Grounding full compensation device based on adjustable impedance adjustment

Abstract

The utility model discloses a grounding full compensation device based on adjustable impedance adjustment, which comprises a first transformer and a second transformer which are connected in parallel on a three-phase bus, the first transformer is a Z-type transformer, and the second transformer is a YY-type transformer. A three-phase winding of a secondary side of the YY type transformer is connected with a neutral point of the Z type transformer through a high-voltage switch, controlled ends of the three high-voltage switches are connected with an output end of the controller, a neutral point of the secondary three-phase winding of the YY type transformer is grounded through an adjustable impedance, and a controlled end of the adjustable impedance is connected with the output end of the controller. And the input end of the controller is also connected with a voltage transformer for measuring the three-phase voltage of the bus. According to the utility model, full compensation of grounding reactive current, active current and harmonic current can be realized through the transformer, the high-voltage switch and the adjustable impedor, the structure is simple, the reliability is high, the cost and insulation requirements are reduced, and the structure of a control system is simplified.

Description

Technical Field

[0001] The utility model relates to the technical field of single-phase grounding protection devices for distribution networks, in particular to a full compensation device. Background Art

[0002] The ground fault active full compensation device is generally composed of a power transformer, a step-up transformer, a vacuum contactor, an active power compensator (APC), a controller, etc. When a single-phase ground fault occurs, the controller adjusts the output voltage of the active power compensator, which can compensate the voltage and current at the single-phase ground fault point to close to 0, completely eliminate the arc when a single-phase ground fault occurs, and can also use the disturbance method to accurately select the line, which is a better solution to the single-phase ground fault.

[0003] The advantage of using active equipment is that the output voltage is inverted by high-power power electronic equipment, which has the characteristics of no step difference in output voltage and high adjustment accuracy; however, power electronic equipment also has other problems, such as large losses and low reliability of power electronic equipment. If the tap position is adjusted by a three-phase transformer, a three-phase multi-position high-voltage on-load switch needs to be configured, which has the disadvantages of high cost, high insulation requirements and complex control system. Utility Model Content

[0004] The technical problem to be solved by the utility model is to provide a grounding full compensation device based on adjustable impedance regulation which has a simple structure, high reliability and low cost.

[0005] In order to solve the above technical problems, the technical solutions adopted by the present utility model are as follows.

[0006] A grounding full compensation device based on adjustable impedance adjustment comprises a first transformer and a second transformer connected in parallel on a three-phase bus, wherein the first transformer is a Z-type transformer, the second transformer is a YY-type transformer, the three-phase windings on the secondary side of the YY-type transformer are respectively connected to the neutral point of the Z-type transformer via a high-voltage switch, the controlled ends of the three high-voltage switches are connected to the output end of a controller, the neutral point of the secondary three-phase winding of the YY-type transformer is grounded via an adjustable impedance, and the controlled end of the adjustable impedance is connected to the output end of the controller; the input end of the controller is also connected to a voltage transformer for measuring the three-phase voltage of the bus.

[0007] The above-mentioned grounding full compensation device based on adjustable impedance adjustment, the adjustable impedance is at least one of an adjustable resistor, an adjustable reactor and an adjustable capacitor.

[0008] In the above-mentioned grounding full compensation device based on adjustable impedance adjustment, the connection group of the Z-type transformer is ZN11.

[0009] In the above-mentioned grounding full compensation device based on adjustable impedance regulation, the connection group of the YY type transformer is YNyn6.

[0010] Due to the adoption of the above technical scheme, the technical progress achieved by the present invention is as follows.

[0011] The utility model does not need to use an inverter power supply with a power electronic device, and can achieve full compensation for ground reactive current, active current and harmonic current only through a transformer, a high-voltage switch and an adjustable impedance. The utility model has a simple structure and high reliability. It also does not need to configure a three-phase multi-position high-voltage on-load switch, avoids the operation of frequently adjusting the transformer tap position, reduces costs and insulation requirements, and simplifies the control system structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is the system wiring diagram of Example 1;

[0013] Figure 2 This is the system wiring diagram of Example 2;

[0014] Figure 3 This is the system wiring diagram of Example 3.

[0015] Among them: BYQ1. first transformer, BYQ2. second transformer, PT. voltage transformer, KA. A-phase high-voltage switch, KB. B-phase high-voltage switch, KC. C-phase high-voltage switch, Z. adjustable resistor, KZQ. controller, L. adjustable reactor, C. adjustable capacitor. DETAILED DESCRIPTION

[0016] The present invention will be further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0017] Example 1

[0018] A grounding full compensation device based on adjustable impedance adjustment comprises a first transformer BYQ1, a second transformer BYQ2, a controller KZQ, a voltage transformer PT, an adjustable impedance and three-phase high-voltage switches KA, KB and KC.

