Electrical access structure of hybrid energy storage system and frequency modulation system of thermal power plant unit

Abstract

The utility model discloses a kind of electrical access structure of hybrid energy storage system and thermal power plant generating unit frequency modulation system, including generating unit high plant transformer section, generating unit public transformer section, hybrid energy storage system is respectively connected generating unit high plant transformer section and generating unit public transformer section;Hybrid energy storage system includes lithium iron phosphate battery energy storage system and supercapacitor energy storage system, lithium iron phosphate battery energy storage system includes lithium iron phosphate battery energy storage system one and lithium iron phosphate battery energy storage system two;Generating unit high plant transformer section includes first generating unit high plant transformer section and second generating unit high plant transformer section, and first generating unit high plant transformer section includes generating unit high plant transformer IA section and generating unit high plant transformer IB section;Second generating unit high plant transformer section includes generating unit high plant transformer IIA section and generating unit high plant transformer IIB section;Generating unit public transformer section includes generating unit public transformer A section and generating unit public transformer B section;First generating unit high plant transformer section and generating unit public transformer A section are connected, and second generating unit high plant transformer section is connected with generating unit public transformer B section.

Description

Technical Field

[0001] This utility model belongs to the field of power system energy storage technology, specifically relating to an electrical access structure for a hybrid energy storage system and a frequency regulation system for thermal power plant units. Background Technology

[0002] Against the backdrop of energy transition and the construction of new power systems, the demand for thermal power units to participate in grid frequency regulation is becoming increasingly urgent. The performance standard for the frequency regulation index Kp value of AGC (Automatic Generation Control) of coal-fired units has been raised to more than 1.5 times the benchmark value, placing higher demands on regulation rate and accuracy. Traditional pure thermal power units suffer from response delays due to mechanical inertia, making it difficult to meet the demand for second-level frequency regulation commands. Therefore, it is imperative to introduce energy storage systems to form a combined thermal and energy storage frequency regulation unit. Hybrid energy storage systems have become the mainstream solution due to their technological complementarity: lithium iron phosphate batteries provide high energy density to support continuous frequency regulation, while supercapacitors (SC) achieve instantaneous power compensation through ultra-high power density. However, the existing electrical connection structure has significant shortcomings:

[0003] Insufficient flexibility: Most projects use a single energy storage system directly connected to the 6kV busbar of the generating unit. When a section of the busbar is under maintenance, the energy storage system completely shuts down, resulting in a frequency regulation capacity reduction of over 40%. Low switching reliability: Traditional manual switching cabinets rely on physical mechanical interlocks, requiring power outages during switching, which cannot meet the requirements for frequency regulation continuity. Poor topology adaptability: The 6kV section of the high-voltage substation carries the core auxiliary equipment load of the generating unit, while the 6kV section of the public substation connects to public loads. Existing technology does not distinguish between energy storage characteristics and busbar functions, leading to power quality issues.

[0004] The failure rate of combined thermal power and energy storage frequency regulation projects due to electrical access design flaws reached 34.2%, severely impacting compensation benefits. Therefore, there is an urgent need to develop a hybrid energy storage electrical access solution with multi-segment redundant access capabilities, a fast and safe switching mechanism, and a load characteristic matching structure to fundamentally improve system availability and frequency regulation economy. Utility Model Content

[0005] The purpose of this invention is to overcome the problem that the connection between the energy storage system and the original electrical system of the power plant is not flexible and reliable enough, and to propose an electrical access structure for a hybrid energy storage system and a frequency regulation system for thermal power plant units.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] In a first aspect, this utility model provides an electrical access structure for a hybrid energy storage system, including a high-voltage transformer section for the generating unit and a common transformer section for the generating unit, wherein the hybrid energy storage system is connected to both the high-voltage transformer section for the generating unit and the common transformer section for the generating unit.

[0008] Hybrid energy storage systems include lithium iron phosphate battery energy storage systems and supercapacitor energy storage systems. Lithium iron phosphate battery energy storage systems include lithium iron phosphate battery storage system one and lithium iron phosphate battery storage system two.

[0009] The high-voltage transformer section of the unit includes the first high-voltage transformer section and the second high-voltage transformer section of the unit. The first high-voltage transformer section of the unit includes the high-voltage transformer IA section and the high-voltage transformer IB section.

