CN219496588U - High-voltage circuit breaker opens and shuts three-phase back-to-back capacitor bank test device - Google Patents

Abstract

The utility model discloses a test device for a high-voltage circuit breaker switching three-phase back-to-back capacitor bank, which is applied to 40.5kV and below. The lengths of the 3 stacks of capacitance towers are inconsistent, and the 3 stacks of capacitance towers are arranged in parallel. According to the utility model, two stacks of capacitor towers are used as power supply side capacitor towers, so that the influence of in-loop inductance on the surge peak value and the surge frequency can be obviously reduced, the capacitance of the power supply side capacitor towers can be further reduced, the surge frequency in the loop is improved, and greater economic benefit is realized.

Description

High-voltage circuit breaker opens and shuts three-phase back-to-back capacitor bank test device

Technical Field

The utility model belongs to the field of high-voltage switch product tests, and particularly relates to a device for testing an open-close three-phase back-to-back capacitor bank of a high-voltage circuit breaker with a voltage level of 40.5kV or below.

Background

In recent years, with the continuous acceleration of industrialization progress, industrial electricity is continuously increased, the construction pace of the country on the power grid is continuously increased, the load of the power grid is continuously increased, and adverse effects on the stability of the power grid are necessarily caused, so that in order to ensure the stable development of the power grid, the capacity of the power grid is increased, the quality of electric energy is ensured, the power factor of the power grid is improved, the power transmission capacity of the power grid is increased, and sufficient reactive compensation is required to be provided on the premise of ensuring active balance. At present, most of the capacitor banks are installed in a transformer substation for centralized compensation, in order to adjust reactive power conveniently during operation, the capacitor banks are sometimes divided into a plurality of groups, each group is controlled by a circuit breaker, a control signal is sent out by a reactive power compensation automatic control system according to the fluctuation condition of a load, the groups are connected in parallel, and the parallel capacitor banks are also called back-to-back capacitor banks for short.

When one or more groups of capacitors are operated on the same line, the other group of capacitors are put into operation, and at the moment of closing, larger closing surge current is generated in the newly put-in capacitor group. The re-plunged capacitor bank and the operating capacitor bank are typically closely spaced, with very little, almost zero inductance therebetween, and the re-plunged capacitor bank approximates a short circuit condition, so that the operating capacitor bank will charge the re-plunged capacitor bank and full surge closing surge current will flow into the re-plunged capacitor bank. When the system voltage is at the moment of switching on at the maximum value, the inrush current reaches the maximum value, and the amplitude of the inrush current possibly reaches tens of times of rated current, so that the electrical life of the circuit breaker contact which is responsible for the switching operation of the capacitor bank is affected. At the same time, since the inductance of the connection line between the capacitors is small, a high oscillation frequency is also generated.

In order to ensure the safe operation of the circuit breaker in the system, the circuit breaker needs to be subjected to back-to-back capacitor bank opening and closing tests in a laboratory before entering a power grid. The back-to-back capacitor bank opening and closing test loop needs to meet 2 indexes simultaneously: the inrush peak and the inrush frequency are closed. At present, the open-close test loop device of the capacitor bank with the voltage class of 40.5kV and below in laboratories at home and abroad is composed of two parallel capacitor towers, wherein one capacitor tower is used as a power source side capacitor tower and used for simulating a capacitor bank which is put into operation in a system, the other capacitor tower is used as a load side capacitor tower and used for simulating a capacitor bank to be put into operation again, and a tested breaker is connected in series with the capacitor bank of the load side capacitor tower to simulate actual switching of the system.

The back-to-back capacitor bank opening and closing test loop device of the current 40.5kV and below voltage class high-voltage circuit breaker mainly has the following problems: 1. the inherent inductance of the loop between towers has great influence on the closing inrush peak value and the inrush frequency, so that the closing inrush peak value and the inrush frequency of two core parameters in the test are lower; 2. the structure is arranged in the test process, the adjustment margin is small, and the parameter requirements of some electric power users on the research test can not be met; 3. because to overcome the influence of loop inductance on test parameters, a capacitor needs to be added in a power supply side capacitor tower to improve the closing surge current peak value, and the magnitude of capacitance determines the input cost of the device, so that the investment of the structural arrangement is large; 4. two stacks of parallel capacitor towers are long in power supply side capacitor tower circuit, large in capacitance and large in occupied area.

