A thermal power energy storage distributed high voltage direct current convergence segmented frequency modulation system and method

Abstract

The present invention discloses a thermal power energy storage distributed high-voltage direct current convergence segmented frequency regulation system and method, which relates to the field of thermal power energy storage, including: the electric energy generated by the generator enters the thermal power energy storage segmented commutation access unit through the outlets of the first generator and the second generator; the electric energy enters the energy storage grid-connected converter through the energy storage AC bus, and enters the energy storage DC boost convergence unit using a virtual impedance AC droop control scheme to complete power regulation control. The present invention adopts a segmented power regulation strategy to accurately match the output fluctuations of the thermal power units with the changes in load demand, reducing the bus voltage oscillation caused by power mutations; by dynamically allocating the charging and discharging power of the energy storage unit and coordinating the timing of the commutation module, the energy storage utilization rate is optimized, the equipment life is extended, and the single point failure risk of traditional centralized commutation is avoided, thereby enhancing the redundancy reliability of the system; the modular segmented design can flexibly expand the commutation capacity and reduce the cost of system upgrades.

Description

Technical Field

[0001] The present invention relates to the field of thermal power energy storage, and in particular to a thermal power energy storage distributed high-voltage direct current convergence segmented frequency modulation system and method. Background Art

[0002] Currently, the typical design of the auxiliary power system for large thermal power units uses a step-down transformer at the generator outlet. This can be divided into two stages of transformation: the first stage steps down the generator outlet voltage from 20kV to 6kV, and the second stage steps down from 6kV to 400V. Both stages use power frequency transformers and involve AC power. As unit capacity continues to increase, the capacity of the auxiliary power system is also increasing. The larger the capacity of the high-voltage auxiliary power transformer, the greater the short-circuit current in the auxiliary power system, placing higher demands on the short-circuit breaking capacity of the high-voltage switch. To meet the short-circuit thermal stability requirements, the high-voltage cables in the auxiliary power system need to be thicker, increasing investment costs. Traditional high-voltage auxiliary power transformers use large power frequency transformers. In order to increase the capacity of the auxiliary power system, they are often upgraded. This is costly and time-consuming, delaying the normal power generation of the power plant.

[0003] Adopting a DC network in the utility power system effectively addresses some bottlenecks in the development of traditional AC utility power systems. Compared to traditional AC utility power systems, DC networking offers numerous advantages: It offers greater power capacity; DC networking eliminates the need to consider phase angle and frequency, enabling the interconnection of asynchronous systems. Connecting utility loads to the DC utility power system through rectifiers improves power conversion efficiency and reduces equipment losses. This enables variable-frequency drive of loads, simplifies internal load circuitry, and reduces both failure rates and equipment costs. Summary of the Invention

[0004] In view of the above-mentioned problems, the present invention is proposed.

[0005] Therefore, the technical problem solved by the present invention is: how to achieve dynamic power coordination between thermal power units and distributed energy storage, improve frequency regulation accuracy and system redundancy and fault tolerance through a segmented high-voltage commutation architecture and an adaptive droop control strategy, while suppressing high-voltage DC bus voltage fluctuations.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: a thermal power energy storage distributed high voltage direct current convergence segmented frequency modulation system, which includes the following steps:

[0007] A thermal power energy storage segmented commutation access unit includes a first generator and a second generator provided in the thermal power energy storage segmented commutation access unit. The first generator and the second generator are respectively stepped up to 330 kV by a first main transformer and a second main transformer and connected to a 330 kV power grid. The outlets of the first generator and the second generator are connected to 20 kV AC energy storage segment A and B busbars, and are respectively connected to the segment A energy storage grid-connected converter and the segment B energy storage grid-connected converter through the segment A energy storage AC grid-connected switch and the segment B energy storage AC grid-connected switch;

[0008] An energy storage DC boost busbar unit, comprising a 28.28 kV DC energy storage busbar provided on the energy storage DC boost busbar unit and connected to a first energy storage access switch and a second energy storage access switch respectively;

[0009] The first energy storage access switch is connected in sequence to the first power electronic transformer high-voltage converter, the high-frequency transformer, the first power electronic transformer low-voltage converter, and the first energy storage module;

[0010] The second energy storage access switch is connected to the second power electronic transformer high-voltage converter, the high-frequency transformer, the second power electronic transformer low-voltage converter and the second energy storage module in sequence.