[0010] The second unit's high-voltage transformer section includes the unit's high-voltage transformer section IIA and the unit's high-voltage transformer section IIB;

[0011] The common transformer section of the unit includes common transformer section A and common transformer section B;

[0012] The high-voltage transformer section of the first unit is connected to the common transformer section A of the unit, and the high-voltage transformer section of the second unit is connected to the common transformer section B of the unit.

[0013] Furthermore, each energy storage circuit outgoing line is equipped with one energy storage outgoing line switchgear and one plant service section energy storage incoming line switchgear, forming a switchgear group.

[0014] Furthermore, the energy storage outgoing switchgear and the plant service section energy storage incoming switchgear form a redundant switching channel.

[0015] Furthermore, the energy storage systems in the hybrid energy storage system switch between bus sections and are interlocked through secondary circuits, with each energy storage system only connected to a single outgoing line during operation.

[0016] Furthermore, the interlock uses electrical logic interlocking, and the interlock prevents two incoming switch cabinets from closing simultaneously.

[0017] Furthermore, the rated voltage of both the high-voltage transformer section and the common transformer section is 6kV.

[0018] Furthermore, the first lithium iron phosphate battery energy storage system is connected to the dual-section busbar A of the high-voltage transformer of the unit, and the second lithium iron phosphate battery energy storage system is connected to the dual-section busbar B of the high-voltage transformer of the unit.

[0019] Furthermore, the supercapacitor energy storage system is connected to the 6kV section of the unit's common transformer.

[0020] Secondly, this utility model provides a frequency regulation system for thermal power plant units, which uses an electrical access structure of a hybrid energy storage system.

[0021] Compared with the prior art, the present invention has the following beneficial technical effects:

[0022] This invention proposes an electrical access structure for a hybrid energy storage system. Through a reasonable electrical access structure design, this invention enables the hybrid energy storage system to be stably and reliably connected to the existing electrical system of the power plant. Each energy storage system can be flexibly switched, and the interlocking function ensures the safety of operation, which is conducive to improving the efficiency and stability of unit frequency regulation. Attached Figure Description

[0023] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of the present invention in any way. Furthermore, the shapes and proportions of the components in the drawings are merely schematic to aid in understanding the present invention and do not specifically limit the shapes and proportions of the components. In the drawings:

[0024] Figure 1 This is a simplified connection diagram of the electrical access structure of a hybrid energy storage system according to this utility model.

[0025] Figure 2 This is a wiring diagram of the electrical access structure of a hybrid energy storage system according to an embodiment of the present invention.

[0026] Among them, 1 is the first lithium iron phosphate battery energy storage system, 2 is the second lithium iron phosphate battery energy storage system, 3 is the supercapacitor energy storage system, 4 is the IA section of the high-voltage transformer for the generator unit, 5 is the IB section of the high-voltage transformer for the generator unit, 6 is the IIA section of the high-voltage transformer for the generator unit, 7 is the IIB section of the high-voltage transformer for the generator unit, 8 is the A section of the common transformer for the generator unit, 9 is the B section of the common transformer for the generator unit, 10 is the energy storage outgoing switchgear, and 11 is the energy storage incoming switchgear for the plant service section. Detailed Implementation

[0027] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0028] It should be noted that when an element is referred to as being "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only embodiments.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0030] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this utility model are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the utility model described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0031] Example 1

[0032] An electrical access structure for a hybrid energy storage system includes a high-voltage transformer section for the generating unit and a common transformer section for the generating unit, wherein the hybrid energy storage system is connected to both the high-voltage transformer section and the common transformer section for the generating unit.

[0033] The hybrid energy storage system includes a lithium iron phosphate battery energy storage system and a supercapacitor energy storage system 3. The lithium iron phosphate battery energy storage system includes a lithium iron phosphate battery storage system 1 and a lithium iron phosphate battery storage system 2.

[0034] The high-voltage transformer section of the unit includes the first high-voltage transformer section and the second high-voltage transformer section. The first high-voltage transformer section includes the high-voltage transformer section IA 4 and the high-voltage transformer section IB 5.

