Series compensation device

Abstract

The present application provides a series compensation device, comprising: a series compensation capacitor, a metal oxide voltage limiter, a main circuit breaker, a first detection circuit, a second detection circuit and a control circuit; after the first detection circuit and the second detection circuit are connected in parallel, they are connected in series with the metal oxide voltage limiter to form a series circuit; the series compensation capacitor, the main circuit breaker and the series circuit are connected in parallel respectively; the first detection circuit comprises a first current sensor and a first comparator, and the second detection circuit comprises a second current sensor and a second comparator; the output end of the first current sensor is connected to the input end of the first comparator, and the output end of the second current sensor is connected to the input end of the second comparator; the output ends of the first comparator and the second comparator are connected to the control circuit; the present application can effectively reduce the protection action time of the series compensation device and improve the reliability of the series compensation device by quickly controlling the circuit breaker in the control circuit.

Description

Technical Field

[0001] The present application relates to the technical field of electrical equipment, and in particular to a series compensation device. Background Art

[0002] The series compensation device is an important technical means in the power system. By connecting capacitors in series in the transmission line, the inductive reactance of the transmission line is compensated, thereby improving the transmission capacity and efficiency of the transmission line and reducing voltage drop and transmission loss. At the same time, the series compensation device can improve the stability of the system, reduce voltage fluctuations caused by load changes or faults, and prevent system oscillations and voltage collapse. The main circuit breaker and the auxiliary circuit breaker play a key control and protection role in the series compensation device. The main circuit breaker is responsible for the access and protection of the entire series compensation device, and the auxiliary circuit breaker is used to provide flexible control and protection of specific components in the series compensation device. In practical applications, the reasonable configuration and operation of the main circuit breaker and the auxiliary circuit breaker are crucial to ensure the stability and safety of the power system. Therefore, the action speed of the main circuit breaker and the auxiliary circuit breaker is particularly important. However, in the related art, the closing condition of the main circuit breaker and the auxiliary circuit breaker in the series compensation device is to first collect the current at the series compensation capacitor, and then control the closing of the main circuit breaker and the auxiliary circuit breaker after processing the current through software, so that the series compensation device has the problem of long action time and poor reliability of the whole group of protection. Summary of the invention

[0003] The present application provides a series compensation device, which can effectively reduce the protection action time of the series compensation device and improve the reliability of the series compensation device by quickly controlling the circuit breaker in the control circuit.

[0004] The technical solution of this application is implemented as follows:

[0005] The present application provides a series compensation device, which includes a series compensation capacitor, a metal oxide voltage limiter, a main circuit breaker, a first detection circuit, a second detection circuit and a control circuit; after the first detection circuit and the second detection circuit are connected in parallel, they are connected in series with the metal oxide voltage limiter to form a series circuit; the series compensation capacitor, the main circuit breaker and the series circuit are connected in parallel respectively; the first detection circuit includes a first current sensor and a first comparator, and the second detection circuit includes a second current sensor and a second comparator; the output end of the first current sensor is connected to the input end of the first comparator, and the output end of the second current sensor is connected to the input end of the second comparator; the output end of the first comparator and the output end of the second comparator are connected to the control circuit; wherein the output signals of the output end of the first comparator and the output end of the second comparator are used to control the opening and closing state of the circuit breaker in the control circuit; and when the circuit breaker is in a closed state, the damping circuit in the control circuit is connected in parallel with the series circuit.

[0006] In the above scheme, when the output signals of the output ends of the first current sensor and the second current sensor are voltage signals, the first detection circuit further includes a first resistor, a second resistor and a third resistor, the output end of the first current sensor includes a first positive phase output end and a first negative phase output end, the input end of the first comparator includes a first positive phase input end and a first negative phase input end; the first positive phase output end of the first current sensor is connected to the first positive phase input end of the first comparator, and the first positive phase output end is connected in series with the first resistor and then grounded; the first negative phase output end of the first current sensor is respectively connected to the power supply end and the first end of the second resistor, the second end of the second resistor is respectively connected to the first negative phase input end of the first comparator and the first end of the third resistor; the second end of the third resistor is grounded.

[0007] In the above scheme, the second detection circuit also includes a fourth resistor, a fifth resistor and a sixth resistor, the output end of the second current sensor includes a second positive phase output end and a second negative phase output end, and the input end of the second comparator includes a second positive phase input end and a second negative phase input end; the first current sensor is connected in parallel with the second current sensor; the second positive phase output end of the second current sensor is connected to the second positive phase input end of the second comparator, and the second positive phase output end is connected in series with the fourth resistor and then grounded; the second negative phase output end of the second current sensor is respectively connected to the power supply end and the first end of the fifth resistor, and the second end of the fifth resistor is respectively connected to the second negative phase input end of the second comparator and the first end of the sixth resistor; the second end of the sixth resistor is grounded.

[0008] In the above scheme, when the output signals of the output ends of the first current sensor and the second current sensor are current signals, the first detection circuit also includes a seventh resistor and an eighth resistor, the output end of the first current sensor includes a first positive phase output end and a first negative phase output end, the input end of the first comparator includes a first positive phase input end and a first negative phase input end; the input end of the second comparator includes a second negative phase input end; the first current sensor is connected in series with the eighth resistor to form a first series circuit; the first positive phase output end of the first current sensor is connected to the first positive phase input end of the first comparator, and the first positive phase output end is connected in series with the seventh resistor and then grounded; the first negative phase output end of the first current sensor is connected to the power supply end; the first negative phase input end of the first comparator is connected to the second negative phase input end of the second comparator.

[0009] In the above scheme, the second detection circuit also includes a ninth resistor, a tenth resistor, an eleventh resistor and a twelfth resistor, the output end of the second current sensor includes a second positive phase output end and a second negative phase output end, and the input end of the second comparator also includes a second positive phase input end; the second current sensor is connected in series with the twelfth resistor to form a second series circuit, and the first series circuit and the second series circuit are connected in parallel; the second positive phase output end of the second current sensor is connected to the second positive phase input end of the second comparator, and the second positive phase output end is connected in series with the ninth resistor and then grounded; the second negative phase output end of the second current sensor is respectively connected to the power supply end and the first end of the tenth resistor, and the second end of the tenth resistor is respectively connected to the second negative phase input end of the second comparator and the first end of the eleventh resistor; the second end of the eleventh resistor is grounded.

[0010] In the above scheme, the first reference signal of the first inverting input terminal is equal to the second reference signal of the second inverting input terminal, and the ratio between the resistance value of the eighth resistor and the resistance value of the twelfth resistor is equal to the ratio between the minimum operating current and the maximum operating current of the metal oxide voltage limiter.

[0011] In the above scheme, the circuit breaker includes a first circuit breaker, and the damping circuit includes a first damping circuit; the first circuit breaker and the first damping circuit are connected in series to form a damping branch, and the output end of the first comparator and the output end of the second comparator are respectively connected to the damping branch.

[0012] In the above scheme, the output signal of the output end of the first comparator is a first output signal, and the output signal of the output end of the second comparator is a second output signal; the first output signal is used to control the first circuit breaker to close when the output signal of the output end of the first current sensor is greater than the first reference signal of the first inverting input end; the second output signal is used to control the first circuit breaker to close when the output signal of the output end of the second current sensor is greater than the second reference signal of the second inverting input end.

[0013] In the above scheme, the circuit breaker includes a second circuit breaker and a third circuit breaker, and the damping circuit includes a second damping circuit and a third damping circuit; the second circuit breaker and the second damping circuit are connected in series to form a first damping branch, and the output end of the first comparator is connected to the first damping branch; the third circuit breaker and the third damping circuit are connected in series to form a second damping branch, and the output end of the second comparator is connected to the second damping branch.

