Bidirectional intelligent voltage regulating device and system for tail end of low-voltage transformer area

Abstract

The utility model discloses a bidirectional intelligent voltage regulating device and system for the tail end of a low-voltage transformer area, and belongs to the technical field of low-voltage power distribution network electric energy quality treatment. The device comprises an acquisition unit, an execution unit and a reactive compensation unit. The acquisition unit is used for acquiring line tail end electrical parameters; the output end of the acquisition unit is connected with the input end of an external control unit; the execution unit responds to a control instruction of the control unit; and the reactive compensation unit comprises at least one group of capacitor branches and at least one group of reactor branches, and is used for inputting the capacitor branches according to the control instruction to send out capacitive reactive lifting voltage or inputting the reactor branches to absorb capacitive reactive (namely sending out inductive reactive) reducing voltage. According to the utility model, localized and automatic bidirectional reactive power compensation is carried out at the tail end of the transformer area, so that the problem of voltage bidirectional out-of-limit caused by distributed photovoltaic access and load fluctuation is effectively solved, and the device has the characteristics of rapid response, accurate treatment and low cost.

Description

TECHNICAL FIELD

[0001] The utility model relates to low voltage distribution network electric energy quality management technical field especially relates to a kind of two-way intelligent voltage regulating device and system for low-voltage area end. BACKGROUND

[0002] Low-voltage area is the terminal power supply unit of power system, usually with a 10kV / 0.4kV distribution transformer as core, constitute the "last kilometer" connecting power grid and user, its operation quality is directly related to the power safety and stability of the majority of residents and small and micro enterprise users.

[0003] In recent years, with the large-scale access of distributed photovoltaic, the power flow of low-voltage area changes from traditional one-way radiation to two-way interaction mode with power return ability. In photovoltaic high production period, reverse power flows through line impedance, which easily leads to line end voltage over-limit operation, seriously reduces low-voltage area voltage qualification rate and threatens the safety of electrical equipment.

[0004] At the same time, low-voltage area load itself presents significant day-night fluctuation characteristics, especially in low-voltage area with long power supply radius, night load peak often causes line end voltage to be low.

[0005] Therefore, under the influence of source and load double fluctuation, the same power supply line end of low-voltage area often faces the two-way limit problem of voltage being too high (overvoltage) during the day and voltage being too low (undervoltage) at night; the problem is random and fast in time scale and significantly different in spatial distribution, which puts high requirements on response speed, adjustment direction and self-adaptive ability of treatment measures, and traditional single voltage regulation method has been difficult to effectively cope with. UTILITY MODEL CONTENT

[0006] The utility model aims at providing a kind of two-way intelligent voltage regulating device and system for low-voltage area end to solve the problem of line end voltage two-way limit caused by distributed photovoltaic power return and resident load fluctuation, realize the two-way, dynamic compensation of inductive and capacitive reactive power, quickly and accurately stabilize end voltage and improve power supply quality.

[0007] To achieve the above object, the utility model provides the following scheme:

[0008] Firstly, the utility model provides a kind of two-way intelligent voltage regulating device for low-voltage area end, comprising: acquisition unit, execution unit and reactive power compensation unit;

[0009] The input end of the above-mentioned acquisition unit is used to be connected to the end of low-voltage distribution line to collect the electrical parameter of low-voltage distribution line, and the output end is used to be connected with the input end of external control unit;

[0010] The aforementioned reactive power compensation unit includes at least one set of capacitor branches and at least one set of reactor branches, wherein both capacitor branches and reactor branches are connected between the phase line and the neutral line of the low-voltage distribution line.

[0011] The aforementioned execution unit includes multiple sets of switching devices corresponding to capacitor branches and reactor branches respectively; the control terminal of each set of switching devices is used to connect to the control signal output terminal of the external control unit, and the main circuit contacts of each set of switching devices are connected in series to the corresponding capacitor branch or reactor branch respectively;

[0012] The switching devices are used to close or open according to the control signal of the external control unit to control the corresponding capacitor branch or reactor branch to be connected or disconnected, thereby realizing reactive power compensation of the low-voltage power distribution line.

