CN110058071A - Zero sequence current sensor circuit topology and switch pole - Google Patents

Abstract

The invention provides a circuit topology and a switch pole of a zero-sequence current sensor, comprising: a three-phase phase-sequence current sensor, the phase-sequence current and zero-sequence current of each phase of the three-phase electricity share one primary of the three-phase phase-sequence current sensor The current acquisition coil is used for acquisition; for the current transformer, one end of the primary side of the current transformer is connected to the primary current acquisition coil through the zero sequence output loop, and the other end of the primary side of the current transformer is grounded, and is connected to the primary current through the phase sequence output loop. The other end of the acquisition coil is connected; the resistor R _I0 is connected in parallel with the secondary side of the current transformer. The error introduced by the interference of space magnetic field and magnetic leakage is avoided, and the size of the current transformer is greatly reduced; The problem of affecting the phase sequence accuracy due to the series resistance on the side neutral line and the disadvantages of zero-sequence impedance matching and requiring the configuration of high-power resistors.

Description

Zero-sequence current sensor circuit topology and switch pole

technical field

The present invention relates to the technical field of electronic circuits, and in particular, to a circuit topology and a switch pole of a zero-sequence current sensor.

Background technique

The zero-sequence current sensor is a sensor that collects the zero-sequence current in the distribution network line. The patent publication number CN108051689A discloses a zero-sequence current sensor, which is composed of at least two petal contacts to form a ring-shaped iron core. One end of the wire is fixed, and the other end of the wire is fixed by the bracket ring; the petal contacts of the zero-sequence current sensor are welded together to form an integral body, and the two ends of the petal contacts are also provided with fixed springs; the number of petal contacts is 8; the turns ratio of the zero-sequence current sensor is 2000:1; it is installed and applied to the user side of the power grid.

At present, three-phase feed-through electromagnetic zero-sequence current transformers such as racetrack type and circular type are mainly used to collect zero-sequence current, and phase-sequence current and zero-sequence current are collected by independent coils. The current transformer needs to pass the three-phase current through the transformer, and a large error is introduced due to the three-phase space magnetic field interference and magnetic leakage. In addition, it is bulky, especially for on-column switches, and it is inconvenient to install. Therefore, the application is greatly limited.

The technical solutions currently used mainly include the following:

Phase-sequence zero-sequence independent coils as shown in Figure 1, feedthrough or racetrack zero-sequence current transformers, phase-sequence zero-sequence splits as shown in Figure 2, three-phase integrated zero-sequence current transformers, and as shown in Figure 2 The phase-sequence zero-sequence independent coil shown in Figure 3 is a three-phase split zero-sequence current sensor.

Figure 4 shows a simple phase-sequence zero-sequence sharing coil method, but there are several drawbacks that are difficult to solve under this method:

(1) As a safety requirement, the secondary side of the three-phase phase sequence current sensor must be directly grounded at one point, and it is not feasible to directly connect the resistor in series with the neutral line of the secondary side of the phase sequence current transformer;

(2) It is difficult to select the resistance value of the sampling resistor. If the resistance value is too large, it will directly affect the accuracy of the phase sequence. If the resistance value is too small, the accuracy of the zero sequence is difficult to achieve;

(3) Considering the saturation coefficient, the power requirement of the sampling resistor is large, so the volume is large;

(4) Since a certain temperature range needs to be met, the temperature coefficient of the sampling resistor is required to be very low, and the power of the resistor is required to be large, so the production of the resistor is difficult, and the price is high, which is not practical.

SUMMARY OF THE INVENTION

In view of the defects in the prior art, the purpose of the present invention is to provide a circuit topology and a switch pole of a zero-sequence current sensor.

A zero-sequence current sensor circuit topology provided according to the present invention includes:

A three-phase phase-sequence current sensor, the phase-sequence current and zero-sequence current of each phase of the three-phase electricity are collected by sharing a primary current acquisition coil of the three-phase phase-sequence current sensor;

A current transformer, one end of the primary side of the current transformer is connected to the primary current acquisition coil through a zero-sequence output loop, the other end of the primary side of the current transformer is grounded, and is connected to the primary current through a phase-sequence output loop The other end of the primary current collection coil is connected;

The resistor R _I0 is connected in parallel with the secondary side of the current transformer.

Preferably, the three-phase phase-sequence current sensor includes three primary current collection coils, and the phase-sequence current and zero-sequence current of each phase are collected by sharing one primary current collection coil of the three-phase phase-sequence current sensor.

