An intelligent multifunctional medium voltage line voltage regulator and a power supply system including the same

Abstract

The present invention discloses an intelligent multifunctional medium voltage line voltage regulator, comprising a voltage regulator body; a load voltage regulating switch is arranged on the top of the voltage regulator body; a controller is arranged on the voltage regulator body; a current transformer, an iron core and a coil are arranged inside the voltage regulator body; the controller is used for data acquisition, analysis and judgment, record storage, communication, remote control and control and distribution; the controller includes a processing unit MCU, an acquisition unit, an HMI unit, an input unit, an output unit and a communication unit; the controller calculates various operating parameters of the system according to the collected system voltage and current signals, and identifies the flow direction by integrating the changes of the system voltage, current and power, and determines the current actual power supply side and load side of the system; and can also determine the working mode of the voltage regulator in real time. The intelligent multifunctional medium voltage line voltage regulator of the present invention has the advantages of automatic identification of flow direction, timely conversion of voltage input and output, good output voltage stability, and light overall weight.

Description

Technical Field

[0001] The invention relates to a voltage regulating device, in particular to an intelligent multifunctional medium voltage line voltage regulator and a power supply system comprising the same. Background Art

[0002] my country is a vast country with a vast territory and uneven economic development in various regions. At the same time, there are great differences in the power supply networks in various regions. In economically developed areas, the power load is relatively large, the power load is concentrated, and the substations are densely distributed. The power supply range of 10kV distribution lines generally does not exceed 15 kilometers. In relatively backward economic areas, the power load is small, the load is relatively dispersed, and the substations are sparsely distributed; therefore, the power supply radius in many places exceeds the normal range. In some old, remote and remote areas, the power supply radius may reach more than 50 kilometers. Long-distance power transmission will inevitably cause the voltage in the middle and back ends of the line to be too low or fluctuate greatly.

[0003] For areas with a long power supply radius (more than 15 kilometers), the wire diameter is relatively thin, the power factor is greater than 0.9, there is no line transformation plan, or the transformation cost is too high, and there is no money to implement 35 kV substation layout transformation in the short term. The voltage of low-voltage users in the terminal distribution area is low, and it is difficult to meet the power supply quality requirements of 10 kV lines using substation voltage regulation. The low voltage of the medium voltage system directly affects industrial and agricultural production and people's normal life.

[0004] Currently, there are two measures to solve the low voltage problem in medium voltage system.

[0005] 1. Install reactive power compensation devices to reduce reactive power loss. Although installing reactive power compensation devices can alleviate the voltage at the back end to a certain extent, the voltage increase is small.

[0006] 2. Solve the problem by installing a Y-connected medium-voltage line voltage regulator. The Y-connected medium-voltage line voltage regulator consists of an autotransformer with N taps, an on-load voltage regulator, an automatic controller that can track the voltage at the end of the line according to the load size, and several accessories.

[0007] The Y-connected autotransformer is divided into a main coil and a voltage regulating coil. The voltage regulating coil is a winding with multiple taps. These taps are connected in series between the input and output through different contacts of the on-load tap changer. By changing the tap position, the autotransformer ratio is changed to achieve the purpose of adjusting the voltage. The Y-connected medium-voltage line voltage regulator is an autotransformer. Compared with general transformers of the same capacity, it has the advantages of simple structure, less materials, and small size. However, the Y-connected medium-voltage line voltage regulator has the following shortcomings:

[0008] 1) Short-circuit current has a great impact on the power system. Since the high and low voltage windings of the star-connected autotransformer are electrically connected, its short-circuit impedance is only (1-k / 1) square times that of an ordinary double-winding transformer of the same capacity (parameter k is the line voltage ratio). Therefore, after the autotransformer is used in the power system, the three-phase short-circuit current will increase significantly. Since the neutral point of the autotransformer must be directly grounded, the single-phase short-circuit current of the system will increase greatly, sometimes even exceeding the three-phase short-circuit current. However, the triangle-connected autotransformer has no neutral point grounding, and the short-circuit current has a relatively smaller impact on the power system.

[0009] 2) The third harmonic of the line cannot be eliminated. In order to effectively reduce the impact of the third harmonic on the system, the 10KV winding of the distribution transformer is basically D-connected. The Y-connected medium-voltage line voltage regulator cannot eliminate the third harmonic.

[0010] 3) It cannot run with a missing phase. The Y-connected medium voltage line voltage regulator can only work with three phases and cannot run with a missing phase.

[0011] 4) Transportation conditions limit the use of the product. Compared with general transformers of the same capacity, Y-connected medium-voltage line voltage regulators have the advantages of small size and light weight. However, larger capacity Y-connected medium-voltage line voltage regulators are still very heavy: 10000KVA products weigh 7.3 tons; 4000KVA products weigh 4.2 tons. At present, this product is manufactured and transported as a whole. The transportation conditions in old, remote and remote areas are poor, which limits the application and promotion of this product.

