Capacitor for high-voltage power transmission and distribution

Abstract

The invention discloses a capacitor for high-voltage power transmission and distribution, which comprises a capacitor bank, a bypass switch, a bus voltage monitoring device and a bypass switch control device, and is characterized in that one end of the capacitor bank is connected with an alternating current bus, and the other end of the capacitor bank is grounded; the capacitor bank comprises a first capacitor unit and a second capacitor unit which are connected in series, and the bypass switch is connected in parallel with the second capacitor unit; the bus voltage monitoring device is connected with the AC bus and the bypass switch control device. The bypass switch control device is connected with the bypass switch; a bus voltage monitoring device monitors the voltage of an alternating current bus in real time to obtain real-time voltage data and transmits the real-time voltage data to a bypass switch control device; the bypass switch control device controls the bypass switch to be turned on or turned off according to the received real-time voltage data, so that the first capacitor unit and the second capacitor unit are connected to the alternating current bus, and the voltage supporting capacity when the voltage of the power grid is reduced due to disturbance is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of high-voltage power transmission and distribution, and in particular to a capacitor for high-voltage power transmission and distribution. Background Art

[0002] As an important device for reactive power compensation in substations, shunt capacitor banks are used to provide reactive power to the power system to improve the power factor. The current mainstream dynamic reactive power compensation devices include SVG and phase regulators, but phase regulators are expensive, and the compensation capacity of SVG compensation devices will be reduced when the grid voltage drops, and the ability to support the grid voltage will become weaker.

[0003] It can be seen that how to provide a new type of capacitor that can have a stronger voltage support capability when the grid voltage is disturbed and reduced has become a technical problem that needs to be urgently solved by those skilled in the art. Summary of the invention

[0004] The present invention provides a capacitor for high-voltage power transmission and distribution, which solves the problem of how to provide a new type of capacitor which has a stronger voltage support capability when the grid voltage is disturbed and reduced.

[0005] In order to solve the above technical problems, the present invention provides a high-voltage power transmission and distribution capacitor, including a capacitor bank, a bypass switch, a bus voltage monitoring device and a bypass switch control device: wherein,

[0006] One end of the capacitor bank is connected to the AC bus, and the other end is grounded; the capacitor bank includes a first capacitor unit and a second capacitor unit, the first capacitor unit and the second capacitor unit are connected in series, and the bypass switch is connected in parallel with the second capacitor unit; one end of the bus voltage monitoring device is connected to the AC bus, and the other end is connected to the bypass switch control device; the bypass switch control device is connected to the bypass switch;

[0007] The bus voltage monitoring device is used to monitor the voltage of the AC bus in real time, obtain real-time voltage data and send it to the bypass switch control device;

[0008] The bypass switch control device is used to receive the real-time voltage data and control the bypass switch to open or close according to the real-time voltage data, so that the first capacitor unit and the second capacitor unit are connected to the AC bus.

[0009] As a preferred solution, the second capacitor unit includes a plurality of capacitor sub-units connected in series, and each of the capacitor sub-units is connected in parallel with a bypass switch.

[0010] As one of the preferred schemes, the first capacitor unit includes a first capacitor sub-unit, the second capacitor unit includes a second capacitor sub-unit, a third capacitor sub-unit and a fourth capacitor sub-unit; the bypass switch includes a first bypass switch, a second bypass switch and a third bypass switch; the second capacitor sub-unit is connected in parallel with the first bypass switch, the third capacitor sub-unit is connected in parallel with the second bypass switch, and the fourth capacitor sub-unit is connected in parallel with the third bypass switch.

[0011] As one preferred solution, the first capacitor sub-unit, the second capacitor sub-unit, the third capacitor sub-unit and the fourth capacitor sub-unit each include a plurality of capacitors connected in parallel and having the same voltage level.

[0012] As a preferred solution, the rated voltages of the first capacitor sub-unit, the second capacitor sub-unit, the third capacitor sub-unit and the fourth capacitor sub-unit decrease in sequence.