[0013] Secondly, this utility model provides a bidirectional intelligent voltage regulation system for the end of a low-voltage distribution area, including a low-voltage power distribution line and a bidirectional intelligent voltage regulation device for the end of a low-voltage distribution area as described above; the acquisition unit and reactive power compensation unit of the device are connected in parallel to the end of the low-voltage power distribution line.

[0014] According to the specific embodiments provided by this utility model, the following technical effects are disclosed:

[0015] This invention provides a bidirectional intelligent voltage regulating device and system for the end of a low-voltage distribution area. By connecting the acquisition unit to the end of the low-voltage distribution line, it obtains the real electrical parameters of the line end in real time, enabling the external control unit to generate control signals based on more accurate load conditions. This effectively improves the control inaccuracies, overcompensation, or undercompensation problems caused by the inconsistency between the electrical conditions of the measurement point (such as the beginning of the line or the distribution transformer side) and the load side in traditional devices, achieving accurate perception and compensation target tracking of the reactive power state at the end of the line. The external control unit generates control signals in real time based on electrical parameters and drives multiple sets of switching devices in the execution unit to independently control at least one set of capacitor branches and at least one set of reactor branches to be connected or disconnected. This achieves a breakthrough in compensation function and direction, solving the problem that passive compensation devices with a single property (such as capacitive only) cannot adapt to dynamic load changes and may exacerbate voltage over-limits under specific operating conditions (such as overvoltage during high photovoltaic power generation). Thus, it achieves bidirectional and dynamic compensation for inductive and capacitive reactive power in low-voltage distribution lines, effectively stabilizing the voltage at the end of the line and improving power supply quality. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram illustrating the application environment of a bidirectional intelligent voltage regulating device for the end of a low-voltage distribution area according to one embodiment of the present invention.

[0018] Figure 2 This is a schematic diagram of the structure of a bidirectional intelligent voltage regulating device for the end of a low-voltage distribution area according to one embodiment of the present invention.

[0019] Figure 3 This is a circuit diagram of a heat dissipation unit in a bidirectional intelligent voltage regulating device for the end of a low-voltage distribution area, according to one embodiment of the present invention.

[0020] Figure 4 This is a schematic diagram of the circuit connection between the external control unit and the reactive power compensation unit in one embodiment of the present invention.

[0021] Figure label:

[0022] 1-Distribution transformer, 2-Distributed photovoltaic, 3-Line start end, 4-Line end, 5-Reactor branch, 6-Capacitor branch. Detailed Implementation

[0023] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0024] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, the utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0025] like Figure 1As shown, in the low-voltage distribution area where a large number of distributed photovoltaic (PV) units are connected, due to the backfeeding of PV power, the voltage distribution of the low-voltage distribution lines exhibits an abnormal characteristic: the voltage at the beginning of the line (3) is normal, while the voltage at the end of the line (4) is severely exceeding the limit. Specifically, the voltage at the beginning of the line (3), which is close to the distribution transformer (1), remains within the normal range of 228-230V. However, at the end of the line (4), which is far from the distribution transformer (1), as the PV output increases, the backfeeding power generates a voltage rise component across the line impedance, causing the voltage at the grid connection point to gradually climb to 240-260V, far exceeding the upper limit of the acceptable voltage for residential electricity.

[0026] Currently, the mainstream equipment for addressing voltage exceedance issues in low-voltage distribution areas mainly includes on-load tap-changing transformers, static var generators, and reactive power regulation from photovoltaic inverters. However, all of them have certain limitations and are difficult to economically and effectively solve the bidirectional voltage exceedance problem at the end of line 4 in low-voltage distribution areas.

[0027] On-load tap-changing transformers: Their tap-changing function is essentially to change the transformer turns ratio, and they do not have reactive power compensation capabilities; their triggering mechanism is simple, only responding to the bus voltage and unable to sense the voltage status at the end of the line; they rely on the action of mechanical tap changers, which has a delay of 3-5 minutes, making it difficult to adapt to the rapid fluctuations in photovoltaic output and load.

[0028] Static var generators (SVRs): While they can achieve continuous reactive power regulation, the cost of a single unit is high, and the control algorithm is complex. In weak power grid environments such as low-voltage distribution areas, they are prone to stability issues such as harmonic amplification. In addition, they have stringent requirements for the operating environment. Conventional equipment has a narrow temperature range (-10℃ to 40℃), making it difficult to operate stably for a long time in outdoor distribution area environments with high summer temperatures (above 40℃).