[0014] In the above scheme, the output signal of the output end of the first comparator is a first output signal; the output signal of the output end of the second comparator is a second output signal; the first output signal is used to control the second circuit breaker to close when the output signal of the output end of the first current sensor is greater than the third reference signal of the first inverting input end; the second output signal is used to control the third circuit breaker to close when the output signal of the output end of the second current sensor is greater than the fourth reference signal of the second inverting input end.

[0015] This application has the following beneficial effects:

[0016] In the present application, a first detection circuit and a second detection circuit are added to the series compensation device, and the current flowing through the metal oxide voltage limiter is detected by the first current sensor in the first detection circuit and the second current sensor in the second detection circuit. In addition, the output end of the first current sensor in the first detection circuit is connected to the input end of the first comparator, and the output end of the second current sensor in the second detection circuit is connected to the input end of the second comparator. In this way, the output signal of the output end of the first current sensor is input to the input end of the first comparator, and the output signal of the output end of the second current sensor is input to the input end of the second comparator, so that the output signal of the output end of the first comparator and the output end of the second comparator can be determined. When the output signal of the output end of the first comparator and the output end of the second comparator is a high-level signal, it means that the current flowing through the metal oxide voltage limiter is too large, and the line where the series compensation device is located fails, and it is necessary to quickly control the circuit breaker in the control circuit to close, so that the damping circuit in the control circuit is connected in parallel with the series circuit, that is, the damping circuit is quickly connected to the series compensation device, so as to realize the rapid protection of the series compensation device, effectively reduce the protection action time of the series compensation device, and improve the reliability of the series compensation device. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of a 10 KV bus voltage circuit provided in an embodiment of the present application;

[0018] Figure 2 It is a structural schematic diagram of a 10 KV bus voltage circuit after adding a series compensation device provided in an embodiment of the present application;

[0019] Figure 3 It is a schematic diagram of the internal structure of a series compensation device provided by the related technology;

[0020] Figure 4 This is an optional circuit structure diagram of a series compensation device provided in an embodiment of the present application;

[0021] Figure 5 It is an optional circuit structure of the first detection circuit 111 provided in the embodiment of the present application;

[0022] Figure 6 This is another optional circuit structure diagram of the series compensation device provided in the embodiment of the present application;

[0023] Figure 7 It is another optional circuit structure of the first detection circuit 111 provided in the embodiment of the present application;

[0024] Figure 8 This is another optional circuit structure diagram of the series compensation device provided in the embodiment of the present application;

[0025] Fig. 9 is a schematic diagram of the circuit structure of the damping branch in the series compensation device provided in an embodiment of the present application;

[0026] Fig.10 is a schematic diagram of the circuit structure of the first damping branch and the second damping branch in the series compensation device provided in an embodiment of the present application;

[0027] Fig.11 This is another optional circuit structure diagram of the series compensation device provided in the embodiment of the present application.

[0028] Description of reference numerals:

[0029] Power supply: 100, resistor: 101, inductor: 102, end power supply: 103, capacitor: 104, main circuit breaker: 105, series compensation capacitor: 106, metal oxide voltage limiter: 107, auxiliary circuit breaker: 108, resistor: 109, damper: 110, first detection circuit: 111, second detection circuit: 112, control circuit: 113, first current sensor: 114, second current sensor: 115, first resistor: 116, second resistor: 117, third resistor: 118, first comparator: 119, power supply end: 120, fourth resistor: 121, fifth resistor: 12 2, sixth resistor: 123, second comparator: 124, seventh resistor: 125, eighth resistor: 126, ninth resistor: 127, tenth resistor: 128, eleventh resistor: 129, twelfth resistor: 130, first circuit breaker: 131, first damping loop: 132, thirteenth resistor: 132-1, first damper: 132-2, second circuit breaker: 133, third circuit breaker: 134, second damping loop: 135, fourteenth resistor: 135-1, second damper: 135-2, third damping loop: 136, fifteenth resistor: 136-1, third damper: 136-2. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be further described in detail below in conjunction with the accompanying drawings. The described embodiments should not be regarded as limiting the present application. All other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of this application.

[0031] In the following description, reference is made to “some embodiments”, which describe a subset of all possible embodiments, but it will be understood that “some embodiments” may be the same subset or different subsets of all possible embodiments and may be combined with each other without conflict.

[0032] In the following description, the terms "first / second / third" involved are merely used to distinguish similar objects and do not represent a specific ordering of the objects. It can be understood that "first / second / third" can be interchanged with a specific order or sequence where permitted, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein.

[0033] In the embodiments of the present application, the term "module" or "unit" refers to a part of a structure with a predetermined function, and works together with other related parts to achieve a predetermined goal, and can be fully or partially implemented by using software, hardware (such as processing circuits or memory) or a combination thereof.

[0034] Unless otherwise defined, all technical and scientific terms used in the embodiments of the present application have the same meanings as those commonly understood by those skilled in the art. The terms used in the embodiments of the present application are only for the purpose of describing the embodiments of the present application and are not intended to limit the present application.

[0035] See also Figure 1 , Figure 1 This is a schematic diagram of the structure of the 10 KV bus voltage circuit provided in the embodiment of the present application. Figure 1 The circuit structure shown is explained.

[0036] In a 10 KV bus voltage line, including a power source 100, a resistor 101, an inductor 102 and a terminal power source 103, the bus voltage of the power source 100 is (i.e. 10 KV), the voltage across the resistor in the line is , the voltage across the inductor 102 is , the terminal voltage of the terminal power supply 103 is . Terminal voltage It can be calculated by the following formula (1):

[0037] (1)

[0038] Depend on Figure 1 It can be seen that when the line length increases, Increase, which will lead to When the line length increases to a certain length, the voltage at the end of the line will be reduced to a level that does not meet the power voltage level. At this time, in order to increase the voltage at the end of the line, it is necessary to adjust the voltage at the end of the line by connecting a capacitor 104 in series, such as Figure 2 As shown, Figure 2 This is a structural diagram of the 10KV bus voltage line after adding a series compensation device.

[0039] The voltage across capacitor 104 is At this time, the voltage at the end of the line is It can be calculated by the following formula (2):

[0040] (2)

[0041] in, , , is the current in the line, is the reactance of the inductor 102, is the reactance of capacitor 104, , , is an imaginary unit, is the angular frequency, is the inductance value of the inductor 102, is the capacitance value of capacitor 104. Then the voltage across inductor 102 is The voltage across capacitor 104 The calculation formula for addition is shown in formula (3):

[0042] (3)

[0043] when hour, ,but At this point, it can be seen that after adding the series compensation device, the end voltage of the line Significant improvement.

[0044] See also Figure 3 , Figure 3 This is a schematic diagram of the internal structure of the series compensation device provided by the relevant technology. Figure 3 The internal structure shown is explained.

[0045] In the related art, the series compensation device includes a main circuit breaker 105, a series compensation capacitor 106, a metal oxide voltage limiter 107, an auxiliary circuit breaker 108, a resistor 109 and a damper 110. The main circuit breaker 105 is mainly used to control the connection and disconnection of the series compensation device. It is responsible for connecting the series compensation device under normal operation and disconnecting the series compensation device in case of failure or maintenance to protect the safety of equipment and systems. In the event of a failure, the main circuit breaker 105 can be closed to quickly disconnect the series compensation device, isolate the faulty part, prevent the fault from spreading, and protect the normal operation of other parts of the system. When the series compensation device needs to be maintained or repaired, the main circuit breaker 105 can be closed manually or automatically to ensure the safety of the operator.