Therefore, the three-phase back-to-back capacitor bank opening and closing test device of the high-voltage circuit breaker with the voltage level of 40.5kV or below can reduce the influence of the loop connecting bus in the capacitor tower ring on test parameters; the capacitance of the capacitor towers at the power supply side is reduced, so that the investment cost and the occupied area of the device are reduced, the surge peak value and the surge frequency of the closing surge can be ensured to meet the standard requirement, the application range of the device can be expanded by changing the internal relation among the capacitor towers in the device, the requirement of higher test parameters of some electric power users is met, the economic benefit of the device is expanded, and the test device is required to be improved.

Disclosure of Invention

The utility model aims to: in order to reduce the influence of a loop connection bus in the capacitor tower ring on test parameters; the capacitance of the capacitor towers at the power supply side is reduced, so that the investment cost and the occupied area of the device are reduced, the surge peak value and the surge frequency of the closing surge can be ensured to meet the standard requirements, the application range of the device can be expanded by changing the internal relation among the capacitor towers in the device, and the applicant designs a high-voltage breaker opening-closing three-phase back-to-back capacitor bank test device.

The technical scheme is as follows: in order to solve various defects and problems brought by the traditional technical scheme, the utility model provides a test device for a high-voltage circuit breaker switching three-phase back-to-back capacitor bank, which is applied to 40.5kV and below.

The lengths of the 3 stacks of capacitance towers are inconsistent, and the 3 stacks of capacitance towers are arranged in parallel.

Still further, the lightning arrester is a zinc oxide lightning arrester, and is connected to the interelectrode and neutral point of each phase loop of each capacitor tower.

Furthermore, the discharging resistor is connected with each phase loop of the load side capacitor tower in parallel, the discharging resistor is woven by glass fiber cloth, the non-inductive winding method is adopted, the material is nickel-chromium wire, and the discharging resistor is switched by a pneumatic switch.

The utility model uses 2 stacks of capacitor towers to form a power supply side capacitor tower in parallel, so that the connecting buses in the rings of the power supply side capacitor tower are in parallel connection, and the inductance value of the power supply side capacitor tower is far lower than that of the power supply side capacitor tower which is formed by 1 stack of capacitor towers through reasonable design of the lengths of the 2 stacks of capacitor towers. The reduced inductance means that the total capacitance of the power supply side capacitor tower can be greatly reduced compared with a structure in which two capacitor towers are parallel, the reduced capacitance accounts for about 40% of the total capacitance of the device, and the total capacitance of the load side capacitor tower is determined by the test current. Therefore, the inrush frequency in the ring is obviously improved, and the input cost of the whole device can be reduced.

The utility model also improves the internal structure of the capacitor and related materials by improving the production process of the capacitor, so that the withstand voltage level of the single capacitor is improved, the capacitor does not need to be protected by an external fuse, the inhibition effect of a damping resistor on the peak value of the related surge current is reduced, the volume of the capacitor is reduced, and the length of a capacitor tower is correspondingly reduced.

Meanwhile, when the utility model is arranged and designed, the distance between 3 stacks of capacitor towers is correspondingly reduced, namely the in-loop inductance is reduced when the requirements of insulation requirements between towers and later maintenance are met.

Because of the characteristic that the lengths of the 3 stacks of capacitor towers are inconsistent, the neutral point loop of the 3 stacks of capacitor towers is connected to the capacitance side close to the corresponding capacitor side of the load side capacitor tower 400A (the lowest 1-gear current) through reasonably distributing the capacitance of the load side capacitor towers, so that the length of a connecting bus in the loop of the power side capacitor tower to the load side capacitor tower when a small current test is performed is reduced, and the peak value and the inrush frequency of the combined inrush current can also meet the standard requirement.

The 3-stack capacitor towers of the utility model can be arranged in a delta shape or a Y shape or an inverted Y shape besides being arranged in parallel. The preferred scheme provided by the utility model is that 3 stacks of capacitor towers are arranged in parallel.

The beneficial effects are that: compared with the traditional technical scheme, the utility model has the beneficial effects that:

(1) According to the utility model, two stacks of capacitor towers are used as power supply side capacitor towers, so that the influence of in-loop inductance on the surge peak value and the surge frequency can be obviously reduced, the capacitance of the power supply side capacitor towers can be further reduced, the surge frequency in the loop is improved, and meanwhile, the total investment cost of projects is reduced by more than one third, so that greater economic benefit is realized.

(2) According to the utility model, the volume of a single capacitor is reduced by optimizing the internal structure of the capacitor and using the novel material, so that the occupied area of the whole device is reduced, and meanwhile, the withstand voltage level of the single capacitor is improved, so that the capacitor does not need the protection of an external fuse, and the inhibition effect of the inherent damping resistance of the external fuse on the surge peak value is reduced.

