Zero-carbon micro-grid low-power-consumption SVG full-load test device

Abstract

The invention discloses a zero-carbon micro-grid low-power-consumption SVG full-load test device which comprises a magnetizing transformer, a boosting transformer, a low-voltage cabinet, a low-voltage compensation cabinet, a high-voltage cabinet, a current transformer, a voltage transformer and an energy storage cabinet. According to the zero-carbon micro-grid low-power-consumption SVG full-load test device provided by the invention, the zero-carbon micro-grid low-power-consumption SVG full-load test device is provided with a magnetizing transformer, a boosting transformer, a low-voltage cabinet, a low-voltage compensation cabinet, a high-voltage cabinet, a current transformer, a voltage transformer, an energy storage cabinet and the like, so that the device can store energy when the electricity price is low at night, and the energy can be used in a test; power is supplied to the boosting transformer in an off-grid power supply mode, the low-voltage SVG is additionally arranged on the low-voltage side to balance reactive power, energy storage and power supply efficiency is improved, full-current and full-voltage tests of the SVG can be achieved, meanwhile, energy consumption is reduced, occupancy of power grid capacity is reduced, influences on a power grid and other users during test faults are effectively eliminated, and the service life of the power grid is prolonged. And the test reliability is higher.

Description

Technical Field

[0001] The present invention relates to the technical field of power supply schemes for high-power impact load tests, and more specifically, to a zero-carbon microgrid low-power SVG full-load test device. Background Art

[0002] In recent years, with the continuous development of my country's power industry, a large-scale high-voltage transmission network has gradually formed, and the requirements for reactive power of the power grid have become increasingly stringent. SVG (reactive power compensation device), like active power supply, is an indispensable part of ensuring the power quality of the power system, reducing power grid losses and ensuring its safe operation. Unbalanced reactive power of the power grid will lead to huge fluctuations in the system voltage, which may cause damage to electrical equipment, system voltage collapse and stability damage accidents in severe cases. Therefore, SVG is very important to the power system. After decades of development, a wide variety of SVGs have been formed.

[0003] However, in the prior art, SVG test equipment is an impact load of the power grid, which has great uncertainty for the power grid. The tested equipment needs to be put into operation instantly, and it is uncertain when to exit. Especially for the static reactive power generator SVG, its design power is getting larger and larger, and the demand for electricity during the test is also getting larger and larger. Once a trip occurs, the impact on the power grid is also great. There are problems such as high capacity expansion fee, high reactive power consumption, and inability to achieve dynamic reactive power adjustment. Summary of the invention

[0004] In order to overcome the above-mentioned defects of the prior art, the present invention provides a zero-carbon microgrid low-power SVG full-load test device to solve the problem that the traditional folding rack for home accessories mentioned in the above background technology can only be folded for storage, and the traditional folding rack is usually large in size and weight when in use. Therefore, it is troublesome, time-consuming and labor-intensive to carry the folding rack for home accessories, and the traditional folding rack cannot be adjusted in real time according to the number and volume of the home accessories to be placed to save storage space, so it is easy to cause a waste of storage space and occupy room space.

[0005] In order to achieve the above-mentioned object, the present invention provides the following technical solutions: a zero-carbon microgrid low-power SVG full-load test device, comprising a magnetizing transformer, a step-up transformer, a low-voltage cabinet, a low-voltage compensation cabinet, a high-voltage cabinet, a current transformer, a voltage transformer and an energy storage cabinet, wherein the magnetizing transformer is used to eliminate the excitation inrush current when the step-up transformer is put into operation without load, the step-up transformer is used to step up the low-voltage electricity output by the energy storage device to the rated voltage required by the SVG, the low-voltage cabinet is used to provide power switch access and measurement protection for the power grid, the energy storage cabinet and the magnetizing transformer, the low-voltage compensation cabinet is used to provide on-site compensation for the low-voltage bus, and improve the active efficiency of the energy storage cabinet output, the high-voltage cabinet is used to provide high-voltage power supply to the tested equipment and provide line protection at the same time, the current transformer is used to provide detection current for metering protection, the voltage transformer provides reference voltage for the SVG system in addition to the secondary voltage for metering protection, the energy storage cabinet is used to charge when the power grid is in the low valley, and provide working power to the tested equipment during the SVG test;

[0006] As a further description of the above technical solution, the energy storage cabinet includes an energy storage unit, a battery management system (BMS) and a power conversion system (PCS). The energy storage unit is used to store electrical energy. The battery management system (BMS) is used to monitor the state of the battery, including parameters such as voltage, current, and temperature, to ensure that the battery operates within a safe range and extend the battery life. The power conversion system (PCS) is responsible for converting the AC power of the power grid into DC power or converting the DC power of the energy storage unit into AC power.