[0035] The second unit's high-voltage transformer section includes high-voltage transformer section IIA 6 and high-voltage transformer section IIB 7;

[0036] The common transformer section of the unit includes common transformer section A 8 and common transformer section B 9;

[0037] The high-voltage transformer section of the first unit is connected to the common transformer section A 8 of the unit, and the high-voltage transformer section of the second unit is connected to the common transformer section B 9 of the unit.

[0038] The hybrid energy storage system is connected to both the high-voltage transformer section and the common transformer section of the generating unit. The high-voltage transformer section is further subdivided into multiple sections (IA, IB, IIA, IIB). The supercapacitor energy storage system is connected to sections A and B of the common transformer section. This multi-section connection method avoids the risk of the entire energy storage system failing due to a single connection point failure. Even if one section fails, the energy storage systems in other sections can still operate normally, providing power support to the generating unit, greatly improving power supply reliability. Lithium iron phosphate battery energy storage system one and energy storage system two are connected to different high-voltage transformer sections, forming a configuration similar to a dual power supply. When one power source (transformer section) fails, the other can continue to supply power to the relevant loads, ensuring the continuous operation of critical equipment and reducing losses caused by power outages. Because the energy storage system is connected to multiple transformer sections, the power output of the lithium iron phosphate battery energy storage system and the supercapacitor energy storage system can be flexibly allocated according to the load requirements and operating conditions of different transformer sections. For example, during peak load periods in the IA section of the generator unit's high-voltage transformer, the energy from the lithium iron phosphate battery energy storage system connected to that section can be prioritized. In scenarios requiring rapid response to power changes, the advantage of connecting the supercapacitor energy storage system to the generator unit's common transformer section can be utilized to quickly provide or absorb power, meeting the system's dynamic needs. This connection structure facilitates system expansion. If future energy storage capacity increases or new energy storage devices are needed, appropriate transformer sections can be selected for connection based on actual conditions, without requiring large-scale modifications to the entire system. Furthermore, during equipment maintenance, only certain energy storage circuits or switchgear can be operated without affecting the normal operation of other parts, improving system maintainability. Lithium iron phosphate battery energy storage systems are characterized by high energy density and large energy storage capacity, making them suitable for providing long-term power support to the generator unit. Supercapacitor energy storage systems, on the other hand, have advantages such as high power density, fast charging and discharging speeds, and long cycle life, enabling rapid response to system power fluctuations. Connecting these two energy storage systems to different transformer sections allows for optimized configuration based on their respective characteristics, maximizing their efficiency in different scenarios and improving the overall performance of the hybrid energy storage system. By connecting lithium iron phosphate battery energy storage system one and energy storage system two to different high-voltage transformer sections, the load and energy storage characteristics of each section can be better balanced. Based on the load type and power consumption patterns of different transformer sections, the capacity and power of the energy storage system can be rationally allocated, avoiding situations of excess or insufficient energy storage in certain sections and improving the utilization rate of energy storage resources.

[0039] Each energy storage circuit outgoing line is equipped with one energy storage outgoing line switchgear 10 and one plant service section energy storage incoming line switchgear 11, forming a switchgear group.

[0040] Each energy storage circuit outgoing line is equipped with one energy storage outgoing switchgear and one plant service section energy storage incoming switchgear, forming a switchgear group. This clear circuit division makes system operation and management more convenient. Maintenance personnel can quickly locate and isolate faulty circuits for inspection and maintenance, reducing troubleshooting time and improving operation and maintenance efficiency. The independent switchgear group provides convenient conditions for monitoring and control of the energy storage system. By installing monitoring equipment on the switchgear, parameters such as current, voltage, and power of the energy storage circuit can be collected in real time, enabling precise monitoring of the energy storage system's operating status. Simultaneously, based on this monitoring data, remote control and automated adjustment of the energy storage system can be achieved, improving the system's operation and management level.

[0041] The energy storage outgoing switchgear 10 and the plant service section energy storage incoming switchgear 11 form a redundant switching channel.

