Arc Suppression Coil Complete Set Neutral Point Grounding Protection Equipment

Neutral point grounding protection equipment

Arc suppression coil complete set

Small/low current earth-fault line selection device

Arc suppression coil and grounding transformer complete device

Intelligent arc suppression coil grounding compensation device is mainly used in neutral point grounding through the arc suppression coil of 6kV,10kV,35kV power grids. It automatically tracks and compensates the grid capacitive current to keep it in the setting parameter range, eliminates grid system internal over-voltage and resonance over-voltage, it will automatically alarm when grounding fault occurs in the power grid, and has remote output interfaces to communicate with the host computer. This device is characterized by fast response speed, high accuracy, and solving the problem of crashes, etc. It is the best grounding electrical equipment for the vast of medium voltage distribution networks.

Purpose of installing arc suppression coil at neutral point:

1.Automatically eliminate the instantaneous single-phase grounding fault of the power grid.

2.When a permanent (metal) single-phase grounding fault occurs, there are two options: tripping after the fault line is detected by the line selection device or the microcomputer grounding protection. The power grid operates with a fault within a certain time, after the dispatching department transfers the load, it delays to trip the faulty line, which makes the power grid highly reliable.

Overall structure of the complete set of bias magnetic arc suppression coil

The device is composed of grounding transformer, bias magnetic arc suppression coil, microcomputer controller, current transformer, etc.

 1.Grounding transformer

The arc-suppression coil system must have a neutral point when it is connected, and the arc-suppression coil is connected at its neutral point. The role of the grounding transformer is to construct the system neutral point with the grounding transformer when the neutral point not drawn of the power system is triangle-type wiring or Y-type wiring.

The grounding transformer is a Z-type wiring transformer, that is, a transformer with ZN,yn11 connection. Because the high-voltage side of the transformer uses Z-type wiring, each phase of the winding consists of two sections and is located on two iron cores of different phases. The two sections of the coils are connected in reverse polarity, the zero-sequence magnetic flux generated by two-phase windings cancel each other out. So the zero sequence impedance is very low, and the no-load loss is very small. The transformer capacity can be used 100%. When an ordinary transformer is used with an arc suppression coil, the capacity of the arc suppression coil does not exceed 20% of the transformer capacity, but the Z-type transformer can match with an arc suppression coil of 90% -100% its capacity, which can save investment.
 

In addition to the arc suppression coil, the grounding transformer can also carry a secondary load instead of a station transformer. When there is a secondary load, the primary capacity of the grounding transformer should be the sum of the capacity of the arc extinguishing coil and the secondary load, when the grounding transformer does not have a secondary load, the capacity of the grounding transformer is equal to the capacity of the arc suppression coil.
 

2. Arc-suppression coil with magnetic bias

The Arc-suppression coil with magnetic bias automatic tracking compensation control system adopts a magnetized iron core section arranged in the AC coil, and changes the magnetic permeability of the iron core by applying a DC excitation current to achieve continuous adjustable inductance. When single-phase grounding occurs in the power grid, the system can instantly adjust the inductance to compensate the grounding capacitor current. This system leads the industry with its excellent technical performance of stepless continuous and static adjustable electric control. It is a replacement product of traditional air-gap, on-load and turn-adjusting, and on-load capacity adjusting arc suppression coils.
 

Arc suppression coil characteristics

1.The inductance of the bias magnetic arc suppression coil body can be adjusted continuously and instantaneously, and the adjustment speed is fast.

2.The body of the bias magnetic arc extinguishing coil has a completely static structure, without any mechanical moving parts inside, no contact, high reliability and long service life.
 

Other devices:

1.Turning arc-suppression coil& grounding transformer complete set

2.Bias magnetic arc suppression coil& grounding transformer complete set

3.Adjustable capacity arc suppression coil& grounding transformer complete set

4.Phase-controlled arc suppression coil complete set

5.Arc extinguishing& harmonic elimination and overvoltage protection device

6.Small current grounding fault line selection device

Turning arc-suppression coil& grounding transformer complete set

The turn-adjusting arc suppression coil is provided with a plurality of taps of the arc suppression coil, and the on-load adjustment switch is used to adjust the tap of the arc suppression coil to change the inductance value, so as to realize the output of the inductor current to the ground for the purpose of automatic tracking compensation.

Working principle

When the power grid is operating normally, the microcomputer controller of the arc suppression coil calculates the capacitance current to the ground in the current mode of the grid through real-time measurement and calculation. According to the preset minimum residual current value or detuning degree to determine the gear position where the arc suppression coil should be in, the on-load voltage regulating tap is controlled by the controller to adjust it to the required compensation position. After a ground fault occurs, the residual current at the fault point can be limited to the setting range to play an effective arc extinguishing and ensure the safety of the power supply system.

