A voltage regulating device and its control and protection system, and control and protection method

Abstract

The present invention discloses a voltage regulating device and its control and protection system, as well as a control and protection method. The voltage regulating device includes: a first transformer, a second transformer, a switching device, an AC contactor, an input circuit breaker, an output circuit breaker, a bypass circuit breaker, and a controller. The first transformer is composed of three single-phase isolation transformers, and the second transformer is a three-phase transformer with multiple voltage levels on the secondary side. The number of switching devices selected depends on the number n of voltage levels on the secondary side of the second transformer. The controller is used to perform current and voltage acquisition on the power grid system side, current and voltage acquisition on the secondary side circuits of the two transformers, and contactor disconnection of each phase circuit, conduction and disconnection of the switching device, and disconnection of the circuit breaker. The present invention solves the problem that existing voltage regulating devices have unreasonable transformer design parameters for different load conditions, resulting in low economic efficiency for large-scale application and an inability to ensure reliable operation.

Description

Technical Field

[0001] The present invention belongs to the technical field of line voltage regulation, and in particular relates to a voltage regulating device and a control and protection system and a control and protection method thereof. Background Art

[0002] In response to the "dual carbon" goals, my country's distributed renewable energy power generation system installation scale in the distribution network has rapidly expanded. However, the uncontrolled access of multiple renewable energy sources to the grid can cause serious power quality problems. For example, the output of photovoltaic and wind turbines is affected by uncertain factors such as weather. Their randomness and volatility can cause voltage fluctuations in the distribution system. On the other hand, with the economic development of rural areas, the demand for power quality is becoming increasingly higher. However, the medium and low voltage distribution network architecture is relatively weak. There are problems such as excessively long transmission lines, periodic and seasonal load fluctuations, and aging or damage of distribution equipment. These problems lead to low voltage at the end of the distribution line. Therefore, voltage regulators play the most direct and effective role in solving the above problems.

[0003] However, existing voltage regulators generally suffer from problems such as a narrow on-load voltage regulation range, limited mechanical voltage regulation times, insufficient flexibility, poor economic efficiency due to irrational transformer design parameters for different load conditions, and limited ability to handle line conditions. With the advancement of power electronics technology, power electronic devices such as thyristors have been widely used as voltage tap changers, enabling rapid voltage regulation with significantly better regulation than mechanical on-load voltage regulators and increasing voltage regulation flexibility. Therefore, how to apply power electronics to voltage regulators to improve the economic efficiency of large-scale deployment and optimize control and protection strategies for reliable operation remain key challenges that need to be addressed.

[0004] Chinese patent publication number CN113363988A discloses a method, device, and medium for optimizing power grid operation based on an on-load tap-changing transformer, including: decomposing the on-load tap-changing transformer into a circuit model consisting of an ideal transformer and a constant impedance; analyzing the circuit model to obtain the relationship between the voltage and phase angle across the transformer, as well as the active power and reactive power flowing through the transformer; obtaining the active power equation and reactive power equation for each node of the power grid; based on the circuit model, obtaining a linear equation for limiting the number of adjustments of the on-load tap-changing transformer according to preset constraints; and adjusting the taps of the on-load tap-changing transformer according to the linear equation for limiting the number of adjustments of the on-load tap-changing transformer and the active power equation and reactive power equation for each node of the power grid to achieve power flow and voltage adjustment. The on-load tap-changing transformer described in this invention has the characteristic of a limited number of adjustments, and the circuit model analysis, power equation acquisition, and constraint processing involved in the power grid operation optimization method of this invention require efficient computing resources and algorithm support. Summary of the Invention

[0005] The present invention provides a voltage regulating device and its control and protection system, as well as a control and protection method, aiming to solve the problem that the existing voltage regulating device has unreasonable transformer design parameters for different load conditions, resulting in low economy in large-scale application and unguaranteed reliable operation.

[0006] To solve the above technical problems, the present invention provides a voltage regulating device, comprising: a first transformer, a second transformer, a switching device, an AC contactor, an input circuit breaker, an output circuit breaker, a bypass circuit breaker and a controller. The first transformer is composed of three single-phase isolation transformers, and the second transformer is a three-phase transformer with multiple voltage levels on the secondary side. The number of switching devices selected depends on the number n of voltage levels on the secondary side of the second transformer. The controller is used to perform current and voltage acquisition on the power grid system side, current and voltage acquisition on the secondary side circuits of the two transformers, and shutdown of the contactors of each phase circuit, conduction and shutdown of the switching devices, and shutdown of the line circuit breaker.