[0046] The auxiliary circuit breaker 108 mainly provides flexible control and protection for specific components to meet the needs of different operating modes. The auxiliary circuit breaker 108 can also be used to protect capacitor banks or other key components. When the capacitor bank has abnormal conditions such as overcurrent and overvoltage, the auxiliary circuit breaker 108 can be quickly closed to prevent equipment damage. Under different load conditions, the degree of series compensation of the series compensation device can be adjusted through the operation of the auxiliary circuit breaker 108 to optimize the operating state of the power system.

[0047] In a specific operation scenario, when the power system is operating normally, the main circuit breaker 105 and the auxiliary circuit breaker 108 are both in the disconnected state, and the series compensation device operates normally to compensate the transmission line. When a transmission line or equipment fault is detected, the main circuit breaker 105 will close quickly to isolate the faulty part. If the fault only involves the capacitor bank, the auxiliary circuit breaker 108 will disconnect the relevant capacitor bank for protection. When the series compensation device needs to be repaired, the operator can first close the main circuit breaker 105, and then close the auxiliary circuit breaker 108 as needed to ensure safe operation.

[0048] In summary, the main circuit breaker 105 and the auxiliary circuit breaker 108 play a key control and protection role in the series compensation device. In practical applications, the reasonable configuration and operation of the main circuit breaker 105 and the auxiliary circuit breaker 108 are crucial to ensure the stability and safety of the power system, so the action speed of the main circuit breaker 105 and the auxiliary circuit breaker 108 is particularly important. In the related art, the closing condition of the main circuit breaker 105 and the auxiliary circuit breaker 108 in the series compensation device is to collect the current at the series compensation capacitor, and control the main circuit breaker 105 and the auxiliary circuit breaker 108 after processing the current through software. There are problems such as long action time of the whole group of protection (for example, 50ms) and poor reliability.

[0049] Based on the above problems existing in the related art, the embodiment of the present application provides a series compensation device, in which a first detection circuit and a second detection circuit are added, and in the first detection circuit, the output end of the first current sensor is connected to the input end of the first comparator, and in the second detection circuit, the output end of the second current sensor is connected to the input end of the second comparator. In this way, when the output signal of the output end of the first current sensor is greater than the reference signal of the input end of the first comparator, and / or the output signal of the output end of the second current sensor is greater than the reference signal of the input end of the second comparator, the circuit breaker in the control circuit can be quickly controlled to close, so that the damping circuit in the control circuit is connected in parallel with the series circuit, so as to realize rapid protection of the series compensation device, effectively reduce the protection action time of the series compensation device, and improve the reliability of the series compensation device.

[0050] See also Figure 4 , Figure 4This is an optional circuit structure diagram of the series compensation device provided in the embodiment of the present application. Figure 4 The circuit structure shown is explained.

[0051] In some embodiments, the series compensation device includes: a main circuit breaker 105, a series compensation capacitor 106, a metal oxide voltage limiter 107, a first detection circuit 111, a second detection circuit 112 and a control circuit 113; after the first detection circuit 111 and the second detection circuit 112 are connected in parallel, they are connected in series with the metal oxide voltage limiter 107 to form a series circuit; the series compensation capacitor 106, the main circuit breaker 105 and the series circuit are connected in parallel respectively; the first detection circuit 111 includes a first current sensor and a first comparator, and the second detection circuit 112 includes a second current sensor and a second comparator; the output end of the first current sensor is connected to the input end of the first comparator, and the output end of the second current sensor is connected to the input end of the second comparator; the output end of the first comparator and the output end of the second comparator are connected to the control circuit 113.

[0052] In this embodiment, the metal oxide voltage limiter 107 is a nonlinear voltage-dependent resistor used to protect the circuit from overvoltage damage. When the voltage exceeds the rated value, the resistance of the metal oxide voltage limiter 107 will drop rapidly, thereby limiting the overvoltage to a safe level. The first detection circuit 111 and the second detection circuit 112 can respectively detect the current flowing through the metal oxide voltage limiter 107 through the first current sensor in the first detection circuit 111 and the second current sensor in the second detection circuit 112, and detect the working state of the metal oxide voltage limiter 107 through the current change detected by the first current sensor and the second current sensor, that is, whether it is limiting the overvoltage, thereby ensuring the safe operation of the power system. The output type of the output signal of the output end (i.e., the secondary side) of the first current sensor and the second current sensor can be a voltage signal and a current signal, that is, the current flowing through the metal oxide voltage limiter 107 detected by the primary side of the first current sensor and the second current sensor is proportionally converted into an output voltage signal or a current signal.

[0053] Then, by inputting the output signal of the output end of the first current sensor into the first comparator and comparing it with the reference signal of the input end of the first comparator, the output end of the first comparator is controlled to output a high level or low level output signal. The output signal of the output end of the second current sensor can also be input into the second comparator and compared with the reference signal of the input end of the second comparator to control the output end of the second comparator to output a high level or low level output signal. The output signal of the output end of the first comparator and the output end of the second comparator is used to control the opening and closing state of the circuit breaker in the control circuit 113; and when the circuit breaker is in the closed state, the damping circuit in the control circuit 113 is connected in parallel with the series circuit. That is, the damping circuit is quickly connected in the series compensation circuit to ensure the safety of the line. Here, high level or low level refers to the definition of high and low levels in digital circuits, for example, the high level is a voltage between 2.5-5 V, and the low level is a voltage between 0-1.5 V.

[0054] Through the embodiment of the present application, the first detection circuit 111 and the second detection circuit 112 are connected in parallel to provide redundant detection for the series compensation device, thereby improving the reliability of the series compensation device. If a detection circuit (the first detection circuit 111 or the second detection circuit 112) fails, the other detection circuit can still work to ensure the safety of the line. In addition, when the output signal of the output end of the first current sensor is greater than the reference signal of the input end of the first comparator, and / or the output signal of the output end of the second current sensor is greater than the reference signal of the input end of the second comparator, the circuit breaker in the control circuit can be quickly controlled to close, so that the damping circuit in the control circuit is quickly connected, thereby realizing rapid protection of the series compensation device, effectively reducing the protection action time of the series compensation device, and improving the reliability of the series compensation device.

[0055] In some embodiments, the current sensor can be a voltage type current sensor. When the output signals of the output ends of the first current sensor 114 and the second current sensor 115 are voltage signals, the first detection circuit 111 also includes a first resistor 116, a second resistor 117 and a third resistor 118. The output end of the first current sensor 114 includes a first positive phase output end and a first negative phase output end, and the input end of the first comparator 119 includes a first positive phase input end and a first negative phase input end; the first positive phase output end of the first current sensor 114 is connected to the first positive phase input end of the first comparator 119, and the first positive phase output end is connected in series with the first resistor 116 and then grounded; the first negative phase output end of the first current sensor 114 is respectively connected to the power supply end 120 and the first end of the second resistor 117, and the second end of the second resistor 117 is respectively connected to the first negative phase input end of the first comparator 119 and the first end of the third resistor 118; the second end of the third resistor 118 is grounded.

[0056] In this embodiment, an optional circuit structure of the first detection circuit 111 is as follows: Figure 5 As shown, the first positive phase output terminal of the first current sensor 114 is connected to the first positive phase input terminal of the first comparator 119, and the first positive phase output terminal is connected in series with the first resistor 116 and then grounded. The current flowing into the first positive phase input terminal of the first comparator 119 is limited by the first resistor 116, thereby protecting the first comparator 119 from normal operation.