[0012] Therefore, it is urgent to develop a new type of medium voltage line regulator to solve the above problems. Summary of the invention

[0013] The technical problem to be solved by the present invention is to provide an intelligent multifunctional medium voltage line voltage regulator to completely solve the problem of medium voltage line voltage fluctuation.

[0014] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows.

[0015] An intelligent multifunctional medium voltage line voltage regulator, the structural features of which are: comprising a voltage regulator body 1; a load voltage regulating switch 2 is arranged on the top of the voltage regulator body 1; a controller 3 is arranged on one side of the voltage regulator body 1; a current transformer 4, an iron core 5 and a coil 6 are arranged inside the voltage regulator body 1;

[0016] The controller is used for data collection, analysis and judgment, record storage, communication, remote control and control distribution; the controller includes a processing unit MCU, a collection unit, an HMI unit, an input unit, an output unit and a communication unit; the controller calculates various operating parameters of the system based on the collected system voltage and current signals, and comprehensively identifies the flow direction by combining the changes in the system voltage, current and power, and judges the current actual power supply side and load side of the system, and also judges the working mode of the voltage regulator in real time based on the flow direction and the voltage changes before and after the voltage regulator when adjusting the gear.

[0017] Furthermore, the controller also includes a real-time clock; the real-time clock is used to provide a time reference for system event generation and information statistics.

[0018] Furthermore, the controller also includes a storage unit; the storage unit is used to save system operation parameters and statistical data.

[0019] Furthermore, the controller also includes a power supply; the power supply is used to complete the conversion of AC power supply to board-level DC power supply, providing a stable DC working power supply for the controller.

[0020] Furthermore, the processing unit MCU is preferably TMS320F2812.

[0021] Furthermore, the HMI unit includes but is not limited to a liquid crystal screen and a keyboard.

[0022] Furthermore, the communication unit includes but is not limited to an RS485 communication cable.

[0023] Furthermore, the signals collected by the controller include but are not limited to AC analog quantities.

[0024] Furthermore, the AC analog quantity includes but is not limited to voltage, current, active power, reactive power, power factor and frequency.

[0025] The present invention also discloses a power supply system including the above-mentioned intelligent multifunctional medium voltage line voltage regulator, which also includes a front-end power supply circuit breaker QF1, a bypass power supply circuit breaker QF2, an isolating knife QS, a front lightning arrester FV1 and a rear lightning arrester FV2.

[0026] The beneficial effects of the present invention are:

[0027] The intelligent multifunctional medium voltage line voltage regulator of the present invention comprises a voltage regulator body; a load tap changer is arranged on the top of the voltage regulator body; a controller is arranged on one side of the voltage regulator body; a current transformer, an iron core and a coil are arranged inside the voltage regulator body; the controller is used for data acquisition, analysis and judgment, record storage, communication, remote control and control and distribution; the controller comprises a processing unit MCU, an acquisition unit, an HMI unit, an input unit, an output unit and a communication unit; the controller collects system voltage and current signals to calculate various operating parameters of the system, and comprehensively identifies the flow direction by combining the changes in the system voltage, current and power, and judges the current actual power supply side and load side of the system; and also judges the working mode of the voltage regulator in real time according to the flow direction and the voltage changes before and after the voltage regulator when the gear is adjusted.

[0028] The intelligent multifunctional medium voltage line voltage regulator of the present invention is a new product developed by carrying out multiple reforms and innovations on the existing Y-connected medium voltage line voltage regulator. The main improvements include the following aspects.

[0029] 1. The voltage regulator coil is changed to a triangle connection and an extended triangle connection.

[0030] 2. Add appropriate control and hardware circuits to realize the identification of flow direction and bidirectional voltage regulation.

[0031] 3. Based on the characteristics of delta-connected transformers that can work with missing phases, we develop and produce intelligent multifunctional medium-voltage line voltage regulators, namely: single-phase line voltage regulator (single phase); two-phase line voltage regulator (V connection operation); three-phase delta-connected line voltage regulator and three-phase delta-connected combined line voltage regulator.

[0032] The present invention can meet the performance index requirements of the country and the industry, that is, meet the standard requirements of no-load loss, no-load current, load loss and short-circuit impedance.

[0033] The intelligent multifunctional medium voltage line voltage regulator of the present invention has the advantages of automatically identifying the flow direction, timely changing the voltage input and output, good output voltage stability, light overall weight, and being able to better meet the needs of old, remote and small user service areas. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a structural schematic diagram of the intelligent multifunctional medium voltage line voltage regulator of the present invention.

[0035] Figure 2 It is a structural block diagram of a controller of an intelligent multifunctional medium voltage line voltage regulator of the present invention.

[0036] Figure 3 It is a schematic diagram of the intelligent multifunctional medium voltage line voltage regulator of the present invention when it is connected to a power supply system.

[0037] Figure 4 Schematic diagram of the connection of triangles.

[0038] Figure 5 Schematic diagram of the connection of the extended triangle.

[0039] Figure 6 Schematic diagram of the connection of some extended triangles.

