Power distribution network phase power supply feed-in type flexible grounding and voltage arc extinction complete equipment

Abstract

The utility model discloses power distribution network phase power supply feed-in type flexible grounding and voltage arc extinction complete equipment. The complete equipment comprises a transformer bank and a voltage arc extinction measurement and control cabinet. The transformer bank consists of a grounding transformer and an injection transformer; the voltage arc extinction measurement and control cabinet comprises a measurement and control unit, a phase selection control unit and an injection voltage adjusting unit. The signal input end of the measurement and control unit is connected with the power distribution network; the signal output end of the measurement and control unit is connected with the phase selection control unit and the injection voltage adjusting unit. A secondary coil leading-out terminal of the grounding transformer is connected with a primary coil of the injection transformer through the phase selection control unit, the injection regulation and control resistor Rx and the injection voltage regulation unit; the dotted terminal of the secondary coil of the injection transformer is connected with the neutral point of the grounding transformer, and the synonym terminal of the secondary coil of the injection transformer is grounded. According to the utility model, the active step-down arc-extinguishing function of the single-phase earth fault phase of the power distribution network can be realized, and the single-phase earth fault arc-extinguishing effect of the power distribution network is improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of distribution network fault processing, and in particular relates to a distribution network phase power feed-in type flexible grounding and voltage arc suppression complete set of equipment. Background Art

[0002] Distribution networks have complex topologies and highly variable operating conditions, resulting in a high incidence of line faults, with single-phase ground faults accounting for a high proportion. Fault arc currents are low, and exhibit complex patterns and evolution characteristics, ranging from transient to continuous, making fault identification and suppression extremely difficult. Prolonged operation with ground faults poses a serious threat to personnel and equipment safety. If ground faults are not promptly extinguished, they can easily cause arc flash overvoltages, electrical fires, and widespread power outages, seriously threatening distribution network operations.

[0003] On the other hand, the choice of distribution network grounding method has been a long-standing topic of debate both domestically and internationally. Each grounding method has its own operating environment, scope of application, and shortcomings. Traditional neutral point grounding methods are determined during grid construction and generally remain unchanged during operation. Only the arc suppression coil reactance can be adjusted within a limited range. However, existing arc suppression coil tuning technology generally only adjusts according to grounding residual current or detuning degree. This makes it difficult to simultaneously achieve good results in suppressing three-phase unbalanced voltage, ferroresonant overvoltage, accelerating ground fault arc extinguishing, and facilitating fault line selection. It cannot effectively suppress persistent arc-flash grounding faults such as cable lines, and the arc suppression effect of faults is limited. It is prone to generating three-phase unbalanced voltage and ferroresonant overvoltage, posing certain safety risks. Moreover, the complete sets of equipment manufactured based on current arc suppression technology occupy a large area and have low space utilization. Utility Model Content

[0004] The utility model provides a complete set of flexible grounding and voltage arc suppression equipment for phase power supply feeding of distribution network, which can realize the active voltage reduction and arc suppression function of the phase of single-phase grounding fault in distribution network, and improve the arc suppression effect of single-phase grounding fault in distribution network.

[0005] The technical solution provided by this utility model is:

[0006] A complete set of flexible grounding and voltage arc suppression equipment for phase power feeding of distribution network, including a transformer group and a voltage arc suppression measurement and control cabinet;

[0007] The transformer group consists of a grounding transformer and an injection transformer. The secondary coil of the injection transformer is connected in series between the neutral point of the grounding transformer and the earth. The secondary coil of the grounding transformer is output to the primary coil of the injection transformer.

[0008] In some possible implementations, a damping resistor is connected in series between the secondary coil of the injection transformer and the ground, and a shorting switch is connected in parallel across both ends of the damping resistor.