[0057] When the first current sensor 114 and the second current sensor 115 are both voltage-type current sensors, the voltage-type current sensors usually work based on the transformer principle. The primary side (i.e., input end) of the first current sensor 114 and the second current sensor 115 is connected in series with the metal oxide voltage limiter 107. When current flows through the metal oxide voltage limiter 107, the current will generate an alternating magnetic field on the primary side of the first current sensor 114 and the second current sensor 115. The secondary side (i.e., output end) coils in the first current sensor 114 and the second current sensor 115 induce a voltage through the alternating magnetic field, and the voltage is proportional to the primary side current. Since the number of turns of the primary side coil is greater than the number of turns of the secondary side coil, the output voltage of the secondary side is less than the input voltage of the primary side, which plays a role in reducing the voltage. By measuring the voltage on the secondary side of the first current sensor 114 and the second current sensor 115, the current size of the primary side can be indirectly determined. At this time, the output signals of the output terminals of the first current sensor 114 and the second current sensor 115 are voltage signals, the first positive phase output terminal of the first current sensor 114 is connected to the first positive phase input terminal of the first comparator 119, the first negative phase output terminal of the first current sensor 114 is connected to the first end of the second resistor 117, the second end of the second resistor 117 is connected to the first end of the third resistor 118; the second end of the third resistor 118 is grounded. In this way, the output signal of the first positive phase output terminal of the first current sensor 114 is input to the first positive phase input terminal of the first comparator 119, and the input signal of the first positive phase input terminal of the first comparator 119 can be determined. The second resistor 117 and the third resistor 118 form a voltage divider, and the voltage value (i.e., the reference signal) of the first negative phase input terminal of the first comparator 119 can be determined based on the resistance values ​​of the second resistor 117 and the third resistor 118. By comparing the input signal of the first positive phase input terminal of the first comparator 119 with the reference signal of the first negative phase input terminal, it is determined whether the output terminal of the first comparator 119 outputs a high-level output signal or a low-level output signal. When the input signal of the first positive input terminal of the first comparator 119 is greater than or equal to the reference signal of the first inverting input terminal, the output terminal of the first comparator 119 outputs a high-level output signal; when the input signal of the first positive input terminal of the first comparator 119 is less than the reference signal of the first inverting input terminal, the output terminal of the first comparator 119 outputs a low-level output signal, and the control circuit subsequently connected to the comparator can act or maintain according to the high level or low level output by the comparator to ensure line safety.

[0058] Through the embodiment of the present application, the output end of the first current sensor 114 is connected to the input end of the first comparator 119, and the first comparator 119 compares the output signal of the output end of the first current sensor 114 with the reference signal of the first inverting input end of the first comparator 119, and controls the output of the first comparator 119 to output a high-level or low-level output signal. When the output end of the first comparator 119 outputs a low-level output signal, it indicates that the line is working normally, and the circuit breaker in the control circuit 113 is kept open; when the output end of the first comparator 119 outputs a high-level output signal, it indicates that the line has a fault, and the circuit breaker in the control circuit 113 is quickly controlled to close, so that the damping circuit in the control circuit 113 is quickly connected, so as to achieve rapid protection of the series compensation device.

[0059] In some embodiments, the second detection circuit 112 also includes a fourth resistor 121, a fifth resistor 122 and a sixth resistor 123, the output end of the second current sensor 115 includes a second positive phase output end and a second negative phase output end, and the input end of the second comparator 124 includes a second positive phase input end and a second negative phase input end; the first current sensor 114 is connected in parallel with the second current sensor 115; the second positive phase output end of the second current sensor 115 is connected to the second positive phase input end of the second comparator 124, and the second positive phase output end is connected in series with the fourth resistor 121 and then grounded; the second negative phase output end of the second current sensor 115 is respectively connected to the power supply end 120 and the first end of the fifth resistor 122, and the second end of the fifth resistor 122 is respectively connected to the second negative phase input end of the second comparator 124 and the first end of the sixth resistor 123; the second end of the sixth resistor 123 is grounded.

[0060] In this embodiment, another optional circuit structure diagram of the series compensation device is as follows: Figure 6 As shown, the second positive phase output terminal of the second current sensor 115 is connected to the second positive phase input terminal of the second comparator 124, and the second positive phase output terminal is connected in series with the fourth resistor 121 and then grounded. The current flowing into the second positive phase input terminal of the second comparator 124 is limited by the fourth resistor 121, thereby protecting the normal operation of the second comparator 124.

[0061] When the output signals of the output terminals of the first current sensor 114 and the second current sensor 115 are voltage signals, the second positive phase output terminal of the second current sensor 115 is connected to the second positive phase input terminal of the second comparator 124, the second negative phase output terminal of the second current sensor 115 is connected to the first terminal of the fifth resistor 122, the second terminal of the fifth resistor 122 is connected to the first terminal of the sixth resistor 123; the second terminal of the sixth resistor 123 is grounded. In this way, the output signal of the second positive phase output terminal of the second current sensor 115 is input to the second positive phase input terminal of the second comparator 124, and the input signal of the second positive phase input terminal of the second comparator 124 can be determined. And the fifth resistor 122 and the sixth resistor 123 form a voltage divider, and the voltage value (i.e., the reference signal) of the second negative phase input terminal of the second comparator 124 can be determined based on the resistance values ​​of the fifth resistor 122 and the sixth resistor 123. By comparing the input signal of the second positive phase input terminal of the second comparator 124 with the reference signal of the second negative phase input terminal, it is determined whether the output terminal of the second comparator 124 outputs a high-level output signal or a low-level output signal. When the input signal at the second positive input terminal of the second comparator 124 is greater than or equal to the reference signal at the second inverting input terminal, the output terminal of the second comparator 124 outputs a high-level output signal; when the input signal at the second positive input terminal of the second comparator 124 is less than the reference signal at the second inverting input terminal, the output terminal of the second comparator 124 outputs a low-level output signal.

[0062] Through the embodiment of the present application, the output end of the second current sensor 115 is connected to the input end of the second comparator 124, and the second comparator 124 compares the output signal of the output end of the second current sensor 115 with the reference signal of the second inverting input end of the second comparator 124, and controls the output of the second comparator 124 to output a high level or a low level output signal. When the output end of the second comparator 124 outputs a low level output signal, it indicates that the line is working normally, and the circuit breaker in the control circuit 113 is kept open; when the output end of the second comparator 124 outputs a high level output signal, it indicates that the line has a fault, and the circuit breaker in the control circuit 113 is quickly controlled to close, so that the damping circuit in the control circuit 113 is quickly connected, so as to achieve rapid protection of the series compensation device.

[0063] In some embodiments, the current sensor can also be a current type current sensor. When the output signals of the output ends of the first current sensor 114 and the second current sensor 115 are current signals, the first detection circuit 111 also includes a seventh resistor 125 and an eighth resistor 126. The output end of the first current sensor 114 includes a first positive phase output end and a first negative phase output end, and the input end of the first comparator 119 includes a first positive phase input end and a first negative phase input end; the first current sensor 114 is connected in series with the eighth resistor 126 to form a first series circuit; the first positive phase output end of the first current sensor 114 is connected to the first positive phase input end of the first comparator 119, and the first positive phase output end is connected in series with the seventh resistor 125 and then grounded; the first negative phase output end of the first current sensor 114 is connected to the power supply end 120; the first negative phase input end of the first comparator 119 is connected to the second negative phase input end of the second comparator 124.

[0064] In this embodiment, another optional circuit structure of the first detection circuit 111 is as follows: Figure 7 As shown, the first positive phase output terminal of the first current sensor 114 is connected to the first positive phase input terminal of the first comparator 119, and the first positive phase output terminal is connected in series with the seventh resistor 125 and then grounded. The current flowing into the first positive phase input terminal of the first comparator 119 is limited by the seventh resistor 125, thereby protecting the first comparator 119 from normal operation.