[0040] Figure 7 This is a schematic diagram of a single-phase voltage regulator installed in two phases (V-connected).

[0041] Figure 8 This is a schematic diagram of a three-phase line voltage regulator using a three-phase integral production and overall installation (delta connection).

[0042] Fig. 9 This is a schematic diagram of a three-phase combined line voltage regulator when it is installed in a split-phase production site combination (delta connection). DETAILED DESCRIPTION

[0043] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention.

[0044] See also Figure 1-Figure 9 The present invention discloses an intelligent multifunctional medium voltage line voltage regulator, comprising a voltage regulator body 1; a load voltage regulating switch 2 is arranged on the top of the voltage regulator body 1; a controller 3 is arranged on one side of the voltage regulator body 1; a current transformer 4, an iron core 5 and a coil 6 are arranged inside the voltage regulator body 1;

[0045] The controller is used for data collection, analysis and judgment, record storage, communication, remote control and control distribution; the controller includes a processing unit MCU, a collection unit, an HMI unit, an input unit, an output unit and a communication unit; the controller calculates various operating parameters of the system based on the collected system voltage and current signals, and comprehensively identifies the flow direction by combining the changes in the system voltage, current and power, and judges the current actual power supply side and load side of the system, and also judges the working mode of the voltage regulator in real time based on the flow direction and the voltage changes before and after the voltage regulator when adjusting the gear.

[0046] like Figure 1The intelligent multifunctional medium voltage line voltage regulator of the present invention mainly includes a voltage regulator body, an on-load voltage regulating switch, a dynamic voltage regulating controller and accessories. The voltage regulator can be connected to a laptop computer through a serial port to USB interface or connected to a handheld PDA (Personal Digital Assistant) terminal through local WIFI to achieve local data download, data viewing and parameter setting; it can also use the 4G network to transmit the operation data of the distribution transformer in the substation area to the internal management server of the enterprise in real time through an external 4G module. The monitoring center can directly view and remotely monitor the data of the on-site voltage regulator, and the substation can query and browse the data through the Web.

[0047] Furthermore, the controller also includes a real-time clock; the real-time clock is used to provide a time reference for system event generation and information statistics.

[0048] Furthermore, the controller also includes a storage unit; the storage unit is used to save system operation parameters and statistical data.

[0049] Furthermore, the controller also includes a power supply; the power supply is used to complete the conversion of AC power supply to board-level DC power supply, providing a stable DC working power supply for the controller.

[0050] Furthermore, the processing unit MCU is TMS320F2812.

[0051] Furthermore, the HMI unit includes a liquid crystal screen and a keyboard.

[0052] Furthermore, the communication unit includes an RS485 communication cable.

[0053] Furthermore, the signal collected by the controller includes an AC analog quantity.

[0054] Furthermore, the AC analog quantity includes but is not limited to voltage, current, active power, reactive power, power factor and frequency.

[0055] As the control center of the entire intelligent multifunctional medium voltage line regulator, the dynamic voltage regulator controller mainly completes the functions of data collection, analysis and judgment, record storage, communication, remote control and control distribution. Figure 2 , is a hardware structure diagram of a dynamic voltage regulation controller, which is mainly composed of a processing unit MCU, a collection unit, a real-time clock, a storage unit, a power supply, an HMI (Human Machine Interface, human-machine interaction) unit, an input unit, an output unit, and a communication unit. The processing unit MCU is preferably TMS320F2812.

[0056] The sampling unit: completes the collection of input voltage, output voltage, and output current signals, calculates various operating power parameters of the system, identifies phase information, and provides a criterion for the control and protection decision of the system;

[0057] The real-time clock: provides a system real-time clock as a time reference for system event generation and information statistics;

[0058] The storage unit: acts as the system real-time operation memory and Flash storage, saves the system operation parameters and statistical data stored in it, and will not be lost when power is off;

[0059] The power supply: completes the conversion of AC power supply to board-level DC power supply, providing stable DC working power supply for MCU and peripherals;

[0060] The HMI unit provides a Chinese LCD display and keyboard operation interface, which can facilitate on-site commissioning and operation and maintenance personnel to view equipment operation information, set and manually control equipment parameters;

[0061] The input unit: the optical coupling isolation input signal is used as the tap switch gear feedback and the body, the switch non-electrical protection circuit breaker closing state feedback signal;

[0062] The output unit: a relay output circuit, used for the gear lifting and lowering of the tap changer and the opening and closing of the circuit breaker, fault output, flow direction output, and oil filter output control;

[0063] The communication unit provides local 485 communication signals to the outside, implements standard Modbus and balanced 101 protocols, supports the expansion connection of local micro-power data transmission radio, WIFI, and 4G modules, and realizes on-site debugging and remote four-remote functions of the equipment.

[0064] The controller has the following functions.

[0065] 1. Collection, measurement, monitoring and statistical information include AC analog quantity, statistical data, harmonic data and monitored state quantity.

[0066] 1) AC analog quantity: including voltage, current, active power, reactive power, power factor, frequency, etc.