Preferably, the zero-sequence output terminals a ₁ , b ₁ , and c ₁ of the three primary current collection coils are connected to form the zero-sequence output loop.

Preferably, the phase sequence output terminals a _h , b _h , and _ch of the three primary current collection coils are respectively connected to one end of the positive sequence sampling resistors R _Ia , R _Ib , and R _Ic , and the positive sequence sampling resistors R _Ia , R Ib , R Ic The other ends of R _Ib and R _Ic are connected to form the phase sequence output circuit.

Preferably, a voltage collection device is also included, which collects the voltage value across the resistor R _I0 .

Preferably, the three-phase electricity adopts a Y-shaped connection.

Preferably, the three-phase phase sequence current sensor is connected to the neutral point of the Y-shaped connection.

A zero-sequence current sensor circuit topology provided according to the present invention includes:

A three-phase phase-sequence current sensor, the phase-sequence current and zero-sequence current of each phase of the three-phase electricity are collected by sharing a primary current acquisition coil of the three-phase phase-sequence current sensor;

A current transformer, one end of the primary side of the current transformer is connected to the primary current acquisition coil through a zero-sequence output loop, the other end of the primary side of the current transformer is grounded, and is connected to the primary current through a phase-sequence output loop The other end of the primary current collection coil is connected;

A resistor R _I0 is connected in parallel with the secondary side of the current transformer;

The three-phase phase-sequence current sensor includes three primary current collection coils, and the phase-sequence current and zero-sequence current of each phase are collected by sharing one primary current collection coil of the three-phase phase-sequence current sensor;

The zero-sequence output terminals a ₁ , b ₁ , and c ₁ of the three primary current collection coils are connected to form the zero-sequence output loop;

The phase-sequence output terminals a _h , b _h and _ch of the three primary current collection coils are respectively connected to one end of the positive-sequence sampling resistors R _Ia , R _Ib , R _Ic , and the positive-sequence sampling resistors R _Ia , R _Ib , The other end of R _Ic is connected to form the phase sequence output circuit;

It also includes a voltage acquisition device, which collects the voltage value across the resistor R _I0 ;

The three-phase electricity adopts Y-shaped wiring;

The three-phase phase sequence current sensor is connected to the neutral point of the Y-shaped connection.

A switch pole provided according to the present invention includes the above-mentioned zero-sequence current sensor circuit topology.

Preferably, the circuit topology of the zero-sequence current sensor and the switch pole are integrally molded.

Compared with the prior art, the present invention has the following beneficial effects:

1. The zero-sequence current is directly collected by the three-phase phase-sequence current sensor. The phase-sequence current and the zero-sequence current share a primary current collection coil, which avoids the interference of the space magnetic field and errors introduced by magnetic leakage, etc., and the collection accuracy is greatly improved. The volume of the current transformer is greatly reduced, which is not only easy to install, but also can be directly poured into the switch pole to integrate with the switch;

2. The zero-sequence output circuit and the phase-sequence output circuit are isolated by a current transformer, which not only solves the problem of directly connecting the resistance in series with the neutral line of the secondary side of the phase-sequence current transformer and affects the phase-sequence accuracy, but also solves the problem of The disadvantages of zero-sequence impedance matching and the requirement to configure high-power resistors.

Description of drawings

Other features, objects and advantages of the present invention will become more apparent by reading the detailed description of non-limiting embodiments with reference to the following drawings:

1 to 3 are schematic structural diagrams of three existing zero-sequence current sensors;

FIG. 4 is a schematic structural diagram of a phase sequence and zero sequence shared coil;

FIG. 5 is a schematic structural diagram of the present invention.

Detailed ways

The present invention will be described in detail below with reference to specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that, for those skilled in the art, several changes and improvements can be made without departing from the inventive concept. These all belong to the protection scope of the present invention.

As shown in FIG. 5 , a circuit topology of a zero-sequence current sensor provided according to this embodiment includes:

Three-phase phase-sequence current sensor, the phase-sequence current and zero-sequence current of each phase of three-phase electricity share a primary current acquisition coil of the three-phase phase-sequence current sensor to collect;

Current transformer, one end of the primary side of the current transformer is connected to the primary current acquisition coil through the zero sequence output loop, the other end of the primary side of the current transformer is grounded, and is connected to the other end of the primary current acquisition coil through the phase sequence output loop ;

The resistor R _I0 is connected in parallel with the secondary side of the current transformer.