[0019] The first transformer BYQ1 and the second transformer BYQ2 are both connected to the three-phase bus ABC phase, wherein the first transformer is a Z-type transformer, and the second transformer is a YY-type transformer. The three-phase windings on the secondary side of the YY-type transformer are respectively connected to the neutral point of the Z-type transformer via a high-voltage switch, and the controlled ends of the three high-voltage switches are connected to the output end of the controller KZQ.

[0020] The neutral point of the secondary three-phase winding of the YY type transformer is grounded via an adjustable impedance, and the controlled end of the adjustable impedance is connected to the output end of the controller; the input end of the controller is also connected to a voltage transformer PT for measuring the three-phase voltage of the bus.

[0021] In this embodiment, the adjustable impedance is an adjustable resistor Z, the connection group of the Z-type transformer is ZN11, the connection group of the YY-type transformer is YNyn6, the transformation ratio of the primary winding to the secondary winding is N, and the voltage directions are opposite; the purpose of using the YY-type transformer with the YNyn6 connection group is that when a phase grounding fault occurs, the reverse phase voltage of the fault phase can be transformed by the YY-type transformer. The connection relationship between the various electrical equipment is as follows: Figure 1 shown.

[0022] During the operation of this embodiment, when the controller detects that a single-phase grounding occurs in a phase of the system, the controller performs phase judgment and closes the high-voltage switch KA, KB or KC of the corresponding phase for compensation. During the compensation process, the controller adjusts the resistance value of the adjustable resistor Z according to the voltage value collected by the voltage transformer, compensates the active current, reactive current and harmonic current of the system to the ground, makes the voltage and current at the grounding point close to zero, and completes the full compensation operation.

[0023] Example 2

[0024] The difference between this embodiment and embodiment 1 is that the adjustable impedance is an adjustable reactor L, and its system wiring diagram is as follows: Figure 2 The controller adjusts the inductance value of the adjustable reactor L according to the voltage value collected by the voltage transformer, compensates the active current, reactive current and harmonic current of the system to the ground, and makes the voltage and current at the grounding point close to zero.

[0025] Example 3

[0026] The difference between this embodiment and embodiment 1 is that the adjustable impedance is an adjustable capacitor C, and its system wiring diagram is as follows: Figure 3 The controller adjusts the capacitance value of the adjustable capacitor C according to the voltage value collected by the voltage transformer, compensates the active current, reactive current and harmonic current of the system to the ground, and makes the voltage and current of the grounding point close to zero.

[0027] Of course, in the present invention, the adjustable impedance can also be a combination of any two or three of the adjustable resistor Z, the adjustable reactor L and the adjustable capacitor C. After the combination, the adjustable impedances can be connected in series, in parallel or in a combination of series and parallel.

[0028] In the utility model, the secondary winding of the second transformer BYQ2 is connected to the neutral point of the first transformer BYQ1, which can compensate for the fault phase voltage of the single-phase grounding fault, but it cannot be reduced to 0V due to the influence of the internal impedance of the transformer. The higher the system capacitance current, the higher the residual voltage of the fault phase. The neutral point of the secondary winding of the second transformer BYQ2 can continue to reduce the residual voltage of the fault phase by hanging an adjustable impedance until the fault phase voltage is 0V. At the same time, the application of the utility model reduces the number of switches, simplifies the control logic, and reduces the production and maintenance costs.

Claims

1. A grounding full compensation device based on adjustable impedance adjustment, characterized in that: The invention comprises a first transformer (BYQ1) and a second transformer (BYQ2) connected in parallel on a three-phase bus, wherein the first transformer is a Z-type transformer, the second transformer is a YY-type transformer, the three-phase windings on the secondary side of the YY-type transformer are respectively connected to the neutral point of the Z-type transformer via a high-voltage switch, the controlled ends of the three high-voltage switches are connected to the output end of a controller (KZQ), the neutral point of the secondary three-phase winding of the YY-type transformer is grounded via an adjustable impedance, and the controlled end of the adjustable impedance is connected to the output end of the controller; the input end of the controller is also connected to a voltage transformer (PT) for measuring the three-phase voltage of the bus.

2. A grounding full compensation device based on adjustable impedance adjustment according to claim 1, characterized in that: The adjustable impedance is at least one of an adjustable resistor (Z), an adjustable reactor (L) and an adjustable capacitor (C).

3. A grounding full compensation device based on adjustable impedance adjustment according to claim 1, characterized in that: The connection group of the Z-type transformer is ZN11.

4. A grounding full compensation device based on adjustable impedance adjustment according to claim 1, characterized in that: The connection group of the YY type transformer is YNyn6.

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