[0067] 2) Statistics:

[0068] (1) Hourly data;

[0069] (2) Daily upshift and downshift times, average actuation time, maximum actuation time, and minimum actuation time;

[0070] (3) Total number of operations and oil filtering times.

[0071] 3) Harmonic data: voltage (current) harmonic content and total distortion rate, voltage harmonic percentage.

[0072] 4) Monitored state quantity:

[0073] (1) Operation status of high voltage line voltage regulator controller;

[0074] (2) Incoming and outgoing switch position signals, etc.;

[0075] (3) Tap changer position signal;

[0076] (4) Transformer gas relay position status;

[0077] (5) Transformer pressure relief valve position status;

[0078] (6) Transformer oil thermometer position status.

[0079] 2. The control quantity output includes the following five aspects:

[0080] 1) Circuit breaker closing and opening control;

[0081] 2) Fault alarm output control;

[0082] 3) Flow indication output control;

[0083] 4) Tap changer up / down control;

[0084] 5) Oil filter motor control.

[0085] 3. It has protection, alarm and recording functions, including the following two aspects.

[0086] 1) It has multiple protection / warning functions such as overvoltage, undervoltage, overcurrent, overload, loss of voltage, power outage, overheating, etc., and can simultaneously complete record storage and reporting. SOE stores no less than 250 records.

[0087] 2) It should have self-diagnosis and self-recovery functions, be able to self-diagnose each functional board and important chip, send alarm information in case of failure, and automatically reset in case of abnormality.

[0088] 4. Communication related functions; the communication protocols to be supported include IEC101, Modbus and other protocols.

[0089] like Figure 3 The present invention also discloses a power supply system including the intelligent multifunctional medium voltage line voltage regulator, the system also includes a front-end power supply circuit breaker QF1, a bypass power supply circuit breaker QF2, an isolating knife QS, a front lightning arrester FV1 and a rear lightning arrester FV2.

[0090] like Figure 3It is a schematic diagram of connecting the voltage regulator of the present invention to the power supply system, QF1 is the front-end power supply circuit breaker of the voltage regulator, QF2 is the bypass power supply circuit breaker, QS is the isolating knife, FV1 and FV2 are the lightning arresters at the front and rear ends of the voltage regulator; HWOSZ-S-XL is the voltage regulator of the present invention.

[0091] The dynamic multifunctional medium voltage line voltage regulator of the present invention is mainly used in the 10kV transmission line of the 35kV central substation. According to the different configurations of the line, there may be substations at the beginning and end of the line, and there may also be small hydropower connected to the grid in the center of the line. Small hydropower is connected to the grid for power generation in the flood season and consumes electricity from the grid in the dry season. From the installation point of the voltage regulator, the switching of the power supply substations at the beginning and end of the line. The changes in the power generation and power consumption status in the flood and dry seasons in small hydropower areas will cause the direction of the active current in the line to change. In order to adapt to the changes in the line working conditions, requirements are put forward for the control system of the voltage regulator. It must be able to automatically identify the changes in the system flow direction, and change its own operation mode accordingly, and effectively improve the voltage quality problem of the system through the means of two-way regulation.

[0092] The dynamic multifunctional medium voltage line voltage regulator of the present invention can calculate various operating parameters of the system based on the collected system voltage and current signals, and comprehensively identify the changes in system voltage, current and power to identify the current direction of the power supply side and load side of the system.

[0093] The trend from Figure 3 The flow is defined as forward when the power supply side flows to the load side; at this time, the power supply side is on the left side of the voltage regulator, and the right side is the load side; the flow is defined as reverse when the power supply side flows from the load side to the power supply side, and at this time, the power supply side is on the right side of the voltage regulator, and the left side is the load side.

[0094] like Figure 3 The power supply system determines the flow direction according to the system sampling information, and determines in real time which of the following three modes the voltage regulator is operating in according to the flow direction and the voltage change before and after the voltage regulator during the gear adjustment. The three modes are forward operation mode, reverse small hydropower operation mode and reverse double substation operation mode.

[0095] 1. Forward operation mode: P>0, the power flow direction is from the power supply side to the load side. At this time, Uo is used as the adjustment target, 1->N gear is for voltage increase, N->1 gear is for voltage reduction; where P represents the system active power, 1->N means that the switch adjustment direction is from the lowest gear to the highest gear; similarly, N->1 means that the switch adjustment direction is from the highest gear to the lowest gear;

[0096] 2. Reverse small hydropower operation mode: P<0, the flow direction is from the load side to the power supply side. At this time, Uo is used as the regulation target, 1->N gear increases the voltage, and N->1 gear decreases the voltage;

[0097] 3. Reverse double substation operation mode: P<0, the flow direction is from the load side to the power supply side. At this time, Ui is used as the adjustment target, 1->N gear is used for voltage reduction, and N->1 gear is used for voltage increase.