[0007] As a further description of the above technical solution, the power conversion system (PCS) includes a bidirectional inverter, a rectifier and an inverter, wherein the bidirectional inverter is used to realize AC / DC and DC / AC bidirectional conversion, the rectifier is used to convert AC power into DC power and charge the energy storage unit, and the inverter is used to convert the DC power of the energy storage unit into AC power and supply it to the load;

[0008] As a further description of the above technical solution, the energy storage cabinet also includes a control and management system and a protection and safety device, wherein the control and management system is used to monitor and manage the overall operation of the energy storage cabinet, and the protection and safety device is used to ensure the safe operation of the energy storage cabinet;

[0009] As a further description of the above technical solution, the control and management system includes an energy management system (EMS), a central control unit (CCU) and a remote monitoring system. The energy management system (EMS) is used to optimize the charging and discharging strategy of the energy storage unit to achieve efficient use of energy. The central control unit (CCU) is responsible for coordinating the work of various devices in the energy storage cabinet and receiving instructions from the EMS. The remote monitoring and control is achieved through the Internet or a dedicated network, which is convenient for operation and maintenance management;

[0010] As a further description of the above technical solution, the protection and safety equipment includes a circuit breaker, a fuse, an isolating switch and a fire fighting system. The circuit breaker is used to cut off the overloaded or short-circuited circuit to protect the energy storage unit and the power conversion system. The fuse is used to melt when the current is too large to protect the circuit from damage. The isolating switch is used to manually or automatically cut off the power supply for easy inspection and maintenance. The fire fighting system is used to perform fire fighting and first aid when a fire occurs in the energy storage unit under extreme circumstances.

[0011] As a further description of the above technical solution, the energy storage cabinet adopts a grid-connected power supply mode. After the low-voltage SVG is put into operation, the magnetizing transformer and the step-up transformer are put into operation in sequence to form a microgrid.

[0012] Compared with the prior art, the present invention has the following beneficial effects:

[0013] 1. The present invention provides a zero-carbon microgrid low-power SVG full-load test device with components such as a magnetizing transformer, a step-up transformer, a low-voltage cabinet, a low-voltage compensation cabinet, a high-voltage cabinet, a current transformer, a voltage transformer and an energy storage cabinet, so that the device can store energy at night when the electricity price is low for use during the test. The step-up transformer is powered by an off-grid power supply mode, and a low-voltage SVG is installed on the low-voltage side to balance the reactive power, thereby improving the energy storage power supply efficiency. The full-current and full-voltage test of the SVG can be achieved, while reducing energy consumption, reducing the occupation of the grid capacity, and effectively eliminating the impact of test failures on the grid and other users, thereby making the test more reliable.

[0014] 2. The present invention converts the power supply of the power grid into direct current and stores it in the battery through the energy storage cabinet. When testing the SVG, the direct current is inverted into alternating current to supply the entire system. The energy storage cabinet adopts the grid-connected power supply mode. After the low-voltage SVG is put into operation, the magnetizing transformer and the step-up transformer are put into operation in sequence to form a microgrid, which can realize low-power full-current and full-voltage tests. Through the hedging test of two sets of SVG, the energy consumption and cost can be greatly reduced, and the occupation of the power grid capacity is reduced. As long as the energy storage cabinet and the transformer are reasonably matched, the device can perform full-current and full-voltage tests on SVG of all capacities. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0016] Figure 1 It is a schematic diagram of the system structure of the present invention.

[0017] Figure 2It is a circuit flow chart of the present invention.

[0018] Figure 3 It is a system flow chart of the present invention. DETAILED DESCRIPTION

[0019] The following is a description of the implementation of the present invention by specific embodiments. People familiar with the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] In order to enable those skilled in the art to better understand the present application, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0021] See attached Figure 1 , 2 As shown in 3, a zero-carbon microgrid low-power SVG full-load test device includes a magnetizing transformer for eliminating the excitation surge current when the step-up transformer is put into operation without load, a step-up transformer for stepping up the low voltage output of the energy storage device to the rated voltage required by the SVG, a low-voltage cabinet for providing power switch access and measurement protection for the power grid, the energy storage cabinet, and the magnetizing transformer, a low-voltage compensation cabinet for providing on-site compensation for the low-voltage bus, and improving the active efficiency of the energy storage cabinet output, a high-voltage cabinet for providing high-voltage power supply to the tested equipment, and line protection at the same time, a current transformer for metering protection and providing detection current, a voltage transformer for providing a reference voltage for the SVG system in addition to the secondary voltage for metering protection, and an energy storage cabinet for charging during the low power consumption of the power grid, and providing working power to the tested equipment during the SVG test. The energy storage cabinet includes:

[0022] Energy storage unit (Battery Modules) and battery management system (BMS). The energy storage unit is used to store electrical energy, and the battery management system is used to monitor the status of the battery, including parameters such as voltage, current, and temperature, to ensure that the battery operates within a safe range and extend the battery life;

[0023] Power Conversion System (PCS): The power conversion system is responsible for converting the AC power of the grid into DC power, or converting the DC power of the energy storage unit into AC power. It includes: a bidirectional inverter, which is used to realize AC / DC and DC / AC bidirectional conversion and is a key device in the energy storage cabinet; a rectifier, which is used to convert AC power into DC power to charge the energy storage unit; and an inverter, which is used to convert the DC power of the energy storage unit into AC power for supplying the load.

[0024] Control and management system: The control and management system is used to monitor and manage the overall operation of the energy storage cabinet, including: Energy Management System (EMS), which is used to optimize the charging and discharging strategy of the energy storage unit to achieve efficient use of energy; Central Control Unit (CCU), which is responsible for coordinating the work of various devices in the energy storage cabinet and receiving instructions from the EMS; Remote monitoring system, which realizes remote monitoring and control through the Internet or a dedicated network to facilitate operation and maintenance management.

[0025] Protection and safety equipment Protection and safety equipment, Protection and safety equipment Protection and safety equipment are used to ensure the safe operation of the energy storage cabinet, including: Circuit breaker: used to cut off overloaded or short-circuited circuits to protect energy storage units and power conversion systems; Fuse: blows when the current is too large to protect the circuit from damage; Isolating switch: manually or automatically cuts off the power supply for easy inspection and maintenance; Fire fighting system: Fire may occur in the energy storage unit under extreme circumstances, and special fire fighting equipment is required.

[0026] like Figure 1 , 2 As shown in Figure 3, the energy storage cabinet converts the power of the power grid into direct current and stores it in the battery. When the SVG is tested, the direct current in the battery is inverted into alternating current to supply the entire system. At the same time, the energy storage cabinet adopts the grid-connected power supply mode. The low-voltage SVG is put into operation, and then the magnetizing transformer is put into operation. At this time, the magnetizing transformer is also powered by the grid. When the magnetizing transformer reaches a steady state, the step-up transformer is put into operation. At this time, the grid and the energy storage cabinet simultaneously supply power to the step-up transformer. When the step-up transformer reaches steady-state operation, the switches are disconnected in turn, the magnetizing transformer is removed, the energy storage device is changed to off-grid mode, and the energy storage cabinet no longer exchanges energy with the grid. At this time, the energy storage cabinet is used as the power supply, and a microgrid is formed by the low-voltage compensation, the step-up transformer and the tested equipment. The power supply of the energy storage cabinet is new energy or the electricity price at night, and our test can be carried out at any time, so our energy consumption is much more economical than taking electricity directly from the grid, thus achieving low carbon or zero carbon.

[0027] After the step-up transformer is in steady-state operation, the high-voltage cabinet is put into operation and preparations for the test are started. SVG is a dynamic reactive compensation device, and its active power does not exceed 2% of its output capacity at most. If we only have one device for the test, the theoretical capacity of the SVG is as large as the capacity of the transformer. This consumes a lot of power, and it is reactive power, so the test is not economical. Therefore, a test SVG is needed, which provides variable reactive power, and the tested equipment dynamically tracks it to ensure the dynamic balance of reactive power at every moment. The power supply (energy storage cabinet) only needs to provide active power, and the selection of the transformer can also be calculated according to the maximum active power loss of the two devices. For example, if a set of 100Mvar SVG is tested, if only this set of equipment is used, the step-up transformer also needs 100MVA, and the energy storage cabinet also needs to provide at least the same output capacity. If another 100Mvar SVG is used as a hedge, the capacity of the step-up transformer and the energy storage cabinet only needs to be 100*2*2%=4MVA. In this way, low power consumption can be achieved. Such a small capacity can be directly made into a container, reducing the indoor floor space. It makes investment and construction very convenient.

