An adjustable capacity high voltage series compensation device

Abstract

This utility model relates to the field of high-voltage power transmission and distribution technology, and discloses an adjustable-capacity high-voltage series compensation device, including a core compensation unit, a bypass protection unit, a damping circuit, and a control system. The core compensation unit has at least two parallel capacitor branches controlled by independent switching switches for step-wise adjustment of the compensation capacity. The control system includes a safety interlocking system, which includes a first interlocking module and a second interlocking module that are independent of each other. The first interlocking module is used to forcibly lock all independent switching switches in the open state when the bypass switch is closed; the second interlocking module is used to prohibit operation of the incoming and outgoing line isolating switches of the device when the bypass switch is not closed. This utility model, by combining hardware forced interlocking with intelligent control, eliminates the risk of misoperation and significantly improves the safety, reliability, and adaptability of the device operation to the power grid.

Description

Technical Field

[0001] This utility model relates to the field of high-voltage power transmission and distribution technology, and in particular to a high-voltage series compensation device with adjustable capacity. Background Technology

[0002] In high-voltage transmission systems, the inductive impedance of the lines is a major factor causing voltage loss and limiting transmission capacity. Series capacitor compensation is a widely used and cost-effective method to offset line inductive reactance.

[0003] Currently, mainstream fixed series compensation devices have a fixed capacitor capacity, making them unsuitable for lines with varying impedances. More importantly, when a line fault causes overvoltage, the protection system will bypass the entire device, completely losing its compensation function and affecting system stability. While Controllable Series Compensation (TCSC) can achieve continuous adjustment of the compensation level, it relies on high-power thyristors and other power electronic devices, resulting in high cost, complex structure, and significant harmonic issues, making it difficult to promote its application in all situations.

[0004] Therefore, the market urgently needs a new type of series compensation device that can flexibly adjust the compensation capacity, and has high reliability, low cost and simple structure. Utility Model Content

[0005] To overcome the above shortcomings, this utility model provides an adjustable capacity high voltage series compensation device, which aims to improve and solve the problems of fixed series compensation devices with unadjustable compensation degree and complete loss of function after protection, as well as controllable series compensation devices with high cost and complex structure.

[0006] To achieve the above objectives, this utility model adopts the following technical solution: an adjustable-capacity high-voltage series compensation device, connected in series to the inlet and outlet terminals of a high-voltage line, further comprising:

[0007] The core compensation unit is set in parallel between the incoming and outgoing terminals and includes at least two parallel capacitor branches. Each capacitor branch consists of a capacitor bank and an independent switching switch connected in series.

[0008] The bypass protection unit includes a bypass switch and a metal oxide surge arrester connected in parallel across the core compensation unit.

[0009] The damping circuit consists of a resistor and an inductor connected in series in the main circuit between the input and output terminals.

[0010] The control system is configured to achieve stepped adjustment of the compensation capacity by selectively closing or opening individual switching switches and includes:

[0011] The safety interlocking system is used to forcibly restrict the operation of bypass switches and independent switching switches.

[0012] As a further description of the above technical solution: the control system includes:

[0013] The zero-crossing switching module detects line voltage and branch current in real time and controls the independent switching switch to close at the voltage zero-crossing point and open at the current zero-crossing point.

[0014] The voltage monitoring module, connected to the metal oxide surge arrester, is used to identify primary and secondary overvoltage signals.

[0015] As a further description of the above technical solution: the control system also includes:

[0016] The logic execution module, in response to the signal from the voltage monitoring module, performs the following operations:

[0017] When a first-level overvoltage signal is triggered, the currently closed independent switching switches will be disconnected first.

[0018] When the secondary overvoltage signal is triggered, the bypass switch is closed and all independent switching switches are forcibly disconnected.

[0019] As a further description of the above technical solution: the independent switching switch is a high-voltage vacuum contactor, whose rated breaking capacity is not less than the rated inrush current of the capacitor bank.

[0020] As a further description of the above technical solution: the independent switching switch is a vacuum contactor, whose rated current is not less than 1.5 times the rated current of the capacitor bank, the capacity of the capacitor bank is configured in a binary ratio, and the capacity ratio of adjacent branches is 1:2.

[0021] As a further description of the above technical solution: the main circuits of the input and output terminals are connected in series with an input isolating switch and an output isolating switch.

[0022] As a further description of the above technical solution: the safety interlocking system includes:

[0023] The first interlocking module is connected to the bypass switch and all independent switching switches. When the bypass switch is detected to be closed, the output signal forces all switching switches to disconnect and remains locked.

[0024] The second interlocking module is linked with the bypass switch, the incoming disconnect switch, and the outgoing disconnect switch, and allows the disconnect switch to open only when the bypass switch is closed.

[0025] As a further description of the above technical solution: the second interlocking module can physically block the operation of the disconnecting switch operating handle when the bypass switch is open through a mechanical interlocking mechanism; or cut off the control circuit of the disconnecting switch drive mechanism through an electrical interlocking contact.