[0098] When the power flow is reversed, the change of Ui and Uo before and after the gear adjustment is automatically used to determine which side is the side that needs voltage adjustment; if ΔUi>ΔUo, it indicates that it is a dual substation operation mode; if ΔUi<ΔUo, it indicates that it is a small hydropower operation mode. The mode can be saved after identification, and it will be re-identified after each reverse gear adjustment, so that the controller can automatically determine the current working mode according to the power flow direction, and ensure that after switching between different working modes, the gear adjustment can be performed correctly to change the turns ratio of the voltage regulator inlet and outlet lines to achieve the purpose of stabilizing the voltage on the load side, and ensure the voltage regulation effect under unidirectional and bidirectional power supply modes.

[0099] like Figure 3 In the figure, QF2 is the bypass power supply circuit breaker, which is used to start the bypass power supply function.

[0100] (I) When the bypass is enabled, the control action logic includes the power-on processing stage SA, the automatic operation stage SB, the bypass stage SC and the fast downshift SD. The symbol: -> points to the processing part to be entered next time, that is, the next step to be entered; {} is the judgment condition. This bypass stage is a working state in the program, not an actual system bypass.

[0101] 1. In the power-on processing stage SA, according to the closed or open status of the voltage regulator front-end power supply circuit breaker QF1 and the bypass power supply circuit breaker QF2, there are four cases: SA1, SA2, SA3 and SA4; wherein QF1=1 indicates that the circuit breaker QF1 is closed, and QF2=0 indicates that the circuit breaker QF2 is open.

[0102] (1) SA1: QF1 = 1, QF2 = 0;

[0103] {In the base file}——>Automatically run SB2; indicates to enter step SB2;

[0104] {Not in the reference range}——> Rapidly adjust the voltage to the qualified voltage SD1; indicating that the process will enter step SD1;

[0105] (2) SA2: QF1 = 1, QF2 = 1;

[0106] {In the reference gear}——>{No fault signal}——>Automatically run SB3;

[0107] {There is a fault signal} -> main circuit breaker QF1 -> bypass SC2;

[0108] {Not in the base file} -> Main circuit breaker QF1 -> Enter SA3;

[0109] (3) SA3: QF1 = 0, QF2 = 1;

[0110] ——>Quickly adjust to the base file SD2;

[0111] (4) SA4: QF1 = 0, QF2 = 0;

[0112] {In base gear}——>Bypass SA3;

[0113] {Not in the base range}——>Quickly drop to the base range SD4.

[0114] 2. Similar to the power-on processing stage SA, the automatic operation stage SB is also divided into four cases: SB1, SB2, SB3 and SB4.

[0115] (1) SB1: QF1 = 0, QF2 = 0

[0116] ——>SA4

[0117] (2) SB2: QF1 = 1, QF2 = 0

[0118] Automatic up / down shift -> {normal operation} -> SB2;

[0119] {There is a fault signal and it is in the reference position} -> Close the bypass circuit breaker QF2 -> SB3;

[0120] (Overvoltage fault) {There is a fault signal and the up / down gear refuses to move, voltage>11.7KV}——>trip main breaker QF1——>SC1;

[0121] Among them, the "(overvoltage fault)" is a prerequisite; in the case of an overvoltage fault, the action will be executed only if the conditions in the brackets "there is a fault signal and the gear shifting refuses to move, and the voltage is >11.7KV" are met; that is, the action will be executed only if both conditions are met at the same time;

[0122] (3) SB3: QF1 = 1, QF2 = 1

[0123] {In the reference gear} -> {No fault signal} -> Bypass circuit breaker QF2 -> Automatic operation SB2;

[0124] {There is a fault signal} -> main circuit breaker QF1 -> bypass SC2;

[0125] {Not in the base file} -> Main circuit breaker QF1 -> Enter SB4;

[0126] (4) SB4: QF1 = 0, QF2 = 1

[0127] ——>Bypass SC2.

[0128] 3. The bypass stage SC is divided into 4 cases: SC1, SC2, SC3 and SC4.

[0129] (1) SC1: QF1 = 0, QF2 = 0

[0130] Close bypass circuit breaker -> bypass SC2;

[0131] (2) SC2: QF1 = 0, QF2 = 1

[0132] {There is a fault signal}——>Bypass SC2;

[0133] {No fault signal}——>Enter SA3;

[0134] (3) SC3: QF1 = 1, QF2 = 0

[0135] ——>Enter SA1;

[0136] (4) SC4: QF1 = 1, QF2 = 1

[0137] Sub-main circuit breaker -> bypass SC2.

[0138] 4. Quick downshift SD is divided into 4 cases: SD1, SD2, SD3 and SD4.

[0139] (1) SD1: QF1 = 1, QF2 = 0

[0140] Rapidly adjust the voltage to the qualified voltage -> {the voltage is qualified or at the reference level and there is no fault signal} -> automatically run SB2;

[0141] {There is a fault signal and it is in the reference gear}——>Automatically run SB2;

[0142] (2) SD2: QF1 = 0, QF2 = 1

[0143] Quickly adjust to the reference position -> {no fault signal} -> close the main circuit breaker -> enter SA2;

[0144] {There is a fault signal}——>Bypass SC2;

[0145] (3) SD3: QF1 = 1, QF2 = 1

[0146] ——>Enter SA2;

[0147] (4) SD4: QF1 = 0, QF2 = 0

[0148] Quickly adjust to the base gear --> enter SA4.

