltage stability and suppress power overshoot and oscillation during AC side power regulation. The AC sides of the A and B sets of motor side inverter devices are connected to the A and B sets of energy storage grid-connected circuit breakers in the thermal power energy storage segmented grid-connected unit; the thermal power energy storage segmented boost unit is divided into A and B sections of high-voltage energy storage units. The energy storage module is connected to the AC energy storage section A and B through the commutation device and the boost transformer. The AC energy storage section A and B are connected to the AC side of the A and B sets of energy storage side rectifier devices in the energy storage I-shaped commutation unit.

[0025] A computer device includes a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the steps of the I-shaped commutation method for thermal power energy storage are implemented.

[0026] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of the I-shaped commutation method for thermal power energy storage.

[0027] The beneficial effects of the present invention are as follows: The I-shaped commutation method for thermal power energy storage provided by the present invention innovatively adopts back-to-back I-shaped commutation units, which are similar to MMC flexible direct current transmission and are divided into an energy storage-side rectifier device and a motor-side inverter device. The energy storage-side rectifier device and the motor-side inverter device are connected by a DC bus, which improves power supply reliability. The DC bus can also be expanded to connect more loads, forming a flexible direct current network system. The use of back-to-back I-shaped commutation units allows for flexible energy storage access. The two sections of energy storage can independently assist a thermal power unit in frequency regulation, or jointly assist a unit in frequency regulation. Furthermore, by controlling the back-to-back I-shaped commutation units, the two sections of energy storage can simultaneously assist two thermal power units in frequency regulation. A droop control scheme is adopted in the energy storage-side rectifier device and the motor-side inverter device to maintain bus voltage stability and suppress power overshoot and oscillation during AC-side power regulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0029] Figure 1 This is a flow chart of the I-shaped commutation method for thermal power energy storage provided by the first embodiment of the present invention.

[0030] Figure 2 This is a structural diagram of the I-shaped commutation system for thermal power energy storage provided by the second embodiment of the present invention.

[0031] Figure: 100, thermal power energy storage segmented grid-connected unit; 200, energy storage I-shaped commutation unit; 300, thermal power energy storage segmented boosting unit; 101, generator #1; 102, main transformer #1; 103, 330kV AC busbar; 104, 20kV high-voltage grid-connected busbar section A for energy storage; 105, energy storage grid-connected circuit breaker set A; 106, 20kV high-voltage grid-connected busbar section B for energy storage; 107, energy storage grid-connected circuit breaker set B; 108, generator #2; 109, main transformer #2; 201, motor-side inverter set A; 202, motor-side inverter set B; 203, energy storage DC high-voltage grid-connected circuit breaker; 204, energy storage-side rectifier set A; 205, energy storage-side rectifier set B; 301 , AC 20kV energy storage section A; 302, Section A #1 energy storage grid-connected switch; 303, Section A #1 energy storage transformer; 304, Section A energy storage system converter cabinet 1; 305, Section A #1 energy storage module; 306, Section A #n energy storage grid-connected switch; 307, Section A #n energy storage transformer; 308, Section A energy storage system converter cabinet n; 309, Section A #n energy storage module; 310, AC 20kV energy storage section B; 311, Section B #1 energy storage grid-connected switch; 312, Section B #1 energy storage transformer; 313, Section B energy storage system converter cabinet 1; 314, Section B #1 energy storage module; 315, Section B #m energy storage grid-connected switch; 316, Section B #m energy storage transformer; 317, Section B energy storage system converter cabinet m; 318, Section B #m energy storage module. DETAILED DESCRIPTION

[0032] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0033] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0034] Example 1, with reference to Figure 1 , which is the first embodiment of the present invention, provides an I-shaped commutation method for thermal power energy storage, including: constructing an energy storage unit, boosting and then converging it into an AC energy storage system; installing an I-shaped commutation unit, connecting the energy storage side rectifier device and the motor side inverter device with a DC bus; configuring the energy storage unit to assist the thermal power unit in frequency regulation, supporting single-stage or combined regulation; and implementing a droop control scheme to maintain system stability and suppress instability during power regulation.

