66kV combined reactive power compensation device for 750kV transformer substation

Abstract

The utility model discloses a 66kV combined reactive power compensation device for a 750kV transformer substation, which comprises a bus bar connected with a main transformer, a branch bus bar is led out from the bus bar, and the branch bus bar is connected with the bus bar through a switch device; the bus bar is connected with an SVG dynamic reactive power compensation device; the branch bus is connected with a reactor and a capacitor; three groups of reactors are arranged, one group of capacitors are arranged, and the reactors and the capacitors jointly form a fixed reactive power compensation device. The utility model has the beneficial effects that stable and reliable reactive compensation can be provided, the equipment layout is optimized, the occupied area and maintenance workload of a transformer substation are reduced, and the operation efficiency of equipment and the overall stability of a power grid are effectively improved.

Description

Technical Field

[0001] The utility model relates to the field of electric power, in particular to a 66kV combined reactive power compensation device for a 750kV transformer substation. Background Art

[0002] With the rapid development and integration of renewable energy, the voltage regulation and reactive power compensation requirements of power systems have become increasingly complex. Traditional substations typically rely on fixed reactive power compensation equipment. For example, the 66kV reactive power compensation system in a 750kV substation typically uses a combination of shunt reactors and shunt capacitors to maintain system voltage stability. While these devices can meet the grid's reactive power needs to a certain extent, their slow response speed and large adjustment range make them difficult to adapt to the dynamic changes in the grid after the integration of renewable energy. Furthermore, the simultaneous configuration of inductive and capacitive reactive power compensation devices in urban substations poses challenges in economic viability, making it difficult to effectively control operating costs. Therefore, the exploration of more advanced reactive power compensation solutions is particularly necessary. Summary of the Invention

[0003] In order to solve the above technical problems, the utility model provides a 66kV combined reactive power compensation device for a 750kV substation.

[0004] The utility model is realized through the following technical solutions:

[0005] The utility model discloses a 66kV combined reactive power compensation device for a 750kV substation, comprising a busbar connected to a main transformer, wherein a branch busbar is led out from the busbar, and the branch busbar is connected to the busbar via a switchgear; an SVG dynamic reactive power compensation device is connected to the busbar; reactors and capacitors are connected to the branch busbars; three groups of reactors are provided, and one group of capacitors is provided, and the reactors and capacitors together constitute a fixed reactive power compensation device.

[0006] In substations, the 750kV voltage level is a high voltage level used for long-distance power transmission, while the 66kV voltage level is used for voltage conversion between regional power grids and user power grids. The utility model is connected to the main transformer via a busbar, which is responsible for converting high-voltage electrical energy into a voltage level suitable for transmission or power consumption. The busbar is equivalent to an electricity distribution node, which transmits electrical energy to multiple branch buses and controls the flow of power on the busbars through switching devices. The SVG dynamic reactive power compensation device is mainly used to quickly respond to the reactive power demand of the power grid, adjust the voltage and stabilize the power grid. The reactor and capacitor form a fixed reactive power compensation device to provide stable reactive power compensation. The function of the reactor is to absorb reactive power, while the capacitor provides reactive power. The two work together to ensure the reactive balance of the power grid.

[0007] Furthermore, the busbars are connected to station-use high-voltage switchgear, which is connected to the power transformer at the distribution station. Station-use high-voltage switchgear is a critical piece of equipment in a substation, used to control and protect electrical equipment and prevent power system overloads or failures. The station-use high-voltage switchgear is connected to the power transformer at the distribution station to ensure a reliable power supply within the substation. The station transformer is the power supply system used by the power supply station itself, and its safe operation directly affects the functionality of the entire substation. Therefore, this high-voltage switchgear has excellent insulation performance and fault protection capabilities to prevent the impact of power fluctuations or short circuits.

[0008] Furthermore, voltage transformers are connected to the aforementioned busbars and branch buses. Voltage transformers are devices used to reduce high voltage to a measurable level while ensuring electrical isolation from secondary measurement equipment. Voltage transformers convert the 66kV high voltage to a standard measurement voltage value, typically 100V or other standard values, allowing operators and equipment to safely measure voltage. This type of equipment plays a key role in the substation's automation and monitoring systems. By measuring voltage data on the busbars, reactive power compensation can be adjusted in real time to ensure grid voltage stability.