[0029] Reactive power regulation of photovoltaic inverters: The priority of reactive power output is lower than that of active power generation. During periods of low or no photovoltaic output (such as at night), there is a problem of insufficient regulation capacity. Moreover, it is usually designed to output inductive reactive power (for voltage reduction), which cannot provide capacitive reactive power to address low voltage issues during peak nighttime loads, and it cannot solve the undervoltage condition in bidirectional over-limit operations.

[0030] In summary, existing technologies are insufficient to meet the complex, rapid, and bidirectional voltage management requirements at the end of low-voltage distribution lines due to slow response, lack of compensation capabilities, high costs, poor environmental adaptability, unidirectional functions, and blind spots.

[0031] Therefore, this utility model provides a bidirectional intelligent voltage regulating device for the end of a low-voltage distribution area, deployed at the end 4 of the low-voltage distribution area line. For example... Figure 2 As shown, this device addresses the shortcomings of the aforementioned prior art by designing a data acquisition unit, an execution unit, and a reactive power compensation unit.

[0032] The input terminal of the acquisition unit is used to connect to the end 4 of the low-voltage power distribution line to acquire the electrical parameters (voltage and current) of the low-voltage power distribution line, and its output terminal is used to connect to the input terminal of the external control unit.

[0033] The reactive power compensation unit includes at least one set of capacitor branches 6 and at least one set of reactor branches 5, wherein both capacitor branches 6 and reactor branches 5 are connected between the phase line and the neutral line of the low-voltage distribution line.

[0034] The execution unit includes multiple sets of switching devices corresponding to the capacitor branch and the reactor branch respectively; the control terminal of each set of switching devices is used to connect to the control signal output terminal of the external control unit, and the main circuit contacts of each set of switching devices are connected in series to the corresponding capacitor branch 6 or reactor branch 5 respectively.

[0035] Each set of switching devices is used to close or open according to the control signal of the external control unit to control the corresponding capacitor branch 6 or reactor branch 5 to be connected or disconnected, thereby realizing reactive power compensation of the low-voltage power distribution line.

[0036] This invention provides a bidirectional intelligent voltage regulating device for the end of a low-voltage distribution area. By connecting the acquisition unit to the end of the low-voltage distribution line 4, the device acquires the real electrical parameters of the end of the line 4 in real time, enabling the external control unit to generate control signals based on more accurate load conditions. This effectively improves the problems of control inaccuracy, overcompensation, or undercompensation caused by the inconsistency between the measurement point (such as the beginning of the line 3 or the distribution transformer 1 side) and the load side in traditional devices. It achieves accurate perception and compensation target tracking of the reactive power state of the end of the line 4. By generating control signals in real time based on electrical parameters through the external control unit, and driving multiple sets of switching devices of the execution unit, it independently controls at least one set of capacitor branches 6 and at least one set of reactor branches 5 to be connected or disconnected. This achieves a breakthrough in compensation function and direction, solving the problem that passive compensation devices with a single property (such as only capacitive reactive power) cannot adapt to dynamic load changes and may aggravate voltage over-limit under certain operating conditions (such as overvoltage during large photovoltaic power generation). Thus, it realizes bidirectional and dynamic compensation of inductive and capacitive reactive power of low-voltage distribution lines, effectively stabilizing the voltage at the end of the line 4 and improving power supply quality. This device overcomes many limitations of existing technologies:

[0037] Compared to on-load tap-changing transformers, this device has reactive power compensation capabilities and a faster response speed, enabling it to track rapid fluctuations in photovoltaic power and load. Compared to static var generators, this device is based on mature capacitor and reactor switching technologies, resulting in significantly lower costs and higher environmental adaptability and reliability. Compared to reactive power regulation of photovoltaic inverters, this device achieves all-weather, bidirectional reactive power support. It can activate reactor branch 5 during peak daytime photovoltaic power generation to absorb capacitive reactive power (i.e., generate inductive reactive power) to suppress overvoltage, and activate capacitor branch 6 during peak nighttime load to provide capacitive reactive power to raise undervoltage.