[0011] As a preferred solution of the thermal power energy storage distributed high-voltage direct current bus segmented frequency modulation system described in the present invention, the energy storage direct current boost bus unit includes connecting the 28.28kV direct current energy storage busbar to the section A energy storage grid-connected converter and the section B energy storage grid-connected converter in the unit through the section A energy storage direct current grid-connected circuit breaker and the section B energy storage direct current grid-connected circuit breaker, respectively, so that the energy storage electric energy interacts with the generator through the segmented high-voltage converter device.

[0012] As a preferred solution of the thermal power energy storage distributed high-voltage direct current convergence segmented frequency regulation system described in the present invention, wherein: the segmented frequency regulation system adopts a segmented commutation solution, using two sets of segmented high-voltage commutation devices, and the two sets of devices are connected through a structure to perform power regulation control;

[0013] One section of energy storage assists the frequency regulation of the first generator or the second generator alone, or assists the frequency regulation of the first and second generators simultaneously, thereby completing the frequency regulation of the auxiliary thermal power unit;

[0014] The two sets of segmented high-voltage converter devices are a first power electronic transformer high-voltage converter and a second power electronic transformer high-voltage converter.

[0015] As a preferred embodiment of the distributed HVDC bus segmented frequency regulation system for thermal power energy storage described in the present invention, the segmented high-voltage commutation device adopts a virtual impedance AC droop control scheme in the segmented high-voltage commutation device. By establishing voltage-active power and frequency-reactive power droop control equations and using adaptive virtual impedance to compensate for the voltage-active power droop coefficient, the two sets of segmented high-voltage commutation devices are used to assist the thermal power unit in achieving optimal frequency regulation performance.

[0016] An adaptive DC droop control scheme is adopted in each energy storage grid-connected converter, which uses an adaptive DC active power-voltage droop coefficient to adjust according to the DC voltage regulation range, active power regulation amount and voltage regulation rate;

[0017] The energy storage grid-connected converter includes a section A energy storage grid-connected converter, a section B energy storage grid-connected converter, a first power electronic transformer high-voltage converter, a first power electronic transformer low-voltage converter, a second power electronic transformer high-voltage converter, and a second power electronic transformer low-voltage converter.

[0018] Another object of the present invention is to provide a method for segmented frequency regulation of distributed high-voltage direct current (HVDC) convergence in thermal power generation and energy storage.

[0019] To solve the above technical problems, the present invention provides the following technical solutions: a method for segmented frequency modulation of distributed high-voltage direct current (HVDC) convergence in thermal power energy storage, comprising: the electric energy generated by the generator enters the thermal power energy storage segmented commutation access unit through the outlets of the first generator and the second generator;

[0020] Electric energy enters the energy storage grid-connected converter through the energy storage AC bus, and enters the energy storage DC boost bus unit using a virtual impedance AC droop control scheme to complete power regulation control.

[0021] As a preferred solution of the distributed high-voltage direct current (HVDC) convergence segmented frequency modulation method for thermal power energy storage described in the present invention, the virtual impedance AC droop control solution is to establish voltage-active power and frequency-reactive power droop control equations, which are expressed as follows:

[0022] ,

[0023] in, is the output voltage amplitude of the i-th set of segmented high-voltage converter devices; Output voltage reference value for the i-th set of segmented high-voltage converter devices; is the voltage-active power droop coefficient of the i-th set of segmented high-voltage converter equipment; Output / absorb active power for i sets of segmented high-voltage converter devices; Output frequency current value for the i-th set of segmented high-voltage commutation devices; Outputting a frequency reference value for the i-th set of segmented high-voltage commutation devices; is the frequency-reactive power droop coefficient of the i-th segmented high-voltage converter device; Output / absorb reactive power for the i-th set of segmented high-voltage converter devices.