[0009] In some possible implementations, the voltage arc suppression measurement and control cabinet includes a measurement and control unit, a phase selection control unit, and an injection voltage adjustment unit;

[0010] The signal input end of the measurement and control unit is connected to the power distribution network; the signal output end of the measurement and control unit is connected to the phase selection control unit and the injection voltage adjustment unit;

[0011] The primary coil lead-out terminals A, B, and C of the grounding transformer are respectively connected to the three-phase power supply terminals of the distribution network; the secondary coil lead-out terminals of the grounding transformer are connected to the primary coil of the injection transformer via the phase selection control unit, the injection control resistor Rx, and the injection voltage adjustment unit; the like-name ends of the secondary coil of the injection transformer are connected to the neutral point O of the grounding transformer, and the opposite-name ends of the secondary coil of the injection transformer are grounded.

[0012] In some possible implementations, the phase selection control unit includes switches a1, a2, b1, b2, c1, and c2;

[0013] The injection voltage adjustment unit includes a plurality of tap switches.

[0014] The secondary coil lead-out terminal of the above-mentioned grounding transformer is connected to the primary coil of the injection transformer via the phase selection control unit, the injection control resistor Rx and the injection voltage adjustment unit, including:

[0015] The secondary coil lead-out terminals a, b, and c of the grounding transformer are connected to one end of the injection regulating resistor Rx via switches a1, b1, and c1, respectively. The other end of the injection regulating resistor Rx is connected to taps of different gears at the same-name end of the primary coil of the injection transformer via multiple tap changers; and the secondary coil lead-out terminals a, b, and c of the grounding transformer are connected to the opposite-name end of the primary coil of the injection transformer via switches a2, b2, and c2, respectively.

[0016] In some possible implementations, it also includes an arc suppression coil with adjustable gear position and a control device thereof;

[0017] The neutral point is grounded via an arc suppression coil.

[0018] In some possible implementations, the voltage arc suppression measurement and control cabinet further includes an injection loop overcurrent and short-circuit protection circuit.

[0019] In some possible implementations, the transformer group is based on a combination of a grounding transformer and an injection transformer with a common oil tank, and an oil level gauge, a pressure relief valve and an oil temperature thermometer seat are provided on the oil tank cover of the transformer group.

[0020] In some possible implementations, the voltage arc suppression measurement and control cabinet further includes a transformer monitoring device, a high and low voltage temperature and humidity control device for the measurement and control cabinet, a wireless communication module, and a power supply circuit.

[0021] In some possible implementations, the housing of the complete equipment is provided with a mounting structure for mounting the complete equipment on a distribution line pole.

[0022] Beneficial effects:

[0023] When a single-phase grounding fault occurs in the distribution network, the present invention can automatically adjust the phase and magnitude of the zero-sequence voltage injected into the neutral point of the distribution network according to the phase difference and fault characteristics of the grounding fault, control the voltage at the single-phase grounding fault point to be lower than the arc reignition voltage at the fault point, perform full fault current compensation, and realize active voltage reduction and arc extinguishing at the grounding fault point. When equipped with an arc suppression coil, the complete set of equipment can control the arc suppression coil to the position with the minimum residual current in the distribution network in real time according to the real-time measurement of the distribution network's ground capacitance current. Therefore, the present invention can improve the effect of arc extinguishing in distribution network faults. In addition, the present invention can adopt a similar pole-mounted installation method in a substation, greatly reducing the equipment on-site installation period and cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of the circuit structure of an embodiment of the present application;

[0025] Figure 2 This is a schematic diagram of an embodiment of the present application;

[0026] Figure 3 This is a schematic diagram of the oil tank cover structure of a transformer group in one embodiment of the present application. DETAILED DESCRIPTION

[0027] In order to make the technical solutions and functions implemented by the present invention clearer, the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0028] The circuit structure diagram of an embodiment of the present application is as follows Figure 1 As shown, the box part is the equipment part. are the three-phase power supply potential of the distribution network, C0 is the capacitance of the distribution network to the ground, G0 is the leakage conductance of the distribution network to the ground, R f is the fault grounding resistance, T1 is a Z-type grounding transformer, and a feedback line voltage switching switch a is provided on the secondary side. x 、b x 、c x (x=1,2), T2 is an adjustable voltage injection transformer, R x The injection control resistor is an adjustable resistor that can be used to adjust the injection voltage. S is the power supply potential feedback input control switch, closed when voltage is injected and open when voltage is not injected. L0 is the arc suppression coil. The primary and secondary winding turns ratio of the grounding transformer T1 is N1:N2, and the primary and secondary transformation ratio K of the injection transformer T2 is adjustable. They represent the voltage and current at the injection neutral point of the injection transformer connected to the neutral point of the distribution network.

