Thermal power energy storage high-voltage splitting transformation system and method

Abstract

The invention discloses a thermal power energy storage high-voltage splitting transformation system and method, and relates to the technical field of power systems and energy storage, and the method comprises the steps: respectively connecting a generator outlet of a thermal power generating unit to a 20kV energy storage bus section A and a 20kV energy storage bus section B; a branch A and a branch B of a high-voltage split transformer are respectively connected to a section A and a section B of a 20kV energy storage bus; the energy storage module is connected to a 975V energy storage bus, and the 975V energy storage bus is connected to a direct current circuit breaker; and the voltage of the direct-current 975V energy storage bus is kept stable through the centralized current conversion device. Convergence energy storage concentrated alternating current / direct current conversion is realized by adopting a concentrated current conversion device, an innovative direct current active voltage droop control scheme is adopted in the concentrated current conversion device, the direct current 975V energy storage bus voltage can be maintained to be more stable, a direct current networking form is adopted in an energy storage direct current conversion convergence unit, and an energy storage module is connected to a grid through DC-DC direct current. The output voltage of the energy storage device is consistent, and the service life of energy storage is prolonged.

Description

Technical Field

[0001] The present invention relates to the field of power systems and energy storage technology, and in particular to a thermal power energy storage high-voltage splitting transformation system and method. Background Art

[0002] In the design of traditional large-scale thermal power plant power system, the distribution and transmission of electric energy mainly rely on the tap-down transformer at the generator outlet. This process usually includes two-stage transformation: first, the 20kV voltage at the generator outlet is stepped down to 6kV; then, the 6kV voltage is stepped down again to 400V for plant use. Both stages of the step-down process use power frequency transformers, and the entire system is based on AC operation.

[0003] However, with the increasing capacity of thermal power units, the capacity demand of the plant power system is also increasing, which leads to a significant increase in the capacity demand of high-voltage plant transformers. At the same time, the short-circuit current of the plant power system also increases, which puts higher requirements on the short-circuit breaking capacity of the high-voltage switch. In order to meet these requirements, thicker cables need to be selected to ensure short-circuit thermal stability, which undoubtedly increases the investment cost.

[0004] In addition, traditional high-voltage power plant transformers use industrial frequency transformers, which are large and heavy. When the capacity of the power plant power system needs to be increased, the high-voltage power plant transformers often need to be remodeled, which is not only expensive, but also takes a long time to complete, and may affect the normal operation of the power plant.

[0005] In order to solve these problems, the industry has begun to explore new solutions. Among them, DC networking is seen as a potential alternative. Compared with the traditional AC power supply system, DC networking has the advantages of large power supply capacity, no need to consider phase angle and frequency, and the ability to interconnect asynchronous systems. By connecting the power supply load to the DC power supply system through a rectifier, the power conversion efficiency can be improved, equipment losses can be reduced, and variable frequency drive of the load can be achieved. These advantages make DC networking have great potential in optimizing the power supply system.

[0006] Therefore, in order to overcome the limitations of the traditional AC power plant system, it is particularly important to develop a new type of thermal power energy storage high-voltage split transformer system. The system aims to improve equipment reliability, reduce investment costs, and meet the needs of large thermal power units for power plant systems by introducing innovative technologies such as DC networking and high-voltage split transformers. Summary of the invention

[0007] In view of the above-mentioned problems, the present invention is proposed.

[0008] Therefore, the technical problem solved by the present invention is: in the design of the power supply system of the traditional large-scale thermal power unit, the capacity demand of the power supply system increases due to the increase of the unit capacity, which increases the capacity demand of the high-voltage transformer and the short-circuit current, and then puts forward higher requirements for the short-circuit breaking capacity of the high-voltage switch and the short-circuit thermal stability of the cable, resulting in an increase in investment cost. At the same time, the traditional power frequency transformer is large in size, the cost of capacity expansion and transformation is high, and it affects the normal operation of the power plant, so it is necessary to seek a more efficient, economical and easy to expand the power distribution and transmission solution.