[0149] (ii) When the bypass enable is turned off, the bypass power supply circuit breaker QF2 is disconnected, that is, QF2 = 0. The control logic at this time is divided into two situations: OA state and OB state; OA is the power-on processing stage; OB is the automatic operation stage;

[0150] 1. The OA status is divided into two cases: OA1 and OA2.

[0151] (1) OA1: QF1 = 1

[0152] {In the base file}——>Automatically run OB1;

[0153] {Not in the reference range} -> Quickly adjust the voltage to the qualified voltage -> Automatically run OB1;

[0154] (2) OA2: QF1 = 0

[0155] {Closing is not allowed}——>OA2;

[0156] {Closing is allowed and there is no fault} -> Close the main breaker QF1 -> OA1;

[0157] {When fault occurs}——>OA2;

[0158] 2. The OB status is divided into two cases: OB1 and OB2.

[0159] (1) OB1: QF1 = 1

[0160] ——>Automatically run OB1;

[0161] (Overvoltage fault) {There is a fault signal and the gear shifting fails to move, the voltage is >11.7KV}——> the main circuit breaker QF1 is tripped

[0162] Among them, the "(overvoltage fault)" is a prerequisite; in the case of an overvoltage fault, the action will be executed only if the conditions in the brackets "there is a fault signal and the gear shifting refuses to move, and the voltage is >11.7KV" are met; that is, the action will be executed only if both conditions are met at the same time;

[0163] (2) OB2: QF1 = 0

[0164] ——>OA2.

[0165] The intelligent multifunctional medium voltage line voltage regulator of the present invention breaks the design idea of ​​the Y-connected line voltage regulator. The voltage regulator coil is connected in triangle and extended triangle respectively. It has the function of automatically identifying the flow direction and can timely change the voltage input and output, perform bidirectional voltage regulation, and always keep the output voltage stable. The three-phase triangle connection line voltage regulator can provide three-phase integral type and three-phase combined type (phase production site combination installation), reduce the single piece transportation weight to better serve the elderly, children and remote users.

[0166] In the present invention, the on-load voltage regulator 2 adopts a 10KV on-load voltage regulator, and the output of the voltage regulator is stabilized by adjusting the number of turns of the voltage regulator coil. The intelligent multifunctional medium-voltage line voltage regulator is a specially designed voltage regulator, which is mainly composed of three groups of autocoil and a closed magnetic circuit-iron core. The coil is divided into a main coil and a voltage regulator coil. The voltage regulator coil is a winding with multiple taps. These taps are connected in series between the input and output through different contacts of the on-load voltage regulator. The autocoil taps are divided into several taps by changing the tap position, and the terminal of the corresponding gear is connected.

[0167] According to Faraday's law of electromagnetic induction:

[0168]

[0169] It can be concluded that when the input voltage changes, the on-load voltage regulator is controlled to change the number of turns of the voltage regulating coil, and a stable output voltage can be obtained. A voltage transformer is installed at the output line end. The sampled voltage value signal obtained by the voltage transformer is input into the controller, and the controller controls the operation of the on-load voltage regulator.

[0170] The coil is a three-phase auto-coupling coil. Each phase coil is composed of a common coil (also called "main coil") and a voltage regulating coil (also called "series coil"). The connection of the three-phase coil is a triangle connection.

[0171] There are three ways to connect the coils of a three-phase delta-connected autotransformer: delta connection, extended delta connection and partially extended delta connection.

[0172] like Figure 4 The schematic diagram of the connection of the triangle is as follows: Figure 4 , the entire coil of each phase of the transformer is connected in a triangle. The autotransformer with full triangle connection ignores the same phase of the current of the series winding and the common winding of the same phase of the no-load current. The phase shift α between the high and low line voltages of the same phase depends on the phase transformation ratio Kω.

[0173] Line transformation ratio K:

[0174] like Figure 5 This is a schematic diagram of the extended triangle connection. The common coil of the transformer is connected in a triangle, and the voltage regulating coil is on the extended line of the triangle. The autotransformer with extended triangle connection ignores the same phase of the series winding and the common winding current of the same phase of the no-load current. The phase shift α between the high and low voltage line voltages of the same phase depends on the phase transformation ratio Kω.

[0175] Line transformation ratio K:

[0176] like Figure 6The diagram is a schematic diagram of a partially extended triangle connection. The common coil and part of the voltage regulating coil of the transformer are inside the triangle, and part of the voltage regulating coil is on the extended line of the triangle. The current and voltage of the autotransformer in the partially extended triangle connection have the above two characteristics, and the line voltage ratio is calculated according to the above formula.

[0177] In the voltage regulator of the present invention, the calculation formula of the benefit coefficient Ks of the autotransformer is: Ks=Pm / Pn, where Pm is the structural capacity of the transformer and Pn is the capacity passed by the transformer.