[0009] Furthermore, the busbars are connected to zinc oxide arresters. Zinc oxide arresters are highly efficient overvoltage protection devices, primarily used to protect substations and other electrical equipment from damage caused by lightning strikes and power fluctuations. When transient high voltages occur in the power system, such as overvoltages caused by lightning or power failures, zinc oxide arresters can quickly conduct and divert excess current to the ground, thereby protecting the equipment from damage. Due to the excellent nonlinear volt-ampere characteristics of zinc oxide materials, arresters rarely conduct under normal operating voltages but respond quickly to overvoltages, making them essential protective components for substations.

[0010] Furthermore, the switchgear between the above-mentioned busbar and the branch busbar is an HGIS combination electrical appliance, which includes a shell and components encapsulated in the shell. The components include an isolating switch, an earthing switch, a circuit breaker, a current transformer and a high-voltage live display device. The various components are connected and interlocked with each other through the control cabinet; the connection method between the above-mentioned busbar and the SVG dynamic reactive power compensation device is the same as the connection method between the busbar and the branch busbar, and the same switchgear is used.

[0011] An HG IS (high-voltage gas-insulated switchgear) integrates multiple electrical components into a sealed housing, using a gas insulating medium (typically SF6) to insulate the electrical equipment. The advantages of HG IS equipment include a small footprint, compact structure, low maintenance, and strong resistance to environmental interference. The switchgear contains important switches and protective equipment such as disconnectors, earthing switches, circuit breakers, and current transformers, all of which are interlocked and controlled by a control cabinet to ensure the safety and reliability of the system during operation. This integrated design improves substation operational efficiency and reduces the complexity of external wiring for equipment.

[0012] Furthermore, the SVG dynamic reactive power compensation device includes a double-grounding disconnector connected to the busbar, the double-grounding disconnector is connected in series with a bypass circuit breaker, a reactor and an IGBT module, a lightning arrester is connected in parallel between the double-grounding disconnector and the bypass circuit breaker, and a starting resistor is connected in parallel on both sides of the bypass circuit breaker.

[0013] The primary function of the SVG dynamic reactive power compensation device is to regulate grid reactive power and ensure grid voltage stability. The SVG utilizes IGBT modules (insulated gate bipolar transistors) for efficient reactive power regulation, enabling rapid response to grid demand. A double-grounded disconnector ensures safety during equipment maintenance, while a bypass circuit breaker provides an emergency operation path in the event of an SVG failure. The bypass circuit breaker's starting resistor limits overcurrent during circuit breaker operation, preventing equipment damage. Protected by lightning arresters, the device can operate in harsh electrical environments, ensuring the grid's reactive power regulation function.

[0014] Furthermore, the above-mentioned reactor is a dry-type hollow shunt reactor. A dry-type hollow shunt reactor is a device commonly used in reactive power compensation devices. It generates reactance by inducing voltage to offset the reactive power in the power system. The hollow design means that the device has no magnetic core, which can reduce eddy current losses under high voltage conditions. The dry structure means that the equipment does not require insulating oil cooling, has low maintenance requirements, and is environmentally friendly. The function of the reactor is to balance the reactive power in the power grid and prevent voltage fluctuations caused by excess or insufficient reactive power.

[0015] Furthermore, the capacitors described above are complete sets of frame-type shunt capacitors. Frame-type shunt capacitors are a type of reactive power compensation device used to provide reactive power and stabilize grid voltage. Capacitors store and release electrical energy, helping to regulate voltage within the grid. The frame-type structure facilitates installation and maintenance, while also increasing reactive power compensation capacity by combining multiple capacitors. Installed as a complete set, these devices can provide reactive power support when the grid voltage falls below its rated value, maintaining system voltage stability.

[0016] Furthermore, the above-mentioned reactors and capacitors are connected to the branch busbar through the HG IS combination electrical appliance; the above-mentioned HG IS combination electrical appliance includes a shell and components encapsulated in the shell, and the components include an isolating switch, a grounding switch, a circuit breaker, a current transformer and a high-voltage live display device. The various components are connected and interlocked with each other through the control cabinet.

[0017] The beneficial effects of the present invention are:

[0018] Improving grid voltage stability: The SVG dynamic reactive power compensation device works in conjunction with a fixed reactive power compensation device consisting of reactors and capacitors to adjust the grid's reactive power in real time, quickly responding to the grid's reactive power needs. This effectively improves grid voltage stability and prevents voltage fluctuations from damaging equipment and the power system.