[0007] The three-phase A, B, and C primary-side incoming terminals of the first transformer are connected to the input line respectively. The primary-side outgoing terminals X, Y, and Z of the first transformer are connected to the primary-side incoming terminals D, E, and F of the second transformer. The primary-side outgoing terminals G, H, and I of the second transformer form a star connection. The secondary-side outgoing terminal of the second transformer leads to n voltage level taps according to the needs of the grid users. Each tap is connected to one end of a switching device. The other end of each corresponding n switching devices is output and connected to the secondary-side outgoing terminals M, N, and O of the first transformer. The secondary-side outgoing terminals J, K, and L of the second transformer are connected to the secondary-side incoming terminals P, Q, and R of the first transformer.

[0008] The AC contactor is connected in parallel between the secondary side output terminal and the input terminal of the first transformer; the input circuit breaker is connected in series before the primary side input terminals A, B, and C of the first transformer, with one end connected to the input line and the other end connected to the primary side input terminals A, B, and C of the first transformer; the output circuit breaker is connected in series after the primary side input terminals D, E, and F of the second transformer, with one end connected to the primary side input terminals D, E, and F of the second transformer and the other end connected to the downstream power supply line; one end of the bypass circuit breaker is connected to the front end of the input circuit breaker and the other end is connected to the rear end of the output circuit breaker.

[0009] Preferably, the calculation formula for the current flowing through the primary winding of the second transformer in the voltage regulating device is specifically:

[0010]

[0011] Where, I T2w1 is the current flowing through the primary winding of the second transformer; k is the percentage of the rated voltage that the voltage regulator needs to adjust the maximum output voltage, 0 <k<1;S NU is the load capacity of the substation; m is the rated phase voltage of the line.

[0012] The calculation formula for the rated current of the primary side of the second transformer is set as:

[0013] I T2N =xI T2w1

[0014] Where, I T2N is the rated current of the primary side of the second transformer, and x is the margin coefficient.

[0015] The calculation formula for the rated current of the primary side of the first transformer in the voltage regulating device is set to:

[0016] I T1N =x(I load +I T2N )

[0017] Where, I T1N is the rated current of the primary side of the first transformer; x is the margin coefficient; I load I is the load current flowing through the primary winding of the first transformer; T2N is the rated current of the primary side of the second transformer.

[0018] Preferably, in the voltage regulating device, the rated voltage of the secondary winding of the second transformer is set to be consistent with the rated voltage of the secondary winding of the first transformer, and the voltage regulating device outputs 1 / (1-k) times the maximum voltage.

[0019] Preferably, the calculation formula for the operating peak current of the switching device is set to:

[0020]

[0021] Where, I M is the operating peak current of the switching device; I T1N is the rated current of the primary side of the first transformer; U T2w2 is the secondary winding voltage of the second transformer; U T1w2 is the secondary winding voltage of the first transformer;

[0022] The calculation formula for the operating peak voltage of the switching device is set to:

[0023]

[0024] Where U M is the operating peak voltage of the switching device; U T1w2 is the secondary winding voltage of the second transformer.

[0025] On the other hand, the present invention provides a control and protection system for a voltage regulating device, comprising a data acquisition module, a fault monitoring module, a state switching module, and a switch action module.

[0026] The data acquisition module is used to collect the line current and voltage at the first transformer inlet terminal and the secondary circuit current and voltage of the voltage regulating device.

[0027] The fault monitoring module is used to monitor and judge the faults of the voltage regulating device circuit and the voltage regulating device itself according to the signals from the data acquisition module.

[0028] The state switching module is used to switch the state according to the fault monitoring results and the four operating state marks of the voltage regulating device. The voltage regulating device is set to have four operating states, namely hot standby state, normal operating state, temporary fault state, and permanent fault state.

[0029] The switch action module is used to control the action sequence of the switch device and the circuit breaker according to the mark of the operating state of the voltage regulating device by the state switching module.