[0024] As a preferred solution of the distributed HVDC convergence segmented frequency modulation method for thermal power energy storage described in the present invention, the virtual impedance AC droop control solution includes using adaptive virtual impedance to compensate for the voltage-active power droop coefficient to improve the active power distribution accuracy. The expression is:

[0025] ,

[0026] in, The actual power rating output / absorption for the i-th set of segmented high-voltage converter devices; 、 The output / absorption actual power rating of the first and second sets of segmented high-voltage converter devices; is the grid connection point voltage of the i-th set of segmented high-voltage converter devices, i.e., the output voltage of generators #1 and #2; 、 is the adaptive virtual impedance, is the reference value of energy storage output voltage;

[0027] ,

[0028] in, It is the active power PI adjustment proportional coefficient.

[0029] As a preferred solution of the thermal power energy storage distributed high-voltage direct current bus segmented frequency modulation method described in the present invention, the virtual impedance AC droop control solution also includes stabilizing the energy storage bus voltage of the energy storage DC boost bus unit, and adopting an adaptive DC active power-voltage droop coefficient in the traditional DC active power voltage droop control method, which is expressed as:

[0030] ,

[0031] ,

[0032] in, is the DC side output voltage of the jth set of energy storage grid-connected converter; is the DC energy storage bus voltage reference value; is the DC active power-voltage droop coefficient in the control system of the j-th energy storage grid-connected converter; is the current value of active power output / absorbed by the j-th set of energy storage grid-connected converter; is the target value of active power output / absorption of the j-th set of energy storage grid-connected converter, is the fixed voltage droop control coefficient, is the maximum DC voltage adjustment range of the j-th set of energy storage grid-connected converters; is the maximum active power regulation of the j-th set of energy storage grid-connected converter; is the DC voltage regulation rate of the j-th set of energy storage grid-connected converters. When the deviation is larger, the adaptive DC active power-voltage droop coefficient becomes smaller. When facing the same active power regulation amount, the voltage variation range is reduced.

[0033] A computer device includes a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, it implements the steps of the above-mentioned method for segmented frequency modulation of distributed high-voltage direct current (HVDC) bus of thermal power energy storage.

[0034] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of the above-mentioned method for segmented frequency modulation of distributed high-voltage direct current (HVDC) bus of thermal power generation and energy storage.

[0035] The beneficial effects of the present invention are as follows: the present invention adopts a segmented power regulation strategy to accurately match the output fluctuations of thermal power units with changes in load demand, reducing bus voltage oscillations caused by power mutations; by dynamically allocating the charging and discharging power of the energy storage unit and coordinating the timing of the commutation module, the energy storage utilization rate is optimized, the equipment life is extended, and the single point failure risk of traditional centralized commutation is avoided, thereby enhancing the redundancy reliability of the system; the modular segmented design can flexibly expand the commutation capacity and reduce the cost of system upgrades. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] 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 work.

[0037] Figure 1 This is a structural diagram of a distributed high-voltage direct current (HVDC) convergence and segmented frequency modulation system for thermal power generation and energy storage provided by the first embodiment of the present invention.

[0038] Including: 1. Thermal power energy storage segmented commutation access unit, 11. First generator, 12. No. 1 main transformer, 13. 330kV power grid system, 14. Section A energy storage AC grid-connected switch, 15. Section A energy storage grid-connected converter, 16. Section A energy storage DC grid-connected circuit breaker, 17. Section B energy storage AC grid-connected switch, 18. Section B energy storage grid-connected converter, 19. Section B energy storage DC grid-connected circuit breaker, 110. Second generator, 111. No. 2 main transformer, 2. Energy storage DC boost busbar, 21. 28.28kV DC energy storage busbar, 22. First energy storage access switch, 23. First power electronic transformer high-voltage converter, 24. High-frequency transformer, 25. First power electronic transformer low-voltage converter, 26. First energy storage module, 27. Second energy storage access switch, 28. Second power electronic transformer high-voltage converter, 29. Second power electronic transformer low-voltage converter, 210. Second energy storage module. DETAILED DESCRIPTION

[0039] To make the above-mentioned objects, features, and advantages of the present invention more clearly understood, the following detailed description of the specific embodiments of the present invention is given in conjunction with the accompanying drawings. It is obvious that the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in this field without creative work should fall within the scope of protection of the present invention.