[0019] Optimizing technical and economic efficiency: Under the same external boundary factors, the combined arrangement of fixed reactive compensation and SVG dynamic reactive compensation devices not only fully utilizes the flexible adjustment advantages of SVG dynamic reactive compensation devices, but also improves the technical and economic efficiency of reactive compensation devices, achieving cost-effectiveness optimization.

[0020] Improve the convenience of construction and operation and maintenance: This combined layout design not only improves the effect of reactive power compensation, but also further simplifies the construction and operation and maintenance process of the equipment, facilitates installation and maintenance, and greatly improves the overall operational convenience of the equipment.

[0021] Efficient reactive power compensation: The SVG dynamic reactive power compensation device achieves rapid regulation through IGBT modules, accurately adjusting the output or absorption of reactive power to ensure the dynamic balance of reactive power in the grid, thereby preventing overvoltage or undervoltage.

[0022] The utility model not only provides stable and reliable reactive power compensation, but also optimizes the equipment layout, reduces the footprint of the substation and the maintenance workload, and effectively improves the operating efficiency of the equipment and the overall stability of the power grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 : Schematic diagram of the layout of the utility model;

[0024] Figure 2 : Electrical wiring diagram of the utility model;

[0025] Figure 3 : Schematic diagram of the layout of the SVG dynamic reactive power compensation device of the utility model;

[0026] Figure 4 : Electrical wiring diagram of the utility model SVG dynamic reactive power compensation device;

[0027] Figure 5 : Schematic diagram of the arrangement of the utility model in a 750kV substation;

[0028] In the figure: 1-main transformer, 2-busbar, 3-branch busbar, 4-SVG dynamic reactive power compensation device, 5-reactor, 6-capacitor, 7-station high-voltage switchgear, 8-voltage transformer, 9-zinc oxide arrester. DETAILED DESCRIPTION

[0029] The present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0030] Example: Figure 1-5 As shown, a 66kV combined reactive power compensation device for a 750kV substation includes a busbar 2 connected to a main transformer 1, from which branch buses 3 extend, which are connected to the busbar 2 via switchgear; an SVG dynamic reactive power compensation device 4 is connected to the busbar 2; and reactors 5 and capacitors 6 are connected to the branch buses 3. Three groups of reactors 5 and one group of capacitors 6 are provided, and the reactors 5 and capacitors 6 together constitute a fixed reactive power compensation device.

[0031] In the substation, the 750kV voltage level is a high voltage level and is used for long-distance power transmission, while the 66kV voltage level is used for voltage conversion between the regional power grid and the user power grid. The utility model is connected to the main transformer 1 through the busbar 2. The main transformer 1 is responsible for converting high-voltage electric energy into a voltage level suitable for transmission or power consumption. The busbar 2 is equivalent to an electric power distribution node, which transmits electric energy to multiple branch buses 3 and controls the power flow of the busbars through switching devices. The SVG dynamic reactive power compensation device 4 is mainly used to quickly respond to the reactive power demand of the power grid, adjust the voltage and stabilize the power grid. The reactor 5 and the capacitor 6 form a fixed reactive power compensation device to provide stable reactive power compensation. The function of the reactor 5 is to absorb reactive power, while the capacitor 6 is to provide reactive power. The two work together to ensure the reactive balance of the power grid.

[0032] The busbar 2 is connected to a station-use high-voltage switchgear 7, which is connected to the power transformer of the distribution station. The station-use high-voltage switchgear 7 is a critical device in the substation, used to control and protect electrical equipment and prevent power system overload or failure. The station-use high-voltage switchgear 7 is connected to the power transformer of the distribution station to ensure a reliable supply of electricity within the substation. The station transformer is the power supply system used by the power supply station itself, and its safe operation directly affects the function of the entire substation. Therefore, this high-voltage switchgear has excellent insulation performance and fault protection capabilities to prevent the impact of power fluctuations or short circuits.

[0033] The busbars 2 and branch buses 3 are each connected to a voltage transformer 8. Voltage transformers 8 are used to reduce high voltage to a measurable level while ensuring electrical isolation from secondary measurement equipment. Voltage transformers 8 convert the 66kV high voltage to a standard measurement voltage, typically 100V or other standard values, allowing operators and equipment to safely measure voltage. This type of equipment plays a key role in the substation's automation and monitoring systems. By measuring busbar voltage data, reactive power compensation can be adjusted in real time to ensure grid voltage stability.