[0035] S1: Build an energy storage unit, boost the voltage and then converge it into the AC energy storage system.

[0036] Construct the A and B section energy storage units to assist the frequency regulation of the two thermal power units. The A and B section energy storage boosts the voltage, and after boosting, it converges to the energy storage A and B section with the AC boosted voltage.

[0037] S2. Install the I-shaped commutation unit and connect the energy storage side rectifier device and the motor side inverter device with a DC bus.

[0038] The innovative back-to-back I-shaped commutation units, similar to MMC flexible DC transmission, consist of a storage-side rectifier and a generator-side inverter. These two units are connected by a DC bus, improving power supply reliability. The DC bus can also be expanded to accommodate additional loads, forming a flexible DC network system. The back-to-back I-shaped commutation units allow for flexible energy storage integration. Two sections of energy storage can independently assist in frequency regulation for a single thermal power unit, or they can be combined to assist in frequency regulation. Furthermore, by controlling the back-to-back I-shaped commutation units, the two sections can simultaneously assist in frequency regulation for two thermal power units.

[0039] S3. Configure energy storage units to assist thermal power units in frequency regulation, supporting single-stage or combined regulation.

[0040] The use of back-to-back I-shaped commutation units allows flexible access to energy storage. Two sections of energy storage can independently assist a certain thermal power unit in frequency regulation, or jointly assist a certain unit in frequency regulation. By controlling the back-to-back I-shaped commutation units, the two sections of energy storage can simultaneously assist two thermal power units in frequency regulation.

[0041] S4. Implement droop control scheme to maintain system stability and suppress instability during power regulation.

[0042] By controlling the back-to-back I-shaped commutation units, two sections of energy storage can simultaneously assist two thermal power units in frequency regulation. A droop control scheme is employed in both the energy storage-side rectifier and the motor-side inverter to maintain bus voltage stability and improve power stability during AC-side power regulation. Specifically, voltage-current droop control is employed in the energy storage-side rectifier. This droop control has been improved to incorporate an impedance error elimination control algorithm. This ensures that the A and B energy storage-side rectifiers are not subject to current regulation deviations caused by line impedance during power regulation, thus ensuring bus voltage stability. Voltage-power droop control is employed in the motor-side inverter. This droop control has been improved to introduce a variable slope droop coefficient to suppress active power overshoot and power oscillations that fail to recover to a stable value in a timely manner when the motor-side inverter responds to thermal power unit frequency regulation.

[0043] The rectifier device on the energy storage side adopts voltage-current droop control, that is, the voltage-current linear relationship expression is established:

[0044] (1)

[0045] in, is the current value of the AC side voltage of the i-th energy storage side rectifier device, is the AC side voltage regulation target value of the i-th energy storage side rectifier device, is the output current of the i-th energy storage side rectifier device, is the impedance value of the rectifier device on the i-th energy storage side, that is, the voltage-current droop coefficient.

[0046] In conventional voltage-current droop control, the output current of the energy storage side rectifier device cannot be accurately matched due to the difference in impedance parameters. After considering the difference in impedance parameters, the output current relationship between the first and second energy storage side rectifier devices is:

[0047] (2)

[0048] in, and is the line impedance from the AC side to the neutral grid connection point of the first and second energy storage side rectifier devices, and The output current is for the first and second energy storage side rectifier devices. The voltage at the neutral grid connection point can be expressed as:

[0049] (3)

[0050] Where R is the equivalent line impedance at the grid connection point. In order to ensure that the A and B energy storage side rectifier devices will not have current regulation deviations caused by line impedance during power regulation, a bus voltage stability impedance error elimination control algorithm is adopted. The line impedances of equations (2) and (3) are introduced into equation (1), resulting in:

[0051] (4)

[0052] The droop control scheme of formula (4) can suppress the current regulation deviation caused by line impedance, ensure the output voltage of the rectifier devices on the energy storage side of sets A and B are consistent, and prevent the voltage difference at the neutral grid connection point from causing circulating current, thus ensuring the stability of the bus voltage.