[0042] During normal operation, the energy storage system supplies power to the plant service section via the main channel (the path connected by one of the switchgear cabinets). When a fault occurs in the energy storage outgoing switchgear in the main channel or the energy storage incoming switchgear in the plant service section, such as burnt-out switch contacts or control circuit failure leading to power outage, the redundant switching channel can be quickly put into use. The system automatically or manually switches to the backup channel, and the channel consisting of another energy storage outgoing switchgear and the corresponding energy storage incoming switchgear in the plant service section continues to supply power to the plant service section, greatly shortening the power outage time and ensuring the continuous operation of important loads. The traditional single-channel power supply mode has the risk of a single point of failure. Once the only switchgear fails, the connection between the entire energy storage system and the plant service section will be interrupted. The design of the redundant switching channel eliminates this single point of failure risk. Even if a switchgear fails, it will not affect the energy storage system's power supply to the plant service section, improving the redundancy and reliability of the power supply. During the charging and discharging process of the energy storage system, power fluctuations may occur. The redundant switching channel can act as a buffer mechanism. When the power transmission of the main channel is unstable, a portion of the power is quickly switched to the backup channel, making the power delivered to the plant service section smoother and more stable. For example, during rapid discharge of a lithium iron phosphate battery energy storage system, if a brief contact failure occurs in the main channel's outgoing switchgear, causing a power drop, the backup channel can promptly replenish the power, preventing voltage and frequency fluctuations in the plant auxiliary section and ensuring the normal operation of the plant auxiliary equipment. The load on the plant auxiliary section may suddenly increase or decrease, such as during the start-up or shutdown of large equipment. Redundant switching channels can better handle such sudden load changes. When the load suddenly increases, the main channel may not be able to provide sufficient power in time. In this case, the backup channel can quickly come into play, jointly supplying power to the load, ensuring that the voltage and frequency of the plant auxiliary section remain stable within the allowable range, and preventing system collapse due to sudden load changes. When planned maintenance is required on the outgoing switchgear or the incoming switchgear of the plant auxiliary section, it is not necessary to interrupt the power supply from the energy storage system to the plant auxiliary section. The load can be switched to the backup channel first, and then the switchgear on the main channel can be inspected and maintained. After the maintenance is completed, the load can be switched back to the main channel, or the current channel can be kept running as needed. This operation and maintenance method improves the flexibility and safety of maintenance, and reduces the time and scope of power outages caused by maintenance. When an anomaly occurs in the power supply between the energy storage system and the plant auxiliary power section, the existence of redundant switching channels allows for troubleshooting by switching channels one by one. First, switch to the backup channel and observe whether the power supply returns to normal. If it does, the main channel is faulty; if the backup channel also has a problem, further inspection of the energy storage system and other parts of the plant auxiliary power section is possible. This step-by-step troubleshooting method can quickly and accurately locate the fault, improving the efficiency of fault handling. Redundant switching channels allow the energy storage outgoing switchgear and the plant auxiliary power section energy storage incoming switchgear to be used alternately, preventing any single switchgear from operating under high load for extended periods.By rationally allocating power supply tasks and balancing the usage time and load of each switchgear, wear and aging of equipment are reduced, the service life of the switchgear is extended, and replacement costs are lowered. Prolonged high-load operation can easily lead to increased internal temperature of the switchgear, accelerating the aging of insulation materials and damaging electronic components. The use of redundant switching channels allows switchgear more rest time, reducing the risk of overheating, ensuring the equipment operates in a suitable temperature environment, and improving equipment reliability and stability.

[0043] In a hybrid energy storage system, the various energy storage systems switch between bus sections and are interlocked via secondary circuits. Each energy storage system only connects to a single outgoing line during operation.