[0029] The embodiment of the present application is a complete set of flexible grounding and voltage arc suppression equipment for power supply feeding of distribution network, including a transformer group, a voltage arc suppression measurement and control cabinet, and supporting primary and secondary equipment, etc. The schematic diagram is as follows: Figure 2 shown.

[0030] The transformer group consists of a grounding transformer and an injection transformer. The secondary coil of the injection transformer is connected in series between the neutral point of the grounding transformer and the earth. The secondary coil of the grounding transformer is output to the primary coil of the injection transformer.

[0031] In some embodiments, a damping resistor is connected in series between the secondary coil of the injection transformer and the ground, and a shorting switch is connected in parallel across the damping resistor.

[0032] In some embodiments, the voltage arc suppression measurement and control cabinet includes a measurement and control unit, a phase selection control unit, and an injection voltage adjustment unit;

[0033] The signal input end of the measurement and control unit is connected to the distribution network, and the signal output end is connected to the phase selection control unit and the injection voltage adjustment unit, and is used to monitor whether a single-phase grounding fault occurs in the distribution network. After detecting the occurrence of a single-phase grounding fault, the grounding fault phase is determined. According to the grounding fault phase and fault characteristics, the phase of the zero-sequence voltage injected into the neutral point of the distribution network is selected by the phase selection control unit, and the magnitude of the zero-sequence voltage injected into the neutral point of the distribution network is adjusted by the injection voltage adjustment unit.

[0034] The phase selection control unit includes a plurality of switches for controlling the phase difference of the zero-sequence voltage injected into the neutral point of the distribution network;

[0035] The injection voltage adjustment unit is used to adjust the gear position of the tap connected to the primary coil of the injection transformer, thereby adjusting the magnitude of the zero-sequence voltage injected into the neutral point of the distribution network;

[0036] The primary coil lead-out terminals A, B, and C of the grounding transformer are respectively connected to the three-phase power supply terminals of the distribution network; the secondary coil lead-out terminals (low-voltage side terminals) of the grounding transformer are connected to the primary coil (primary side) of the injection transformer via the phase selection control unit, the injection control resistor Rx, and the injection voltage adjustment unit; the like-name ends of the secondary coil (secondary side) of the injection transformer are connected to the neutral point O, and the opposite-name ends of the secondary coil of the injection transformer are grounded.

[0037] The connection of the same-name end of the secondary coil of the injection transformer to the neutral point O of the grounding transformer may be that the same-name end of the secondary coil of the injection transformer is connected to the neutral point O of the grounding transformer via the power supply potential feedback input control switch S.

[0038] Furthermore, the phase selection control unit includes switches a1, a2, b1, b2, c1 and c2;

[0039] Furthermore, the injection voltage adjustment unit includes a plurality of tap switches.

[0040] The secondary coil lead-out terminal of the above-mentioned grounding transformer is connected to the primary coil of the injection transformer via the phase selection control unit, the injection control resistor Rx and the injection voltage adjustment unit, including:

[0041] The secondary winding lead-out terminals a, b, and c of the grounding transformer are connected to one end of the injection regulating resistor Rx through switches a1, b1, and c1 respectively, and the other end of the injection regulating resistor Rx is connected to multiple tap switches (such as Figure 1 The k1, k2, and k3 shown in the figure are connected to the taps of the same end of the primary coil of the injection transformer at different gears (such as Figure 1 and the grounding transformer's secondary coil lead-out terminals a, b, and c are connected to the opposite-name terminals (non-same-name terminals) of the primary coil of the injection transformer via switches a2, b2, and c2, respectively.