[0038] Therefore, this device effectively solves the problem of bidirectional voltage exceeding the limit at the end of the low-voltage distribution area line 4 caused by distributed photovoltaic 2 access and load fluctuation. Through bidirectional and dynamic compensation of capacitive reactive power and inductive reactive power, it achieves rapid, accurate, economical and reliable management of the voltage at the end of the line 4, thereby improving power supply quality and voltage qualification rate.

[0039] In one exemplary embodiment, the present invention provides a bidirectional intelligent voltage regulating device for the end of a low-voltage distribution area, which is directly connected to a 400V three-phase four-wire (A, B, C, N) distribution line at the end of the low-voltage distribution area. The various units of the device work collaboratively, as follows:

[0040] The acquisition unit is used to acquire electrical parameters of the end 4 of the low-voltage distribution line in real time. It includes a voltage sampling circuit and a current sampling circuit. The input end of the voltage sampling circuit is used to connect to the phase line and neutral line (A, B, C, N) of the low-voltage distribution line to obtain real-time analog voltage signals of each phase. The output end of the voltage sampling circuit is connected to the voltage input end of the external control unit to convert the analog voltage signal into a data signal and send it to the external control unit. The current sampling circuit includes a current transformer fitted into the phase line of the low-voltage distribution line to acquire real-time analog current signals of each phase. The secondary output end of the current transformer is connected to the current input end of the external control unit to calculate the analog current signal and convert it into a data signal and send it to the external control unit.

[0041] An external control unit (such as a microprocessor or microcontroller) connects its input to the output of the acquisition unit to receive data signals. Based on preset voltage thresholds, a reactive power compensation control algorithm, and the received data signals, the external control unit determines the voltage status (overvoltage, undervoltage, or normal) of the monitoring point in real time and generates corresponding control commands. The control signal output of the external control unit connects to the execution unit to send these control commands. Furthermore, the external control unit connects to the communication unit via a built-in communication interface (such as a RS-485 bus) to support remote data interaction.

[0042] The execution unit includes multiple sets of switching devices (such as relays, contactors, or thyristor switching devices) corresponding to capacitor branches and reactor branches, respectively, for receiving and executing control commands. The control terminal of each set of switching devices is connected to the corresponding control signal output terminal of the external control unit, and its main circuit contacts are connected in series to the corresponding capacitor branch 6 or reactor branch 5 in the reactive power compensation unit. When the external control unit issues a control command, the corresponding switching device operates, thereby engaging or disengaging the corresponding compensation branch (i.e., capacitor branch 6 or reactor branch 5).

[0043] The reactive power compensation unit is used to directly compensate the power grid for reactive power to regulate voltage. It includes at least one set of capacitor branches 6 and at least one set of reactor branches 5. Both capacitor branches 6 and reactor branches 5 are connected between the phase line and the neutral line of the low-voltage distribution line. When capacitor branch 6 is switched on, it can generate capacitive reactive power to raise the voltage. When reactor branch 5 is switched on, it can absorb capacitive reactive power (i.e., generate inductive reactive power) to lower the voltage. By controlling the grouping and sequential switching of multiple sets of switching devices, the reactive power compensation capacity can be finely adjusted, thereby achieving smooth and precise bidirectional voltage regulation.

[0044] The bidirectional intelligent voltage regulating device for the end of a low-voltage distribution area provided by this utility model operates according to the following closed-loop process after being powered on:

[0045] S1. The acquisition unit continuously acquires the voltage analog signal and current analog signal at the end of the low-voltage line 4, converts them into data signals, and uploads them to the external control unit.

[0046] S2. The external control unit analyzes the received data signal based on preset overvoltage and undervoltage thresholds and performs the following judgments:

[0047] If the data signal is greater than or equal to the overvoltage threshold, it is determined to be an overvoltage state;

[0048] If the data signal is less than or equal to the undervoltage threshold, it is determined to be in an undervoltage state;

[0049] If the data signal is greater than the undervoltage threshold and less than the overvoltage threshold, it is determined to be in a normal state.

[0050] Based on the judgment result, the external control unit generates corresponding control commands:

[0051] When an overvoltage condition is detected, the control command generated by the external control unit is used to control the connection of reactor branch 5 or the disconnection of capacitor branch 6.

