Thermal power storage I-shaped current conversion method and system

Abstract

The invention discloses a thermal power energy storage I-shaped current conversion method and system, and relates to the technical field of energy storage current conversion, and the method comprises the steps: constructing an energy storage unit, boosting, and converging to an AC energy storage system; installing an I-shaped current conversion unit, and connecting an energy storage side rectifying device and a motor side inversion device through a direct current bus; an energy storage unit is configured to assist the thermal power generating unit in frequency adjustment, and single-section or combined adjustment is supported; a droop control scheme is implemented to maintain system stability and suppress an unstable phenomenon during power regulation. The back-to-back I-shaped conversion unit is adopted, energy storage is flexibly connected, two sections of energy storage independently assist a certain thermal power generating unit in frequency modulation or jointly assist a certain thermal power generating unit in frequency modulation, and by controlling the back-to-back I-shaped conversion unit, the two sections of energy storage assist two thermal power generating units in frequency modulation at the same time. A droop control scheme is adopted in an energy storage side rectifying device and a motor side inversion device, the bus voltage is maintained to be stable, and the phenomena of power overshoot and oscillation during alternating current side power adjustment are restrained.

Description

Technical Field

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

[0002] In the field of power supply systems for modern large-scale thermal power units, traditional design solutions have long relied on power frequency transformers to achieve the conversion and distribution of electric energy. Typically, starting from the 20kV voltage at the generator outlet, it is transformed through two stages, first reduced to 6kV, and then further reduced to 400V. The entire process uses power frequency transformers to process AC power. However, as the capacity of thermal power units continues to rise, the capacity of power supply systems has also continued to increase accordingly, and this traditional model has gradually exposed many serious problems.

[0003] First, the increase in the capacity of high-voltage transformers leads to a sharp increase in the short-circuit current of the power supply system. This not only puts forward more stringent requirements on the short-circuit breaking capacity of high-voltage switches, but also requires the use of thicker cables to ensure that the high-voltage cables of the power supply system can meet the requirements of thermal stability under short-circuit conditions, which undoubtedly greatly increases the investment cost. Secondly, the traditional power frequency transformer itself has the disadvantage of being bulky. When the power plant is required to increase the capacity of the power supply system in order to obtain a larger power supply system capacity, it faces the difficulties of high transformation costs and long construction period. During the transformation, the power plant cannot generate electricity normally, which seriously affects the production and operation efficiency of the power plant. In sharp contrast, the application of DC networking in the power supply system has brought new hope for solving these problems. DC networking has many significant advantages. Its power supply capacity is larger than that of traditional AC networking, and it can better meet the growing power demand of the power supply system. At the same time, DC networking does not need to consider the two factors of phase angle and frequency, thereby realizing the interconnection of asynchronous systems, which provides greater flexibility for the access of power supply loads. The factory load is connected to the DC factory power system through a rectifier, which not only improves the power conversion efficiency and reduces equipment losses, but also realizes the 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 make full use of the advantages of DC networking, overcome the various disadvantages brought by traditional industrial frequency transformers, optimize the performance of thermal power energy storage systems and improve their efficiency, so as 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] In order to solve the above technical problems, the present invention provides the following technical solutions: a thermal power energy storage I-shaped commutation method, comprising: constructing an energy storage unit, boosting and converging to an AC energy storage system; installing an I-shaped commutation unit, connecting an energy storage side rectifier and a motor side inverter 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 and a motor side inverter, and the energy storage side rectifier and the motor side inverter are connected by a DC bus, and the DC bus is extended to connect the load to form a flexible DC networking system; configuring an energy storage unit to assist the thermal power unit in frequency regulation, supporting single-stage or joint regulation; implementing a droop control scheme 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 two thermal power units, and the A and B sections are energy storage boosted, and after boosting, they are converged to the energy storage A and B sections of the voltage after AC boosting.

[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 adopting back-to-back I-shaped commutation units to enable flexible access to energy storage, and two sections of energy storage 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 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 the bus voltage stability and improve the 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. The phenomenon that 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 the energy storage side rectifier adopting voltage-current droop control, that is, establishing a voltage-current linear relationship expression expressed as: , 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 ith 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 stability impedance error elimination control algorithm is adopted, which is expressed as: , 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.

[0012] As a preferred solution of the I-shaped commutation method for thermal power energy storage of the present invention, the voltage-power droop control includes adopting voltage-power droop control in the inverter device on the motor side, realizing DC voltage static difference regulation by 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: , 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: , 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 at 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.

[0013] 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.

[0014] 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 section A and section B busbars 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 DC transmission line. A DC circuit breaker is arranged on the wiring harness, and a droop control scheme is adopted in the energy storage side rectifier device and the motor side inverter device to maintain the stability of the bus voltage 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, and the energy storage module is connected to the AC energy storage section A and B sections through the commutation device and the boost transformer, and the AC energy storage section A and B sections 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.

[0015] A computer device comprises a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the I-shaped commutation method of thermal power energy storage as described above when executing the computer program.

[0016] 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 as described above.