[0042] Furthermore, the primary coil (high-voltage coil) lead-out terminals A, B, and C of the grounding transformer are connected to the 10kV distribution network. It is a multi-layer cylindrical type, wound in the left direction, with the coil wound tightly and the ends flush.

[0043] Furthermore, the primary coil (low-voltage coil) of the injection transformer leads to terminals aa2 and xx2, which are connected to the arc-extinguishing voltage source and the measurement and control unit. It is wound in the left direction, and the high and low voltage coils are wound in a loop.

[0044] Furthermore, an arc suppression coil and its control device are provided inside the complete set of equipment; the neutral point is grounded via the arc suppression coil.

[0045] Furthermore, a variable frequency low current signal with a power of about 1W is injected into the low-voltage side of the injection transformer, and the return voltage signal is measured to find the resonant frequency of the distribution network and calculate the ground insulation parameters of the distribution network, such as ground capacitance, ground resistance and damping rate.

[0046] Furthermore, after obtaining the distribution network's ground capacitance C0 value, the ideal arc suppression coil inductance value can be calculated, and the arc suppression coil can be promptly controlled to the position with the minimum residual current in the distribution network. This approach is beneficial to reducing the injection current of the injection transformer and the grounding transformer, and further reducing the capacity requirements of the two devices.

[0047] Furthermore, the transformer group is based on a combination of a grounding transformer and an injection transformer with a common oil tank.

[0048] Furthermore, an oil level gauge, a pressure relief valve and a thermometer seat are provided on the oil tank cover of the transformer group, which are used to monitor the oil level of the transformer, prevent the internal pressure of the transformer from being too high, and monitor the internal oil temperature of the transformer group respectively.

[0049] Furthermore, the voltage arc suppression measurement and control cabinet is the core control part of the entire set of equipment, which can be divided into a high-voltage room, a resistance room and a low-voltage control room.

[0050] The high-voltage chamber includes a main incoming line circuit breaker and an injection phase selection and gear switching switch (contactor) array, which mainly realizes the functions of injection voltage phase selection, injection voltage size adjustment (transformer gear adjustment, which also includes an adjustable voltage source) and injection circuit overcurrent and short-circuit protection;

[0051] The resistance chamber contains a ground fault analysis resistor and an injection control resistor;

[0052] The low-voltage control room, comprising a measurement and control unit, transformer monitoring equipment, temperature and humidity control devices in the measurement and control cabinet, a wireless communication module, and power supply circuitry, is the core control component of the entire equipment set. The transformer oil tank cap is equipped with an oil level gauge, a pressure relief valve, and a thermometer holder, which serve as the sensor components of the transformer monitoring system.

[0053] Furthermore, the measurement and control unit adopts a 32-bit high-performance processor, and the smart boards in the device are connected through a high-speed and high-performance communication bus, which ensures the reliability of data communication between the smart plug-ins and is easy to expand.

[0054] Furthermore, the measurement and control unit can monitor parameters such as the distribution network's ground capacitance current (the sum of the currents flowing through the capacitance of each phase of the distribution network) and ground conductance in real time. When equipped with an arc suppression coil, the complete set of equipment can control the arc suppression coil to the position that minimizes the residual current in the distribution network based on the real-time measurement of the distribution network's ground capacitance current. This allows the coil's inductance to be adjusted, changing the compensation current and reducing the residual current at the fault point.

[0055] In this equipment, the measurement and control unit detects the three-phase voltage of the distribution network and calculates the zero-sequence voltage in real time. When the zero-sequence voltage is detected to be greater than 15% of the phase voltage or the change in zero-sequence voltage is greater than 3%, it is determined that a single-phase grounding fault has occurred in the distribution network. After detecting a single-phase grounding fault, the measurement and control unit determines that the phase with the smallest phase voltage is the fault phase based on the grounding fault phase.