[0013] As one preferred solution, the rated voltage of the first capacitor subunit is: Wherein, k is the reactance compensation rate; Un is the rated line voltage of the AC bus; and the rated voltage of the second capacitor subunit is: The rated voltage of the third capacitor subunit is: The rated voltage of the fourth capacitor subunit is:

[0014] As one preferred solution, the bypass switch control device includes a communication module, a quantization module, a comparison module and a control module; wherein,

[0015] The communication module is used to receive real-time voltage data transmitted from the bus voltage monitoring device;

[0016] The quantization module is used to quantify the rated reactive power demand data of the AC system according to the rated line voltage of the AC bus, and to quantify the actual reactive power output data of the original reactive power compensation device according to the real-time voltage data, so as to obtain a reactive power data difference according to the rated reactive power demand data and the actual reactive power output data;

[0017] The comparison module is used to quantify reactive capacity data of the capacitor bank under several states according to the real-time voltage data, and compare the reactive capacity data with the reactive data difference to obtain a comparison result;

[0018] The control module is used to control the corresponding bypass switch to close or open according to the comparison result, so that the first capacitor sub-unit, the second capacitor sub-unit, the third capacitor sub-unit and the fourth capacitor sub-unit are correspondingly connected to the AC bus.

[0019] As one preferred solution, the first reactive capacity data of the capacitor bank in the first state is Q1=Ut 2 / 3(4ωC-ωL), where Ut is the real-time voltage data, ω is the angular frequency, C is the capacitance of each capacitor in the capacitor bank, and L is the reactance; the second reactive capacity data of the capacitor bank in the second state is Q2=Ut 2 / 3(3ωC-ωL); the third reactive capacity data of the capacitor bank in the third state is Q3=Ut 2 / 3(2ωC-ωL); the fourth reactive capacity data of the capacitor bank in the fourth state is Q4=Ut 2 / 3(ωC-ωL).

[0020] As one preferred solution, the control module is further used for:

[0021] When the reactive data difference is not less than the first reactive capacity data and less than the second reactive capacity data, controlling the first bypass switch, the second bypass switch and the third bypass switch to be closed, so that the first capacitor subunit is connected to the AC bus, and the capacitor bank is in the first state;

[0022] When the reactive data difference is not less than the second reactive capacity data and less than the third reactive capacity data, control the first bypass switch to open, and control the second bypass switch and the third bypass switch to close, so that the first capacitor subunit and the second capacitor subunit are connected to the AC bus, and the capacitor bank is in the second state;

[0023] When the reactive data difference is not less than the third reactive capacity data and less than the fourth reactive capacity data, the first bypass switch and the second bypass switch are controlled to be opened, and the third bypass switch is controlled to be closed, so that the first capacitor subunit, the second capacitor subunit and the third capacitor subunit are connected to the AC bus, and the capacitor bank is in the third state;

[0024] When the reactive data difference is not less than the fourth reactive capacity data, the first bypass switch, the second bypass switch and the third bypass switch are controlled to open, so that the first capacitor sub-unit, the second capacitor sub-unit, the third capacitor sub-unit and the fourth capacitor sub-unit are connected to the AC bus, and the capacitor group is in the fourth state.

[0025] As a preferred solution, the bypass switch is a power electronic switch or a fast mechanical switch.

[0026] Compared with the prior art, the embodiments of the present invention have the following advantages:

[0027] (1) By designing the capacitor bank in units of different levels, when the AC system is disturbed, some capacitors can be removed to increase the capacitance of the capacitors, thereby increasing the reactive output of the capacitors at the same bus voltage to reduce the harm of the system disturbance to the power grid;

[0028] (2) By real-time monitoring of the voltage of the AC bus and dynamically adjusting the number of capacitor units connected according to the magnitude of the AC bus voltage drop, the bus voltage can be effectively supported. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solution of the present invention, the drawings required for use in the implementation mode will be briefly introduced below. Obviously, the drawings described below are only some implementation modes of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0030] Figure 1 It is a structural diagram of a capacitor for high-voltage power transmission and distribution provided by a certain embodiment of the present invention;