[0017] 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 a back-to-back I-shaped commutation unit, which is similar to the MMC flexible direct current transmission, and is divided into a rectifier device on the energy storage side and an inverter device on the motor side. The rectifier device on the energy storage side and the inverter device on the motor side are connected by a DC bus to improve the reliability of power supply. The DC bus can also be expanded later to connect more loads to form a flexible DC networking system. The back-to-back I-shaped commutation unit can be used to flexibly access energy storage. Two sections of energy storage can assist a thermal power unit in frequency regulation alone, or jointly assist a unit in frequency regulation. Furthermore, by controlling the back-to-back I-shaped commutation unit, the two sections of energy storage can simultaneously assist two thermal power units in frequency regulation. 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 the stability of the bus voltage and suppress power overshoot and oscillation during AC side power regulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0019] Figure 1 This is a flow chart of the I-shaped commutation method for thermal power energy storage provided in the first embodiment of the present invention.

[0020] Figure 2 This is a structural diagram of an I-shaped commutation system for thermal power energy storage provided in the second embodiment of the present invention.

[0021] In the figure: 100, thermal power energy storage segmented grid-connected unit; 200, energy storage I-shaped commutation unit; 300, thermal power energy storage segmented booster unit; 101, generator #1; 102, main transformer #1; 103, 330kV AC bus; 104, energy storage 20kV high-voltage grid-connected bus section A; 105, A set of energy storage grid-connected circuit breaker; 106, energy storage 20kV high-voltage grid-connected bus section B; 107, B set of energy storage grid-connected circuit breaker; 108, generator #2; 109, main transformer #2; 201, A set of motor-side inverter device; 202, B set of motor-side inverter device; 203, energy storage DC high-voltage grid-connected circuit breaker; 204, A set of energy storage side rectifier device; 205, B set of energy storage side rectifier device; 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

[0022] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0023] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and 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.

[0024] Example 1, reference 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, and merging it into an AC energy storage system after boosting; installing an I-shaped commutation unit, and 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.

[0025] S1. Build an energy storage unit and boost the voltage before converging to the AC energy storage system.

[0026] Construct 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, the voltage is converged to the energy storage section A and B after the AC boost voltage.

[0027] S2. Install an I-shaped commutation unit and connect the rectifier device on the energy storage side and the inverter device on the motor side with a DC bus.

[0028] The innovative back-to-back I-shaped commutation unit is used, which is similar to the MMC flexible DC transmission. It is divided into a rectifier on the energy storage side and an inverter on the motor side. The rectifier on the energy storage side and the inverter on the motor side are connected by a DC bus to improve the reliability of power supply. The DC bus can also be expanded later to connect more loads to form a flexible DC networking system. The back-to-back I-shaped commutation unit can make the energy storage flexibly connected. The two sections of energy storage can assist a certain thermal power unit in frequency regulation alone, or jointly assist a certain unit in frequency regulation. Furthermore, by controlling the back-to-back I-shaped commutation unit, the two sections of energy storage can simultaneously assist two thermal power units in frequency regulation.

[0029] S3. Configure energy storage units to assist thermal power units in frequency regulation, supporting single-stage or combined regulation.

[0030] Back-to-back I-shaped commutation units are used to enable flexible access to energy storage. Two sections of energy storage can independently assist a thermal power unit in frequency regulation, or can 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.

[0031] S4. Implement droop control scheme to maintain system stability and suppress instability during power regulation.

[0032] 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 adopted in the energy storage side rectifier and the motor side inverter to maintain the stability of the bus voltage and improve the power stability during AC side power regulation. Specifically, the energy storage side rectifier adopts voltage-current droop control, and the droop control is improved to enter the impedance error elimination control algorithm to ensure that the A and B energy storage side rectifiers will not have current regulation deviations caused by line impedance during the power regulation process, thereby ensuring the stability of the bus voltage. Voltage-power droop control is adopted in the motor side inverter, and the droop control is improved to introduce a variable slope droop coefficient to suppress the overshoot of active power and the inability of power oscillation to recover to a stable value in time when the motor side inverter responds to the frequency regulation of the thermal power unit.

[0033] The rectifier device on the energy storage side adopts voltage-current droop control, that is, the voltage-current linear relationship expression is established: (1) 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 ith 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.

[0034] 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: (2) 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 of the first and second energy storage side rectifier devices. The voltage at the neutral grid connection point can be expressed as: (3) Where R is the equivalent line impedance of the grid connection point. In order to ensure that the A and B energy storage side rectifier devices will not have current regulation deviation caused by line impedance during power regulation, the bus voltage stability impedance error elimination control algorithm is adopted, and the line impedance of equations (2) and (3) is introduced into equation (1), and the following is obtained: (4) The droop control scheme of formula (4) can suppress the current regulation deviation caused by line impedance, ensure that the output voltages 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.

[0035] Voltage-power droop control is adopted in the inverter device on the motor side, and the DC voltage static difference adjustment is realized through active power regulation, and the voltage-power linear relationship expression is established: (5) In order to suppress the overshoot of active power and the inability of power oscillation to recover to a stable value in time when the inverter device on the motor side 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: (6) in, is the variable slope droop adjustment coefficient, is the power change rate proportional coefficient, is the power change rate.