[0034] A zinc oxide lightning arrester 9 is connected to the busbar 2. The zinc oxide lightning arrester 9 is a highly effective overvoltage protection device, primarily used to protect substations and other electrical equipment from damage caused by lightning strikes and power fluctuations. When a transient high voltage occurs in the power system, such as an overvoltage caused by lightning or a power failure, the zinc oxide lightning arrester 9 can quickly conduct and direct the excess current to the ground, thereby protecting the equipment from damage. Due to the excellent nonlinear volt-ampere characteristics of the zinc oxide material, the lightning arrester barely conducts under normal operating voltage but responds quickly to overvoltage, making it an essential protective element in substations.

[0035] The switchgear between the busbar 2 and the branch busbar 3 is an HGIS switchgear. The HGIS switchgear includes a housing and components encapsulated in the housing. The components include a disconnector, an earthing switch, a circuit breaker, a current transformer, and a high-voltage live display device. The various components are interconnected and interlocked through a control cabinet. The connection method between the busbar 2 and the SVG dynamic reactive power compensation device 4 is the same as the connection method between the busbar 2 and the branch busbar 3, and the same switchgear is used.

[0036] HGIS (High Voltage Gas-Insulated Switchgear) is a device that integrates multiple electrical components into a sealed housing, using a gas insulating medium (usually SF6 gas) to achieve insulation between electrical equipment. The advantages of HGIS equipment are its small footprint, compact structure, low maintenance workload, and strong resistance to environmental interference. The switchgear contains important switches and protection equipment such as disconnectors, earthing switches, circuit breakers, and current transformers. Interlocking control is performed through the control cabinet to ensure the safety and reliability of the system during operation. This integrated design can improve the operating efficiency of the substation and reduce the complexity of the external wiring of the equipment.

[0037] Isolating switches are used to cut off power during equipment overhaul or maintenance, isolating the equipment from the power system and ensuring operational safety. When the isolating switch is open or closed, an external mechanical indicator indicates whether the equipment is energized.

[0038] The earthing switch grounds the equipment after the disconnector is disconnected, further enhancing operational safety and avoiding the risk of electric shock to operators when the equipment is energized.

[0039] The circuit breaker is the core protection component of HGIS, primarily used to automatically disconnect the circuit when a short circuit or fault occurs in the power system. Using gas insulation and arc extinguishing technology, the circuit breaker can interrupt the fault current in an extremely short time, preventing equipment damage.

[0040] The current transformer reduces the current to a safe measurement range and transmits the signal to the protection device and metering equipment, facilitating real-time monitoring of the system's current conditions.

[0041] The high-voltage live display device is used to monitor whether the high-voltage equipment is in a live state and to indicate through signals whether safe operation can be performed.

[0042] Each component forms an interlocking structure through internal busbars and connectors. The connections are as follows: The disconnector connects to the main circuit, interrupting or connecting the current; the grounding switch connects to the ground wire after the disconnector is disconnected; the circuit breaker is located between the disconnector and the main circuit, providing short-circuit protection; current transformers are installed at both ends of the circuit breaker for current monitoring; and the high-voltage live indicator is connected to the disconnector to indicate whether the circuit is live. Centralized control of the operation of each component is achieved through the control cabinet, ensuring system protection and operational safety.

[0043] The SVG dynamic reactive power compensation device 4 includes a double-grounding disconnector connected to the busbar 2, which is connected in series with a bypass circuit breaker, a reactor, and an IGBT module. A lightning arrester is connected in parallel between the double-grounding disconnector and the bypass circuit breaker, and starting resistors are connected in parallel on both sides of the bypass circuit breaker.

[0044] The primary function of the SVG dynamic reactive power compensation device 4 is to regulate grid reactive power and ensure grid voltage stability. The SVG utilizes IGBT modules (insulated gate bipolar transistors) for efficient reactive power regulation, enabling rapid response to grid demand. A double-grounded disconnector ensures safety during equipment maintenance, while a bypass circuit breaker provides an emergency operation path in the event of an SVG failure. The bypass circuit breaker's starting resistor limits overcurrent during circuit breaker operation, preventing equipment damage. Protected by lightning arresters, this device can operate in harsh electrical environments, ensuring the grid's reactive power regulation function.

[0045] The IGBT module is the core component of the SVG, responsible for converting direct current into alternating current that matches the reactive power requirements of the grid. It controls the output or absorption of reactive power through rapid switching operations, ensuring grid voltage stability.

[0046] The reactor is connected in series with the IGBT module. Its main function is to filter and suppress the interference of harmonics on the power grid and provide necessary reactive power. It can absorb reactive power when reactive power is insufficient and prevent voltage fluctuations.