Components of turn-adjusting arc suppression coil

The turn-adjusting arc suppression coil complete device generally consists of grounding transformer, turn-adjusting arc suppression coil, on-load section switch, microcomputer controller, control cabinet, damping resistance box, current transformer, voltage transformer,  lightning arrester, isolator and other parts.

Bias magnetic arc suppression coil& grounding transformer complete set

The bias magnetic arc extinguishing coil has an iron core magnetizing section arranged in its AC working coil. By changing the DC assisted magnetic flux on the magnetic circuit of the iron core magnetizing section, the AC equivalent permeability is adjusted to achieve the purpose of continuously adjustable inductance. Its DC excitation winding adopts reverse-serial connection to make the power frequency voltages induced on the entire winding cancel each other out. Through the closed-loop adjustment of the output current of the three-phase full-control rectifier circuit, the control of the excitation current of the arc suppression coil is realized. The core controller continuously monitors the neutral point displacement voltage and the arc suppression coil current to realize automatic tracking and detection of the capacitor current under normal operating conditions of the power grid, dynamic compensation under fault operating conditions, and automatic recovery after the fault disappears.

Working principle

When the power grid is running normally, the microcomputer controller of the arc suppression coil calculates the capacitance current to ground in the current mode of the grid through real-time measurement and calculation, and judges the output inductor current of the arc suppression coil based on the preset minimum residual current value or detuning. After the ground fault occurs, adjust the reactance value of the arc suppression coil to output the compensation current.

Residual current at the fault point can be limited in the setting range to effectively extinguish the arc and ensure the safety of the power supply system.

Components of bias magnetic arc suppression coil

The complete set of bias magnetic arc extinguishing coil is generally composed of grounding transformer, bias magnetic arc extinguishing coil, microcomputer controller, control cabinet, current transformer, voltage transformer, lightning arrester, isolator, etc

6kV and 10kV system control cabinet without flat wave reactor, 35kV and 66kV system control cabinet with flat wave reactor.

The neutral point arc suppression coil compensation system of the generator requires no additional grounding transformer.

If the 35kV and 66kV systems have a neutral point, no additional grounding transformer is required.

Adjustable capacity arc suppression coil& grounding transformer complete set

Adjustable capacity arc suppression coil body is composed of main winding and secondary winding. The secondary winding is connected to the capacitor adjustment cabinet. The 4 to 5 groups of vacuum contactors control the switching to the secondary adjust the capacitors. The inductive current of the arc suppression coil is adjusted by using the opposite phase of the capacitive current and the inductive current. When the secondary capacitors are all disconnected, the main winding has the smallest inductive reactance and the largest inductor current. After the secondary winding has capacitors connected, according to the principle of impedance conversion, it is equivalent to connecting the same power capacitors at both ends of the main winding, so that the inductor current is reduced. Therefore, the inductance of the main winding and the magnitude of the inductor current can be controlled by adjusting the capacity of the secondary capacitor.

Working principle

The capacity-adjusting arc suppression coil uses the refraction principle of the transformer to add the secondary capacitor load winding of the arc suppression coil. At the same time, several groups (usually four to five groups) of low-voltage capacitors are connected in parallel to the secondary winding of the arc suppression coil. The on-off combination of the vacuum switch or the reverse-parallel thyristor controlled by the controller is used to control the quantity of the secondary capacitor input to adjust the secondary capacitive reactance of the arc suppression coil to change the magnitude of the inductor current on the primary side of the arc suppression coil.

Components of the capacity-adjusting arc suppression coil

Complete set of capacity-adjusting arc suppression coils are generally composed of grounding transformers, capacity-adjusting arc suppression coils, capacitor regulation cabinets, microcomputer controllers, control cabinet, damping resistor boxes, current transformers, voltage transformers, lightning arresters, isolators, etc.

Phase-controlled arc suppression coil complete set

The phase-controlled arc suppression coil uses advanced algorithms to select lines for high-voltage grounding lines. The line selection is accurate and fast. It is widely used in the distribution station of power supply industry, power plants, metallurgy, mining, coal, papermaking, petrochemical and other large factories and mining companies. It is suitable for the voltage level of 6~66KV. It is an ideal replacement product of the old arc suppression coil, and it is also the first choice of supporting products for the grounding compensation and line selection device of the new substation.

Composition of the device

Phase-controlled arc suppression coil is composed of grounding transformer, phase-controlled arc suppression coil, local control cabinet, computer controller, etc

Arc extinguishing& harmonic elimination and overvoltage protection device

 Arc-suppression& harmonic elimination and over-voltage protection devices can limit the phase-to-phase and phase-to-ground over-voltage of the neutral point ineffectively grounding system to the safe range of the power grid, it completely solve the threat of various over-voltages to the power grid, and improve the reliability  of safe power supply of the power grid.