[0053] Voltage-power droop control is adopted in the inverter device on the motor side. The DC voltage static difference is adjusted by active power regulation, and the voltage-power linear relationship expression is established:

[0054] (5)

[0055] In order to suppress the phenomenon that the active power overshoot exceeds the limit and the power oscillation cannot be restored to the stable value in time when the motor-side inverter device responds to the frequency adjustment of the thermal power unit, a variable slope droop coefficient scheme is adopted. The variable slope droop coefficient can be expressed as:

[0056] (6)

[0057] in, is the variable slope droop adjustment coefficient, is the power change rate proportional coefficient, is the power change rate.

[0058] The variable slope droop coefficient can be automatically adjusted according to the power change rate, and the active power differential coefficient can suppress power oscillation. Introducing the variable slope droop coefficient into the voltage-power linear relationship expression, we can get:

[0059] (7)

[0060] in, is the real-time value of the DC side voltage of the inverter device on the i-th motor side, is the DC side voltage reference value of the i-th motor side inverter device, is the output power reference value of the inverter device on the i-th motor side; is the actual output power value of the inverter device on the i-th motor side, is the variable slope droop coefficient.

[0061] Furthermore, the present invention constructs A and B section energy storage units to flexibly assist the frequency regulation of two thermal power units. The A and B section energy storage is boosted to 20kV and converged into the AC 20kV energy storage A and B sections.

[0062] The innovative back-to-back I-shaped commutation unit is similar to the MMC flexible DC transmission, which is divided into a storage-side rectifier device and a motor-side inverter device. The energy storage-side rectifier device and the motor-side inverter device are connected by a DC bus to improve power supply reliability. The DC bus can also be expanded later to connect more loads to form a flexible DC networking system.

[0063] The use of back-to-back I-shaped commutation units allows for flexible access to energy storage. Two sections of energy storage can independently assist a thermal power unit in frequency regulation, or jointly assist a unit in frequency regulation. Furthermore, by controlling the back-to-back I-shaped commutation units, the two sections of energy storage can simultaneously assist two thermal power units in frequency regulation.

[0064] A droop control scheme is adopted in the rectifier device on the energy storage side and the inverter device on the motor side to maintain bus voltage stability and suppress power overshoot and oscillation during AC side power regulation.

[0065] Example 2, reference Figure 2, which is the second embodiment of the present invention, is different from the previous embodiment in that it provides a thermal power energy storage I-shaped commutation system, including: a thermal power energy storage segmented grid-connected unit 100, an energy storage I-shaped commutation unit 200 and a thermal power energy storage segmented boosting unit 300.

[0066] The thermal power generators in the thermal power energy storage segmented grid-connected unit 100 are stepped up from 20kV to 330kV via the main transformer and connected to the 330kV power system. Energy storage high-voltage grid-connected busbars A and B are arranged at the outlets of the #1 and #2 generators, i.e., on the low-voltage side of the main transformer.

[0067] The energy storage I-shaped commutation unit 200 consists of motor-side inverters (sets A and B) and energy storage-side rectifiers (sets A and B). These are connected via a DC transmission line, with DC circuit breakers installed on the DC transmission line. Droop control is implemented in both the energy storage-side rectifiers and the motor-side inverters to maintain bus voltage stability and suppress power overshoot and oscillation during AC power regulation. The AC sides of the motor-side inverters (sets A and B) are connected to the energy storage grid-connected circuit breakers (sets A and B) in the thermal power energy storage segmented grid-connected unit 100.

[0068] The thermal power energy storage segmented boost unit 300 is divided into A and B section high-voltage energy storage units. The energy storage module is integrated into the AC 20kV energy storage section A and B section through the commutation device and the boost transformer. The AC 20kV energy storage section A and B section are connected to the AC side of the A and B sets of energy storage side rectifier devices in the energy storage I-shaped commutation unit 200.

[0069] like Figure 2 As shown, 101 is generator #1, 102 is main transformer #1, 103 is 330kV AC bus, 104 is 20kV high-voltage grid-connected bus section A for energy storage, 105 is set A of energy storage grid-connected circuit breaker, 106 is 20kV high-voltage grid-connected bus section B for energy storage, 107 is set B of energy storage grid-connected circuit breaker, 108 is generator #2, and 109 is main transformer #2.