[0052] When the voltage is determined to be undervoltage, the control command generated by the external control unit is used to control the connection of capacitor branch 6 or the disconnection of reactor branch 5.

[0053] When the condition is determined to be normal, the external control unit maintains the current control commands.

[0054] The overvoltage and undervoltage thresholds mentioned above can be set remotely or locally according to the actual situation of the transformer area.

[0055] S3. The execution unit responds to the control command issued by the external control unit, drives the corresponding switching device to perform the actual connection or disconnection of the specified capacitor branch 6 or reactor branch 5.

[0056] S4. After compensation is enabled or disabled, the acquisition unit obtains new data signals and uploads them to the external control unit. The external control unit then makes a new judgment and decision, and stabilizes the data signals within the qualified range through closed-loop adjustment.

[0057] Through the above process, this utility model realizes the localized, automated, bidirectional, and refined management of the voltage of the four pairs of voltages at the end of the low-voltage distribution area line, effectively solving the problem of bidirectional voltage over-limit caused by distributed photovoltaic 2 and load fluctuations.

[0058] As an optional implementation, this utility model provides a bidirectional intelligent voltage regulating device for the end of a low-voltage distribution area, which also includes a protective cabinet and a heat dissipation unit. The aforementioned data acquisition unit, execution unit, and reactive power compensation unit are all installed inside the protective cabinet. The heat dissipation unit is used to automatically start and stop heat dissipation based on the temperature inside the protective cabinet. Specifically, the heat dissipation unit includes a temperature switch and at least one cooling fan; the power supply circuit of the temperature switch and the cooling fan are linked. When the temperature switch detects that the temperature inside the cabinet exceeds the start threshold, the power supply circuit of the cooling fan is turned on, and the cooling fan starts dissipating heat; when the temperature drops to the stop threshold, the power supply circuit is turned off, and the cooling fan stops.

[0059] As a preferred implementation method, such as Figure 3 As shown, the heat dissipation unit can employ an independent temperature-controlled heat dissipation circuit. This circuit includes a temperature switch K installed in the heat-generating area inside the protective cabinet, and multiple cooling fans (FS1-FS4) connected in parallel. The contacts of the temperature switch K are directly connected in series in the common power supply circuit of the cooling fans, and a fuse FU4 is also connected in series in the circuit for protection.

[0060] In one specific implementation, the protective cabinet is equipped with two sets of air inlets and ventilation holes, as well as terminals for connecting low-voltage power lines. The cooling fans adopt a two-intake, two-outtake layout, installed at the air inlets and outlets of the protective cabinet respectively, forming a forced convection airflow duct with the ventilation holes on the cabinet. When the internal temperature exceeds the activation threshold (e.g., 45°C), the contacts of temperature switch K close, and all cooling fans start simultaneously; when the temperature drops to the stop threshold (e.g., 42°C), the contacts open, and all cooling fans stop. This independent cooling design, directly triggered by the temperature switch, improves the reliability of the device during long-term operation in high-temperature outdoor environments.

[0061] As an optional implementation, in order to achieve refined reactive power compensation for three-phase unbalanced loads, the capacitor branch 6 of the above-mentioned reactive power compensation unit includes a phase-specific compensation capacitor branch. Specifically, the phase-specific compensation capacitor branch is connected between the single-phase line and the neutral line of the low-voltage distribution line via switching devices to achieve independent phase-specific control.

[0062] The specific connection method for the phase compensation capacitor branch can include single-phase connection or star connection, etc.

[0063] As one implementation method, a single-phase connection is adopted: that is, in the phase-compensation capacitor branch, each single-phase capacitor has one independent end connected to a phase of the three-phase line through a switching device, and the other end is directly connected to the neutral line (N).

[0064] As another implementation method, a star connection is adopted: that is, one end of the three sets of capacitors in the phase compensation capacitor branch is connected to the three-phase line through a switching device, and the other end is connected together to form a star point, which is then connected to the neutral line (N).

[0065] Both of the above connection methods can enable the external control unit to independently control the connection or disconnection of each phase capacitor, so as to achieve the purpose of phase compensation.