[0065] When the first current sensor 114 and the second current sensor 115 are both current-type current sensors, the current-type current sensors usually work based on the electromagnetic effect. The primary side (i.e., the input end) of the first current sensor 114 and the second current sensor 115 is connected in series with the metal oxide voltage limiter 107. When current flows through the metal oxide voltage limiter 107, the primary side of the first current sensor 114 and the second current sensor 115 can use the electromagnetic effect (such as the Hall effect, mutual inductance principle, etc.) to convert the current into a current signal proportional to it. The output current signal is usually small, for example, the current signal can be a standard 4~20 mA or 0~10 mA signal. By measuring the current on the secondary side of the first current sensor 114 and the second current sensor 115, the current size on the primary side can be indirectly determined. At this time, the output signals of the output terminals of the first current sensor 114 and the second current sensor 115 are current signals, the first positive phase output terminal of the first current sensor 114 is connected to the first positive phase input terminal of the first comparator 119, and the first negative phase output terminal of the first current sensor 114 is connected to the second negative phase input terminal of the second comparator 124. In this way, the output signal of the first positive phase output terminal of the first current sensor 114 is input to the first positive phase input terminal of the first comparator 119, and the input signal of the first positive phase input terminal of the first comparator 119 can be determined, and the voltage value (i.e., the reference signal) of the first negative phase input terminal of the first comparator 119 is equal to the voltage value of the second negative phase input terminal of the second comparator 124. By comparing the input signal of the first positive phase input terminal of the first comparator 119 with the reference signal of the first negative phase input terminal, it is determined whether the output terminal of the first comparator 119 outputs a high level output signal or a low level output signal. When the input signal of the first positive input terminal of the first comparator 119 is greater than or equal to the reference signal of the first inverting input terminal, the output terminal of the first comparator 119 outputs a high-level output signal; when the input signal of the first positive input terminal of the first comparator 119 is less than the reference signal of the first inverting input terminal, the output terminal of the first comparator 119 outputs a low-level output signal.

[0066] Through the embodiment of the present application, the output end of the first current sensor 114 is connected to the input end of the first comparator 119, and the first comparator 119 compares the output signal of the output end of the first current sensor 114 with the reference signal of the first inverting input end of the first comparator 119, and controls the output of the first comparator 119 to output a high-level or low-level output signal. When the output end of the first comparator 119 outputs a low-level output signal, it indicates that the line is working normally, and the circuit breaker in the control circuit 113 is kept open; when the output end of the first comparator 119 outputs a high-level output signal, it indicates that the line has a fault, and the circuit breaker in the control circuit 113 is quickly controlled to close, so that the damping circuit in the control circuit 113 is quickly connected, so as to achieve rapid protection of the series compensation device.

[0067] In some embodiments, the second detection circuit 112 also includes a ninth resistor 127, a tenth resistor 128, an eleventh resistor 129 and a twelfth resistor 130, the output end of the second current sensor 115 includes a second positive phase output end and a second negative phase output end, and the input end of the second comparator 124 includes a second positive phase input end and a second negative phase input end; the second current sensor 115 is connected in series with the twelfth resistor 130 to form a second series circuit, and the first series circuit and the second series circuit are connected in parallel; the second positive phase output end of the second current sensor 115 is connected to the second positive phase input end of the second comparator 124, and the second positive phase output end is connected in series with the ninth resistor 127 and then grounded; the second negative phase output end of the second current sensor 115 is respectively connected to the power supply end 120 and the first end of the tenth resistor 128, and the second end of the tenth resistor 128 is respectively connected to the second negative phase input end of the second comparator 124 and the first end of the eleventh resistor 129; the second end of the eleventh resistor 129 is grounded.

[0068] In this embodiment, another optional circuit structure diagram of the series compensation device is as follows: Figure 8 As shown, the second positive phase output terminal of the second current sensor 115 is connected to the second positive phase input terminal of the second comparator 124, and the second positive phase output terminal is connected in series with the ninth resistor 127 and then grounded. The current flowing into the second positive phase input terminal of the second comparator 124 is limited by the ninth resistor 127, thereby protecting the second comparator 124 from normal operation.

[0069] When the output signals of the output terminals of the first current sensor 114 and the second current sensor 115 are current signals, the second positive phase output terminal of the second current sensor 115 is connected to the second positive phase input terminal of the second comparator 124, the second negative phase output terminal of the second current sensor 115 is connected to the first terminal of the tenth resistor 128, the second terminal of the tenth resistor 128 is connected to the first terminal of the eleventh resistor 129; the second terminal of the eleventh resistor 129 is grounded. In this way, the output signal of the second positive phase output terminal of the second current sensor 115 is input to the second positive phase input terminal of the second comparator 124, and the input signal of the second positive phase input terminal of the second comparator 124 can be determined. And the tenth resistor 128 and the eleventh resistor 129 form a voltage divider, and the current value (i.e., the reference signal) of the second negative phase input terminal of the second comparator 124 can be determined based on the resistance values ​​of the tenth resistor 128 and the eleventh resistor 129. By comparing the input signal of the second positive phase input terminal of the second comparator 124 with the reference signal of the second negative phase input terminal, it is determined whether the output terminal of the second comparator 124 outputs a high level output signal or a low level output signal. When the input signal at the second positive input terminal of the second comparator 124 is greater than or equal to the reference signal at the second inverting input terminal, the output terminal of the second comparator 124 outputs a high-level output signal; when the input signal at the second positive input terminal of the second comparator 124 is less than the reference signal at the second inverting input terminal, the output terminal of the second comparator 124 outputs a low-level output signal.

[0070] The first current sensor 114 is connected in series with the eighth resistor 126 to form a first series circuit, the second current sensor 115 is connected in series with the twelfth resistor 130 to form a second series circuit, the first series circuit and the second series circuit are connected in parallel, and the current flowing through the metal oxide voltage limiter 107 is detected by the first series circuit and the second series circuit to determine the working state of the metal oxide voltage limiter 107, that is, whether it is limiting overvoltage, so as to ensure the safe operation of the power system. In addition, if the detection circuit where the first series circuit is located or the detection circuit where the second series circuit is located (the first detection circuit 111 or the second detection circuit 112) fails, the other detection circuit can still work to ensure the safety of the line.

[0071] Through the embodiment of the present application, the output end of the second current sensor 115 is connected to the input end of the second comparator 124, and the second comparator 124 compares the output signal of the output end of the second current sensor 115 with the reference signal of the second inverting input end of the second comparator 124, and controls the output of the second comparator 124 to output a high level or a low level output signal. When the output end of the second comparator 124 outputs a low level output signal, it indicates that the line is working normally, and the circuit breaker in the control circuit 113 is kept open; when the output end of the second comparator 124 outputs a high level output signal, it indicates that the line has a fault, and the circuit breaker in the control circuit 113 is quickly controlled to close, so that the damping circuit in the control circuit 113 is quickly connected, so as to achieve rapid protection of the series compensation device.

[0072] In some embodiments, the first reference signal of the first inverting input terminal is equal to the second reference signal of the second inverting input terminal, and the ratio between the resistance of the eighth resistor 126 and the resistance of the twelfth resistor 130 is equal to the ratio between the minimum operating current and the maximum operating current of the metal oxide voltage limiter 107.

[0073] In this embodiment, the metal oxide voltage limiter 107 has a minimum operating current, for example, the minimum operating current may be 45 mA; the metal oxide voltage limiter 107 also has a maximum operating current, that is, the maximum current that the metal oxide voltage limiter 107 can withstand, for example, the maximum operating current may be 60 mA. The first comparator 119 is used to output a high level to the control circuit when the current of the metal oxide voltage limiter 107 reaches the minimum operating current, so that the circuit breaker is closed; the second comparator 124 is used to output a high level to the control circuit when the first comparator 119 fails and the current of the metal oxide voltage limiter 107 reaches the maximum operating current, so that the circuit breaker is closed. In order to make the first reference signal at the first inverting input terminal of the first comparator 119 equal to the second reference signal at the second inverting input terminal of the second comparator 124, that is, the thresholds of the first comparator 119 and the second comparator 124 are the same, that is, the reference currents are the same, so that only one reference current can be set and input to the first comparator 119 and the second comparator 124 at the same time, without setting different reference currents for the first comparator 119 and the second comparator 124 respectively, which can save costs and simplify the circuit.