[0056] When the measurement and control unit detects a single-phase ground fault in the distribution network, it automatically adjusts the phase and magnitude of the zero-sequence voltage injected into the distribution network neutral point based on the ground fault phase and fault characteristics. This controls the voltage at the single-phase ground fault point to be lower than the arc reignition voltage at the fault point, compensates for the full fault current (including active, reactive, and harmonic components), and achieves active voltage reduction and arc extinguishing at the ground fault point. This ensures complete arc extinguishing of the instantaneous fault.

[0057] Furthermore, the phase and magnitude of the zero-sequence voltage injected into the neutral point of the distribution network are adjusted according to the fault phase type. The specific adjustment method is to select the six switches of the phase control unit to achieve the output of the opposite phase voltage of the fault on the secondary side of the grounded transformer. The adjustment method can be referred to in the table:

[0058] Fault phase Phase A fault Phase B fault Phase C fault Output reverse voltage a2, c1 b2, a1 c2, b1

[0059] According to the adjustment method in the above table, for example, when phase A fails, a2 and c1 of the six switches are closed, and the rest are disconnected; when phase B fails, b2 and a1 of the six switches are closed, and the rest are disconnected; when phase C fails, c2 and b1 of the six switches are closed, and the rest are disconnected.

[0060] The arc extinguishing method of this equipment is to inject a phase voltage opposite to the fault phase into the neutral point of the distribution network. The reverse phase voltage comes from the output voltage of the low-voltage side of the grounding transformer after switch regulation. This voltage is injected into the neutral point after being boosted by the injection transformer T2, which can reduce the fault phase voltage to below the critical arc extinguishing voltage, extinguish the arc from the arc maintenance adjustment value, and completely extinguish the arc, eliminating the grounding fault.

[0061] Furthermore, while this set of equipment is performing voltage arc extinguishing, the residual current of the distribution network has been reduced to the minimum through the arc extinguishing coil control method before the voltage is injected. After the voltage arc is extinguished, the residual current of the distribution network disappears. When the measurement and control unit detects that the grounding fault disappears, the entire set of equipment can quickly exit the compensation state.

[0062] Furthermore, the complete set of equipment is designed with a flexible interface that can determine whether to configure a pre-adjusted arc suppression coil based on the grounding capacitance current level of the distribution network. Generally speaking, arc suppression coils are required when the ground capacitance current level of the distribution network is greater than 10A. The primary coil of the injection transformer of this equipment is set with different gears: x1, x2, x3, x4, x5, x6, and x7, which are used to adjust the compensation current. Among them, the three gears x1, x2, and x3 can be used for ungrounded systems, and the four gears x4, x5, x6, and x7 can be used for grounded systems.

[0063] Furthermore, the housing of the complete equipment is provided with a mounting structure for mounting the complete equipment on a distribution line tower. The complete equipment may be mounted in, but not limited to, a pole-mounted installation, and may be installed outdoors within a substation.

[0064] After testing, the above-mentioned distribution network phase power feedback type flexible grounding and voltage arc suppression scheme has the following advantages:

[0065] (1) The single-phase high-resistance ground fault detection capability of up to 16kΩ can quickly handle the budding single-phase ground fault to prevent the ground fault from further deteriorating and expanding;

[0066] (2) Effectively avoid tripping of fault lines caused by transient single-phase grounding faults, reducing the probability of power outages caused by single-phase grounding faults by 50%;

[0067] (3) When the voltage reduction and arc suppression is started, the complete set of equipment can quickly clamp the non-fault phase voltage to Double the phase voltage, which can effectively avoid the occurrence of 4 to 8 times intermittent arc grounding overvoltage;

[0068] (4) During compensation, the busbar fault phase residual pressure is small and the grounding point step voltage is low, which can greatly reduce the risk of electric shock to people at the single-phase grounding point;

[0069] (5) It greatly reduces the on-site installation period and cost of equipment, helps the operation management and maintenance of complete sets of equipment, and improves the availability of complete sets of equipment.