[0066] By configuring the aforementioned phase-specific compensation capacitor branches, the external control unit can formulate differentiated activation or deactivation strategies based on the independent voltage and current data of each phase acquired by the acquisition unit. For example, when only phase A voltage is detected to exceed the upper limit, the phase-specific compensation capacitor branch connected between phase A and the neutral line can be individually deactivated to reduce the reactive power output of that phase, thereby suppressing overvoltage, without needing to activate phases B and C. This configuration achieves precise and independent management of unbalanced voltage in the three-phase line, significantly improving the targeting of voltage regulation and the overall voltage qualification rate of the transformer area.

[0067] In another exemplary embodiment, such as Figure 4As shown, this utility model provides a bidirectional intelligent voltage regulating device for the end of a low-voltage distribution area. It is connected to a 400V low-voltage power distribution line via a three-phase four-wire connection. On the incoming line side of the device, fuses (FU1, FU2, FU3) are connected in series on the three phase lines respectively as short-circuit protection for the main circuit.

[0068] The input terminals of the external control unit are equipped with voltage terminals (Ua, Ub, Uc, Un) and current terminals (Ia). / Ia, Ib / Ib, Ic / Ic Its output terminals are equipped with multiple control output terminals (K1-K12) and a common terminal (COM).

[0069] The primary sides of current transformers TAa, TAb, and TAc are respectively mounted on the three-phase lines, and their secondary output terminals are respectively connected to the current terminals (Ia) of an external control unit. With Ia, Ib With Ib, Ic (with Ic). For example, the second-order endons Ta of TAa. Terminal Ia is connected to the external control unit, respectively, along with Ta. The second-order endons Tb of Ia and TAb Terminal Ib is connected to the control unit, respectively, along with Tb. The secondary endons Tc of Ib and TAc Terminal Ic of the external control unit is connected to Tc. With Ic.

[0070] Switching devices FK1 and FK2 are used to connect or disconnect the two sets of phase-compensation capacitor branches, respectively, and switching devices FK3 and FK4 are used to connect or disconnect the two sets of reactor branches 5, respectively. Taking FK1 as an example, the control terminals k1~k3 of FK1 are connected between the output terminals K1~K3 of the external control unit and the common terminal COM, respectively, and its main circuit contact v1 is connected in series in the phase-compensation capacitor branch.

[0071] Grouping on / off: The external control unit can drive the corresponding switching devices by independently controlling the output terminals K1-K8, thereby enabling the independent or combined on / off of the two groups of reactor branches 5 and the two groups of phase compensation capacitor branches, achieving fine adjustment of reactive power compensation capacity.

[0072] This utility model also provides an application scenario in which the bidirectional intelligent voltage regulating device of this utility model for the end of a low-voltage distribution area is deployed at the end of a typical rural low-voltage distribution area line 4 where distributed photovoltaic 2 is connected.

[0073] In this application example, the low-voltage distribution area has a long power supply radius, and the four users at the end of the line are far from the distribution transformer 1 (e.g., about 600 meters). Since most users have installed rooftop photovoltaic systems, during the midday peak photovoltaic power generation period, power backflow causes the voltage at the end of the line 4 to seriously exceed the upper limit; while during the nighttime peak load period, the voltage at the end of the line 4 is at risk of exceeding the lower limit.

[0074] To solve this bidirectional voltage over-limit problem, the device of this invention is connected in parallel at the end 4 of the low-voltage line. The device operates automatically after power-on, and its working process is as follows:

[0075] Midday overvoltage condition: When the device detects that the voltage is continuously higher than the preset overvoltage threshold, the external control unit generates a control command to drive the execution unit to engage reactor branch 5, absorbing capacitive reactive power (i.e. generating inductive reactive power), thereby stabilizing the voltage to within the acceptable range.

[0076] Nighttime undervoltage condition: When the device detects that the voltage is continuously lower than the preset undervoltage threshold, the external control unit generates a control command to drive the execution unit to connect to capacitor branch 6, and output capacitive reactive power to support the voltage, thereby raising the voltage to the qualified range.

[0077] Throughout the process, the device operates autonomously in a closed loop based on local measurement data, without relying on remote master station intervention, achieving real-time, bidirectional, and automated management of the voltage at the end of line 4. Practical application shows that after deploying this device, the voltage qualification rate at the end of line 4 in the distribution area has been significantly improved, effectively ensuring power supply quality and electricity safety.