[0031] Figure 2 is a structural diagram of a capacitor for high-voltage power transmission and distribution provided by another embodiment of the present invention;

[0032] Figure 3 is a structural diagram of a bypass switch control device 4 provided in one embodiment of the present invention;

[0033] Figure 4 It is a flow chart of a control method of a capacitor for high-voltage power transmission and distribution provided by a certain embodiment of the present invention;

[0034] Reference numerals:

[0035] Among them, a is a first capacitor subunit; b is a second capacitor subunit; c is a third capacitor subunit; d is a fourth capacitor subunit. DETAILED DESCRIPTION

[0036] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings and embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. The purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] In the description of this application, the terms "first", "second", "third", etc. are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first", "second", "third", etc. may explicitly or implicitly include one or more of the feature. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0038] In the description of the present application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be a connection between the two components. The terms "vertical", "horizontal", "left", "right", "upper", "lower" and similar expressions used herein are for illustrative purposes only, and do not indicate or imply that the system or component referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0039] In the description of this application, it should be noted that, unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those commonly understood by those skilled in the art. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood by specific circumstances.

[0040] In one embodiment, if Figure 1 As shown, the present invention provides a capacitor for high-voltage power transmission and distribution, including a capacitor bank 1, a bypass switch 2, a bus voltage monitoring device 3 and a bypass switch control device 4: wherein,

[0041] One end of the capacitor bank 1 is connected to the AC bus 5, and the other end is grounded; the capacitor bank 1 includes a first capacitor unit 11 and a second capacitor unit 12, the first capacitor unit 11 and the second capacitor unit 12 are connected in series, and the bypass switch 2 is connected in parallel with the second capacitor unit 12; one end of the bus voltage monitoring device 3 is connected to the AC bus 5, and the other end is connected to the bypass switch control device 4; the bypass switch control device 4 is connected to the bypass switch 2;

[0042] The bus voltage monitoring device 3 is used to monitor the voltage of the AC bus 5 in real time, obtain real-time voltage data and send it to the bypass switch control device 4;

[0043] The bypass switch control device 4 is used to receive the real-time voltage data, and control the bypass switch 2 to open or close according to the real-time voltage data, so that the first capacitor unit 11 and the second capacitor unit 12 are connected to the AC bus 5 .

[0044] Specifically, one end of the capacitor bank 1 is connected to the AC bus 5 through a series reactor and a circuit breaker, and the other end is grounded. The present invention realizes the dynamic response of the voltage of the AC bus 5 and the flexible control of the capacitor bank 1 by integrating the capacitor bank 1, the bypass switch 2, the bus voltage monitoring device 3 and the bypass switch control device 4; specifically, the capacitor bank 1 includes two capacitor units connected in series, one of which can be bypassed through the bypass switch 2, so that the high-voltage power transmission and distribution capacitor can control the bypass switch control device 4 to open or close the bypass switch 2 according to the voltage change of the AC bus 5 monitored by the bus voltage monitoring device 3, so as to achieve the purpose of adjusting the access state of the capacitor bank 1, and then adjust the total capacitance value of the capacitor bank 1 to adjust the reactive power compensation of the system and improve the stability and voltage quality of the power grid; through the control of the bypass switch 2, the access mode of the capacitor bank 1 can be flexibly selected to achieve effective adjustment of the capacitance value, so as to increase the voltage support capacity of the power grid voltage when the disturbance is reduced. In addition, the modular design of the capacitor bank 1 is convenient for maintenance and expansion, and the redundant design of the bypass switch 2 also improves the overall reliability of the system.

[0045] In one embodiment, the second capacitor unit 12 includes a plurality of capacitor sub-units connected in series, each of which is connected in parallel to a bypass switch; by providing a plurality of capacitor sub-units, the number of capacitor sub-units connected to the AC bus 5 can be adjusted according to the opening and closing of the corresponding bypass switches, so as to increase the voltage support capacity of the grid voltage when the disturbance is reduced.