(3) According to the utility model, the internal relation of the 3-pile capacitor towers can be flexibly changed by using the inter-tower parallel switch among the 3-pile capacitor towers, when a higher test parameter is proposed by an electric power user, the 2-pile power source side capacitor towers can be connected with the load side capacitor towers in parallel by separating the 1-pile capacitor towers from the inter-tower parallel switch to serve as loads, so that the investment cost is not increased, the application range of the device is widened, and the advantage is that the test device adopting the 2-pile capacitor towers does not exist.

(4) According to the utility model, the distance between towers and the distribution of capacitance of the load side capacitor towers are fully considered, and 3 stacks of capacitor towers are arranged in parallel, so that the wiring of external test samples is more flexible and changeable, the whole device is more compact in arrangement, and the occupied area is smaller.

Drawings

Fig. 1 is a schematic structural diagram of a high-voltage breaker open-close three-phase back-to-back capacitor bank test device according to the present utility model.

Fig. 2 is a schematic diagram of a connecting bus of a capacitor tower according to the present utility model.

Fig. 3 is a schematic diagram of a power side capacitor tower circuit.

Fig. 4 is a phase current diagram of a 630A back-to-back capacitor bank open-close test.

Fig. 5 is a partial enlarged view of fig. 4.

Detailed Description

The present utility model will be described in detail by way of a preferred embodiment, but the scope of the present utility model is not limited to the embodiment.

As shown in FIG. 1, a high-voltage circuit breaker open-close three-phase back-to-back capacitor bank test device is applied to 40.5kV and below, the test device is composed of a capacitor tower A1, a capacitor tower B2, a capacitor tower C3, a lightning arrester 5 and a discharge resistor 4, inductance values of the capacitor tower A1 and the capacitor tower B2 are lower than those of the capacitor tower C3, the capacitor tower A1 and the capacitor tower B2 are used as power supply side capacitor towers, namely connecting buses in the rings of the capacitor tower A1 and the capacitor tower B2 are in parallel connection, the power supply side capacitor tower is formed, the capacitor tower C3 is used as a load side capacitor tower, and a parallel switch 6 is arranged among the capacitor tower A1, the capacitor tower B2 and the capacitor tower C3. The lengths of the capacitor tower A1, the capacitor tower B2 and the capacitor tower C3 are inconsistent, and the capacitor tower A1, the capacitor tower B2 and the capacitor tower C3 are arranged in parallel. The lightning arrester 5 is a zinc oxide lightning arrester, is connected to the interelectrode and neutral point pair of each phase loop of each capacitor tower, and can effectively clamp the interelectrode voltage and the neutral point voltage of the capacitor, thereby better protecting the capacitor bank. The discharging resistor 4 is connected with each phase loop of the load side capacitor tower in parallel and plays a role in releasing residual voltage on a capacitor of the load side capacitor tower. The discharging resistor 4 is woven by glass fiber cloth, a non-inductive winding method is adopted, the material is nickel-chromium wire, and the discharging resistor 4 is switched by a pneumatic switch.

When the parallel switch between towers is arranged at the position of 1, namely the capacitor tower A1 and the capacitor tower B2 are connected in parallel to be used as a power supply side capacitor tower for realizing the open-close test of the three-phase back-to-back capacitor bank of 400A and 630A; when the inter-tower parallel switch is placed at the position of 2, namely the capacitor tower B2 and the capacitor tower C3 are connected in parallel to serve as a load side capacitor tower, and the three-phase back-to-back capacitor bank switching test of 800A is realized. Therefore, the application range of the device is expanded by using the inter-tower parallel switch, and the maximum capacitive current in the actual working condition of the current power system is covered.

As shown in fig. 2, the utility model considers that several current tests are required to be performed in the same device, when the current is small, the input capacitance of the load side capacitor tower 8 is small, the off-surge peak value and the surge frequency parameter of each current are the same, and the input capacitance is in direct proportion to the off-surge peak value, which means that the length of a connecting bus bar in the capacitor tower ring needs to be reduced, because the inductance value is inversely proportional to the off-surge peak value, and the length of the connecting bus bar between the power side capacitor tower 7 and the load side capacitor tower 8 can be reduced by arranging the neutral line 9 in the capacitor tower ring close to the 400A capacitance corresponding to the load side capacitor tower 8 in the design to achieve the purpose of reducing the inductance value in the capacitor tower ring. The SP is a tested breaker, when the test current is 400A, the charging path of the power supply side capacitor tower 7 to the load side capacitor tower 8 is shown by an arrow in fig. 2, and the neutral line 9 is arranged at the end of the capacitor corresponding to the 400A current, but not at the end of the load side capacitor tower 8, so that the length of a connecting bus between the power supply side capacitor tower 7 and the load side capacitor tower 8 is reduced, and the closing inrush current peak value meeting the standard requirement is facilitated.