[0040] Example 1, with reference to Figure 1 According to one embodiment of the present invention, a distributed high-voltage direct current (HVDC) convergence and segmented frequency regulation system for thermal power generation and energy storage is provided, comprising:

[0041] The present invention constructs each energy storage module to boost the voltage through a DC transformer, converge it to a 28.28kV DC energy storage bus, and connect it to the #1 and #2 generator outlets through a segmented high-voltage converter device, assisting the generators in frequency regulation. This can achieve the purpose of a single segment of converged energy storage to assist the frequency regulation of two thermal power units. Furthermore, to achieve voltage stability on the 28.28kV DC energy storage bus, an adaptive DC droop control scheme is adopted in the high-voltage side converter of each energy storage DC transformer to ensure DC bus voltage stability. A virtual impedance AC droop control scheme is adopted in the energy storage grid-connected converter to improve power distribution accuracy during the frequency regulation process, ensuring that the two sets of segmented high-voltage converter devices assist the thermal power units in frequency regulation with optimal performance.

[0042] Construction of thermal power energy storage segmented commutation access unit:

[0043] The first step is to connect the generator to the 330kV power grid system through the main transformer to build the basic framework for subsequent power transmission and interaction.

[0044] The thermal power energy storage segmented commutation access unit includes a first generator and a second generator provided in the thermal power energy storage segmented commutation access unit 1. The first generator and the second generator are respectively stepped up to 330 kV by the first main transformer and the second main transformer and connected to the 330 kV power grid. The outlets of the first generator and the second generator are connected to the AC 20 kV energy storage A and B busbars, and are respectively connected to the A section energy storage grid-connected converter and the B section energy storage grid-connected converter 18 by the A section energy storage AC grid-connected switch and the B section energy storage AC grid-connected switch.

[0045] An energy storage DC boost busbar unit, comprising a 28.28 kV DC energy storage busbar provided on the energy storage DC boost busbar unit and connected to a first energy storage access switch and a second energy storage access switch respectively;

[0046] The first energy storage access switch is connected in sequence to the first power electronic transformer high-voltage converter, the high-frequency transformer, the first power electronic transformer low-voltage converter, and the first energy storage module;

[0047] The second energy storage access switch is connected to the second power electronic transformer high-voltage converter, the high-frequency transformer, the second power electronic transformer low-voltage converter and the second energy storage module in sequence.

[0048] In step 2, building on the generator-grid connection established in step 1, two segmented high-voltage commutation units were installed in the thermal power energy storage segmented commutation access unit 1. Their AC sides were connected to the outputs of generators #1 and #2 via the energy storage grid-connected switches for segments A and B, respectively. This step leveraged the connection established in step 1 to establish the connection between the commutation units and the generator outputs, providing an electrical path for energy storage to assist in generator frequency regulation.

[0049] The 28.28kV DC energy storage busbar is connected to the section A energy storage grid-connected converter and the section B energy storage grid-connected converter in the thermal power energy storage segmented commutation access unit 1 through the section A energy storage DC grid-connected circuit breaker and the section B energy storage DC grid-connected circuit breaker, respectively, so that the energy storage electric energy interacts with the generator through the segmented high-voltage commutation device.

[0050] Energy storage DC boost bus unit construction:

[0051] Step 3: Building on the thermal power energy storage segmented commutation access unit completed in the previous step, construct the energy storage DC boost and converging unit 2. Within this unit, each energy storage module performs DC voltage conversion and DC networking. Due to its simple and efficient networking, it enables rapid initial processing of the power from each energy storage module. This step, building on the system foundation established in the previous step, completes the initial construction of the energy storage component.