[0046] In one embodiment, a high voltage power transmission and distribution capacitor such as Figure 2As shown, the first capacitor unit 11 includes a first capacitor subunit a, the second capacitor unit 12 includes a second capacitor subunit b, a third capacitor subunit c and a fourth capacitor subunit d; the bypass switch 2 includes a first bypass switch, a second bypass switch and a third bypass switch; the second capacitor subunit b is connected in parallel with the first bypass switch, the third capacitor subunit c is connected in parallel with the second bypass switch, and the fourth capacitor subunit d is connected in parallel with the third bypass switch; the first capacitor subunit a, the second capacitor subunit b, the third capacitor subunit c and the fourth capacitor subunit d each include a number of capacitors connected in parallel and having the same voltage level.

[0047] The present invention can achieve more precise control of capacitor capacity by dividing the capacitor group 1 into a first capacitor unit 11 and a second capacitor unit 12, and further subdividing them into multiple capacitor sub-units (first, second, third, and fourth capacitor sub-units). The hierarchical design of the capacitor group 1 allows the capacity of the capacitors put into or removed to be adjusted according to actual needs, thereby more accurately adjusting the reactive power and power factor of the power system, and allows new capacitor sub-units to be easily added on the basis of the existing capacitor group 1 to meet the future growth of reactive power demand of the power system; the setting of the bypass switch makes it possible to isolate and repair any capacitor sub-unit separately without affecting the normal operation of other sub-units, further improving the flexibility of the system; connecting capacitors with the same voltage level in parallel can ensure that each capacitor sub-unit works under the same conditions, reducing the risk of capacitor damage caused by uneven voltage.

[0048] In one embodiment, the rated voltages of the first capacitor subunit a, the second capacitor subunit b, the third capacitor subunit c, and the fourth capacitor subunit d decrease in sequence, and the rated voltage of the first capacitor subunit a is: Wherein, k is the reactance compensation rate; Un is the rated line voltage of the AC bus 5; and the rated voltage of the second capacitor subunit b is: The rated voltage of the third capacitor subunit c is: The rated voltage of the fourth capacitor subunit d is:

[0049] Specifically, the hierarchical design adopted by the capacitor group 1 in the present invention is hierarchical, starting from the high-voltage side, into a first capacitor subunit a, a second capacitor subunit b, a third capacitor subunit c and a fourth capacitor subunit d, so as to more accurately control the input and removal of the capacitor group 1 and realize flexible adjustment of reactive power. The hierarchical design can also enhance the anti-disturbance capability of the power system. When the system is subjected to external disturbances, that is, when the voltage of the AC bus 5 is reduced, the capacitor group 1 can respond quickly, provide necessary reactive support, and help the system restore stability.

[0050] It should be noted that the second capacitor unit 12 may also include three capacitor sub-units or five capacitor sub-units, and the number of capacitor sub-units may be adjusted according to demand. Correspondingly, the number of bypass switches needs to be the same as the number of capacitor sub-units in the second capacitor unit 12, and the rated voltage of each capacitor sub-unit can be expressed by the following formula: Here, m is the number of capacitor subunits in the second capacitor unit 12 .

[0051] In one embodiment, the bypass switch control device 4 is used to control the bypass switch to realize the input of different numbers of capacitor sub-units, and its structure is as follows: Figure 3 As shown, it includes a communication module 11, a quantization module 12, a comparison module 13 and a control module 14; wherein,

[0052] The communication module 11 is used to receive the real-time voltage data transmitted from the bus voltage monitoring device 3; wherein the communication module 11 can adopt wired or wireless communication, which is not specifically limited here. In addition, the bus voltage monitoring device 3 includes a monitoring module for real-time monitoring of the voltage of the AC bus 5 and another communication module for data communication with the bypass switch control device 4, which module can also adopt wired or wireless communication, but it must correspond to the communication mode of the communication module 11 in the bypass switch control device 4.