[0026] This utility model has the following beneficial effects:

[0027] 1. In this utility model, the compensation capacity is first adjusted in stages by switching the group capacitors, which can better match the changes in line load, avoid over-compensation or under-compensation problems, and significantly reduce costs compared to TCSC.

[0028] 2. In this utility model, a mature and reliable mechanical switch is used as the switching element, and zero-crossing switching technology is combined to ensure smooth and shock-free operation.

[0029] 3. This utility model has a hierarchical intelligent protection logic. When a low-to-medium level disturbance occurs, it can mitigate the risk by actively reducing the capacity, avoiding the overall shutdown of the device, and maintaining partial compensation and support for the power grid.

[0030] 4. This utility model incorporates a multi-layered electrical and mechanical safety interlock system, which fundamentally eliminates the possibility of misoperation and ensures the safety of equipment and personnel. Attached Figure Description

[0031] Figure 1 A circuit connection diagram of an adjustable-capacity high-voltage series compensation device proposed in this utility model;

[0032] Figure 2 The present invention provides a logic block diagram of an adjustable-capacity high-voltage series compensation device. Detailed Implementation

[0033] 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.

[0034] Reference Figures 1-2 The present invention provides an embodiment of an adjustable-capacity high-voltage series compensation device, which is described in detail below with reference to the accompanying drawings:

[0035] Appendix Figure 1G1 is the incoming disconnect switch; G2 is the outgoing disconnect switch; G3 is the bypass switch; C is the capacitor; R is the resistor; L is the inductor; KK is the safety interlock system; MOV is the metal oxide surge arrester.

[0036] The device is connected in series with a 10kV busbar or other high-voltage lines of different voltage levels. To ensure safety during maintenance, the device is equipped with an incoming disconnect switch and an outgoing disconnect switch at both the incoming and outgoing ends to form a clear physical isolation point.

[0037] Its core lies in the unique structure and combination of compensation, protection and control units, which mainly consists of a core compensation unit, a bypass protection unit, a damping circuit and a control system.

[0038] The core compensation unit is the foundation for achieving adjustable compensation. This unit internally contains at least two parallel capacitor branches. The attached diagram illustrates one such branch as an example, consisting of a capacitor and an independent switching switch connected in series. In the complete device, multiple such branches will exist in parallel, labeled (C1-KM1, C2-KM2,...). By selectively controlling the on / off state of the independent switching switches for each branch, the number of capacitor branches connected in parallel to the main circuit can be flexibly changed, thereby achieving a stepped adjustment of the total compensation capacity of the entire device. The independent switching switch is preferably a high-voltage vacuum contactor.

[0039] The bypass protection unit is connected in parallel across the core compensation unit, providing unified protection for all its components. This unit consists of a bypass switch and a metal oxide surge arrester connected in parallel. The metal oxide surge arrester is responsible for responding to and clamping transient overvoltages, while the bypass switch serves as a final protection measure, rapidly closing in the event of a severe fault to short-circuit the core compensation unit.

[0040] The damping circuit is connected in series in the main circuit topology and consists of a resistor and an inductor connected in series. Its function is to suppress transient inrush currents and operating overvoltages that may occur when the switching switch or bypass switch is activated.

[0041] The control system is responsible for executing regulation commands and protection logic. Internally, the control system includes a zero-crossing switching module for smooth switching and a voltage monitoring module for identifying different levels of overvoltage.

[0042] The control system also integrates a safety interlocking system. The core hardware of this system can consist of one or more latching relays, or it can be implemented using auxiliary contacts of a switch; the choice depends on the specific circumstances. A latching relay is a relay with mechanical or magnetic holding function; its contact state remains unchanged even after the control signal disappears, making it ideal for implementing forced and reliable safety interlocking logic.

[0043] Specifically, this safety interlock system uses the contacts of a latching relay to enforce the following logic:

[0044] The first level of interlocking: One coil of the latching relay is linked to the auxiliary contact of the bypass switch. When the bypass switch is detected to be closed, the latching relay activates and latches itself, its normally open contact opens, and this contact is connected in series in the closing control circuit of all independent switching switches. In this way, as long as the bypass switch is in the closed state, all independent switching switches cannot be physically closed, thus achieving forced interlocking.

[0045] Second-level interlocking: Another set of contacts of the latching relay is used to control the operation of the disconnecting switch. These contacts can be connected in series in the control circuit of the electric operating mechanism that controls the disconnecting switch, or they can drive a mechanical baffle to block the manual operating handle of the disconnecting switch. This set of contacts will only close when the bypass switch is confirmed to be closed and the latching relay is in a safety interlocked state, thus allowing operation of the disconnecting switch.

