Voltage regulating device and control protection system and control protection method thereof

Abstract

The invention discloses a voltage regulating device and a control protection system and method thereof, and the device comprises 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 second transformer is a three-phase transformer with multiple secondary voltage classes, and the number of the selected switching devices depends on the number n of the secondary voltage classes of the second transformer. The controller is used for collecting current and voltage of a power grid system side, collecting current and voltage of secondary side loops of the two transformers, turning off contactors of the loops of all phases, turning on and turning off switching devices and turning off circuit breakers. According to the invention, the problems that the economical efficiency of large-scale application is low and the reliable operation cannot be ensured due to unreasonable transformer design parameters of an existing voltage regulating device under different load conditions at present are solved.

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" goal, the installation scale of my country's distributed new energy power generation system in the distribution network has expanded rapidly, but the uncontrolled access of various renewable energy sources to the grid will cause serious power quality problems. For example, the output of photovoltaic and wind turbines is affected by uncertain factors such as weather, and their randomness and volatility will cause voltage fluctuations in the distribution system. On the other hand, with the economic development of rural areas, the requirements for power quality are getting higher and higher, while the architecture of medium and low voltage distribution networks is relatively weak. There are problems such as long power transmission lines, periodic and seasonal load changes, aging or damage of distribution equipment, etc., which lead to low voltage at the end of the distribution line. Therefore, the voltage regulator plays the most direct and effective role in the above problems.

[0003] However, the existing voltage regulators generally have problems such as narrow on-load voltage regulation range, effective mechanical voltage regulation times, insufficient flexibility, unreasonable transformer design parameters for different load conditions resulting in low economic efficiency, and limited ability of the device to handle line conditions. With the development of power electronics technology, power electronic devices such as thyristors have been widely used as voltage regulator tap changers, which make voltage regulation rapid and the regulation effect is significantly better than mechanical on-load voltage regulators, and also improve the flexibility of voltage regulation. Therefore, how to apply power electronic devices in voltage regulators to improve the economy of large-scale use of voltage regulators and optimize the control and protection strategy for reliable operation of voltage regulators is a hard problem that voltage regulators need to further address.

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

[0005] The present invention provides a voltage regulating device and a control and protection system and a control and protection method thereof, 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 use and unguaranteed reliable operation.

[0006] In order to solve the above technical problems, the present invention provides a voltage regulating device, including: 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, 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, and the controller is used to execute 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 shutdown of each phase circuit, conduction and shutdown of the switching device, and shutdown of the line circuit breaker.

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

[0008] The AC contactor is connected in parallel between the secondary side outlet and the incoming terminal of the first transformer; the input circuit breaker is connected in series before the primary side incoming terminals A, B, and C of the first transformer, one end of which is connected to the input line, and the other end is connected to the primary side incoming terminals A, B, and C of the first transformer; the output circuit breaker is connected in series after the primary side incoming terminals D, E, and F of the second transformer, one end of which is connected to the primary side incoming terminals D, E, and F of the second transformer, and the other end is connected to the rear-end 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] In the formula, 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] In the formula, I T2N is the rated current of the primary side of the second transformer, and x is the margin factor.

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

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

[0017] In the formula, 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 of the operating peak current of the switching device is set to:

[0020]

[0021] In the formula, 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, including 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 incoming line end of the first transformer and the secondary circuit current and voltage of the voltage regulating device.

[0027] The fault monitoring module is used to monitor and judge the line fault of the voltage regulating device and the fault of the voltage regulating device itself according to the signal of 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, transient 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 marking 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. 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 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 circuit is first disconnected, and then the corresponding switch 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, the switch action switching to exit the normal operating state is completed first, that is, the state switching from the normal operating state to the hot standby state or the transient fault state is completed, and then the input circuit breaker and the output circuit breaker of the voltage regulating device are disconnected, and the bypass circuit breaker of the voltage regulating device is closed to completely bypass 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 inlet terminal of the first transformer and the secondary circuit current and voltage of the voltage regulator are collected.

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

[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 have four operating states, namely hot standby state, normal operating state, transient fault state, and permanent fault state.

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

[0039] On the other hand, the present invention further provides 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 of the voltage regulating device as described in any embodiment of the present invention when executing the computer program.