[0074] In order to achieve the above purpose, the resistance value of the eighth resistor 126 and the resistance value of the twelfth resistor 130 need to be designed. Specifically, the reference signal of the first comparator 119 and the second comparator 124, that is, the threshold value is y, and the resistance value of the eighth resistor 126 is The resistance of the twelfth resistor 130 is , the minimum operating current of the metal oxide voltage limiter 107 is , the maximum operating current of the metal oxide voltage limiter 107 is , since the first current sensor 114 and the second current sensor 115 are connected in parallel, the voltage U at both ends is the same, and the eighth resistor 126 and the twelfth resistor 130 are shunted, in order to meet the protection requirements, for the branch where the first current sensor 114 is located, the following formula (4) can be obtained:

[0075] (4)

[0076] and , substituting y into the above formula (4), we can get the following formula (5):

[0077] (5)

[0078] For the branch where the second current sensor 115 is located, the following formula (6) can be obtained:

[0079] (6)

[0080] and ,Will Substituting into the above formula (6), we can get the following formula (7):

[0081] (7)

[0082] After simplification, we can get the following formula (8):

[0083] (8)

[0084] Further simplification can be obtained as follows:

[0085] (9)

[0086] Right now, . For example, according to the typical simulation waveform of the voltage across the series compensation capacitor 106 and the current of the metal oxide voltage limiter 107 during the whole process of a three-phase short circuit in the prior art, it can be seen that when the line is short-circuited, the maximum voltage across the series compensation capacitor 106 is 6 KV, when I1 is equal to 0.5 KA, I2 is equal to 2.2 KA, and R1:R2 is equal to 5:22. In this case, the resistance R1 of the eighth resistor 126 can be set to 3 KΩ, and the resistance R2 of the twelfth resistor 130 can be set to 13.2 KΩ. At this time, the reference current that needs to be set for the first comparator 119 and the second comparator 124 is 135 / 324 KA, which is approximately equal to 416.7 A.

[0087] Through the embodiments of the present application, by limiting the ratio between the resistance value of the eighth resistor 126 and the resistance value of the twelfth resistor 130 to be equal to the ratio between the minimum operating current and the maximum operating current of the metal oxide voltage limiter 107, the first reference signal at the first inverting input terminal of the first comparator 119 is equal to the second reference signal at the second inverting input terminal of the second comparator 124, so that the first reference signal and the second reference signal can be accurately determined based on the resistance value of the eighth resistor 126 and the resistance value of the twelfth resistor 130.

[0088] In some embodiments, the circuit breaker includes a first circuit breaker 131, and the damping circuit includes a first damping circuit 132; the first circuit breaker 131 and the first damping circuit 132 are connected in series to form a damping branch, and the output end of the first comparator 119 and the output end of the second comparator 124 are respectively connected to the damping branch.

[0089] In this embodiment, the circuit structure diagram of the damping branch in the series compensation device is as follows: Fig. 9 As shown, the first damping loop 132 includes a thirteenth resistor 132-1 and a first damper 132-2. The output end of the first comparator 119 and the output end of the second comparator 124 are respectively connected to the damping branch, and the output signal of the output end of the first comparator 119 and the output signal of the output end of the second comparator 124 are used to jointly control the first circuit breaker 131 in the damping branch to close quickly or remain disconnected, thereby controlling the first damping loop 132 to quickly access the line or remain disconnected. When a line fails, and any of the output signals of the output end of the first comparator 119 and the output signal of the output end of the second comparator 124 is a high-level signal, the first circuit breaker 131 is quickly closed, so that the first damping loop 132 is quickly connected to ensure the safety of the line.

[0090] In some embodiments, the output signal of the output end of the first comparator 119 is a first output signal, and the output signal of the output end of the second comparator 124 is a second output signal; the first output signal is used to control the first circuit breaker 131 to close when the output signal of the output end of the first current sensor 114 is greater than the first reference signal of the first inverting input terminal; the second output signal is used to control the first circuit breaker 131 to close when the output signal of the output end of the second current sensor 115 is greater than the second reference signal of the second inverting input terminal.

[0091] In this embodiment, the first reference signal refers to the signal threshold of the voltage signal or current signal at the first inverting input terminal of the first comparator 119, and the second reference signal refers to the signal threshold of the voltage signal or current signal at the second inverting input terminal of the second comparator 124. When the first reference signal is equal to the second reference signal, and the output signal at the output terminal of the first current sensor 114 is less than the first reference signal, the first output signal at the output terminal of the first comparator 119 is a low-level signal, indicating that it is not necessary to control the first circuit breaker 131 to close to connect the first damping loop 132 to ensure the safety of the line. When the first reference signal is equal to the second reference signal, and the output signal at the output terminal of the first current sensor 114 is greater than the first reference signal, the first output signal at the output terminal of the first comparator 119 is a high-level signal, indicating that it is necessary to control the first circuit breaker 131 to close to connect the first damping loop 132 to ensure the safety of the line. Similarly, for the second comparator 124, when the first reference signal is equal to the second reference signal, and the output signal of the output end of the second current sensor 115 is less than the second reference signal, the second output signal of the output end of the second comparator 124 is a low-level signal, indicating that it is not necessary to control the first circuit breaker 131 to close to connect the first damping loop 132 to ensure the safety of the line. When the first reference signal is equal to the second reference signal, and the output signal of the output end of the second current sensor 115 is greater than the second reference signal, the second output signal of the output end of the second comparator 124 is a high-level signal, indicating that it is necessary to control the first circuit breaker 131 to close to connect the first damping loop 132 to ensure the safety of the line.

[0092] In this embodiment, the first reference signal of the first inverting input terminal of the first comparator 119 may not be equal to the second reference signal of the second inverting input terminal of the second comparator 124, that is, the first reference signal may be greater than or less than the second reference signal. When the first reference signal is not equal to the second reference signal, and the output signal of the output terminal of the first current sensor 114 is less than the first reference signal, the first output signal of the output terminal of the first comparator 119 is a low-level signal, indicating that it is not necessary to control the first circuit breaker 131 to close to connect the first damping loop 132 to ensure the safety of the line. When the first reference signal is not equal to the second reference signal, and the output signal of the output terminal of the first current sensor 114 is greater than the first reference signal, the first output signal of the output terminal of the first comparator 119 is a high-level signal, indicating that it is necessary to control the first circuit breaker 131 to close to connect the first damping loop 132 to ensure the safety of the line. Similarly, for the second comparator 124, when the first reference signal is not equal to the second reference signal, and the output signal of the output end of the second current sensor 115 is less than the second reference signal, the second output signal of the output end of the second comparator 124 is a low-level signal, indicating that it is not necessary to control the first circuit breaker 131 to close to connect the first damping loop 132 to ensure the safety of the line. When the first reference signal is not equal to the second reference signal, and the output signal of the output end of the second current sensor 115 is greater than the second reference signal, the second output signal of the output end of the second comparator 124 is a high-level signal, indicating that it is necessary to control the first circuit breaker 131 to close to connect the first damping loop 132 to ensure the safety of the line.

[0093] Through the embodiment of the present application, when the output signal of the output end of the first current sensor 114 is greater than the first reference signal, and / or the output signal of the output end of the second current sensor 115 is greater than the second reference signal, the first damping loop 132 can be quickly connected by outputting a high-level signal to control the closing of the first circuit breaker 131 to ensure the safety of the line. Even if a device in any of the first detection circuit and the second detection circuit fails, the first circuit breaker 131 can be controlled by the output signal of the current sensor and the comparator in the other detection circuit, thereby improving the reliability of the series compensation device.