[0009] In order to solve the above technical problems, the present invention provides the following technical solution: a thermal power energy storage high-voltage splitting transformer system, which comprises the following steps: Thermal power energy storage split grid-connected unit, energy storage centralized current conversion split transformer unit and energy storage DC conversion and merging unit.

[0010] The converged energy storage segments in the thermal power energy storage splitting grid-connected unit are connected to the outlets of the #1 generator and the #2 generator through the energy storage access circuit breaker, and the generator is connected to the 330kV power grid system through the main transformer.

[0011] The energy storage centralized current conversion splitting transformer unit comprises a high-voltage splitting transformer, wherein the high-voltage side of the high-voltage splitting transformer is divided into two branches, A and B.

[0012] The energy storage DC conversion and convergence unit adopts a DC networking mode, the energy storage module is connected to the DC 975V energy storage bus through a DC-DC conversion device, the DC 975V energy storage bus is connected to the energy storage DC circuit breaker in the energy storage centralized conversion and splitting transformer unit, and the energy storage DC circuit breaker is connected to the DC side of the centralized conversion device.

[0013] As a preferred solution of the thermal power energy storage high-voltage splitting and transformation system described in the present invention, the thermal power energy storage splitting and grid-connected unit is responsible for the grid-connected connection between the energy storage system and the thermal power unit.

[0014] The energy storage centralized current conversion splitting transformer unit is responsible for connecting the energy storage bus section A and section B and the centralized current conversion device.

[0015] The energy storage DC conversion and merging unit is responsible for achieving consistent output voltage of the energy storage device and avoiding the generation of circulating current.

[0016] Another object of the present invention is to provide a high-voltage splitting and transformation method for thermal power energy storage, which can improve the operating efficiency and reliability of the energy storage system by optimizing the high-voltage grid-connected mode of energy storage and thermal power units. This method can solve the problems of unstable energy flow and low efficiency between thermal power and energy storage systems and difficulty in accessing distributed energy storage in the prior art.

[0017] In order to solve the above technical problems, the present invention provides the following technical solution: a thermal power energy storage high-voltage splitting and transformation method, comprising: The generator outlet of the thermal power unit is connected to the 20kV energy storage bus section A and the 20kV energy storage bus section B respectively through the energy storage access circuit breaker; the A and B branches of the high-voltage split transformer are connected to the 20kV energy storage bus section A and the 20kV energy storage bus section B respectively; the energy storage module is connected to the 975V energy storage bus, and the 975V energy storage bus is connected to the energy storage DC circuit breaker in the energy storage centralized converter split transformer unit; the DC 975V energy storage bus voltage is maintained stable through the centralized commutation device.

[0018] As a preferred solution of the method described in the present invention, wherein: the convergence energy storage segments in the thermal power energy storage splitting grid-connected unit are connected to the generator outlet of the generator set through the energy storage access circuit breaker.

[0019] As a preferred scheme of the method described in the present invention, the high-voltage side of the high-voltage split transformer is divided into two branches, A and B, which are respectively connected to the 20kV energy storage bus section A and the 20kV energy storage bus section B in the thermal power energy storage split grid-connected unit, and the low-voltage side of the high-voltage split transformer is connected to the AC side of the centralized converter device.

[0020] As a preferred scheme of the method described in the present invention, wherein: the energy storage module is connected to the 975V energy storage bus, including: the energy storage module is connected to the DC 975V energy storage bus through a DC-DC converter, and the DC 975V energy storage bus is connected to the energy storage DC circuit breaker in the energy storage centralized converter split transformer unit, and further connected to the DC side of the centralized converter.

[0021] As a preferred solution of the method described in the present invention, a droop control algorithm is used to maintain the stability of the 975V energy storage bus voltage.