[0070] The above description of the embodiments of the present application is only a partial embodiment of the present application, which is used to enable professionals in this field to implement or use the contents of the present application, and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A complete set of flexible grounding and voltage arc suppression equipment for phase power feeding of distribution network, characterized in that: Including transformer group and voltage arc suppression measurement and control cabinet; The transformer group consists of a grounding transformer and an injection transformer. The secondary coil of the injection transformer is connected in series between the neutral point of the grounding transformer and the earth. The secondary coil of the grounding transformer is output to the primary coil of the injection transformer.

2. The distribution network phase power feed-in type flexible grounding and voltage arc suppression complete equipment according to claim 1, characterized in that: A damping resistor is connected in series between the secondary coil of the injection transformer and the ground, and a short-circuit switch is connected in parallel across both ends of the damping resistor.

3. The distribution network phase power feed type flexible grounding and voltage arc suppression complete equipment according to claim 1, characterized in that: The voltage arc suppression measurement and control cabinet includes a measurement and control unit, a phase selection control unit and an injection voltage adjustment unit; The signal input end of the measurement and control unit is connected to the power distribution network; the signal output end of the measurement and control unit is connected to the phase selection control unit and the injection voltage adjustment unit; The primary coil lead-out terminals A, B, and C of the grounding transformer are respectively connected to the three-phase power supply terminals of the distribution network; the secondary coil lead-out terminals of the grounding transformer are connected to the primary coil of the injection transformer via the phase selection control unit, the injection control resistor Rx, and the injection voltage adjustment unit; the like-name ends of the secondary coil of the injection transformer are connected to the neutral point O of the grounding transformer, and the opposite-name ends of the secondary coil of the injection transformer are grounded.

4. The distribution network phase power feed-in type flexible grounding and voltage arc suppression complete equipment according to claim 3, characterized in that: The phase selection control unit includes switches a1, a2, b1, b2, c1 and c2; The injection voltage adjustment unit includes a plurality of tap switches; The secondary coil lead-out terminal of the grounding transformer is connected to the primary coil of the injection transformer via a phase selection control unit, an injection control resistor Rx and an injection voltage adjustment unit, including: The secondary coil lead-out terminals a, b, and c of the grounding transformer are connected to one end of the injection regulating resistor Rx via switches a1, b1, and c1, respectively. The other end of the injection regulating resistor Rx is connected to taps of different gears at the same-name end of the primary coil of the injection transformer via multiple tap changers; and the secondary coil lead-out terminals a, b, and c of the grounding transformer are connected to the opposite-name end of the primary coil of the injection transformer via switches a2, b2, and c2, respectively.

5. The distribution network phase power feed-in type flexible grounding and voltage arc suppression complete equipment according to claim 1, characterized in that: It also includes an arc suppression coil with adjustable gear position and its control device; The neutral point is grounded via an arc suppression coil.

6. The distribution network phase power feed-in type flexible grounding and voltage arc suppression complete equipment according to claim 1, characterized in that: The voltage arc suppression measurement and control cabinet also includes an injection loop overcurrent and short-circuit protection circuit.

7. The distribution network phase power feed-in type flexible grounding and voltage arc suppression complete equipment according to claim 1, characterized in that: The transformer group is based on a grounding transformer and an injection transformer with a common oil tank. The oil tank cover of the transformer group is provided with an oil level gauge, a pressure relief valve and a thermometer seat.

8. The distribution network phase power feed-in type flexible grounding and voltage arc suppression complete equipment according to claim 1, characterized in that: The voltage arc suppression measurement and control cabinet also includes a transformer monitoring device, a measurement and control cabinet temperature and humidity control device, a wireless communication module and a power supply circuit.

9. The distribution network phase power feed-in type flexible grounding and voltage arc suppression complete equipment according to any one of claims 1 to 8, characterized in that: The housing of the complete equipment is provided with a mounting structure for mounting the complete equipment on a distribution line pole tower.

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