[0052] In step 4, based on the energy storage DC boost busbar unit 2 constructed in step 3, the 28.28kV DC energy storage busbar is connected to the DC side of the energy storage grid-connected converters in sections A and B of the thermal power energy storage segmented commutation access unit 1. This step completes the connection between the two units, enabling energy storage power to interact with the generator through the segmented high-voltage commutation device, thus improving the electrical connection of the entire system.

[0053] Achieve energy storage assisted frequency regulation function:

[0054] Step 5: Based on the already constructed system, a segmented commutation scheme was implemented, employing two sets of segmented high-voltage commutation units. These two units leveraged the system's existing interconnection architecture and, through power regulation control, enabled one section of energy storage to independently assist with frequency regulation for either Generator #1 or Generator #2, or both Generators #1 and #2 simultaneously, ultimately assisting with frequency regulation of the thermal power units.

[0055] In step 6, building on the frequency regulation achieved using segmented high-voltage commutation devices in step 5, a virtual impedance AC droop control scheme was implemented in the energy storage grid-connected converter to improve power distribution accuracy during frequency regulation. By establishing voltage-active power and frequency-reactive power droop control equations and using adaptive virtual impedance to compensate for the voltage-active power droop coefficient, the two segmented high-voltage commutation devices optimized the frequency regulation performance of the thermal power units.

[0056] Maintaining stable energy storage bus voltage: In step 7, to achieve stable DC 28.28kV energy storage bus voltage, an adaptive DC droop control scheme is adopted in each energy storage grid-connected converter based on the entire system architecture and the completed boost bus of the energy storage module.

[0057] In step 8, based on the adaptive DC droop control scheme adopted in step 7, the traditional DC active power voltage droop control equation is improved. By adopting an adaptive DC active power-voltage droop coefficient and adjusting it based on factors such as the DC voltage regulation range, active power regulation amount, and voltage regulation rate, the DC bus voltage deviation during active power regulation is effectively reduced, ensuring DC bus voltage stability.

[0058] Furthermore, it is important to note that a virtual impedance AC droop control scheme is employed in the segmented high-voltage converters. By establishing voltage-active power and frequency-reactive power droop control equations and using adaptive virtual impedance to compensate for the voltage-active power droop coefficient, the two segmented high-voltage converters achieve optimal frequency regulation performance for the auxiliary thermal power units.

[0059] An adaptive DC droop control scheme is adopted in each energy storage grid-connected converter. By adopting an adaptive DC active power-voltage droop coefficient, adjustments are made according to the DC voltage regulation range, active power regulation amount and voltage regulation rate.

[0060] The energy storage grid-connected converter includes a section A energy storage grid-connected converter, a section B energy storage grid-connected converter, a first power electronic transformer high-voltage converter, a first power electronic transformer low-voltage converter, a second power electronic transformer high-voltage converter, and a second power electronic transformer low-voltage converter.

[0061] It should be further explained that:

[0062] The thermal power energy storage distributed high-voltage DC bus segmented commutation system comprises: a thermal power energy storage segmented commutation access unit 1; and an energy storage DC boost bus unit 2. The generator in the thermal power energy storage segmented commutation access unit 1 is connected to the 330kV power grid system via a main transformer and contains two sets of segmented high-voltage commutation devices. The AC side is connected to the #1 and #2 generator outlets via the A and B segment energy storage grid-connected switches, respectively. The DC 28.28kV energy storage bus in the energy storage DC boost bus unit 2 is connected to the DC side of the A and B segment energy storage segmented high-voltage commutation devices via the A and B segment energy storage DC circuit breakers in the thermal power energy storage segmented commutation access unit 1. In the energy storage DC boost bus unit 2, each energy storage module undergoes DC transformation and DC networking, resulting in a simple and efficient networking structure.