[0022] As a preferred solution of the method described in the present invention, the droop control algorithm is expressed as: , in, is the voltage change rate of the energy storage DC bus, is the maximum change rate of the energy storage DC bus voltage, which is set according to the rated capacity of the centralized converter device and the maximum allowable voltage deviation. is the energy storage DC bus voltage regulation value, The maximum power output change allowed by the centralized inverter is: is the voltage change rate threshold, is the current value of the DC 975V energy storage bus voltage, is the target value of DC 975V energy storage bus voltage, It is the DC active power-voltage droop coefficient in the centralized converter control system.

[0023] A computer device comprises a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the above method when executing the computer program.

[0024] A computer-readable storage medium stores a computer program, which implements the steps of the method described above when executed by a processor.

[0025] The beneficial effects of the present invention are as follows: by applying the high-voltage split transformer to the thermal power energy storage grid-connected system, a section of converged energy storage can be used to assist the frequency regulation of two thermal power units. When the auxiliary #1 machine performs frequency regulation, the high-voltage split transformer A branch circuit breaker is closed, and the high-voltage split transformer B branch circuit breaker is disconnected; when the auxiliary #2 machine performs frequency regulation, the high-voltage split transformer B branch circuit breaker is closed, and the high-voltage split transformer A branch circuit breaker is disconnected. A locking logic is set between the high-voltage split transformer A branch circuit breaker and the high-voltage split transformer B branch circuit breaker, and they cannot be closed at the same time.

[0026] The present invention adopts a centralized commutation device to realize centralized AC / DC conversion of energy storage. An innovative DC active voltage droop control scheme is adopted in the centralized commutation device to maintain a more stable DC 975V energy storage bus voltage and reduce the DC bus voltage deviation during active power regulation.

[0027] A DC network is used in the energy storage DC conversion and merging unit. The energy storage module is connected to the grid through DC-DC, which can achieve consistent output voltage of the energy storage device, avoid circulating current, and increase the service life of the energy storage. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] 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 work.

[0029] Figure 1 The overall framework diagram of the thermal power energy storage high-voltage splitting transformation system provided for the first embodiment of the present invention.

[0030] Figure 2 An overall flow chart of the thermal power energy storage high-voltage splitting and transformation method provided for the second embodiment of the present invention.

[0031] In the figure: 1. Thermal power energy storage split grid-connected unit; 2. Energy storage centralized current conversion split transformer unit; 3. Energy storage DC conversion and convergence unit; 1-1. #1 generator; 1-2. #1 main transformer; 1-3. 300kV busbar; 1-4. Energy storage boost transformer high voltage section A grid-connected switch; 1-5. Energy storage boost transformer high voltage section B grid-connected switch; 1-6. #2 generator, 1-7. #2 main transformer; 2-1. Energy storage high voltage split transformer; 2-2. Energy storage centralized converter; 2-3. Energy storage DC circuit breaker; 3-1. DC 975V energy storage busbar; 3-2. #1 energy storage DC-DC converter; 3-3. #1 energy storage module; 3-4. #n energy storage DC-DC converter; 3-5. #1 energy storage module. DETAILED DESCRIPTION

[0032] In order to make the above-mentioned purposes, 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 drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0033] Example 1, reference Figure 1 , which is an embodiment of the present invention, provides a thermal power energy storage high-voltage splitting transformer system, comprising: A thermal power energy storage splitting grid-connected unit 1, an energy storage centralized current conversion splitting transformer unit 2 and an energy storage DC conversion and merging unit 3.

[0034] The converging energy storage segments in the thermal power energy storage split grid-connected unit 1 are connected to the #1 and #2 generator outlets through the energy storage access circuit breaker, and the generators are connected to the 330kV power grid system through the main transformer.

[0035] The energy storage centralized converter split transformer unit 2 includes a high-voltage split transformer, the high-voltage split transformer has two branches, A and B, which are respectively connected to the 20kV energy storage bus section A and the 20kV energy storage bus section B in the thermal power energy storage split grid-connected unit 1, and the low-voltage side of the high-voltage split transformer is connected to the AC side of the centralized converter device.