[0044] When a fault occurs on the bus segment to which an operating energy storage system is connected, such as a short circuit or grounding, the system can quickly switch to another normal bus segment. Since each energy storage system only connects to a single outgoing line during operation, the switching process is relatively simple and direct, quickly restoring power to the load, reducing outage time and scope, and ensuring the continuous operation of critical equipment. The load conditions on the plant's auxiliary bus segments may vary at different times. By switching energy storage systems between bus segments, the system can be connected to the bus segment with the heavier load according to actual load requirements, providing additional power support, improving the flexibility and adaptability of the entire power supply system, and ensuring power quality. The secondary circuit interlocking mechanism is crucial for ensuring the safe operation of the system. Through electrical or logical connections, it ensures that when one energy storage system is connected to a certain outgoing line, other energy storage systems cannot simultaneously connect to that outgoing line or conflicting bus segments. This interlocking function effectively prevents misoperation by maintenance personnel and avoids safety accidents such as short circuits and overloads caused by multiple energy storage systems simultaneously connecting to the same outgoing line or bus segment, protecting equipment and personnel safety. In hybrid energy storage systems, different systems (such as lithium iron phosphate battery energy storage systems and supercapacitor energy storage systems) have different electrical characteristics. By using secondary circuit interlocking and single-circuit outgoing line access, electrical conflicts that may occur when different energy storage systems operate in parallel, such as voltage mismatch and phase inconsistency, can be avoided, ensuring stable system operation. Each energy storage system operates with only a single outgoing line, allowing the protection device to be precisely configured according to the characteristics of that energy storage system and outgoing line. The protection device can reasonably adjust overcurrent, overvoltage, and undervoltage protection parameters based on the energy storage system's capacity, charge / discharge characteristics, and outgoing line load, improving the sensitivity and accuracy of protection, promptly clearing faults, and protecting the energy storage system and outgoing equipment from damage. Compared to multi-circuit outgoing line access, single-circuit outgoing line access simplifies the protection logic. The protection device does not need to consider the mutual influence between multiple energy storage systems and complex parallel protection strategies, reducing the complexity of the protection system and the possibility of malfunction, and improving the reliability and stability of the protection system. By switching energy storage systems between bus sections, the load of each energy storage system can be reasonably distributed, avoiding a single energy storage system operating at high load for extended periods. A balanced usage pattern can reduce wear and aging of energy storage systems, extend their service life, and lower equipment replacement costs. A single-circuit outgoing line connection helps reduce thermal stress generated during operation. Due to the relatively balanced load, the temperature changes of the energy storage system are more stable, avoiding equipment damage caused by localized overheating and improving equipment reliability and stability.

[0045] The interlock employs electrical logic interlocking, prohibiting the simultaneous closure of two incoming switchgear cabinets 11. This electrical logic interlocking, through logical judgment of physical or electrical signals, ensures that only one incoming switchgear cabinet can close under any circumstances, fundamentally preventing short-circuit faults and guaranteeing the safe and stable operation of the hybrid energy storage system and the entire plant power system. Different energy storage systems (such as lithium iron phosphate battery energy storage systems and supercapacitor energy storage systems) have different electrical characteristics, including output voltage, frequency, and power factor. If two incoming switchgear cabinets close simultaneously, the parallel operation of power supplies with different characteristics may cause electrical conflicts, leading to voltage fluctuations, frequency instability, and other problems, affecting the normal operation of the load equipment. Electrical logic interlocking effectively prevents this from happening, ensuring the stability of power supply quality. When two incoming switchgear cabinets close simultaneously, the load current connected to the bus section may exceed its rated capacity, causing overload operation. Overload will cause increased heating of the conductors, contacts, and other components in the bus section and switchgear cabinets, accelerating the aging of insulation materials, reducing equipment lifespan, and even causing equipment burnout. Electrical logic interlocking ensures that the load current of the bus section remains within a safe range by limiting the number of switchgear cabinets that can close simultaneously, protecting the bus section and related equipment from overload damage. Energy storage devices in hybrid energy storage systems (such as lithium iron phosphate batteries and supercapacitors) have strict requirements for charging and discharging processes. If two incoming switchgear cabinets close simultaneously, it may lead to excessive charging and discharging current or abnormal voltage in the energy storage system, damaging the energy storage batteries or capacitors and affecting their performance and lifespan. Electrical logic interlocking can avoid this unreasonable operating mode, providing reliable protection for the energy storage system. When an interlocking situation occurs where two incoming switchgear cabinets cannot close simultaneously, maintenance personnel can quickly determine the cause and location of the fault based on the interlocking logic and the system's operating status. For example, if the interlocking system detects an abnormal auxiliary contact signal in a switchgear cabinet, causing the interlocking action, maintenance personnel can focus on checking the auxiliary contacts and related control circuits of that switchgear cabinet, shortening troubleshooting time and improving maintenance efficiency. When expanding or modifying a hybrid energy storage system, the electrical logic interlocking system can be easily adjusted and upgraded. Based on the new system architecture and operational requirements, the interlocking logic can be redesigned, and relevant electrical components and signal connections can be added or modified to achieve protection for the new system. This flexibility and scalability enable the interlocking system to adapt to the continuous development and changes of hybrid energy storage systems, ensuring the long-term stable operation of the system.