[0047] Double-ground disconnect switches are used to ensure safe operation during equipment maintenance. When SVG equipment is undergoing maintenance, double-ground disconnect switches completely isolate the equipment, preventing live operation.

[0048] In the event of an SVG device failure, the bypass circuit breaker switches to an emergency operation path, ensuring stable power system operation. Starting resistors are connected in parallel on both sides of the bypass circuit breaker to limit overcurrent during circuit breaker operation, preventing equipment damage caused by sudden current surges.

[0049] The arrester is installed between the bypass circuit breaker and the double-grounding disconnector to protect the equipment. When a transient high voltage occurs in the power system, the arrester can quickly conduct the excess current to prevent damage to the equipment.

[0050] SVGs operate by rapidly regulating grid reactive power through IGBT modules. When grid reactive power demand increases, the IGBT modules provide reactive power through switching. When reactive power is excessive, the SVG absorbs the excess. The filtering effect of the reactor ensures stable equipment operation, and the bypass circuit breaker provides an emergency path in the event of a fault. Furthermore, lightning arresters prevent damage to equipment caused by sudden voltage changes, ensuring the safety and stability of the entire system.

[0051] The above-mentioned reactor 5 is a dry-type hollow shunt reactor. A dry-type hollow shunt reactor is a device commonly used in reactive power compensation devices. It generates reactance by inducing voltage to offset the reactive power in the power system. The hollow design means that the device has no magnetic core, which can reduce eddy current losses under high voltage conditions. The dry structure means that the device does not require insulating oil cooling, has low maintenance requirements, and is environmentally friendly. The function of the reactor 5 is to balance the reactive power in the power grid and prevent voltage fluctuations caused by excess or insufficient reactive power.

[0052] The capacitor 6 is a complete set of frame-type shunt capacitors. Frame-type shunt capacitors are a type of reactive power compensation device used to provide reactive power and stabilize grid voltage. Capacitor 6 can store and release electrical energy, helping to regulate voltage within the grid. The frame-type structure makes capacitor 6 easier to install and maintain, and the combination of multiple capacitors can increase reactive power compensation capacity. This complete set of equipment can provide reactive power support when the grid voltage falls below its rated value, maintaining system voltage stability.

[0053] The reactor 5 and capacitor 6 are connected to the branch bus 3 via an HG IS combination electrical appliance. The HG IS combination electrical appliance comprises a housing and components encapsulated in the housing. The components include an isolating switch, an earthing switch, a circuit breaker, a current transformer, and a high-voltage live display device. The various components are interconnected and interlocked via a control cabinet.

[0054] A 750kV substation typically has three main transformers, each responsible for converting high-voltage electricity to a 66kV voltage suitable for use in the regional power grid. This device, connected to each main transformer, provides a reactive power compensation device under each transformer, regulating and stabilizing the voltage level of the regional power grid.

[0055] The busbar 2 of this system is connected to the main transformer 1. The main transformer converts 750kV high-voltage electricity to 66kV, which is then transmitted through the busbar 2 to the branch busbar 3. The branch busbar 3 is connected to a fixed reactive power compensation device consisting of a reactor 5 and a capacitor 6, as well as an SVG dynamic reactive power compensation device 4, via switchgear, to provide static and dynamic reactive power compensation, respectively.

[0056] The fixed reactive power compensation device composed of the reactor 5 and the capacitor 6 balances the supply and demand of reactive power in the power grid by providing stable reactive power, thereby preventing the grid voltage from being too high or too low.

[0057] The SVG dynamic reactive power compensation device 4 responds to fluctuating grid demands in real time by rapidly regulating reactive power, adapting to transient voltage fluctuations to ensure grid voltage stability. The SVG provides precise reactive power regulation through IGBT modules, mitigating voltage fluctuations caused by varying grid loads.

[0058] By connecting one SVG device to each main transformer, the entire 750kV substation can maintain voltage stability under various load conditions. The device's HG IS combination electrical system ensures system reliability and safety. Gas-insulated components minimize interference between devices, and the operation of circuit breakers and disconnectors ensures stable system operation under various operating conditions. Furthermore, the SVG device can rapidly respond to grid anomalies, providing necessary reactive power regulation and collaborating with fixed reactive power compensation devices to maintain grid voltage balance.