[0063] A further improvement of the present invention is that, in order to achieve the purpose of using one section of energy storage to assist the frequency regulation of two thermal power units, this paper adopts a segmented commutation scheme and uses two sets of segmented high-voltage commutation devices. By performing power regulation control on the two sets of segmented high-voltage commutation devices, it is possible to achieve the purpose of using one section of energy storage to assist the frequency regulation of the #1 unit or the #2 unit alone, or to assist the frequency regulation of the #1 unit and the #2 unit simultaneously.

[0064] A further improvement of the present invention is that a virtual impedance AC droop control scheme is adopted in the segmented high-voltage commutation device to improve the power distribution accuracy during the frequency regulation process and ensure that the two sets of segmented high-voltage commutation devices assist the thermal power generation units in achieving optimal frequency regulation performance.

[0065] A further improvement of the present invention is that, in order to achieve DC 28.28kV energy storage bus voltage stability, an adaptive DC droop control scheme is adopted in the high-voltage side converter of each energy storage DC transformer to ensure DC bus voltage stability.

[0066] A further improvement of the present invention is that each energy storage module in the energy storage DC boost confluence unit 2 is DC-transformed and DC-networked, and the networking form is simple and efficient.

[0067] Example 2, an embodiment of the present invention, provides a method for segmented frequency regulation of distributed high-voltage direct current (HVDC) convergence in thermal power energy storage, comprising: the electric energy generated by the generator enters the thermal power energy storage segmented commutation access unit through the outlets of the first generator and the second generator;

[0068] Electric energy enters the energy storage grid-connected converter through the energy storage AC bus, and enters the energy storage DC boost bus unit using a virtual impedance AC droop control scheme to complete power regulation control.

[0069] It should be further explained that:

[0070] The virtual impedance AC droop control scheme is to establish voltage-active power and frequency-reactive power droop control equations, which are expressed as follows:

[0071] (1)

[0072] in, is the output voltage amplitude of the i-th set of segmented high-voltage converter devices; Output voltage reference value for the i-th set of segmented high-voltage converter devices; is the voltage-active power droop coefficient of the i-th set of segmented high-voltage converter equipment; Output / absorb active power for i sets of segmented high-voltage converter devices; Output frequency current value for the i-th set of segmented high-voltage commutation devices; Outputting a frequency reference value for the i-th set of segmented high-voltage commutation devices; is the frequency-reactive power droop coefficient of the i-th segmented high-voltage converter device; Output / absorb reactive power for the i-th set of segmented high-voltage converter devices.

[0073] The output voltage on the AC side of the high-voltage converter device will have low active power distribution accuracy during the frequency regulation process due to the impedance mismatch of the connected transmission line, namely the 20kV energy storage AC bus line, that is, there will be active power regulation deviation.

[0074] Adaptive virtual impedance is used to compensate for the voltage-active power droop coefficient to improve the accuracy of active power distribution. The voltage-active power droop compensation coefficient with adaptive virtual impedance is:

[0075] (2)

[0076] in, The actual power rating output / absorption for the i-th set of segmented high-voltage converter devices; 、 The output / absorption actual power rating of the first and second sets of segmented high-voltage converter devices; is the grid connection point voltage of the i-th set of segmented high-voltage converter devices, i.e., the output voltage of generators #1 and #2; 、 It is an adaptive virtual impedance that can compensate for active power deviation, distribute active power according to capacity, and accurately adjust power according to frequency modulation instructions. is the reference value of energy storage output voltage.

[0077] The adaptive virtual impedance can be expressed as:

[0078] (3)

[0079] in, is the active power PI adjustment proportional coefficient. Substituting the voltage-active power droop compensation coefficient containing the adaptive virtual impedance in formula (2) into the voltage-active power droop control equation in formula (1), the droop control equation after active power deviation compensation can be obtained as follows:

[0080] (4)

[0081] In order to achieve DC 28.28kV energy storage bus voltage stability, an adaptive DC droop control scheme is adopted in the high-voltage side converter of each energy storage DC transformer to ensure DC bus voltage stability.