[0046] Both the high-voltage transformer section and the common transformer section have a rated voltage of 6kV. 6kV is a widely used voltage level in industrial applications, offering good power transmission capacity and economic efficiency. Using the same rated voltage in both sections facilitates more convenient and efficient power distribution and transmission between them. The power supply capacity of each section can be flexibly adjusted according to actual load demands, achieving optimal allocation of power resources. Under the same power transmission conditions, higher voltage results in lower current and lower line losses. The 6kV voltage level effectively controls line current while meeting industrial production load requirements, reducing resistance and reactance losses in transmission lines, improving power transmission efficiency, and lowering energy consumption and operating costs. The use of the same rated voltage in both sections allows maintenance personnel to maintain and manage the equipment according to unified maintenance standards and procedures.

[0047] Lithium iron phosphate battery energy storage system 1 is connected to the A-section dual-section busbar of the power plant substation, and lithium iron phosphate battery energy storage system 2 is connected to the B-section dual-section busbar of the power plant substation. The A and B sections of the power plant substation are typically powered by different power sources or transformers. Connecting the two lithium iron phosphate battery energy storage systems to different busbar sections effectively provides multiple independent power sources for the plant's auxiliary loads. When one power source fails, such as a generator failure, transformer maintenance, or external grid outage, the other energy storage system can still supply power to critical loads through its corresponding busbar section. This significantly improves the reliability of the plant's auxiliary power system, ensuring the continuous operation of critical equipment (such as feedwater pumps and circulating water pumps) and preventing production interruptions and equipment damage due to power outages. The dual-section busbar structure itself has a certain isolation function; when a fault occurs in one busbar section, the fault can be confined to that section and will not rapidly spread to the entire plant's auxiliary power system. Energy storage systems connected to different bus segments can provide power support to loads on non-faulty bus segments after a fault occurs, further reducing the scope of the power outage and mitigating the impact of the fault on production. The two energy storage systems are independently connected to different bus segments and have no direct electrical connection to each other during normal operation. When one energy storage system or its connected bus segment fails, it will not affect the normal operation of the other energy storage system. This independent operation mode facilitates fault location and isolation, allowing maintenance personnel to focus on troubleshooting and repairing the fault point without worrying about the fault spreading to the entire energy storage system or the plant power system. After the fault is repaired, the independent energy storage system can be quickly put back into operation to restore power to the corresponding bus segment. Compared with traditional centralized energy storage systems, this distributed access method reduces the time and complexity of fault recovery and improves system availability and resilience. The lithium iron phosphate battery energy storage system has a fast charge and discharge response capability and can monitor voltage and frequency changes of the bus segment in real time. When bus voltage or frequency fluctuates, the energy storage system can adjust its charging and discharging power to inject or absorb reactive or active power into the grid, thereby regulating the voltage and frequency and keeping them within acceptable ranges, thus improving power quality. Energy storage systems connected to different bus segments can simultaneously improve the power quality of two bus segments, expanding the regulation range and effect. Distributing energy storage systems across different bus segments facilitates decentralized management by maintenance personnel. Each energy storage system can be equipped with independent monitoring and protection devices, allowing maintenance personnel to monitor the system's operating status, charging and discharging power, battery status, and other parameters in real time, promptly identifying and handling anomalies. Simultaneously, decentralized management reduces the management complexity of individual energy storage systems and improves maintenance efficiency.

[0048] The supercapacitor energy storage system is connected to the 6kV section of the unit's public transformer. When the voltage experiences a momentary drop or rise, the supercapacitor can rapidly release or absorb electrical energy, stabilizing the voltage of the 6kV section of the public transformer and providing high-quality power supply to the load, reducing equipment failures and production interruptions caused by voltage fluctuations. The supercapacitor energy storage system can monitor and compensate for harmonic currents in real time by equipping it with appropriate harmonic compensation devices or employing advanced control strategies. Connecting it to the 6kV section of the public transformer can effectively suppress harmonic pollution on that busbar, improve power quality, and protect equipment connected to that busbar from harmonic hazards. The supercapacitor energy storage system can adjust the power distribution of each phase according to the real-time conditions of the three-phase load through reasonable charging and discharging control, achieving three-phase load balance and improving the operating efficiency and stability of the power system.