[0178] 1. The calculation formula of the efficiency coefficient Ks of the triangular-connected autotransformer is:

[0179] Example: When K=1.2, Ks=1.44-1 / 2.078=0.2117.

[0180] When K=1.1, Ks=1.21-1 / 1.0953=0.1102.

[0181] 2. The calculation formula of the efficiency coefficient Ks of the autotransformer with extended triangle connection is:

[0182] Example: When K=1.2, Ks=0.4497 / 2.4=0.1874.

[0183] When K=1.1, Ks=0.2275 / 2.2=0.1034.

[0184] The above calculation process is explained as follows:

[0185] 1) The cost of an autotransformer is much lower than that of an ordinary transformer, especially when K→1;

[0186] 2) Among the autotransformers with triangle connection, the extended triangle connection has a smaller benefit coefficient than the full triangle connection autotransformer, that is, it is the most economical. The present invention adopts the extended triangle connection process and technology, and its economic performance has been fully verified in product research and development.

[0187] In the specific implementation, the core is made of high-quality cold-rolled silicon steel sheets, and the selected high-quality cold-rolled grain-oriented silicon steel sheets adopt the stacking method of step-by-step multi-level seams, with a continuous yoke and a 45° full-bevel seam structure, which improves the magnetic flux distribution and reduces noise. The no-load current and no-turn loss performance parameters are better than the national and industry standards.

[0188] In the voltage regulator of the present invention, the transformer load loss calculation formula is: Pk = 3C*Rx*I n 2 Among them, Pk is the load loss value of each capacity; 3 means 3 phases; C is the additional loss coefficient; Rx is the transformer phase resistance; In is the rated current of each capacity. Calculate the phase resistance that can meet the load loss of each capacity in the capacity segment, so that the appropriate wire cross-section can be selected to complete the design calculation of the voltage regulator.

[0189] In the voltage regulator of the present invention, the calculation formula of the short-circuit impedance is: where u ka % is the resistance voltage drop; u kx % is the reactance voltage drop.

[0190] Since the delta-connected transformer can operate with a missing phase, the voltage regulator of the present invention can be designed as follows: (1) a single-phase line voltage regulator (single phase); (2) a two-phase line voltage regulator (V-connected operation); (3) a three-phase delta-connected line voltage regulator; (4) a three-phase delta-connected combined line voltage regulator.

[0191] According to user requirements, single-phase automatic voltage regulation, two-phase automatic voltage regulation and three-phase automatic voltage regulation line voltage regulator are provided. Three-phase delta connection line voltage regulator can provide three-phase integral type and three-phase combined type (phase production site combined installation), reducing the single piece transportation weight to better serve the elderly, children and remote users. The present invention has the function of automatically identifying the flow direction, can timely change the voltage input and output, perform bidirectional voltage regulation, and can always keep the output voltage stable.

[0192] The schematic diagram of single-phase and three-phase line voltage regulator is shown in Figure 7-9 .in, Figure 7 This is a schematic diagram of a single-phase voltage regulator installed and operated in two phases (V-shaped connection); Figure 8 It is a schematic diagram of a three-phase line voltage regulator when it is produced and installed as a whole (delta connection) using a three-phase integral type; Fig. 9 This is a schematic diagram of a three-phase combined line voltage regulator that is produced in split-phase and assembled on-site (delta connection); the three-phase combined line voltage regulator is designed to be produced as three single-phase transformers (one of which is equipped with an on-load switch) and assembled on-site.

[0193] The intelligent multifunctional line voltage regulator of the present invention can monitor the operating parameters (current, voltage, active power, reactive power, voltage regulation gear, etc.) in real time and record the instantaneous data during the voltage regulation process through the built-in voltage regulation controller, so that the voltage regulator can operate more economically. The operator can perform remote capacity adjustment operations, data viewing, calculation analysis, and curve report generation according to different set permissions.

[0194] Taking 6300KVA and 8000KVA products as examples, their technical performance is shown in Table 1 below.

[0195] Table 1: Technical performance parameters of HWOSZ-S-4000XL / 10—HWOSZ-S-8000XL / 10

[0196]

[0197]

[0198] There is no standard for delta connection line voltage regulator in national standards and national grid standards; the standard for delta connection line voltage regulator in China Southern Power Grid only has technical performance parameters of 6300KVA, 5000KVA and 4000KVA capacity. The present invention can meet the performance index requirements of the country and the industry, that is, meet the standard requirements of no-load loss, no-load current, load loss and short-circuit impedance.

[0199] my country's medium voltage power supply system is a low resistance grounding system. Since the high and low voltage windings of the star-connected autotransformer are electrically connected, its short-circuit impedance is only (1-k / 1) square times that of an ordinary double-winding transformer of the same capacity. Therefore, after the autotransformer is used in the power system, the three-phase short-circuit current will increase significantly. Since the neutral point of the autotransformer must be directly grounded, the single-phase short-circuit current of the system will increase greatly, sometimes even exceeding the three-phase short-circuit current. The delta-connected autotransformer has no neutral point grounding, and the short-circuit current has a relatively small impact on the power system. In other words: if a short-circuit accident occurs, the short-circuit current of the delta-connected line voltage regulator will have a relatively smaller impact on the power system than the star-connected line voltage regulator.