As shown in FIG. 3, the utility model adopts two stacks of capacitor towers as power supply side capacitor towers, and also aims to reduce the connecting bus in the capacitor tower rings, and because the inductance value is in direct proportion to the length in the capacitor tower rings, the 1 stack of capacitor towers at the power supply side end in the two stacks of parallel capacitor tower structures are split into 2 stacks of capacitor towers, so that the length of the connecting bus of the capacitor towers is reduced, and the inductance between the 2 stacks of capacitor towers forms a parallel connection relationship, thereby greatly reducing the inductance value in the power supply side capacitor towers.

L, L1 and L2 represent inductance values corresponding to the tower length of the capacitor tower, and when 2 stacks of power supply side capacitor towers exist, the equivalent inductance value isBecause L1 and L2 are smaller than L, the equivalent inductance value L1 is far smaller than L, and then the total capacitance C1=C1+C2 of the 2-stack power supply side capacitor tower can be smaller than the capacitance C of the 1-stack power supply side capacitor tower, thus saving the investment cost and simultaneously leading the inrush frequency in the capacitor tower ring to be lower

And also becomes larger, and it is easier to reach the standard required value.

Through data analysis after debugging, the obtained closing surge peak value and the surge frequency of the structural device are superior to those of two parallel capacitance tower structural arrangements.

As shown in fig. 4 and 5, the graph is a phase a current diagram and a partial enlarged view of a 630A back-to-back capacitor bank open-close test. The peak value of the closing surge current is 22.5kA, and the standard requirement value is 20kA through the graphs 4 and 5; the inrush frequency is 4623Hz, the standard requirement value is 4250Hz, and the adjustment margin of the two parameters is large, so that the operability in practical tests is strong, such as: the standard requirement value can be set by adjusting the length of the external wiring, the placement position of the test sample, the input capacitance of the power supply side capacitor tower, the inconsistent length of the connecting bus by using the test and the like.

In summary, the three-phase back-to-back capacitor bank switching test of the high-voltage circuit breaker with the voltage level of 40.5kV and below is obviously superior to the prior art that the structure of the capacitor tower with 3 stacks adopts the structure of the capacitor tower with two stacks in parallel. In the novel structural arrangement, the parallel arrangement of the 3 stacks of capacitance towers is optimal, the influence of the connecting bus on test parameters is minimal, and the connecting bus can reasonably select the Y shape, the Y shape or the inverted Y shape according to the arrangement field of the device, so that the influence of the connecting bus on the test parameters is also less than that of the two stacks of parallel capacitance tower structures.

The foregoing is only a preferred embodiment of the utility model, it being noted that: it will be apparent to those skilled in the art that various modifications and adaptations can be made without departing from the principles of the present utility model, and such modifications and adaptations are intended to be comprehended within the scope of the utility model.

Claims (4)

1. High voltage circuit breaker opens and shuts three-phase back-to-back capacitor bank test device is applied to 40.5kV and below voltage, its characterized in that: the test device is composed of 3 stacks of capacitor towers, a lightning arrester (5) and a discharge resistor (4), wherein the 1 st capacitor tower and the 2 nd capacitor tower in the 3 stacks of capacitor towers are used as power source side capacitor towers, namely, connecting buses in the rings of the 2 stacks of capacitor towers are in parallel connection, the power source side capacitor towers are formed, the 3 rd capacitor tower is used as a load side capacitor tower, and a parallel switch (6) is arranged between the 3 stacks of capacitor towers.

2. The high voltage circuit breaker open-close three-phase back-to-back capacitor bank test device of claim 1, wherein: the lengths of the 3 stacks of capacitance towers are inconsistent, and the 3 stacks of capacitance towers are arranged in parallel.

3. The high voltage circuit breaker open-close three-phase back-to-back capacitor bank test device of claim 1, wherein: the lightning arrester (5) is a zinc oxide lightning arrester and is connected with the interelectrode and the neutral point of each phase loop of each capacitor tower.

4. The high voltage circuit breaker open-close three-phase back-to-back capacitor bank test device of claim 1, wherein: the discharging resistor (4) is connected with each phase of loop of the load side capacitor tower in parallel, the discharging resistor (4) is woven by glass fiber cloth, a non-inductive winding method is adopted, the material is nickel-chromium wire, and the discharging resistor (4) is switched through a pneumatic switch.