[0053] The quantization module 12 is used to quantify the rated reactive power demand data Qn of the AC system according to the rated line voltage Un of the AC bus 5, and to quantify the actual reactive output data Qt of the original reactive compensation device according to the real-time voltage data Ut, so as to obtain a reactive data difference △Q=Qn-Qt according to the rated reactive power demand data and the actual reactive output data; wherein the original reactive compensation device is an existing reactive compensation device, such as SVG and phase shifter; and Qn can be obtained by calculation based on the active power demand and power factor of the AC system, or by other methods; Qt can be obtained by calculation based on the current data and phase difference of the AC system, or by other methods; the specific calculation method of the relevant reactive data is not specifically limited here; in addition, the reactive power described in the present invention is reactive power, such as the rated reactive power demand data is the rated reactive power demand data; the AC system is the power grid system to which the AC bus belongs, and the present invention does not limit its specific type here.

[0054] The comparison module 13 is used to quantify the reactive capacity data of the capacitor bank 1 in several states according to the real-time voltage data, and compare the reactive capacity data with the reactive data difference to obtain a comparison result; wherein the first reactive capacity data of the capacitor bank 1 in the first state is Q1=Ut 2 / 3(4ωC-ωL), where ω is the angular frequency, C is the capacitance of each capacitor in the capacitor bank 1, and L is the reactance; the second reactive capacity data of the capacitor bank 1 in the second state is Q2=Ut 2 / 3(3ωC-ωL); the third reactive capacity data of the capacitor bank 1 in the third state is Q3=Ut 2 / 3(2ωC-ωL); the fourth reactive capacity data of the capacitor bank 1 in the fourth state is Q4=Ut 2 / 3(ωC-ωL). It should be noted that the state of the capacitor bank 1 corresponds to the number of capacitor sub-units contained in the capacitor bank 1. If the capacitor bank 1 contains not only four capacitor sub-units but m capacitor sub-units, then the first reactive capacity data of the corresponding capacitor bank 1 in the first state is Q1=Ut 2 / 3(mωC-ωL), the second reactive capacity data of capacitor bank 1 in the second state is Q2=Ut 2 / 3((m-1)ωC-ωL), the mth reactive capacity data of capacitor bank 1 in the mth state is Qm=Ut 2 / 3(ωC-ωL), and it decreases in sequence according to this rule. In addition, the reactive capacity data of capacitor group 1 can also be considered as the reactive compensation capacity required when the voltage of AC bus 5 in the AC system is disturbed, and the corresponding state of capacitor group 1 is the state of capacitor group 1 after it is connected to the corresponding capacitor of AC bus 5.

[0055] The control module 14 is configured to control the corresponding bypass switch 2 to close or open according to the comparison result, so that the first capacitor sub-unit a, the second capacitor sub-unit b, the third capacitor sub-unit c, and the fourth capacitor sub-unit d are correspondingly connected to the AC bus 5; specifically:

[0056] When the reactive power data difference is not less than the first reactive power capacity data and less than the second reactive power capacity data, control the first bypass switch 2, the second bypass switch 2, and the third bypass switch 2 to close, so that the first capacitor sub-unit a is connected to the AC bus 5, and the capacitor bank 1 is in the first state;

[0057] Specifically, when Q1 <= ΔQ < Q2, the reactive power compensation capacity required by the AC system is Q1. Then, it is necessary to make the capacitor bank 1 in the first state, that is, it is necessary to control the first bypass switch 2, the second bypass switch 2, and the third bypass switch 2 to close to connect the first capacitor sub-unit a to the AC bus 5.

[0058] When the reactive power data difference is not less than the second reactive power capacity data and less than the third reactive power capacity data, control the first bypass switch 2 to open, and control the second bypass switch 2 and the third bypass switch 2 to close, so that the first capacitor sub-unit a and the second capacitor sub-unit b are connected to the AC bus 5, and the capacitor bank 1 is in the second state;

[0059] Specifically, when Q2 <= ΔQ < Q3, the reactive power compensation capacity required by the AC system is Q2. Then, it is necessary to make the capacitor bank 1 in the second state, that is, it is necessary to control the first bypass switch 2 to open, and control the second bypass switch 2 and the third bypass switch 2 to close to connect the first capacitor sub-unit a and the second capacitor sub-unit b to the AC bus 5.