[0049] Example 2

[0050] A frequency regulation system for a thermal power plant unit utilizes the electrical access structure of a hybrid energy storage system as described in Embodiment 1. The hybrid energy storage system typically combines supercapacitors and battery energy storage. Supercapacitors possess extremely fast charging and discharging response speeds, capable of reacting to frequency regulation commands within milliseconds, rapidly providing or absorbing active power. While battery energy storage has a relatively slower response speed, it can provide active power support for extended periods. This combination enables the frequency regulation system to quickly respond to rapid fluctuations in grid frequency, meeting the grid's stringent requirements for frequency regulation speed. The hybrid energy storage system combines the advantages of supercapacitors and battery energy storage, utilizing the high power density characteristics of supercapacitors to provide short-term high-power support, and leveraging the high energy density characteristics of battery energy storage to provide long-term active power support. This allows the frequency regulation system to adapt to frequency fluctuations of different scales and types, expanding the frequency regulation capacity range and enhancing the ability to regulate grid frequency. Hybrid energy storage systems undertake some frequency regulation tasks, alleviating the frequency regulation burden on thermal power plant units, reducing frequent start-ups and shutdowns and load changes, thereby lowering the mechanical and thermal stresses of the units and extending the service life of key equipment (such as steam turbines and generators). Simultaneously, the supercapacitors and battery energy storage in hybrid energy storage systems also have long service lives; through proper control and management, their performance advantages can be fully utilized, improving equipment utilization.

[0051] Example 3

[0052] An electrical access structure for a hybrid energy storage system is provided. In this embodiment, the system is connected to the 6kV plant service section and the public service section of a power plant. The interface is the side of the newly added grid connection cabinet in the 6kV plant service section.

[0053] The energy storage power station has one entrance / exit, with the main entrance facing west and the 6kV medium-voltage cable exiting north. The power station area is rectangular, divided into east and west sections, with a fire access road in the middle. From north to south, the eastern part of the power station contains a 5MW supercapacitor energy storage system and a 15MW battery energy storage system. The western part of the power station contains the secondary compartment, grid-connected compartment #1, and grid-connected compartment #2. The main buildings are the PCS and integrated step-up transformer compartment, battery compartment, secondary compartment, grid-connected compartment, and capacitor compartment.

[0054] Four new 6kV busbars will be constructed for the access system. Each 6kV busbar will be connected to the low-voltage side of the high-voltage transformers of Units 1 and 2 (6kV IA, 6kV IIA, 6kV IB, 6kV IIB) and the low-voltage side of the public transformer (6kV A, B). The new cable lines for Unit 1 will be connected to the main plant's plant service section and the public section via cable trenches and overhead cable trays. The new cable lines for Unit 2 will be connected to the main plant's plant service section and the public section via cable trenches. Each 6kV plant service section will have one new high-voltage AC vacuum contactor switchgear added to transfer the original 6kV load to the new switchgear. The old switchgear will be used for energy storage system access, for a total of four switchgears. Each public section will have the original 6kV load transferred to the standby switchgear, and the old switchgear will be used for energy storage system access, for a total of two switchgears.

[0055] See Figure 2 The energy storage power station will construct four 6kV busbars: A, B, C, and D. Sections A and B are battery energy storage busbars, with a single busbar connection. Each section includes three energy storage incoming cabinets, one PT, and two energy storage outgoing cabinets. Sections C and D are supercapacitor energy storage busbars, with a single busbar segmented connection. Each section includes two energy storage incoming cabinets, one segmented switchgear, one isolation cabinet, two PTs, and two energy storage outgoing cabinets.

[0056] The electrical secondary energy storage power station is designed based on the principle of "unmanned operation" (minimum staffing) and operates on a shift system with regular and irregular inspections by operators. It is equipped with a completely independent computer monitoring system—the energy management system for the energy storage power station. The energy management system communicates with the RTU system. The DCS system exchanges information and status with the main control unit of the energy storage system.

[0057] The energy storage control system receives AGC commands and simultaneously monitors the output of the thermal power unit, the output of the energy storage system, and the operating status of the energy storage system. Based on real-time operating data, it judges the overall system status, determines the correction mode and correction amount of the energy storage system to the unit output, and controls the energy storage system to reliably maintain it within the normal operating range.