[0030] Preferably, the faults of the fault monitoring module are divided into transient faults and permanent faults. Transient faults include line overcurrent, overvoltage and overtemperature of switching devices, and permanent faults include failure of switching devices, PT disconnection and CT disconnection.

[0031] Preferably, when the state switching module marks the voltage regulating device as a hot standby state or a transient fault state, the switch action module first locks all switch devices and then closes the AC contactor of the secondary side circuit of the transformer.

[0032] When the state switching module marks the voltage regulating device as a normal operating state, the cross-circuit contactor of the secondary side circuit is first disconnected, and then the corresponding switching device is turned on to start voltage regulation.

[0033] When the state switching module switches the voltage regulating device from the normal operating state to the permanent fault state, it first completes the switch action switching to exit the normal operating state, that is, completes the state switching from the normal operating state to the hot standby state or the transient fault state, and then disconnects the input circuit breaker and the output circuit breaker of the voltage regulating device, closes the bypass circuit breaker of the voltage regulating device, and completely bypasses the voltage regulating device.

[0034] In another aspect, the present invention provides a control and protection method for a voltage regulating device, comprising the following steps:

[0035] The line current and voltage at the first transformer inlet terminal and the secondary circuit current and voltage of the voltage regulating device are collected.

[0036] According to the signal of the data acquisition module, the monitoring and judgment of the voltage regulating device line fault and the voltage regulating device itself fault are completed.

[0037] The state switching is performed according to the fault monitoring results and the four operating state marks of the voltage regulating device. The voltage regulating device is set to four operating states, namely hot standby state, normal operating state, temporary fault state, and permanent fault state.

[0038] According to the marking of the operating status of the voltage regulating device by the status switching module, the action sequence of the switching device and the circuit breaker is controlled.

[0039] On the other hand, the present invention also provides an electronic device, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the control and protection method for the voltage regulating device as described in any embodiment of the present invention is implemented.

[0040] On the other hand, the present invention further provides a computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed by a processor, the control and protection method for the voltage regulating device according to any embodiment of the present invention is implemented.

[0041] Compared with the prior art, the present invention has the following technical effects:

[0042] 1. The present invention provides a voltage regulating device that utilizes power electronic high-power switching devices to switch voltage levels in a secondary circuit. The device adjusts the voltage range according to the line voltage level, load capacity, and user needs, and has the advantages of more flexible and precise voltage regulation and large compensation capacity.

[0043] 2. The control and protection system of the voltage regulating device described in the present invention controls the working state switching of the voltage regulating device through the results of the signal acquisition module and the fault judgment module. The switch action module quickly responds to the action of the corresponding switch according to the working state of the voltage regulating device to ensure the stable operation of the voltage regulating device and the stable and reliable power supply of the downstream circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a circuit structure diagram of the voltage regulating device of the present invention;

[0045] Figure 2 This is an overall structural diagram of the control and protection system of the voltage regulating device of the present invention;

[0046] Figure 3 This is a schematic diagram of the fault judgment logic of the present invention;

[0047] Figure 4 It is a schematic diagram of the state switching of the voltage regulating device described in the present invention. DETAILED DESCRIPTION

[0048] In order to make the objectives, technical solutions and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in combination with specific embodiments of the present application and with reference to the accompanying drawings.

[0049] Example 1

[0050] This embodiment provides a voltage-regulating device, which is composed of two transformers connected together and utilizes power electronic high-power switching devices to switch voltage levels in the secondary circuit. This device has the advantages of more flexible and precise voltage regulation and large compensation capacity. It also provides its main circuit parameter settings and line protection strategy. Based on the line voltage level, load capacity, and user-required voltage range, the rated parameters of the primary sides of the first and second transformers are first designed. The secondary side rated voltage is further designed based on the secondary side voltage environment assessment. Finally, the rated parameters and short-time withstand capability of the switching device are designed based on the normal operation of the circuit in which the switching device is located and the current and voltage environment during fault occurrence.

[0051] See Figure 1 As shown, the voltage regulating device includes: a first transformer, a second transformer, switching devices, an AC contactor, an input circuit breaker, an output circuit breaker, a bypass circuit breaker, and a controller. The first transformer is composed of three single-phase isolation transformers, and the second transformer is a three-phase transformer with multiple voltage levels on the secondary side. The switching devices can be thyristors or IGBTs, and the number of switching devices selected depends on the number n of voltage levels on the secondary side of the second transformer. The controller is used to perform current and voltage acquisition on the power grid system side, current and voltage acquisition on the secondary side circuits of the two transformers, and to shut down the contactors of each phase circuit, conduct and shut down the switching devices, and shut down the line circuit breaker.