[0060] When the reactive power data difference is not less than the third reactive power capacity data and less than the fourth reactive power capacity data, control the first bypass switch 2 and the second bypass switch 2 to open, and control the third bypass switch 2 to close, so that the first capacitor sub-unit a, the second capacitor sub-unit b, and the third capacitor sub-unit c are connected to the AC bus 5, and the capacitor bank 1 is in the third state;

[0061] Specifically, when Q3 <= ΔQ < Q4, the reactive power compensation capacity required by the AC system is Q3. Then, it is necessary to make the capacitor bank 1 in the third state, that is, it is necessary to control the first bypass switch 2 and the second bypass switch 2 to open, and control the third bypass switch 2 to close to connect the first capacitor sub-unit a, the second capacitor sub-unit b, and the third capacitor sub-unit c to the AC bus 5.

[0062] When the reactive data difference is not less than the fourth reactive capacity data, the first bypass switch 2, the second bypass switch 2 and the third bypass switch 2 are controlled to be opened, so that the first capacitor subunit a, the second capacitor subunit b, the third capacitor subunit c and the fourth capacitor subunit d are connected to the AC bus 5, and the capacitor bank 1 is in the fourth state;

[0063] Specifically, when Q4<=△Q, the reactive compensation capacity required by the AC system is Q4, so the capacitor group 1 needs to be in the fourth state, that is, the first bypass switch 2, the second bypass switch 2 and the third bypass switch 2 need to be controlled to open, so as to connect the first capacitor subunit a, the second capacitor subunit b, the third capacitor subunit c and the fourth capacitor subunit d to the AC bus 5.

[0064] In addition, if the capacitor group 1 contains not only four capacitor sub-units but m capacitor sub-units, then the reactive compensation capacity required by the AC system is determined according to the reactive data difference and the reactive capacity data range, and then the number of capacitor sub-units required to be connected to the current bus of the capacitor group 1 is determined, which can also be considered as the number of capacitors required to be connected, so as to control the corresponding bypass switch according to the number to connect the corresponding capacitor sub-unit to the AC bus 5, so that the capacitor group 1 is in a corresponding state. The present invention achieves the purpose of increasing the capacitance value of the capacitor by cutting off part of the capacitor when the AC system is disturbed, thereby increasing the reactive output of the capacitor under the same bus voltage to reduce the harm of the system disturbance to the power grid.

[0065] In one embodiment, the bypass switch 2 is a power electronic switch or a fast mechanical switch; wherein, if the bypass switch 2 adopts a power electronic switch, a turn-off device such as IGBT, IGCT, etc. must be used.

[0066] In one embodiment, a control method for a high voltage power transmission and distribution capacitor is as follows Figure 4 As shown, the method is applied to the aforementioned high-voltage power transmission and distribution capacitors, and the voltage of the AC bus is monitored in real time by a bus voltage monitoring device, and real-time voltage data is obtained and sent to the bypass switch control device; based on the real-time voltage data, the reactive power difference of the AC system and the reactive capacity of the capacitor group under several states are calculated by the bypass switch control device, and it is judged whether the reactive power difference is in the reactive capacity interval of the capacitor group; if so, the bypass switch control device is controlled to send a closing signal according to the reactive power difference corresponding to the real-time voltage data and control the corresponding bypass switch to open or close, so that the capacitor group is in a corresponding working state; if not, the real-time voltage data is updated by the bus voltage monitoring device, and the judgment process is iterated through the updated real-time voltage data.