[0036] The energy storage DC conversion and convergence unit 3 adopts a DC networking mode. The energy storage module is connected to the DC 975V energy storage bus through a DC-DC conversion device. The DC 975V energy storage bus is connected to the energy storage DC circuit breaker in the energy storage centralized conversion and splitting transformer unit 2. The energy storage DC circuit breaker is connected to the DC side of the centralized conversion device to achieve consistent output voltage of the energy storage device, avoid circulating current, and extend the service life of the energy storage.

[0037] Example 2, reference Figure 2, which is an embodiment of the present invention, provides a thermal power energy storage high-voltage splitting and transformation method, comprising: S1: Connect the generator outlet of the thermal power unit to the 20kV energy storage bus section A and section B respectively through the energy storage access circuit breaker.

[0038] The converged energy storage segments in the thermal power energy storage splitting grid-connected unit are connected to the generator outlet through the energy storage access circuit breaker.

[0039] This step realizes the connection between the thermal power unit and the energy storage system, providing a basis for subsequent energy exchange and frequency regulation.

[0040] S2: Connect the A and B branches of the high-voltage split transformer to the 20kV energy storage bus section A and B respectively.

[0041] The energy storage system is connected to the centralized converter using a high-voltage split transformer. The high-voltage side of the high-voltage split transformer is divided into two branches, A and B, which are connected to the energy storage bus sections A and B respectively, and the low-voltage side is connected to the AC side of the centralized converter.

[0042] This design enables a section of combined energy storage to assist two thermal power units in frequency regulation, improving the flexibility and reliability of the system.

[0043] S3: Connect the energy storage module to the 975V energy storage bus, and connect the 975V energy storage bus to the energy storage DC circuit breaker in the energy storage centralized current splitting transformer unit 2.

[0044] Connecting the energy storage module to the 975V energy storage bus includes connecting the energy storage module to the DC 975V energy storage bus through a DC-DC converter, and the DC 975V energy storage bus is connected to the energy storage DC circuit breaker in the energy storage centralized converter split transformer unit, and further connected to the DC side of the centralized converter.

[0045] This step realizes the DC grid connection of the energy storage module, allowing the energy storage device to output a consistent voltage without generating circulating current, thereby increasing the service life of the energy storage.

[0046] S4: Maintain the stability of the DC 975V energy storage bus voltage through a centralized converter.

[0047] The innovative DC active voltage droop control scheme is adopted in the centralized converter device to maintain the DC 975V energy storage bus voltage more stable and reduce the DC bus voltage deviation during the active power regulation process. The traditional DC active voltage droop control equation is: , in, It is represented by the current value of the output power on the AC side of the centralized converter. It is expressed as the target output power value of the AC side of the centralized converter.

[0048] A droop control algorithm is used in the centralized commutation device.

[0049] The droop control algorithm is expressed as, , in, is the voltage change rate of the energy storage DC bus, is the maximum change rate of the energy storage DC bus voltage, which is set according to the rated capacity of the centralized converter device and the maximum allowable voltage deviation. is the energy storage DC bus voltage regulation value, The maximum power output change allowed by the centralized inverter is: is the voltage change rate threshold, is the current value of the DC 975V energy storage bus voltage, is the target value of DC 975V energy storage bus voltage, It is the DC active power-voltage droop coefficient in the centralized converter control system.

[0050] Adaptive droop coefficient As the rate of change of the energy storage DC bus voltage Increase and decrease, effectively suppressing the excessive voltage change caused by power regulation and reducing the DC bus voltage deviation during the active power regulation process.

[0051] This solution can automatically adjust the droop coefficient according to the change rate of the energy storage DC bus voltage, thereby effectively suppressing excessive voltage changes caused by power regulation and reducing the DC bus voltage deviation during active power regulation. This control strategy ensures the stability of the energy storage bus voltage and improves the overall performance of the system.

[0052] 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 for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in each embodiment 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.