[0070] 201 is the inverter device on the motor side of set A, 202 is the inverter device on the motor side of set B, 203 is the energy storage DC high-voltage grid-connected circuit breaker, 204 is the rectifier device on the energy storage side of set A, and 205 is the rectifier device on the energy storage side of set B.

[0071] 301 is the AC 20kV energy storage section A, 302 is the energy storage grid-connected switch #1 in section A, 303 is the energy storage transformer #1 in section A, 304 is the energy storage system converter cabinet 1 in section A, 305 is the energy storage module #1 in section A, 306 is the energy storage grid-connected switch #n in section A, 307 is the energy storage transformer #n in section A, 308 is the energy storage system converter cabinet n in section A, 309 is the energy storage module #n in section A, 310 is the AC 20kV energy storage section B, 311 is the energy storage grid-connected switch #1 in section B, 312 is the energy storage transformer #1 in section B, 313 is the energy storage system converter cabinet 1 in section B, 314 is the energy storage module #1 in section B, 315 is the energy storage grid-connected switch #m in section B, 316 is the energy storage transformer #m in section B, 317 is the energy storage system converter cabinet m in section B, and 318 is the energy storage module #m in section B.

[0072] If the functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the portion that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in various embodiments of the present invention. The aforementioned storage media include various media capable of storing program code, such as USB flash drives, mobile hard drives, read-only memories (ROMs), random access memories (RAMs), magnetic disks, or optical disks.

[0073] The logic and / or steps represented in the flowcharts or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing the logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (e.g., a computer-based system, a system including a processor, or other system that can fetch and execute instructions from an instruction execution system, apparatus, or device). For purposes of this specification, a "computer-readable medium" can be any device that can contain, store, communicate, propagate, or transport a program for use by, or in conjunction with, an instruction execution system, apparatus, or device.

[0074] More specific examples (a non-exhaustive list) of computer-readable media include the following: an electrical connection with one or more wires (electronic devices), a portable computer disk cartridge (magnetic devices), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disc read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium, and then editing, interpreting, or processing in another suitable manner as necessary, and then storing it in a computer memory.

[0075] It should be understood that various components of the present invention may be implemented using hardware, software, firmware, or a combination thereof. In the above-described embodiments, multiple steps or methods may be implemented using software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented using hardware, as in another embodiment, any one of the following technologies known in the art or a combination thereof may be used: a discrete logic circuit having logic gate circuits for implementing logic functions on data signals, an application-specific integrated circuit having suitable combinational logic gate circuits, a programmable gate array (PGA), a field-programmable gate array (FPGA), etc.