[0067] In the embodiment of the present application, based on the problem of how to provide a new type of capacitor that can have a strong voltage support capability when the grid voltage is disturbed and reduced, a high-voltage power transmission and distribution capacitor is designed, which implements a technical solution including a capacitor group, a bypass switch, a bus voltage monitoring device and a bypass switch control device: wherein one end of the capacitor group is connected to the AC bus and the other end is grounded; the capacitor group includes a first capacitor unit and a second capacitor unit, the first capacitor unit and the second capacitor unit are connected in series, and the bypass switch is connected in parallel with the second capacitor unit; one end of the bus voltage monitoring device is connected to the AC bus and the other end is connected to the bypass switch control device; the bypass switch control device is connected to the bypass switch; the bus voltage monitoring device is used to monitor the voltage of the AC bus in real time, obtain real-time voltage data and send it to the bypass switch control device; the bypass switch control device is used to receive the real-time voltage data and control the bypass switch to open or close according to the real-time voltage data, so that the first capacitor unit and the second capacitor unit are connected to the AC bus; according to the amplitude of the AC bus voltage drop, the number of capacitors connected is dynamically adjusted to effectively support the bus voltage.

[0068] In summary, the present invention relates to the technical field of high-voltage power transmission and distribution, and discloses a capacitor for high-voltage power transmission and distribution, including a capacitor group, a bypass switch, a bus voltage monitoring device and a bypass switch control device: wherein, one end of the capacitor group is connected to the AC bus, and the other end is grounded; the capacitor group includes a first capacitor unit and a second capacitor unit, the first capacitor unit and the second capacitor unit are connected in series, and the bypass switch is connected in parallel with the second capacitor unit; the bus voltage monitoring device is respectively connected to the AC bus and the bypass switch control device; the bypass switch control device is connected to the bypass switch; the voltage of the AC bus is monitored in real time by the bus voltage monitoring device, and real-time voltage data is obtained and transmitted to the bypass switch control device; the bypass switch control device controls the bypass switch to be opened or closed according to the received real-time voltage data, so that the first capacitor unit and the second capacitor unit are connected to the AC bus, so as to improve the voltage support capability when the voltage of the power grid is disturbed and reduced.

[0069] Each embodiment in this specification is described in a progressive manner, and the same or similar parts of each embodiment can be directly referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment. It should be noted that the technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, all possible combinations of the technical features in the above-mentioned embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0070] The above-mentioned embodiments only express several preferred implementation modes of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in the technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be regarded as the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be based on the protection scope of the claims.

Claims

1. A capacitor for high voltage power transmission and distribution, characterized in that: It includes capacitor bank, bypass switch, bus voltage monitoring device and bypass switch control device: among which, One end of the capacitor bank is connected to the AC bus, and the other end is grounded; the capacitor bank includes a first capacitor unit and a second capacitor unit, the first capacitor unit and the second capacitor unit are connected in series, and the bypass switch is connected in parallel with the second capacitor unit; one end of the bus voltage monitoring device is connected to the AC bus, and the other end is connected to the bypass switch control device; the bypass switch control device is connected to the bypass switch; The bus voltage monitoring device is used to monitor the voltage of the AC bus in real time, obtain real-time voltage data and send it to the bypass switch control device; The bypass switch control device is used to receive the real-time voltage data and control the bypass switch to open or close according to the real-time voltage data, so that the first capacitor unit and the second capacitor unit are connected to the AC bus.

2. A capacitor for high voltage power transmission and distribution according to claim 1, characterized in that: The second capacitor unit includes a plurality of capacitor sub-units connected in series, and each of the capacitor sub-units is connected in parallel with a bypass switch.

3. A capacitor for high voltage power transmission and distribution according to claim 2, characterized in that: The first capacitor unit includes a first capacitor sub-unit, the second capacitor unit includes a second capacitor sub-unit, a third capacitor sub-unit and a fourth capacitor sub-unit; the bypass switch includes a first bypass switch, a second bypass switch and a third bypass switch; The second capacitor subunit is connected in parallel with the first bypass switch, the third capacitor subunit is connected in parallel with the second bypass switch, and the fourth capacitor subunit is connected in parallel with the third bypass switch.