[0028] During the SVG test, the test equipment outputs the specified reactive power as required, and the tested equipment detects the PT and CT signals in the high-voltage cabinet as the basis for adjustment, which can realize dynamic adjustment and also realize the test of full current and full voltage at low power consumption. At the same time, if one of the SVGs fails and the other device happens to be running at full current, it will cause several times overcurrent in the transformer and energy storage cabinet, and in serious cases, burn out the two devices. Therefore, in order to avoid such accidents, this project has taken the following two measures: First, the two sets of SVG are connected to a circuit breaker at the same time. No matter which device has a problem, the same switch will be tripped, so that the two devices are powered off at the same time. Second, to solve the instantaneous overcurrent generated during the switch action time, if any of them has a tripping accident or exits operation, it will send a signal to the other one to lock the other one. This minimizes the probability of accidents. If some kind of accident does occur and there is a cross-level tripping, it will only cut off the energy storage cabinet, which will not affect other loads on the power grid, let alone cause regional power outages. If the capacity of the energy storage cabinet is large enough, it can also be charged and discharged in turn. Ensure sufficient test time.

[0029] The present invention aims to solve the power supply scheme problem of high-power impact load test, especially to perform full-load test on static reactive generator SVG. The device uses energy storage device to store low-peak power at night, balances reactive power through step-up transformer and low-voltage SVG, improves power supply efficiency, realizes full-load test on SVG, and ensures safe and reliable operation of power supply system.

[0030] Finally: The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. Zero-carbon microgrid low-power SVG full-load test device, characterized by: It includes a magnetizing transformer, a step-up transformer, a low-voltage cabinet, a low-voltage compensation cabinet, a high-voltage cabinet, a current transformer, a voltage transformer and an energy storage cabinet. The magnetizing transformer is used to eliminate the excitation surge current when the step-up transformer is put into operation without load. The step-up transformer is used to step up the low-voltage electricity output by the energy storage device to the rated voltage required by the SVG. The low-voltage cabinet is used to provide power switch access and measurement protection for the power grid, the energy storage cabinet and the magnetizing transformer. The low-voltage compensation cabinet is used to provide on-site compensation for the low-voltage busbar to improve the active efficiency of the energy storage cabinet output. The high-voltage cabinet is used to provide high-voltage power supply to the tested equipment and provide line protection at the same time. The current transformer is used to provide detection current for metering protection. In addition to the secondary voltage for metering protection, the voltage transformer also provides a reference voltage for the SVG system. The energy storage cabinet is used to charge when the power consumption of the power grid is low, and provide working power to the tested equipment during the SVG test.

2. The zero-carbon microgrid low-power SVG full-load test device according to claim 1 is characterized by: The energy storage cabinet includes an energy storage unit, a battery management system and a power conversion system. The energy storage unit is used to store electrical energy. The battery management system is used to monitor the status of the battery, including parameters such as voltage, current, and temperature, to ensure that the battery operates within a safe range and extend the battery life. The power conversion system is responsible for converting the AC power of the power grid into DC power or converting the DC power of the energy storage unit into AC power.

3. The zero-carbon microgrid low-power SVG full-load test device according to claim 2 is characterized by: The power conversion system includes a bidirectional inverter, a rectifier and an inverter. The bidirectional inverter is used to realize AC / DC and DC / AC bidirectional conversion. The rectifier is used to convert AC power into DC power and charge the energy storage unit. The inverter is used to convert the DC power of the energy storage unit into AC power and supply it to the load.

4. The zero-carbon microgrid low-power SVG full-load test device according to claim 3 is characterized by: The energy storage cabinet also includes a control and management system and protection and safety equipment. The control and management system is used to monitor and manage the overall operation of the energy storage cabinet, and the protection and safety equipment is used to ensure the safe operation of the energy storage cabinet.

5. The zero-carbon microgrid low-power SVG full-load test device according to claim 4 is characterized by: The control and management system includes an energy management system, a central control unit and a remote monitoring system. The energy management system is used to optimize the charging and discharging strategy of the energy storage unit to achieve efficient use of energy. The central control unit is responsible for coordinating the work of various devices in the energy storage cabinet and receiving instructions from the EMS. Remote monitoring and control are achieved through the Internet or a dedicated network to facilitate operation and maintenance management.

6. The zero-carbon microgrid low-power SVG full-load test device according to claim 5 is characterized by: The protection and safety equipment includes a circuit breaker, a fuse, an isolating switch and a fire fighting system. The circuit breaker is used to cut off an overloaded or short-circuited circuit to protect the energy storage unit and the power conversion system. The fuse is used to blow when the current is too large to protect the circuit from damage. The isolating switch is used to manually or automatically cut off the power supply for easy inspection and maintenance. The fire fighting system is used to provide fire fighting first aid when a fire occurs in the energy storage unit under extreme circumstances.

7. The zero-carbon microgrid low-power SVG full-load test device according to claim 6 is characterized by: The energy storage cabinet adopts a grid-connected power supply mode. After the low-voltage SVG is put into operation, the magnetizing transformer and the step-up transformer are put into operation in sequence to form a microgrid.

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