[0036] 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: (7) 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 at 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.

[0037] 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 to the AC 20kV energy storage A and B sections.

[0038] The innovative back-to-back I-shaped commutation unit is similar to the MMC flexible DC transmission, which is divided into a rectifier device on the energy storage side and an inverter device on the motor side. The rectifier device on the energy storage side and the inverter device on the motor side are connected by a DC bus to improve the power supply reliability. The DC bus can also be expanded later to connect more loads to form a flexible DC networking system.

[0039] 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 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.

[0040] 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 the stability of the bus voltage and suppress power overshoot and oscillation during power regulation on the AC side.

[0041] 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 boost unit 300.

[0042] The thermal power generator in the thermal power energy storage segmented grid-connected unit 100 is stepped up from 20kV to 330kV through the main transformer and connected to the 330kV power system. At the outlets of the #1 and #2 generators, i.e., the low-voltage side of the main transformer, the energy storage high-voltage grid-connected section A and section B busbars are arranged. 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 device and the energy storage-side rectifier device are connected through a DC transmission line. A DC circuit breaker is arranged on the DC transmission line 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 side of the A and B sets of motor-side inverter devices is 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.

[0043] 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 connected to 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.

[0044] like Figure 2 As shown, 101 is the #1 generator, 102 is the #1 main transformer, 103 is the 330kV AC bus, 104 is the energy storage 20kV high-voltage grid-connected A-section bus, 105 is the A-set energy storage grid-connected circuit breaker, 106 is the energy storage 20kV high-voltage grid-connected B-section bus, 107 is the B-set energy storage grid-connected circuit breaker, 108 is the #2 generator, and 109 is the #2 main transformer.

[0045] 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.

[0046] 301 is the AC 20kV energy storage section A, 302 is the section A #1 energy storage grid-connected switch, 303 is the section A #1 energy storage transformer, 304 is the section A energy storage system converter cabinet 1, 305 is the section A #1 energy storage module, 306 is the section A #n energy storage grid-connected switch, 307 is the section A #n energy storage transformer, 308 is the section A energy storage system converter cabinet n, 309 is the section A #n energy storage module, 310 is the AC 20kV energy storage section B, 311 is the section B #1 energy storage grid-connected switch, 312 is the section B #1 energy storage transformer, 313 is the section B energy storage system converter cabinet 1, 314 is the section B #1 energy storage module, 315 is the section B #m energy storage grid-connected switch, 316 is the section B #m energy storage transformer, 317 is the section B energy storage system converter cabinet m, and 318 is the section B #m energy storage module.

[0047] If the functions are implemented in the form of 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 part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions to enable a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the methods described in various embodiments of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc., which can store program codes.

[0048] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in conjunction with such instruction execution systems, devices or apparatuses. For the purposes of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in conjunction with such instruction execution systems, devices or apparatuses.

[0049] More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or more wires (electronic device), a portable computer disk case (magnetic device), 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 disk read-only memory (CDROM). In addition, the computer-readable medium may even be a 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, followed by editing, deciphering or, if necessary, processing in another suitable manner, and then stored in a computer memory.

[0050] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0051] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. 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 to 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 a rectifier device on the energy storage side and an inverter device on the motor side. The rectifier device on the energy storage side and the inverter device on the motor side are connected by a DC bus, and the DC bus is extended to connect 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.

2. The I-shaped commutation method for thermal power energy storage according to claim 1, characterized in that: The energy storage unit construction includes constructing A and B section energy storage units to assist in frequency regulation of two thermal power units, A and B section energy storage boosting, and after boosting, the boosted energy is converged to the energy storage A and B section of the AC boosted voltage.

3. The I-shaped commutation method for thermal power energy storage according to claim 2, characterized in that: The frequency regulation includes using 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 can 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.

4. The I-shaped commutation method for thermal power energy storage according to claim 3, characterized in that: 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 inverter device on the motor side. The 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 cannot be restored to the stable value in time when the inverter device on the motor side responds to the frequency adjustment of the thermal power unit.

5. The I-shaped commutation method for thermal power energy storage according to claim 4, characterized in that: 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: ， 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 ith 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, ， 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.

6. The I-shaped commutation method for thermal power energy storage according to claim 5, characterized in that: The voltage-power droop control includes adopting voltage-power droop control in the inverter device on the motor side, 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, ， in, is the variable slope droop adjustment coefficient, 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: ， 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 at 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.

7. A system using the I-shaped commutation method for thermal power energy storage as claimed in any one of claims 1 to 6, 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 connected to the power system through a main transformer to step up the voltage, and energy storage high-voltage grid-connected section A and section B busbars 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 device and the energy storage-side rectifier device are connected via a DC transmission line. A DC circuit breaker is arranged on the DC transmission line 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 (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 connected to 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 A and B sets of energy storage side rectifier devices in the energy storage I-shaped commutation unit (200).

8. 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 6 are implemented.

9. 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 6 are implemented.

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