[0059] The solution provided by this utility model can not only be used independently, but can also be used to retrofit existing 750kV substations. For example, in a certain 750kV substation, conventional fixed reactive power compensation devices were used. Each main transformer was equipped with two sets of capacitors and four sets of reactors, arranged in a single busbar unit configuration and equipped with a dual-branch main circuit breaker. While this solution achieved basic reactive power compensation, it suffered from a slow response to load fluctuations.

[0060] To improve the grid's reactive power regulation performance, the present invention's technical solution replaces one set of capacitors and one set of reactors with SVG dynamic reactive compensation devices 4 of equal capacity. These SVGs are directly connected to the busbar 2, enabling rapid response to load fluctuations. The remaining fixed reactive compensation devices remain connected to the branch busbar 3. The substation's layout and footprint remain unchanged, and the layout of the main transformer 1, 66kV busbar, and secondary equipment compartments also require no adjustments.

[0061] This retrofit solution not only rapidly upgraded the grid's reactive power compensation system but also significantly enhanced its operational stability and regulatory flexibility. For example, during peak and valley load fluctuations, the SVG device can quickly provide reactive power regulation, preventing abnormal voltage fluctuations and improving the substation's operational reliability within the grid.

[0062] Therefore, the technical solution of this utility model offers the advantages of rapid retrofitting, optimized layout, and flexible reactive power regulation, making it suitable for upgrading reactive power compensation in existing substations. Through equal capacity replacement, rational equipment layout, and the addition of equipment operation and maintenance channels, this solution can rapidly improve the reactive power compensation capacity of the power grid without changing external boundary conditions, while reducing the complexity and cost of construction and operation and maintenance.

[0063] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent replacements for some of the technical features therein. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A 66kV combined reactive power compensation device for a 750kV substation, comprising a busbar (2) connected to a main transformer (1), characterized in that: The busbar (2) leads to a branch busbar (3), which is connected to the busbar (2) via a switchgear; an SVG dynamic reactive power compensation device (4) is connected to the busbar (2); a reactor (5) and a capacitor (6) are connected to the branch busbar (3); three groups of reactors (5) are provided, and one group of capacitors (6) is provided, and the reactors (5) and the capacitors (6) together constitute a fixed reactive power compensation device.

2. A 66kV combined reactive power compensation device for a 750kV substation according to claim 1, characterized in that: The busbar (2) is connected to a station-use high-voltage switchgear (7), and the station-use high-voltage switchgear (7) is connected to a power transformer for a power distribution station.

3. A 66kV combined reactive power compensation device for a 750kV substation according to claim 1, characterized in that: The busbar (2) and the branch busbar (3) are respectively connected to voltage transformers (8).

4. A 66kV combined reactive power compensation device for a 750kV substation according to claim 1, characterized in that: The busbar (2) is connected to a zinc oxide lightning arrester (9).

5. The 66kV combined reactive power compensation device for a 750kV substation according to claim 1, characterized in that: The switchgear between the busbar (2) and the branch busbar (3) is an HGIS combination electrical appliance, which includes a housing and components encapsulated in the housing. The components include an isolating switch, a grounding switch, a circuit breaker, a current transformer, and a high-voltage live display device. The components are connected and interlocked with each other through a control cabinet. The connection method between the busbar (2) and the SVG dynamic reactive power compensation device (4) is the same as the connection method between the busbar (2) and the branch busbar (3), and the same switchgear is used.

6. A 66kV combined reactive power compensation device for a 750kV substation according to claim 1 or 5, characterized in that: The SVG dynamic reactive power compensation device (4) comprises a double grounding disconnector connected to the busbar (2), the double grounding disconnector being connected in series with a bypass circuit breaker, a reactor and an IGBT module, a lightning arrester being connected in parallel between the double grounding disconnector and the bypass circuit breaker, and starting resistors being connected in parallel on both sides of the bypass circuit breaker.

7. The 66kV combined reactive power compensation device for a 750kV substation according to claim 1, characterized in that: The reactor (5) is a dry-type hollow shunt reactor.

8. The 66kV combined reactive power compensation device for a 750kV substation according to claim 1, characterized in that: The capacitor (6) is a frame-type parallel capacitor complete set.

9. A 66kV combined reactive power compensation device for a 750kV substation according to claim 7 or 8, characterized in that: The reactor (5) and the capacitor (6) are connected to the branch bus (3) via an HGIS combined electrical appliance; the HGIS combined electrical appliance comprises a housing and components encapsulated in the housing, the components comprising an isolating switch, a grounding switch, a circuit breaker, a current transformer and a high-voltage live display device, and the components are connected and interlocked with each other via a control cabinet.

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