[0052] The three phases A, B, and C of the primary side of the first transformer are connected to the three-phase transmission line respectively. The primary side output terminals X, Y, and Z of the first transformer are connected to the primary side input terminals D, E, and F of the second transformer. The primary side output terminals G, H, and I of the second transformer form a star connection. The secondary side output terminal of the second transformer leads to n voltage level taps according to the needs of the power grid users. Each tap (x1, x2...x n , x=D, E, F) is correspondingly connected to one end of a switching device, and the other end of each corresponding n switching devices is output connected to the secondary side output terminals M, N, O of the first transformer, and the secondary side output terminals J, K, L of the second transformer are connected to the secondary side input terminals P, Q, R of the first transformer.

[0053] The AC contactor is connected in parallel between the secondary side output terminal and the input terminal of the first transformer; the input circuit breaker is connected in series before the primary side input terminals A, B, and C of the first transformer, with one end connected to the input line and the other end connected to the primary side input terminals A, B, and C of the first transformer; the output circuit breaker is connected in series after the primary side input terminals D, E, and F of the second transformer, with one end connected to the primary side input terminals D, E, and F of the second transformer and the other end connected to the downstream power supply line; one end of the bypass circuit breaker is connected to the front end of the input circuit breaker and the other end is connected to the rear end of the output circuit breaker.

[0054] As a preferred implementation of this embodiment, the voltage input and output relationship formula of the voltage regulating device is specifically:

[0055]

[0056] Where U in is the input voltage of the voltage regulator; k1 is the first transformer ratio; k2 is the second transformer ratio; U out Output voltage for the voltage regulator.

[0057] According to the load capacity S of the station area N , and the percentage k of the rated voltage that the voltage regulator needs to adjust the maximum output voltage, that is, the voltage regulator needs to provide kS to the load N Power, therefore, when the voltage regulating device operates at the maximum injected voltage, the calculation formula for the current flowing through the primary winding of the second transformer in the voltage regulating device is specifically:

[0058]

[0059] Where, I T2w1 is the current flowing through the primary winding of the second transformer; k is the percentage of the rated voltage that the voltage regulator needs to adjust the maximum output voltage, 0 <k<1;S N U is the load capacity of the substation; m is the rated phase voltage of the line.

[0060] Therefore, the calculation formula for the rated current of the primary side of the second transformer is set as:

[0061] I T2N =xI T2w1

[0062] Where, I T2N is the rated current of the primary side of the second transformer, and x is the margin coefficient, which is generally taken as 1.3.

[0063] The calculation formula for the rated capacity of the second transformer is:

[0064]

[0065] Where S N2 is the rated capacity of the second transformer; I T2N is the rated current of the primary side of the second transformer; U m is the rated phase voltage of the line.

[0066] Since the voltage regulator injects voltage into the line through the first transformer, the rated voltage of the primary side of the first transformer should be:

[0067] U T1w1 =kU m

[0068] Where U T1w1 is the rated voltage of the primary side of the first transformer; k is the percentage of the rated voltage that the voltage regulator needs to adjust the maximum output voltage; U m is the rated phase voltage of the line.

[0069] Since the load current flows through the primary winding of the first transformer, the calculation formula for the current is:

[0070]

[0071] Where, I load is the load current flowing through the primary winding of the first transformer; S N U is the load capacity of the substation; m is the rated phase voltage of the line.

[0072] Since the current of the second transformer branch will also flow through the first transformer, the current of the first transformer is the sum of the load current and the second transformer current. The calculation formula for the rated current of the primary side of the first transformer in the voltage regulating device is set to:

[0073] I T1N =x(I load +I T2N )

[0074] Where, I T1N is the rated current of the primary side of the first transformer; x is the margin coefficient, which is generally 1.3; I load I is the load current flowing through the primary winding of the first transformer; T2N is the rated current of the primary side of the second transformer.

[0075] As a preferred implementation of this embodiment, the voltage input and output relationship formula of the voltage regulating device can be obtained:

[0076]

[0077] Where U T2w2 is the secondary winding voltage of the second transformer, U T1w2 is the secondary winding voltage of the first transformer.