[0082] The traditional DC active voltage droop control equation is:

[0083] (5)

[0084] in, is the DC side output voltage of the high-voltage side converter of the j-th energy storage DC transformer; It is the DC 28.28kV energy storage bus voltage reference value; is the DC active power-voltage droop coefficient in the high-voltage side converter control system of the j-th energy storage DC transformer; is the current value of the active power output / absorbed by the high-voltage side converter of the j-th energy storage DC transformer; is the target value of active power output / absorption of the high-voltage side converter of the j-th energy storage DC transformer. In order to maintain the DC 28.28kV energy storage bus voltage more stable and reduce the DC bus voltage deviation during the active power regulation process, an adaptive DC active power-voltage droop coefficient is adopted, which can be expressed as:

[0085] (6)

[0086] in, is the fixed voltage droop control coefficient, is the maximum DC voltage regulation range of the high-voltage side converter of the j-th energy storage DC transformer; is the maximum active power regulation of the high-voltage side converter of the j-th energy storage DC transformer; is the DC voltage regulation rate of the high-voltage side converter of the j-th energy storage DC transformer. When the deviation is larger, the adaptive DC active power-voltage droop coefficient becomes smaller. When facing the same active power regulation amount, the voltage variation range is reduced, which can effectively reduce the DC bus voltage deviation.

[0087] 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 the 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 enabling 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 media include various media that can store program code, such as USB flash drives, mobile hard drives, read-only memories (ROMs), random access memories (RAMs), magnetic disks, or optical disks.

[0088] 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.

[0089] 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.

[0090] 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.

[0091] 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. A distributed high-voltage direct current (HVDC) convergence and segmented frequency modulation system for thermal power energy storage, characterized in that: include: A thermal power energy storage segmented commutation access unit includes a first generator and a second generator provided in the thermal power energy storage segmented commutation access unit. The first generator and the second generator are respectively stepped up to 330 kV by a first main transformer and a second main transformer and connected to a 330 kV power grid. The outlets of the first generator and the second generator are connected to 20 kV AC energy storage segment A and B busbars, and are respectively connected to the segment A energy storage grid-connected converter and the segment B energy storage grid-connected converter through the segment A energy storage AC grid-connected switch and the segment B energy storage AC grid-connected switch; An energy storage DC boost busbar unit, comprising a 28.28 kV DC energy storage busbar provided on the energy storage DC boost busbar unit and connected to a first energy storage access switch and a second energy storage access switch respectively; The first energy storage access switch is connected in sequence to the first power electronic transformer high-voltage converter, the high-frequency transformer, the first power electronic transformer low-voltage converter, and the first energy storage module; The second energy storage access switch is connected in sequence to the second power electronic transformer high-voltage converter, the high-frequency transformer, the second power electronic transformer low-voltage converter, and the second energy storage module; The energy storage DC boost bus unit includes connecting the DC 28.28kV energy storage busbar to the A section energy storage DC grid-connected circuit breaker and the B section energy storage DC grid-connected circuit breaker respectively in the unit to enable the energy storage electric energy to interact with the generator through the segmented high-voltage converter device; The segmented frequency modulation system adopts a segmented commutation scheme, using two sets of segmented high-voltage commutation devices, and the two sets of devices are connected through a structure to perform power regulation control; One section of energy storage assists the frequency regulation of the first generator or the second generator alone, or assists the frequency regulation of the first and second generators simultaneously, thereby completing the frequency regulation of the auxiliary thermal power unit; The two sets of segmented high-voltage converter devices are a first power electronic transformer high-voltage converter and a second power electronic transformer high-voltage converter; The segmented high-voltage commutation device adopts a virtual impedance AC droop control scheme in the segmented high-voltage commutation device. By establishing voltage active power and frequency reactive power droop control equations and using adaptive virtual impedance to compensate for the voltage active power droop coefficient, the two sets of segmented high-voltage commutation devices are used to assist the thermal power generation unit in achieving optimal frequency regulation performance. An adaptive DC droop control scheme is adopted in each energy storage grid-connected converter. By using an adaptive DC active voltage droop coefficient, it is adjusted according to the DC voltage regulation range, active power regulation amount and voltage regulation rate. The energy storage grid-connected converter includes a section A energy storage grid-connected converter, a section B energy storage grid-connected converter, a first power electronic transformer high-voltage converter, a first power electronic transformer low-voltage converter, a second power electronic transformer high-voltage converter, and a second power electronic transformer low-voltage converter; The virtual impedance AC droop control scheme also includes stabilizing the energy storage bus voltage of the energy storage DC boost bus unit, and adopting an adaptive DC active power-voltage droop coefficient in the traditional DC active power voltage droop control method, which is expressed as: U jdc -U dcref =-D j (P j -P jref ) Among them, U jdc is the DC side output voltage of the jth set of energy storage grid-connected converter; U dcref D is the DC energy storage bus voltage reference value; j is the DC active power-voltage droop coefficient in the control system of the j-th energy storage grid-connected converter; P j P is the current value of the active power output / absorbed by the j-th set of energy storage grid-connected converter; jref is the target value of active power output / absorption of the j-th set of energy storage grid-connected converter, D j1 is the fixed voltage droop control coefficient, ΔU jdcmax is the maximum DC voltage adjustment range of the jth set of energy storage grid-connected converter; ΔP max is the maximum active power regulation of the j-th set of energy storage grid-connected converter; is the DC voltage regulation rate of the j-th set of energy storage grid-connected converters. When the deviation is larger, the adaptive DC active power-voltage droop coefficient becomes smaller. When facing the same active power regulation amount, the voltage variation range is reduced.