[0078] This utility model embodiment also provides a bidirectional intelligent voltage regulation system for the end of a low-voltage distribution area. Specific technical solutions for this system can be found in the foregoing description of the device embodiments, and will not be repeated here.

[0079] In one exemplary embodiment, a bidirectional intelligent voltage regulation system for the end of a low-voltage distribution area is provided, suitable for low-voltage distribution areas with distributed photovoltaic access or large load fluctuations. The system includes a low-voltage distribution line and a bidirectional intelligent voltage regulation device for the end of a low-voltage distribution area as described in any of the foregoing embodiments. The acquisition unit and reactive power compensation unit of the device are connected in parallel to the end 4 of the low-voltage distribution line.

[0080] This document uses specific examples to illustrate the principles and implementation methods of this utility model. The descriptions of the above embodiments are only intended to help understand the device and core ideas of this utility model. Furthermore, those skilled in the art will recognize that, based on the ideas of this utility model, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this utility model.

Claims

1. A bidirectional intelligent voltage regulating device for use at the end of a low-voltage distribution area, characterized in that, include: Acquisition unit, execution unit, and reactive power compensation unit; The input terminal of the acquisition unit is used to connect to the end of the low-voltage power distribution line to acquire the electrical parameters of the low-voltage power distribution line, and its output terminal is used to connect to the input terminal of an external control unit. The reactive power compensation unit includes at least one set of capacitor branches and at least one set of reactor branches, wherein both capacitor branches and reactor branches are connected between the phase line and the neutral line of the low-voltage distribution line. The execution unit includes multiple sets of switching devices corresponding to capacitor branches and reactor branches respectively; the control terminal of each set of switching devices is used to connect to the control signal output terminal of the external control unit, and the main circuit contacts of each set of switching devices are connected in series to the corresponding capacitor branch or reactor branch respectively. The switching devices are used to close or open according to the control signal of the external control unit to control the corresponding capacitor branch or reactor branch to be connected or disconnected, thereby realizing reactive power compensation of the low-voltage power distribution line.

2. The bidirectional intelligent voltage regulating device for the end of a low-voltage distribution area according to claim 1, characterized in that, The acquisition unit includes a voltage sampling circuit and a current sampling circuit; The input terminal of the voltage sampling circuit is used to connect to the phase line and neutral line of the low-voltage power distribution line, and its output terminal is connected to the voltage input terminal of the external control unit. The current sampling circuit includes a current transformer fitted onto the phase line of the low-voltage power distribution line, and the secondary output terminal of the current transformer is connected to the current input terminal of the external control unit.

3. The bidirectional intelligent voltage regulating device for the end of a low-voltage distribution area according to claim 1, characterized in that: The capacitor branch includes a phase-compensation capacitor branch; The phase-compensation capacitor branch is connected between the single-phase line and the neutral line of the low-voltage power distribution line, and the external control unit can independently control the connection or disconnection of the phase-compensation capacitor branch on each phase line.

4. The bidirectional intelligent voltage regulating device for the end of a low-voltage distribution area according to claim 1, characterized in that, It also includes a communication unit; The communication unit is connected to the communication interface of the external control unit via a data bus.

5. The bidirectional intelligent voltage regulating device for the end of a low-voltage distribution area according to claim 1, characterized in that, It also includes protective cabinets; The acquisition unit, external control unit, execution unit, and reactive power compensation unit are all installed inside the protective cabinet; the protective cabinet is provided with terminals for connecting the low-voltage power distribution line.

6. The bidirectional intelligent voltage regulating device for the end of a low-voltage distribution area according to claim 5, characterized in that, It also includes a heat dissipation unit installed inside the protective cabinet; The heat dissipation unit includes a temperature switch and at least one cooling fan; the temperature switch is connected in series in the power supply circuit of the cooling fan.

7. A bidirectional intelligent voltage regulation system for the end of a low-voltage distribution area, characterized in that, It includes a low-voltage power distribution line and a bidirectional intelligent voltage regulating device for the end of a low-voltage distribution area as described in any one of claims 1 to 6; the acquisition unit and the reactive power compensation unit of the device are connected in parallel to the end of the low-voltage power distribution line.

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