[0076] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. I-shaped commutation method for thermal power energy storage, characterized by: include, Build energy storage units, boost the voltage and then converge into the AC energy storage system; Install an I-shaped commutation unit and connect the energy storage side rectifier device and the motor side inverter device with a DC bus; The I-shaped commutation unit includes a back-to-back I-shaped commutation unit, which is divided into an energy storage side rectifier device and a motor side inverter device. The energy storage side rectifier device and the motor side inverter device are connected by a DC bus. The DC bus is extended and connected to the load to form a flexible DC networking system. Configure energy storage units to assist thermal power units in frequency regulation, supporting single-stage or combined regulation; Implement droop control schemes to maintain system stability and suppress instabilities during power regulation; The energy storage unit construction includes constructing A and B section energy storage units to assist in frequency regulation of the two thermal power units, and the energy storage in A and B sections is boosted, and after the boost, the energy is converged to the energy storage in A and B sections after the AC boost voltage; The frequency regulation includes using back-to-back I-shaped commutation units to enable flexible access to energy storage, with two sections of energy storage independently assisting a thermal power unit in frequency regulation, or jointly assisting a unit in frequency regulation. By controlling the back-to-back I-shaped commutation units, the two sections of energy storage simultaneously assist two thermal power units in frequency regulation. The droop control scheme includes adopting a droop control scheme in the energy storage side rectifier device and the motor side inverter device to maintain bus voltage stability and improve power stability during AC side power regulation; The voltage-current droop control is adopted in the rectifier device on the energy storage side, and the voltage-current droop control is improved to enter the impedance error elimination control algorithm; Voltage-power droop control is adopted in the motor-side inverter device. This voltage-power droop control is improved by introducing a variable slope droop coefficient to suppress the phenomenon that the active power overshoot exceeds the limit and the power oscillation fails to recover to the stable value in time when the motor-side inverter device responds to the frequency adjustment of the thermal power unit. The voltage-current droop control includes the energy storage side rectifier device adopting voltage-current droop control, that is, establishing a voltage-current linear relationship expression expressed as: u i =u refi -R di I i Among them, u i is the current value of the AC side voltage of the i-th energy storage side rectifier device, u refi is the AC side voltage regulation target value of the i-th energy storage side rectifier device, I i is the output current of the ith set of energy storage side rectifier device, R di is the impedance value of the rectifier device on the i-th energy storage side, that is, the voltage-current droop coefficient; The bus voltage stabilization impedance error elimination control algorithm is adopted, which is expressed as, u1=(R d1 +R c1 +R)I1+RI2 u2=(R d2 +R c2 +R)I2+RI1 Among them, R c1 and R c2 is the line impedance from the AC side to the neutral grid connection point of the first and second energy storage side rectifier devices, and I1 and I2 are the output currents of the first and second energy storage side rectifier devices.

2. The I-shaped commutation method for thermal power energy storage according to claim 1, characterized in that: The voltage-power droop control includes adopting voltage-power droop control in the motor-side inverter device, realizing DC voltage static difference regulation through active power regulation, and establishing a voltage-power linear relationship expression expressed as: The variable slope droop coefficient scheme is adopted, and the variable slope droop coefficient is expressed as, Among them, α is the variable slope droop adjustment coefficient, β is the power change rate proportional coefficient, is the power change rate; Introducing the variable slope droop coefficient into the voltage-power linear relationship expression, it is expressed as: Among them, U dci is the real-time value of the DC side voltage of the inverter device on the i-th motor side, U refdci is the DC side voltage reference value of the i-th motor side inverter device, P refi is the output power reference value of the inverter device on the i-th motor side, P i is the actual output power value of the inverter device on the i-th motor side, D zi is the variable slope droop coefficient.

3. A system using the I-shaped commutation method for thermal power energy storage according to any one of claims 1 to 2, characterized in that: It comprises a thermal power energy storage segmented grid-connected unit (100), an energy storage I-shaped commutation unit (200) and a thermal power energy storage segmented boosting unit (300); The thermal power generator in the thermal power energy storage segmented grid-connected unit (100) is boosted by a main transformer and connected to the power system. Energy storage high-voltage grid-connected busbars A and B are arranged at the outlets of the #1 and #2 generators. The energy storage I-shaped commutation unit (200) is divided into A and B sets of motor-side inverter devices and A and B sets of energy storage-side rectifier devices. The motor-side inverter devices and the energy storage-side rectifier devices are connected via a DC transmission line. A DC circuit breaker is arranged on the DC transmission line bundle. A droop control scheme is adopted in the energy storage-side rectifier device and the motor-side inverter device to maintain bus voltage stability and suppress power overshoot and oscillation during AC side power regulation. The AC sides of the A and B sets of motor-side inverter devices are connected to the A and B sets of energy storage grid-connected circuit breakers in the thermal power energy storage segmented grid-connected unit (100). The thermal power energy storage segmented boost unit (300) is divided into A and B segment high-voltage energy storage units. The energy storage module is fed into the AC energy storage segment A and B segment through a commutation device and a boost transformer. The AC energy storage segment A and B segment are connected to the AC side of the energy storage side rectifier devices A and B sets in the energy storage I-shaped commutation unit (200).

4. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the I-shaped commutation method for thermal power energy storage according to any one of claims 1 to 2 are implemented.

5. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the I-shaped commutation method for thermal power energy storage according to any one of claims 1 to 2 are implemented.

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