2. A method for segmented frequency modulation of distributed high-voltage direct current (HVDC) bus for thermal power energy storage, using the segmented frequency modulation system for distributed high-voltage direct current (HVDC) bus for thermal power energy storage according to claim 1, characterized in that: The electric energy generated by the generator enters the thermal power energy storage segmented commutation access unit through the outlets of the first generator and the second generator; Electric energy enters the energy storage grid-connected converter through the energy storage AC bus, and enters the energy storage DC boost bus unit using a virtual impedance AC droop control scheme to complete power regulation control.

3. A method for distributed high-voltage direct current (HVDC) convergence and segmented frequency modulation for thermal power energy storage according to claim 2, characterized in that: The virtual impedance AC droop control scheme is to establish voltage-active power and frequency-reactive power droop control equations, which are expressed as follows: Among them, E i is the output voltage amplitude of the i-th set of segmented high-voltage converter devices; E iref is the output voltage reference value of the i-th set of segmented high-voltage converter devices; m i is the voltage-active power droop coefficient of the i-th set of segmented high-voltage converter devices; P i The active power output / absorption of i sets of segmented high-voltage converter devices; ω i The current value of the output frequency of the i-th set of segmented high-voltage converter devices; ω iref Output frequency reference value for the i-th set of segmented high-voltage converter devices; n i is the frequency-reactive power droop coefficient of the i-th segmented high-voltage converter device; Q i Output / absorb reactive power for the i-th set of segmented high-voltage converter devices.

4. A method for distributed high-voltage direct current (HVDC) convergence and segmented frequency modulation for thermal power energy storage according to claim 3, characterized in that: The virtual impedance AC droop control scheme includes using adaptive virtual impedance to compensate for the voltage-active power droop coefficient to improve the active power distribution accuracy. The expression is: Among them, S iref S is the actual power rating output / absorption of the i-th set of segmented high-voltage converter devices; 1ref 、S 2ref The actual power ratings output / absorbed by the first and second sets of segmented high-voltage converter devices.

5. 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 a thermal power energy storage distributed high-voltage direct current bus segmented frequency modulation method according to any one of claims 2 to 4 are implemented.

6. 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 a method for segmented frequency regulation of distributed high-voltage direct current bus of thermal power energy storage as described in any one of claims 2 to 4 are implemented.

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