4. A capacitor for high voltage power transmission and distribution according to claim 3, characterized in that: The first capacitor sub-unit, the second capacitor sub-unit, the third capacitor sub-unit and the fourth capacitor sub-unit each include a plurality of capacitors connected in parallel and having the same voltage level.

5. A capacitor for high voltage power transmission and distribution according to claim 3, characterized in that: Rated voltages of the first capacitor subunit, the second capacitor subunit, the third capacitor subunit, and the fourth capacitor subunit decrease in sequence.

6. A capacitor for high voltage power transmission and distribution according to claim 3, characterized in that: The rated voltage of the first capacitor subunit is: Wherein, k is the reactance compensation rate; Un is the rated line voltage of the AC bus; and the rated voltage of the second capacitor subunit is: The rated voltage of the third capacitor subunit is: The rated voltage of the fourth capacitor subunit is:

7. A capacitor for high voltage power transmission and distribution according to claim 3, characterized in that: The bypass switch control device includes a communication module, a quantization module, a comparison module and a control module; wherein, The communication module is used to receive real-time voltage data transmitted from the bus voltage monitoring device; The quantization module is used to quantify the rated reactive power demand data of the AC system according to the rated line voltage of the AC bus, and to quantify the actual reactive power output data of the original reactive power compensation device according to the real-time voltage data, so as to obtain a reactive power data difference according to the rated reactive power demand data and the actual reactive power output data; The comparison module is used to quantify reactive capacity data of the capacitor bank under several states according to the real-time voltage data, and compare the reactive capacity data with the reactive data difference to obtain a comparison result; The control module is used to control the corresponding bypass switch to close or open according to the comparison result, so that the first capacitor sub-unit, the second capacitor sub-unit, the third capacitor sub-unit and the fourth capacitor sub-unit are correspondingly connected to the AC bus.

8. A capacitor for high voltage power transmission and distribution according to claim 7, characterized in that: The first reactive capacity data of the capacitor bank in the first state is Q1=Ut 2 / 3(4ωC-ωL), where Ut is the real-time voltage data, ω is the angular frequency, C is the capacitance of each capacitor in the capacitor bank, and L is the reactance; the second reactive capacity data of the capacitor bank in the second state is Q2=Ut 2 / 3(3ωC-ωL); the third reactive capacity data of the capacitor bank in the third state is Q3=Ut 2 / 3(2ωC-ωL); the fourth reactive capacity data of the capacitor bank in the fourth state is Q4=Ut 2 / 3(ωC-ωL).

9. A capacitor for high voltage power transmission and distribution according to claim 8, characterized in that: The control module is also used for: When the reactive data difference is not less than the first reactive capacity data and less than the second reactive capacity data, controlling the first bypass switch, the second bypass switch and the third bypass switch to be closed, so that the first capacitor subunit is connected to the AC bus, and the capacitor bank is in the first state; When the reactive data difference is not less than the second reactive capacity data and less than the third reactive capacity data, control the first bypass switch to open, and control the second bypass switch and the third bypass switch to close, so that the first capacitor subunit and the second capacitor subunit are connected to the AC bus, and the capacitor bank is in the second state; When the reactive data difference is not less than the third reactive capacity data and less than the fourth reactive capacity data, the first bypass switch and the second bypass switch are controlled to be opened, and the third bypass switch is controlled to be closed, so that the first capacitor subunit, the second capacitor subunit and the third capacitor subunit are connected to the AC bus, and the capacitor bank is in the third state; When the reactive data difference is not less than the fourth reactive capacity data, the first bypass switch, the second bypass switch and the third bypass switch are controlled to open, so that the first capacitor sub-unit, the second capacitor sub-unit, the third capacitor sub-unit and the fourth capacitor sub-unit are connected to the AC bus, and the capacitor group is in the fourth state.

10. A capacitor for high voltage power transmission and distribution according to claim 1, characterized in that: The bypass switch is a power electronic switch or a fast mechanical switch.

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