[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 of the voltage regulating device as described in 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, which utilizes power electronic high-power switching devices to switch the voltage level in the secondary side circuit, and adjusts the voltage range according to the line voltage level, load capacity and user needs. It 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 voltage regulating device to switch its working state 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 lines. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0046] Figure 3 It is a fault judgment logic schematic diagram 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] Embodiment 1

[0050] The present embodiment provides a voltage regulating device, which is composed of two transformers connected in combination, and uses power electronic high-power switching devices to switch the voltage level in the secondary side circuit, which has the advantages of more flexible and precise voltage regulation and large compensation capacity; and provides its main circuit parameter setting and line protection strategy. According to the line voltage level, load capacity and user's need to adjust the voltage range, the rated parameters of the primary sides of the first transformer and the second transformer are first designed, and the secondary side rated voltage is further designed according to the secondary side voltage environment assessment. Finally, according to the normal operation of the circuit where the switching device is located and the current and voltage environment when a fault occurs, the rated parameters and short-time tolerance of the switching device are designed.

[0051] See also Figure 1 As shown, the voltage regulating device includes: a first transformer, a second transformer, a switch 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, the second transformer is a three-phase transformer with multiple voltage levels on the secondary side, the switch device can be a thyristor or an IGBT, and the number of switch devices selected depends on the number n of the secondary voltage levels 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 the contactor shutdown of each phase circuit, the on and off of the switch device, and the shutdown of the line circuit breaker.

[0052] The three phases A, B, and C of the primary side inlet of the first transformer are connected to the three-phase transmission line respectively, and the primary side outlets X, Y, and Z of the first transformer are connected to the primary side inlet of the second transformer D, E, and F. The primary side outlets G, H, and I of the second transformer form a star connection. The secondary side outlet 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 connected to one end of a switching device respectively, and the other end output of each corresponding n switching devices is connected to the secondary output terminal M, N, O of the first transformer, and the secondary output terminal J, K, L of the second transformer is connected to the secondary input terminal P, Q, R of the first transformer.

[0053] The AC contactor is connected in parallel between the secondary side outlet and the incoming terminal of the first transformer; the input circuit breaker is connected in series before the primary side incoming terminals A, B, and C of the first transformer, one end of which is connected to the input line, and the other end is connected to the primary side incoming terminals A, B, and C of the first transformer; the output circuit breaker is connected in series after the primary side incoming terminals D, E, and F of the second transformer, one end of which is connected to the primary side incoming terminals D, E, and F of the second transformer, and the other end is connected to the rear-end 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-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 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] In the formula, 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] In the formula, I T2N is the rated current of the primary side of the second transformer, and x is the margin factor, which is generally taken as 1.3.

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

[0064]

[0065] In the formula, 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 will flow through the primary winding of the first transformer, the calculation formula of the current flowing through is specifically:

[0070]

[0071] In the formula, 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] In the formula, I T1N is the rated current of the primary side of the first transformer; x is the margin factor, which is generally taken as 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-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 secondary circuit has no voltage drop, the loss is minimal. Therefore, 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 in the voltage regulating device, and the voltage regulating device outputs 1 / (1-k) times the maximum voltage. According to the following relationship between the primary winding and the secondary winding power 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 winding of the first transformer and the second transformer, the appropriate secondary circuit voltage and current can be selected according to the line voltage level to As the boundary, less 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 switch 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 switch device is specifically:

[0080]

[0081] In the formula, 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 regulator 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] In the formula, 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 that the short-circuit current needs to be tolerated. At the same time, the calculation formula for the withstand voltage should be:

[0089]

[0090] Where U T For withstand voltage.

[0091] Embodiment 2

[0092] Accordingly, this embodiment provides a control and protection system for a voltage regulating device, referring to 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 incoming line end of the first transformer and the secondary circuit current and voltage of the voltage regulating device.

[0094] The fault monitoring module is used to monitor and judge the line fault of the voltage regulating device and the fault of the voltage regulating device itself according to the signal of the data acquisition module.

[0095] As a preferred implementation of this embodiment, refer to 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 lasts for 20ms, it is determined as a line overvoltage fault. If any of the three-phase current exceeds the protection setting value and lasts for 20ms, it is determined as a line overcurrent fault. After receiving the radiator relay action feedback signal, it is determined as an overtemperature fault of the switch device. If one phase current is still greater than 2A 40m after the switch device sends the lockout signal, it is determined as a failure fault of the switch 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 )<5A), it is determined as a CT disconnection fault. If there is a line voltage less than 0.7pU and a phase current greater than 0.04In, it is determined as a PT disconnection fault.

[0097] State switching module, see Figure 4As shown, it is used to switch the state according to the fault monitoring result and the four operating state marks of the voltage regulating device. The voltage regulating device is set with 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 marking 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 short-term fault state (no action switching is required to switch the hot standby state to a short-term fault state), the switch action module first locks all switching devices, and when the current of each phase is less than the set value (such as 2A), the AC contactor of the secondary 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 circuit is first disconnected, and then the corresponding switch 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, the switch action switching to exit the normal operating state is completed first, that is, the state switching from the normal operating state to the hot standby state or the transient fault state is completed, and then the input circuit breaker and the output circuit breaker of the voltage regulating device are disconnected, and the bypass circuit breaker of the voltage regulating device is closed to completely bypass the voltage regulating device.