[0058] By utilizing the existing distributed control system (DCS) of the unit, in conjunction with other devices such as electrical RTU and PMU, functions such as control, alarm and interlock protection of the joint frequency regulation system can be realized to meet the needs of rapid frequency regulation and reliable peak shaving of the unit.

[0059] Many embodiments and applications beyond the examples provided will be apparent to those skilled in the art upon reading the foregoing description. Therefore, the scope of this teaching should not be determined by reference to the foregoing description, but rather by reference to the foregoing claims and the full scope of their equivalents. For purposes of completeness, all articles and references, including patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the foregoing claims is not intended as a waiver of that subject matter, nor should it be construed as an indication that the applicant has not considered that subject matter as part of the disclosed utility model subject matter.

[0060] The above content provides a further detailed description of this utility model. It should not be considered that the specific embodiments of this utility model are limited to this. For those skilled in the art, several simple deductions or substitutions can be made without departing from the concept of this utility model, and all such deductions or substitutions should be considered to fall within the scope of protection of this utility model as defined by the submitted claims.

Claims

1. An electrical access structure for a hybrid energy storage system, characterized in that, This includes the high-voltage transformer section of the generating unit and the common transformer section of the generating unit, with the hybrid energy storage system connected to both the high-voltage transformer section and the common transformer section of the generating unit. The hybrid energy storage system includes a lithium iron phosphate battery energy storage system and a supercapacitor energy storage system (3). The lithium iron phosphate battery energy storage system includes lithium iron phosphate battery energy storage system one (1) and lithium iron phosphate battery energy storage system two (2). The high-voltage transformer section of the unit includes the first high-voltage transformer section and the second high-voltage transformer section of the unit. The first high-voltage transformer section includes the high-voltage transformer IA section (4) and the high-voltage transformer IB section (5). The second unit's high-voltage transformer section includes the unit's high-voltage transformer section IIA (6) and the unit's high-voltage transformer section IIB (7); The common transformer section of the unit includes common transformer section A (8) and common transformer section B (9); The first unit's high-voltage transformer section is connected to the unit's common transformer section A (8), and the second unit's high-voltage transformer section is connected to the unit's common transformer section B (9); The lithium iron phosphate battery energy storage system (1) is connected to the IA section (4) and the IIA section (6) of the high-voltage transformer of the unit respectively. The lithium iron phosphate battery energy storage system II (2) is connected to the IB section (5) and the IIB section (7) of the high-voltage transformer of the unit, respectively. The supercapacitor energy storage system (3) is connected to the unit common transformer A section (8) and the unit common transformer B section (9) respectively.

2. The electrical access structure of a hybrid energy storage system according to claim 1, characterized in that, Each energy storage circuit outgoing line is equipped with one energy storage outgoing line switchgear (10) and one plant service section energy storage incoming line switchgear (11), forming a switchgear group.

3. The electrical access structure of a hybrid energy storage system according to claim 2, characterized in that, The energy storage outgoing switchgear (10) and the plant service section energy storage incoming switchgear (11) constitute a redundant switching channel.

4. The electrical access structure of a hybrid energy storage system according to claim 1, characterized in that, In a hybrid energy storage system, the various energy storage systems switch between bus sections and are interlocked via secondary circuits. Each energy storage system only connects to a single outgoing line during operation.

5. The electrical access structure of a hybrid energy storage system according to claim 4, characterized in that, The interlock is an electrical logic interlock, and the interlock prevents the two incoming switch cabinets (11) from closing at the same time.

6. The electrical access structure of a hybrid energy storage system according to claim 1, characterized in that, The rated voltage of both the high-voltage transformer section and the public transformer section is 6kV.

7. The electrical access structure of a hybrid energy storage system according to claim 1, characterized in that, The lithium iron phosphate battery energy storage system one (1) is connected to the A double-section busbar of the high-voltage transformer of the unit, and the lithium iron phosphate battery energy storage system two (2) is connected to the B double-section busbar of the high-voltage transformer of the unit.

8. The electrical access structure of a hybrid energy storage system according to claim 1, characterized in that, The supercapacitor energy storage system (3) is connected to the 6kV section of the unit's common transformer.

9. A frequency regulation system for a thermal power plant unit, characterized in that, The electrical access structure of a hybrid energy storage system as described in any one of claims 1-8.

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