[0200] The invention is a delta connection line voltage regulator, which effectively weakens the influence of the third harmonic on the system.

[0201] This patented product can automatically identify the flow direction and automatically adjust the gear position of the three-phase on-load tap changer by tracking the change of input voltage to ensure stable output voltage. It has reliable operation and high voltage adjustment accuracy. It can not only widely solve the low voltage management of medium-voltage power supply lines, but also can be used for bidirectional power supply of small hydropower.

[0202] The intelligent multifunctional medium voltage line voltage regulator of the present invention is suitable for various power supply systems, and provides single-phase automatic voltage regulation according to user requirements; two-phase automatic and three-phase automatic voltage regulation line voltage regulators have the function of automatically identifying the flow direction, which can timely change the voltage input and output, perform bidirectional voltage regulation, and always maintain the stability of the output voltage. The three-phase delta connection line voltage regulator can provide three-phase integral type and three-phase combined type (phase production site combined installation), reduce the weight of single-piece transportation, and better serve the elderly, children and remote users.

[0203] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0204] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. An intelligent multifunctional medium voltage line regulator, characterized in that: The invention comprises a voltage regulator body (1); a load voltage regulating switch (2) is arranged on the top of the voltage regulator body (1); a controller (3) is arranged on one side of the voltage regulator body (1); a current transformer (4), an iron core (5) and a coil (6) are arranged inside the voltage regulator body (1); the coil of the voltage regulator body (1) is a triangle connection or an extended triangle connection; The controller is used for data collection, analysis and judgment, record storage, communication, remote control and control and distribution; the controller includes a processing unit MCU, a collection unit, an HMI unit, an input unit, an output unit and a communication unit; the controller calculates various operating parameters of the system according to the collected system voltage and current signals, and identifies the flow direction by combining the changes in the system voltage, current and power, and judges the current actual power supply side and load side of the system, and also judges the working mode of the voltage regulator in real time according to the flow direction and the voltage changes before and after the voltage regulator when adjusting the gear; According to the flow direction and the voltage change before and after the voltage regulator during the gear adjustment, it is judged in real time which of the following three modes the voltage regulator is operating in, wherein the three modes are respectively a forward operation mode, a reverse small hydropower operation mode and a reverse double substation operation mode; Forward operation mode: P>0, the power flow direction is from the power supply side to the load side. At this time, Uo is used as the adjustment target, 1->N gear increases the voltage, and N->1 gear decreases the voltage. Among them, P represents the system active power, 1->N means that the switch adjustment direction is from the lowest gear to the highest gear; similarly, N->1 means that the switch adjustment direction is from the highest gear to the lowest gear. Reverse small hydropower operation mode: P<0, the flow direction is from the load side to the power supply side, at this time, Uo is used as the regulation target, 1->N gear increases the voltage, N->1 gear decreases the voltage; Reverse double substation operation mode: P<0, the power flow direction is from the load side to the power supply side. At this time, Ui is used as the regulation target, 1->N gear is used for voltage reduction, and N->1 gear is used for voltage increase.

2. The intelligent multifunctional medium voltage line regulator according to claim 1 is characterized in that: The controller also includes a real-time clock; the real-time clock is used to provide a time reference for system event generation and information statistics.

3. The intelligent multifunctional medium voltage line regulator according to claim 1 is characterized in that: The controller also includes a storage unit; the storage unit is used to store system operation parameters and statistical data.

4. The intelligent multifunctional medium voltage line voltage regulator according to claim 1, characterized in that: The controller also includes a power supply; the power supply is used to complete the conversion of AC power supply to board-level DC power supply, providing a stable DC working power supply for the controller.

5. The intelligent multifunctional medium voltage line regulator according to claim 1 is characterized in that: The processing unit MCU is TMS320F2812.

6. The intelligent multifunctional medium voltage line regulator according to claim 1, characterized in that: The HMI unit includes a liquid crystal screen and a keyboard.

7. The intelligent multifunctional medium voltage line regulator according to claim 1, characterized in that: The communication unit includes an RS485 communication cable.

8. The intelligent multifunctional medium voltage line regulator according to claim 1, characterized in that: The signals collected by the controller include AC analog quantities.

9. The intelligent multifunctional medium voltage line regulator according to claim 8, characterized in that: The AC analog quantity includes voltage, current, active power, reactive power, power factor and frequency.

10. A power supply system comprising the intelligent multifunctional medium voltage line voltage regulator according to any one of claims 1 to 9, characterized in that: It also includes a front-end power supply circuit breaker QF1, a bypass power supply circuit breaker QF2, an isolating switch QS, a front lightning arrester FV1 and a rear lightning arrester FV2.

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