[0094] In some embodiments, the circuit breaker includes a second circuit breaker 133 and a third circuit breaker 134, and the damping circuit includes a second damping circuit 135 and a third damping circuit 136; the second circuit breaker 133 and the second damping circuit 135 are connected in series to form a first damping branch, and the output end of the first comparator 119 is connected to the first damping branch; the third circuit breaker 134 and the third damping circuit 136 are connected in series to form a second damping branch, and the output end of the second comparator 124 is connected to the second damping branch.

[0095] In this embodiment, the circuit structure diagram of the first damping branch and the second damping branch in the series compensation device is as follows: Fig.10 As shown, the second damping loop 135 includes a fourteenth resistor 135-1 and a second damper 135-2, and the third damping loop 136 includes a fifteenth resistor 136-1 and a third damper 136-2. The output end of the first comparator 119 is connected to the first damping branch formed by the second circuit breaker 133 and the second damping loop 135 in series, and the second circuit breaker 133 in the first damping branch is controlled to close quickly or remain disconnected through the output signal of the output end of the first comparator 119, so as to control the second damping loop 135 to quickly access the line or remain disconnected. When a fault occurs in the line and the output signal of the output end of the first comparator 119 is a high-level signal, the second circuit breaker 133 is quickly closed, so that the second damping loop 135 is quickly connected to ensure the safety of the line. At the same time, the output end of the second comparator 124 is connected to the second damping branch formed by the third circuit breaker 134 and the third damping loop 136 in series, and the third circuit breaker 134 in the second damping branch is controlled to be quickly closed or kept open through the output signal of the output end of the second comparator 124, so as to control the third damping loop 136 to quickly access the line or remain disconnected. When a fault occurs in the line and the output signal of the output end of the second comparator 124 is a high-level signal, the third circuit breaker 134 is quickly closed, so that the third damping loop 136 is quickly connected to ensure the safety of the line.

[0096] That is to say, from Fig.10 It can be seen that two groups of detection circuits (i.e., the first detection circuit 111 and the second detection circuit 112) and two groups of damping branches (i.e., the first damping branch and the second damping branch) are simultaneously arranged in the series compensation device, and the connection line where the first detection circuit 111 and the first damping branch are located, and the connection line where the second detection circuit 112 and the second damping branch are located are all operated independently. When the current sensor in any group of detection circuits is damaged, or the circuit breaker in any group of damping branches sends a fault and refuses to operate, the connection line where the other group is located can provide redundant protection.

[0097] Through the embodiment of the present application, a second damping branch is added on the basis of the first damping branch, so that when the current sensor in any group of detection circuits is damaged, or when a device (for example, a circuit breaker) in any group of damping branches fails, the access to the damping circuit can be ensured through another damping branch. In addition, when the output signal of the output end of the first comparator 119 and the output signal of the output end of the second comparator 124 are both high-level signals, two damping circuits can be accessed at the same time to further ensure the safety of the circuit.

[0098] In some embodiments, the output signal of the output end of the first comparator 119 is a first output signal; the output signal of the output end of the second comparator 124 is a second output signal; the first output signal is used to control the second circuit breaker 133 to close when the output signal of the output end of the first current sensor 114 is greater than the third reference signal of the first inverting input terminal; the second output signal is used to control the third circuit breaker 134 to close when the output signal of the output end of the second current sensor 115 is greater than the fourth reference signal of the second inverting input terminal.

[0099] In this embodiment, the third reference signal refers to the signal threshold of the voltage signal or current signal at the first inverting input terminal of the first comparator 119, and the fourth reference signal refers to the signal threshold of the voltage signal or current signal at the second inverting input terminal of the second comparator 124. When the third reference signal is equal to the fourth reference signal, and the output signal at the output terminal of the first current sensor 114 is less than the third reference signal, the first output signal at the output terminal of the first comparator 119 is a low-level signal, indicating that it is not necessary to control the second circuit breaker 133 to close to connect the second damping loop 135 to ensure the safety of the line. When the third reference signal is equal to the fourth reference signal, and the output signal at the output terminal of the first current sensor 114 is greater than the third reference signal, the first output signal at the output terminal of the first comparator 119 is a high-level signal, indicating that it is necessary to control the second circuit breaker 133 to close to connect the second damping loop 135 to ensure the safety of the line. Similarly, for the second comparator 124, when the third reference signal is equal to the fourth reference signal, and the output signal of the output end of the second current sensor 115 is less than the fourth reference signal, the second output signal of the output end of the second comparator 124 is a low-level signal, indicating that it is not necessary to control the third circuit breaker 134 to close to connect the third damping loop 136 to ensure the safety of the line. When the third reference signal is equal to the fourth reference signal, and the output signal of the output end of the second current sensor 115 is greater than the fourth reference signal, the second output signal of the output end of the second comparator 124 is a high-level signal, indicating that it is necessary to control the third circuit breaker 134 to close to connect the third damping loop 136 to ensure the safety of the line.

[0100] In this embodiment, please refer to Fig.11, the third reference signal at the first inverting input terminal of the first comparator 119 may not be equal to the fourth reference signal at the second inverting input terminal of the second comparator 124, that is, the third reference signal may be greater than or less than the fourth reference signal. When the third reference signal is not equal to the fourth reference signal, and the output signal at the output terminal of the first current sensor 114 is less than the third reference signal, the first output signal at the output terminal of the first comparator 119 is a low-level signal, indicating that it is not necessary to control the second circuit breaker 133 to close to connect the second damping loop 135 to ensure the safety of the line. When the third reference signal is not equal to the fourth reference signal, and the output signal at the output terminal of the first current sensor 114 is greater than the third reference signal, the first output signal at the output terminal of the first comparator 119 is a high-level signal, indicating that it is necessary to control the second circuit breaker 133 to close to connect the second damping loop 135 to ensure the safety of the line. Similarly, for the second comparator 124, when the third reference signal is not equal to the fourth reference signal, and the output signal of the output end of the second current sensor 115 is less than the fourth reference signal, the second output signal of the output end of the second comparator 124 is a low-level signal, indicating that it is not necessary to control the third circuit breaker 134 to close to connect the third damping loop 136 to ensure the safety of the line. When the third reference signal is not equal to the fourth reference signal, and the output signal of the output end of the second current sensor 115 is greater than the fourth reference signal, the second output signal of the output end of the second comparator 124 is a high-level signal, indicating that it is necessary to control the third circuit breaker 134 to close to connect the third damping loop 136 to ensure the safety of the line.

[0101] Assume that the third reference signal at the first inverting input terminal of the first comparator 119 is less than the fourth reference signal at the second inverting input terminal of the second comparator 124. In the early stage of a line fault, the current flowing through the metal oxide voltage limiter 107 is small. At this time, the output signal at the output terminal of the first current sensor 114 is greater than the third reference signal, and the output signal at the output terminal of the second current sensor 115 is less than the fourth reference signal, then the first comparator 119 can preferentially output a high level, that is, the first output signal at the output terminal of the first comparator 119 is a high level signal, and the second circuit breaker 133 is controlled to close to connect the second damping circuit 135 to ensure the safety of the line. When the current flowing through the metal oxide voltage limiter 107 continues to increase until the metal oxide voltage limiter 107 is damaged due to excessive current. At this time, the output signal of the output end of the first current sensor 114 is greater than the third reference signal, and the output signal of the output end of the second current sensor 115 is greater than the fourth reference signal, then the first comparator 119 and the second comparator 124 can output high levels at the same time, that is, the first output signal of the output end of the first comparator 119 is a high level signal, and the second output signal of the output end of the second comparator 124 is a high level signal. On the basis of controlling the second circuit breaker 133 to close to connect to the second damping circuit 135, the third circuit breaker 134 can also be controlled to close to connect to the third damping circuit 136, so that the two groups of damping circuits can protect the line at the same time.