[0078] When U T2w2 =U T1w2 When the voltage is the same as that of the secondary winding of the first transformer, the voltage regulator outputs 1 / (1-k) times the maximum voltage. According to the following relationship between the primary and secondary winding powers of the transformer: U1*I1=U2*I2, when U1 and I1 are constant, U2 is inversely proportional to I2. Therefore, when designing the rated voltage of the secondary windings of the first and second transformers, the appropriate secondary circuit voltage and current can be selected according to the line voltage level to achieve the desired effect. As the boundary, smaller than When designing the rated voltage of the secondary winding in the direction, the circuit can be designed as a low-voltage environment.

[0079] As a preferred implementation of this embodiment, the switching device is connected in series in the secondary side circuits of the two transformers, and the calculation formula for the working peak current of the switching device is specifically:

[0080]

[0081] Where, I M is the operating peak current of the switching device; I T1N is the rated current of the primary side of the first transformer; U T2w2 is the secondary winding voltage of the second transformer; U T1w2 is the secondary winding voltage of the first transformer;

[0082] The calculation formula of the operating peak voltage of the switching device is specifically:

[0083]

[0084] Where U M is the operating peak voltage of the switching device; U T1w2 is the secondary winding voltage of the second transformer.

[0085] Considering that the voltage regulating device needs to be able to withstand the fault current and voltage for a short time when a fault occurs, taking the extreme case of three-phase short circuit as an example, when a three-phase short circuit occurs in the line, the calculation formula for the short-circuit current is:

[0086]

[0087] Where, I c is the short-circuit current; R is the line impedance.

[0088] The square product of the time required to withstand the current should be: I c 2t, t is the time required to withstand the short-circuit current. The calculation formula for the withstand voltage should be:

[0089]

[0090] Where U T For the withstand voltage.

[0091] Example 2

[0092] Accordingly, this embodiment provides a control and protection system for a voltage regulating device, see Figure 2 As shown, it includes a data acquisition module, a fault monitoring module, a state switching module and a switch action module.

[0093] The data acquisition module is used to collect the line current and voltage at the first transformer inlet terminal and the secondary circuit current and voltage of the voltage regulating device.

[0094] The fault monitoring module is used to monitor and judge the faults of the voltage regulating device circuit and the voltage regulating device itself according to the signals from the data acquisition module.

[0095] As a preferred implementation of this embodiment, see Figure 3 As shown, the faults of the fault monitoring module are divided into short-term faults and permanent faults. Short-term faults include line overcurrent, overvoltage and overtemperature of switching devices, and permanent faults include failure of switching devices, PT disconnection and CT disconnection.

[0096] If any of the three-phase voltage exceeds the protection setting value and persists for 20ms, it is determined to be a line overvoltage fault. If any of the three-phase current exceeds the protection setting value and persists for 20ms, it is determined to be a line overcurrent fault. Upon receiving the radiator relay action feedback signal, it is determined to be an overtemperature fault of the switching device. If one phase current is still greater than 2A 40m after the switching device sends the lockout signal, it is determined to be a failure of the switching device. (min(I a ,I b ,I c )<0.3A)&&(max(I a ,I b ,I c )>0.5A)&&(max(I a ,I b ,I c If the voltage of one line is less than 0.7 pU and the current of one phase is greater than 0.04 In, it is determined to be a PT disconnection fault.

[0097] State switching module, see Figure 4As shown, it is used to switch the state according to the fault monitoring results and the four operating state marks of the voltage regulating device. The voltage regulating device is set to have four operating states, namely hot standby state, normal operating state, short-term fault state, and permanent fault state.

[0098] The switch action module is used to control the action sequence of the switch device and the circuit breaker according to the mark of the operating state of the voltage regulating device by the state switching module.

[0099] As a preferred implementation mode of this embodiment, when the state switching module marks the voltage regulating device as a hot standby state or a transient fault state (no action switching is required when the hot standby state is switched to a transient fault state), the switch action module first locks all switching devices, and when the current of each phase is less than a set value (such as 2A), the AC contactor of the secondary side circuit of the transformer is closed.

[0100] When the state switching module marks the voltage regulating device as a normal operating state, the cross-circuit contactor of the secondary side circuit is first disconnected, and then the corresponding switching device is turned on to start voltage regulation.