[0102] Embodiment 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 Embodiment 2, and includes the following steps:

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

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

[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 have four operating states, namely hot standby state, normal operating state, transient fault state, and permanent fault state.

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

[0108] Embodiment 4

[0109] This embodiment provides an electronic device, which includes: 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 a voltage regulating device as described in any embodiment of the present invention when executing the computer program.

[0110] Embodiment 5

[0111] This embodiment provides a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the control and protection method of the voltage regulating device as described in 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 than one" 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 be represented by: 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 of ordinary skill in the art will appreciate that the various units and algorithm steps described in the embodiments disclosed herein can be implemented in 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. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0114] Those skilled in the art can 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 several embodiments provided in the present 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 the present 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, which is stored in a storage medium and includes several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present 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), disk or optical disk, and other media that can store program codes.

[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 specification 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: A first transformer, a second transformer, a switch 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. The second transformer is a three-phase transformer with multiple voltage levels on the secondary side. The number of switch 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 shutdown of each phase circuit, conduction and shutdown of the switch devices, and shutdown of the line circuit breaker. The three phases A, B, and C of the primary side inlet of the first transformer are connected to the input line respectively, the primary side outlets X, Y, and Z of the first transformer are connected to the primary side inlet terminals D, E, and F of the second transformer, the primary side outlets G, H, and I of the second transformer form a star connection, and the secondary side outlet of the second transformer leads to n voltage level taps according to the needs of the power grid users, each tap is connected to one end of a switching device, and the other end of each corresponding n switching devices is output and connected to the secondary side outlets M, N, and O of the first transformer, and the secondary side outlets J, K, and L of the second transformer are connected to the secondary side inlet terminals P, Q, and R of the first transformer; The AC contactor is connected in parallel between the secondary side outlet and the incoming terminal of the first transformer; the input circuit breaker is connected in series before the primary side incoming terminals A, B, and C of the first transformer, one end of which is connected to the input line, and the other end is connected to the primary side incoming terminals A, B, and C of the first transformer; the output circuit breaker is connected in series after the primary side incoming terminals D, E, and F of the second transformer, one end of which is connected to the primary side incoming terminals D, E, and F of the second transformer, and the other end is connected to the rear-end 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.

2. The voltage regulating device according to claim 1, characterized in that: The calculation formula for the current flowing through the primary winding of the second transformer in the voltage regulating device is specifically: In the formula, 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 line rated phase voltage; The calculation formula for the rated current of the primary side of the second transformer is set as: I T2N =xI T2w1 In the formula, I T2N is the rated current of the primary side of the second transformer, and x is the margin factor; The calculation formula for the rated current of the primary side of the first transformer in the voltage regulating device is set as: I T1N =x(I load +I T2N ) In the formula, 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.

3. The voltage regulating device according to claim 2, characterized in that: 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.

4. The voltage regulating device according to claim 1, characterized in that: The calculation formula for the operating peak current of the switching device is set to: In the formula, 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; The calculation formula for the operating peak voltage of the switching device is set to: Where U M is the operating peak voltage of the switching device; U T1w2 is the secondary winding voltage of the second transformer.

5. 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 4, 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 regulator; The fault monitoring module is used to monitor and judge the fault of the voltage regulating device line and the fault of the voltage regulating device itself according to the signal of 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 have four operating states, namely 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 marking of the operating state of the voltage regulating device by the state switching module.

6. The control and protection system for the voltage regulating device according to claim 5, 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.

7. The control and protection system for the voltage regulating device according to claim 5, 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 switch 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, the switch action switching to exit the normal operating state is completed first, that is, the state switching from the normal operating state to the hot standby state or the transient fault state is completed, and then the input circuit breaker and the output circuit breaker of the voltage regulating device are disconnected, and the bypass circuit breaker of the voltage regulating device is closed to completely bypass the voltage regulating device.

8. 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 5 to 7, and comprises the following steps: Collecting the line current and voltage at the inlet end of the first transformer and the secondary circuit current and voltage of the voltage regulator; According to the signal from the data acquisition module, the voltage regulator circuit fault and the voltage regulator itself fault are monitored and judged; 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 have four operating states, namely hot standby state, normal operating state, transient fault state, and permanent fault state; According to the marking of the operating state of the voltage regulating device by the state switching module, the action sequence of the switch device and the circuit breaker is controlled.

9. 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 as claimed in claim 8 when executing the computer program.

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

Images