[0046] Working principle: During steady-state operation, the line current flows through a damped circuit composed of resistors and inductors before entering the core compensation unit. Based on load changes or external commands, the control system precisely controls the independent switching switches in each capacitor branch through its internal zero-crossing switching module. Switches close at the voltage zero-crossing point to increase the capacitor bank's capacity, or open at the branch current zero-crossing point to reduce the capacitor bank's capacity, thereby achieving a smooth and shock-free stepped adjustment of the total compensation capacity.

[0047] In the event of a transient overvoltage, the device's protection mechanism responds in stages. First, the metal oxide surge arrester connected in parallel across the core compensation unit will momentarily conduct a clamping voltage. Simultaneously, the voltage monitoring module within the control system will monitor the status of the metal oxide surge arrester in real time and output a first- or second-level overvoltage signal. Upon receiving a first-level signal, the logic execution module will prioritize the "adaptive derating" strategy, which actively disconnects some of the independently switched devices already in operation, mitigating the risk by changing the system's resonant point while preserving some compensation capacity. Only when the fault is severe and a second-level signal is received will the logic execution module execute the final protection, instructing the bypass switch to close and completely short-circuit the core compensation unit.

[0048] All operations of the entire device are subject to the mandatory constraints of a safety interlocking system to ensure absolute safety. This system includes a first interlocking module and a second interlocking module, the core of which can be constructed from hardware such as snap-on relays. The first interlocking module ensures that when the bypass switch is closed, all independently switching switches are forcibly locked in the open state, eliminating the risk of bypass switching capacitors. The second interlocking module links the bypass switch with the isolating switches of the incoming and outgoing lines, ensuring that the isolating switches can only be operated when the bypass switch is closed and there is no current in the main circuit, fundamentally preventing serious misoperation of opening and closing isolating switches under load. The independently switching switches of this device are preferably high-voltage vacuum contactors with rated capacity meeting the requirements, and the capacitor bank capacity can be configured in a binary ratio to achieve optimal regulation performance. Through this combination of structure and control logic, this device achieves economical, flexible, safe, and reliable high-voltage series compensation.

[0049] Finally, it should be noted that the above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Although the present utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. An adjustable-capacity high-voltage series compensation device, connected in series to the inlet and outlet terminals of a high-voltage line, characterized in that, Further includes: The core compensation unit is set in parallel between the incoming and outgoing terminals and includes at least two parallel capacitor branches. Each capacitor branch consists of a capacitor bank and an independent switching switch connected in series. The bypass protection unit includes a bypass switch and a metal oxide surge arrester connected in parallel across the core compensation unit. The damping circuit consists of a resistor and an inductor connected in series in the main circuit between the input and output terminals. The control system is configured to achieve stepped adjustment of the compensation capacity by selectively closing or opening individual switching switches and includes: The safety interlocking system is used to forcibly restrict the operation of bypass switches and independent switching switches.

2. A voltage regulating series compensation device of claim 1, wherein: The control system includes: The zero-crossing switching module detects line voltage and branch current in real time and controls the independent switching switch to close at the voltage zero-crossing point and open at the current zero-crossing point. The voltage monitoring module, connected to the metal oxide surge arrester, is used to identify primary and secondary overvoltage signals.

3. A voltage regulating series compensation device of claim 1, wherein: The control system further includes: The logic execution module, in response to the signal from the voltage monitoring module, performs the following operations: When a first-level overvoltage signal is triggered, the currently closed independent switching switches will be disconnected first. When the secondary overvoltage signal is triggered, the bypass switch is closed and all independent switching switches are forcibly disconnected.

4. The adjustable capacity high-voltage series compensation device according to claim 1, characterized in that: The independent switching switch is a high-voltage vacuum contactor, whose rated breaking capacity is not less than the rated inrush current of the capacitor bank.

5. A voltage regulating series compensation device of claim 1, wherein: The independent switching switch is a vacuum contactor with a rated current not less than 1.5 times the rated current of the capacitor bank. The capacity of the capacitor bank is configured in a binary ratio, and the capacity ratio of adjacent branches is 1:

2.

6. A voltage regulating series compensation device of claim 1, wherein: The main circuits of the input and output terminals are connected in series with an input isolating switch and an output isolating switch.

7. A voltage regulating series compensation device of claim 1, wherein: The safety interlocking system includes: The first interlocking module is connected to the bypass switch and all independent switching switches. When the bypass switch is detected to be closed, the output signal forces all switching switches to disconnect and remains locked. The second interlocking module is linked with the bypass switch, the incoming disconnect switch, and the outgoing disconnect switch, and allows the disconnect switch to open only when the bypass switch is closed.

8. A voltage regulated series compensation device according to claim 7, wherein: The second interlocking module can physically block the operation of the disconnecting switch handle when the bypass switch is open through a mechanical interlocking mechanism; or cut off the control circuit of the disconnecting switch drive mechanism through an electrical interlocking contact.

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