[0101] When the state switching module switches the voltage regulating device from the normal operating state to the permanent fault state, it first completes the switch action switching to exit the normal operating state, that is, completes the state switching from the normal operating state to the hot standby state or the transient fault state, and then disconnects the input circuit breaker and the output circuit breaker of the voltage regulating device, closes the bypass circuit breaker of the voltage regulating device, and completely bypasses the voltage regulating device.

[0102] Example 3

[0103] This embodiment provides a control and protection method for a voltage regulating device. The method is implemented based on the control and protection system for the voltage regulating device described in the second embodiment and includes the following steps:

[0104] The line current and voltage at the first transformer inlet terminal and the secondary circuit current and voltage of the voltage regulating device are collected.

[0105] According to the signal of the data acquisition module, the monitoring and judgment of the voltage regulating device line fault and the voltage regulating device itself fault are completed.

[0106] The state switching is performed according to the fault monitoring results and the four operating state marks of the voltage regulating device. The voltage regulating device is set to four operating states, namely hot standby state, normal operating state, temporary fault state, and permanent fault state.

[0107] According to the marking of the operating status of the voltage regulating device by the status switching module, the action sequence of the switching device and the circuit breaker is controlled.

[0108] Example 4

[0109] This embodiment provides an electronic device, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the control and protection method for a voltage regulating device as described in any embodiment of the present invention is implemented.

[0110] Example 5

[0111] This embodiment provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the control and protection method for a voltage regulating device according to any embodiment of the present invention is implemented.

[0112] In the embodiments of the present application, "at least one" refers to one or more, and "more" refers to two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent the existence of A alone, the existence of A and B at the same time, and the existence of B alone. Among them, A and B can be singular or plural. The character " / " generally indicates that the previous and next associated objects are in an "or" relationship. "At least one of the following" and similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b and c can represent: a, b, c, a and b, a and c, b and c or a and b and c, where a, b, c can be single or multiple.

[0113] Those skilled in the art will appreciate that the various units and algorithm steps described in the embodiments disclosed herein can be implemented using a combination of electronic hardware, computer software, and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0114] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0115] In the several embodiments provided in this application, if any function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the method described in each embodiment of this application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (Read-Only Memory; hereinafter referred to as: ROM), random access memory (Random Access Memory; hereinafter referred to as: RAM), magnetic disk or optical disk, and other media that can store program code.

[0116] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention's description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A voltage regulating device, characterized in that: include: The first transformer, the second transformer, the switching device, the AC contactor, the input circuit breaker, the output circuit breaker, the bypass circuit breaker and the controller. The first transformer is composed of three single-phase isolation transformers, and the second transformer is a three-phase transformer with multiple voltage levels on the secondary side. The number of switching devices selected depends on the number of voltage levels on the secondary side of the second transformer. The controller is used to perform current and voltage acquisition on the power grid system side, current and voltage acquisition on the secondary side circuits of the two transformers, as well as the shutdown of the contactors of each phase circuit, the conduction and shutdown of the switching devices, and the shutdown of the circuit breakers; The three phases A, B, and C of the primary side of the first transformer are connected to the input line respectively. The primary side output terminals X, Y, and Z of the first transformer are connected to the primary side input terminals D, E, and F of the second transformer. The primary side output terminals G, H, and I of the second transformer form a star connection. The secondary side output terminal of the second transformer is connected according to the needs of the grid users. Voltage level taps, each tap is connected to one end of a switching device, each corresponding The other end output of each switching device is connected to the secondary side output terminals M, N, and O of the first transformer, and the secondary side output terminals J, K, and L of the second transformer are connected to the secondary side input terminals P, Q, and R of the first transformer; The AC contactor is connected in parallel between the secondary output terminal and the incoming terminal of the first transformer; the input circuit breaker is connected in series before the primary incoming terminals A, B, and C of the first transformer, with one end connected to the input line and the other end connected to the primary incoming terminals A, B, and C of the first transformer; the output circuit breaker is connected in series after the primary incoming terminals D, E, and F of the second transformer, with one end connected to the primary incoming terminals D, E, and F of the second transformer and the other end connected to the downstream power supply line; one end of the bypass circuit breaker is connected to the front end of the input circuit breaker and the other end is connected to the rear end of the output circuit breaker; The calculation formula for the current flowing through the primary winding of the second transformer in the voltage regulating device is specifically: Where, The current flowing through the primary winding of the second transformer; The voltage regulator needs to adjust the percentage of the maximum output voltage to the rated voltage. ; The load capacity of the substation; is the line rated phase voltage; The calculation formula for the rated current of the primary side of the second transformer is set as: Where, is the rated current of the primary side of the second transformer, is the margin coefficient; The calculation formula for the rated current of the primary side of the first transformer in the voltage regulating device is set to: Where, is the rated current of the primary side of the first transformer; is the margin coefficient; is the load current flowing through the primary winding of the first transformer; is the rated current of the primary side of the second transformer; The calculation formula for the operating peak current of the switching device is set to: Where, is the operating peak current of the switching device; is the rated current of the primary side of the first transformer; is the secondary winding voltage of the second transformer; is the secondary winding voltage of the first transformer; The calculation formula for the operating peak voltage of the switching device is set to: Where, is the operating peak voltage of the switching device; is the secondary winding voltage of the second transformer.