[0053] 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.

[0054] 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.

[0055] 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, multiple 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.

[0056] 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. Thermal power energy storage high voltage splitting transformer system, characterized in that: include: Thermal power energy storage split grid-connected unit, energy storage centralized current conversion split transformer unit and energy storage DC conversion and merging unit; The converged energy storage segments in the thermal power energy storage splitting grid-connected unit are connected to the outlets of the #1 generator and the #2 generator through the energy storage access circuit breaker, and the generators are connected to the 330kV power grid system through the main transformer; The energy storage centralized current conversion split transformer unit comprises a high-voltage split transformer, and the high-voltage side of the high-voltage split transformer is divided into two branches, A and B; The energy storage DC conversion and convergence unit adopts a DC networking method, including an energy storage module connected to a DC 975V energy storage bus through a DC-DC conversion device, the DC 975V energy storage bus is connected to the energy storage DC circuit breaker in the energy storage centralized conversion and splitting transformer unit, and the energy storage DC circuit breaker is connected to the DC side of the centralized conversion device.

2. The thermal power energy storage high-voltage splitting and transformation system according to claim 1, characterized in that: The thermal power energy storage splitting grid-connected unit is responsible for the grid-connected connection between the energy storage system and the thermal power unit; The energy storage centralized current conversion splitting transformer unit is responsible for connecting the 20KV energy storage bus section A and the 20KV energy storage bus section B and the centralized current conversion device; The energy storage DC conversion and merging unit is responsible for achieving consistent output voltage of the energy storage device and avoiding the generation of circulating current.

3. A method using the thermal power energy storage high-voltage splitting and transformation system as claimed in any one of claims 1 to 2, characterized in that: include: Connect the generator outlet of the thermal power unit to the 20kV energy storage bus section A and the 20kV energy storage bus section B respectively through the energy storage access circuit breaker; Connect the A and B branches of the high-voltage split transformer to the 20kV energy storage bus section A and the 20kV energy storage bus section B respectively; Connect the energy storage module to the 975V energy storage bus, and connect the 975V energy storage bus to the energy storage DC circuit breaker in the energy storage centralized current splitting transformer unit; The DC 975V energy storage bus voltage is maintained stable through a centralized converter.

4. The method according to claim 3, characterized in that: The converged energy storage segments in the thermal power energy storage split grid-connected unit are connected to the generator outlet of the generator set through the energy storage access circuit breaker.

5. The method according to claim 4, characterized in that: The high voltage side of the high voltage split transformer is divided into two branches, A and B, which are respectively connected to the 20kV energy storage bus section A and the 20kV energy storage bus section B in the thermal power energy storage split grid-connected unit, and the low voltage side of the high voltage split transformer is connected to the AC side of the centralized converter device.

6. The method according to claim 5, characterized in that: The connecting of the energy storage module to the 975V energy storage bus includes: the energy storage module is connected to the DC 975V energy storage bus through a DC-DC converter, and the DC 975V energy storage bus is connected to the energy storage DC circuit breaker in the energy storage centralized converter split transformer unit, and further connected to the DC side of the centralized converter.

7. The method according to claim 6, characterized in that: A droop control algorithm is used to maintain the stability of the 975V energy storage bus voltage.

8. The method according to claim 7, characterized in that: The droop control algorithm is expressed as, ， in, is the voltage change rate of the energy storage DC bus, is the maximum change rate of the energy storage DC bus voltage, which is set according to the rated capacity of the centralized converter device and the maximum allowable voltage deviation. is the energy storage DC bus voltage regulation value, The maximum power output change allowed by the centralized inverter is: is the voltage change rate threshold, is the current value of the DC 975V energy storage bus voltage, is the target value of DC 975V energy storage bus voltage, It is the DC active power-voltage droop coefficient in the centralized converter control system.

9. 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 method according to any one of claims 3 to 8 are implemented.

10. 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 method according to any one of claims 3 to 8 are implemented.

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