[0102] Through the embodiments of the present application, when the output signal of the output end of the first current sensor 114 is greater than the third reference signal, and / or the output signal of the output end of the second current sensor 115 is greater than the fourth reference signal, the damping circuit can be quickly connected by outputting a high-level signal to control the circuit breaker to close, so as to ensure the safety of the line. The opening and closing of the circuit breaker is realized by a full hardware circuit, and the action time of the whole set of protection is within 20ms, which is faster than the opening and closing of the circuit breaker realized by software. Even if the device in any of the first detection circuit and the second detection circuit fails, the circuit breaker can be controlled by the output signal of the current sensor and the comparator in the other detection circuit, thereby improving the reliability of the series compensation device.

[0103] In some embodiments, when the first comparator 119 fails, the high-level signal output by the second comparator 124 is also input to the controller. After the controller detects the high-level signal, it can be determined that the first comparator 119 fails, and it is necessary to repair the branch where the first comparator 119 is located. Similarly, when the second comparator 124 fails, the high-level signal output by the first comparator 119 is also input to the controller. After the controller detects the high-level signal, it can be determined that the second comparator 124 fails, and it is necessary to repair the branch where the second comparator 124 is located.

[0104] The above is only an embodiment of the present application and is not intended to limit the protection scope of the present application. Any modifications, equivalent substitutions and improvements made within the spirit and scope of the present application are included in the protection scope of the present application.

Claims

1. A series compensation device, characterized in that: include: A series compensation capacitor, a metal oxide voltage limiter, a main circuit breaker, a first detection circuit, a second detection circuit and a control circuit; After the first detection circuit and the second detection circuit are connected in parallel, they are connected in series with the metal oxide voltage limiter to form a series circuit; the series compensation capacitor, the main circuit breaker and the series circuit are connected in parallel respectively; The first detection circuit includes a first current sensor and a first comparator, and the second detection circuit includes a second current sensor and a second comparator; the output end of the first current sensor is connected to the input end of the first comparator, and the output end of the second current sensor is connected to the input end of the second comparator; the output end of the first comparator and the output end of the second comparator are connected to the control circuit; The output signals of the output end of the first comparator and the output end of the second comparator are used to control the opening and closing states of the circuit breaker in the control circuit; and when the circuit breaker is in the closed state, the damping circuit in the control circuit is connected in parallel with the series circuit.

2. The series compensation device according to claim 1, characterized in that: When the output signals of the output terminals of the first current sensor and the second current sensor are voltage signals, the first detection circuit further includes a first resistor, a second resistor and a third resistor, the output terminal of the first current sensor includes a first positive phase output terminal and a first negative phase output terminal, and the input terminal of the first comparator includes a first positive phase input terminal and a first negative phase input terminal; The first positive phase output terminal of the first current sensor is connected to the first positive phase input terminal of the first comparator, and the first positive phase output terminal is connected in series with the first resistor and then grounded; The first inverting output terminal of the first current sensor is respectively connected to the power supply terminal and the first terminal of the second resistor, the second terminal of the second resistor is respectively connected to the first inverting input terminal of the first comparator and the first terminal of the third resistor; the second terminal of the third resistor is grounded.

3. The series compensation device according to claim 2, characterized in that: The second detection circuit further includes a fourth resistor, a fifth resistor and a sixth resistor, the output end of the second current sensor includes a second positive phase output end and a second negative phase output end, the input end of the second comparator includes a second positive phase input end and a second negative phase input end; the first current sensor is connected in parallel with the second current sensor; The second positive phase output terminal of the second current sensor is connected to the second positive phase input terminal of the second comparator, and the second positive phase output terminal is connected in series with the fourth resistor and then grounded; The second inverting output terminal of the second current sensor is respectively connected to the power supply terminal and the first end of the fifth resistor, the second end of the fifth resistor is respectively connected to the second inverting input terminal of the second comparator and the first end of the sixth resistor; the second end of the sixth resistor is grounded.

4. The series compensation device according to claim 1, characterized in that: When the output signals of the output ends of the first current sensor and the second current sensor are current signals, the first detection circuit further includes a seventh resistor and an eighth resistor, the output end of the first current sensor includes a first positive phase output end and a first negative phase output end, the input end of the first comparator includes a first positive phase input end and a first negative phase input end; the input end of the second comparator includes a second negative phase input end; the first current sensor and the eighth resistor are connected in series to form a first series circuit; The first positive phase output terminal of the first current sensor is connected to the first positive phase input terminal of the first comparator, and the first positive phase output terminal is connected in series with the seventh resistor and then grounded; The first inverting output terminal of the first current sensor is connected to the power supply terminal; the first inverting input terminal of the first comparator is connected to the second inverting input terminal of the second comparator.

5. The series compensation device according to claim 4, characterized in that: The second detection circuit further includes a ninth resistor, a tenth resistor, an eleventh resistor and a twelfth resistor, the output end of the second current sensor includes a second positive phase output end and a second negative phase output end, and the input end of the second comparator further includes a second positive phase input end; the second current sensor and the twelfth resistor are connected in series to form a second series circuit, and the first series circuit and the second series circuit are connected in parallel; The second positive phase output terminal of the second current sensor is connected to the second positive phase input terminal of the second comparator, and the second positive phase output terminal is connected in series with the ninth resistor and then grounded; The second inverting output terminal of the second current sensor is respectively connected to the power supply terminal and the first terminal of the tenth resistor, the second terminal of the tenth resistor is respectively connected to the second inverting input terminal of the second comparator and the first terminal of the eleventh resistor; the second terminal of the eleventh resistor is grounded.

6. The series compensation device according to claim 5, characterized in that: The first reference signal of the first inverting input terminal is equal to the second reference signal of the second inverting input terminal, and the ratio between the resistance value of the eighth resistor and the resistance value of the twelfth resistor is equal to the ratio between the minimum operating current and the maximum operating current of the metal oxide voltage limiter.

7. The series compensation device according to claim 3 or 6, characterized in that: The circuit breaker comprises a first circuit breaker, and the damping circuit comprises a first damping circuit; The first circuit breaker and the first damping circuit are connected in series to form a damping branch, and the output end of the first comparator and the output end of the second comparator are respectively connected to the damping branch.

8. The series compensation device according to claim 7, characterized in that: The output signal of the output terminal of the first comparator is a first output signal, and the output signal of the output terminal of the second comparator is a second output signal; The first output signal is used to control the first circuit breaker to close when the output signal of the output terminal of the first current sensor is greater than the first reference signal of the first inverting input terminal; The second output signal is used to control the first circuit breaker to close when the output signal of the output terminal of the second current sensor is greater than the second reference signal of the second inverting input terminal.

9. The series compensation device according to claim 3 or 6, characterized in that: The circuit breaker includes a second circuit breaker and a third circuit breaker, and the damping circuit includes a second damping circuit and a third damping circuit; The second circuit breaker and the second damping circuit are connected in series to form a first damping branch, and the output end of the first comparator is connected to the first damping branch; The third circuit breaker and the third damping circuit are connected in series to form a second damping branch, and the output end of the second comparator is connected to the second damping branch.

10. The series compensation device according to claim 9, characterized in that: The output signal of the output terminal of the first comparator is a first output signal; the output signal of the output terminal of the second comparator is a second output signal; The first output signal is used to control the second circuit breaker to close when the output signal of the output terminal of the first current sensor is greater than the third reference signal of the first inverting input terminal; The second output signal is used to control the third circuit breaker to close when the output signal of the output terminal of the second current sensor is greater than the fourth reference signal of the second inverting input terminal.

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