2. The voltage regulating device according to claim 1, characterized in that: The voltage regulating device sets the rated voltage of the secondary winding of the second transformer to be consistent with the rated voltage of the secondary winding of the first transformer, and the output of the voltage regulating device is times the maximum voltage.

3. A control and protection system for a voltage regulating device, characterized in that: The system is used to implement control and protection of the voltage regulating device according to any one of claims 1 to 2, and includes a data acquisition module, a fault monitoring module, a state switching module, and a switch action module; A data acquisition module, used to collect the line current and voltage at the inlet end of the first transformer and the current and voltage of the secondary circuit of the voltage regulating device; The fault monitoring module is used to monitor and judge the faults of the voltage regulating device circuit and the voltage regulating device itself according to the signals from the data acquisition module; The state switching module is used to switch the state according to the fault monitoring results and the four operating state marks of the voltage regulating device. The voltage regulating device is set to four operating states: hot standby state, normal operating state, transient fault state, and permanent fault state; The switch action module is used to control the action sequence of the switch device and the circuit breaker according to the mark of the operating state of the voltage regulating device by the state switching module.

4. The control and protection system for the voltage regulating device according to claim 3, characterized in that: The faults of the fault monitoring module are divided into short-term faults and permanent faults. Short-term faults include line overcurrent, overvoltage and overtemperature of switching devices, and permanent faults include failure of switching devices, PT disconnection and CT disconnection.

5. The control and protection system for the voltage regulating device according to claim 3, characterized in that: When the state switching module marks the voltage regulating device as a hot standby state or a transient fault state, the switch action module first locks all switch devices and then closes the AC contactor of the secondary circuit of the transformer; When the state switching module marks the voltage regulating device as a normal operating state, the cross-circuit contactor of the secondary circuit is first disconnected, and then the corresponding switching device is turned on to start voltage regulation; When the state switching module switches the voltage regulating device from the normal operating state to the permanent fault state, it first completes the switch action switching to exit the normal operating state, that is, completes the state switching from the normal operating state to the hot standby state or the transient fault state, and then disconnects the input circuit breaker and the output circuit breaker of the voltage regulating device, closes the bypass circuit breaker of the voltage regulating device, and completely bypasses the voltage regulating device.

6. A control and protection method for a voltage regulating device, characterized in that: The method is implemented based on the control and protection system of the voltage regulating device according to any one of claims 3 to 5, and comprises the following steps: Collecting the line current and voltage at the inlet terminal of the first transformer and the secondary circuit current and voltage of the voltage regulating device; According to the signal from the data acquisition module, the voltage regulating device circuit fault and the voltage regulating device itself fault are monitored and judged; The state is switched according to the fault monitoring results and the four operating state marks of the voltage regulating device. The voltage regulating device is set to four operating states: hot standby state, normal operating state, transient fault state, and permanent fault state; According to the marking of the operating status of the voltage regulating device by the status switching module, the action sequence of the switching device and the circuit breaker is controlled.

7. An electronic device, comprising: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the control and protection method for the voltage regulating device according to claim 6 when executing the computer program.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the control and protection method for the voltage regulating device according to claim 6 is implemented.

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