Among them, A, B and C are the primary current acquisition coils of the three-phase phase sequence current, respectively, which convert the primary current into the secondary current i _a , i _b , _ic , and R _Ia , R _Ib , and R _Ic are the phase sequence Positive sequence sampling resistor, respectively convert the secondary current into voltage as phase sequence current; connect the zero-sequence current i ₀₁ generated by connecting a ₁ , b ₁ , and c ₁ of the three current sampling coils A, B, and C to the current One end of the primary side of CT0 of the transformer, and then the output ends of the ABC's ah, bh, ch after being connected in series with the positive sequence sampling resistors are connected to the other end of the primary side of CT0, and a current i ₀₂ is induced in the secondary coil of CT0. A resistor R _I0 is incorporated into the secondary coil of CT0, and the voltage U _I0 collected on R _I0 is the voltage value corresponding to the zero-sequence current.

Specifically, the three-phase phase-sequence current sensor includes three primary current acquisition coils, and the phase-sequence current and the zero-sequence current of each phase share a primary current acquisition coil of the three-phase phase-sequence current sensor for acquisition. The zero-sequence output terminals a ₁ , b ₁ , and c ₁ of the three primary current acquisition coils are connected to form a zero-sequence output loop. The phase sequence output terminals a _h , b _h , and _ch of the three primary current acquisition coils are respectively connected to one end of the positive sequence sampling resistors R _Ia , R _Ib , and R _Ic , and the other ends of the positive sequence sampling resistors R _Ia , R _Ib , and R _Ic are respectively connected. One end is connected to form a phase sequence output circuit.

The three-phase power adopts Y-shaped wiring, and the neutral point of the Y-shaped wiring is used to connect the three-phase phase-sequence current sensor in series to directly collect the zero-sequence current. Errors introduced by interference and magnetic flux leakage, etc., the acquisition accuracy is greatly improved, and the volume of the current transformer is greatly reduced.

The zero-sequence output circuit and the phase-sequence output circuit are isolated by a current transformer, which not only solves the problem of directly connecting resistance in series on the neutral line of the phase-sequence current transformer secondary side and affects the phase-sequence accuracy, but also solves the problem of zero-sequence Impedance matching and disadvantages of requiring high-power resistors (if a resistor is directly connected in series to collect zero-sequence current on the phase-sequence neutral line, high-power resistors are required, increasing the load of the phase-sequence sensor, causing additional losses and heating issues).

The present invention also provides a switch pole, which adopts the above-mentioned zero-sequence current sensor circuit topology. The circuit topology of the zero-sequence current sensor is integrally cast with the switch pole.

In the description of this application, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", The orientation or positional relationship indicated by "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, which is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying the indicated device. Or elements must have a particular orientation, be constructed and operate in a particular orientation, and therefore should not be construed as a limitation of the present application.

Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the above-mentioned specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essential content of the present invention. The embodiments of the present application and features in the embodiments may be combined with each other arbitrarily, provided that there is no conflict.

Claims (10)

1. a kind of zero sequence current sensor circuit topology characterized by comprising

Three-phase phase-sequence current sensor, each phase phase-sequence current of three-phase electricity and zero-sequence current share the three-phase phase-sequence current sense One primary current of device acquires coil to acquire；

One end of current transformer, the primary side of the current transformer passes through zero sequence output loop and the primary current gathering line Circle connection, the other end ground connection of the primary side of the current transformer, and acquired by phase sequence output loop and the primary current The other end of coil connects；

Resistance R_I0, in parallel with the secondary side of the current transformer.

2. zero sequence current sensor circuit topology according to claim 1, which is characterized in that the three-phase phase-sequence electric current passes Sensor includes that three primary currents acquire coil, and the phase-sequence current and zero-sequence current of each phase share the three-phase phase-sequence electric current and pass One primary current of sensor acquires coil to acquire.

3. zero sequence current sensor circuit topology according to claim 2, which is characterized in that three primary currents are adopted Collect the zero sequence output end a of coil₁、b₁、c₁It is connected and constitutes the zero sequence output loop.

4. zero sequence current sensor circuit topology according to claim 2, which is characterized in that three primary currents are adopted Collect the phase sequence output end a of coil_h、b_h、c_hIt is separately connected positive sequence sampling resistor R_Ia、R_Ib、R_IcOne end, the positive sequence sampling resistor R_Ia、R_Ib、R_IcThe other end be connected and constitute the phase sequence output loop.

5. zero sequence current sensor circuit topology according to claim 1, which is characterized in that further include voltage collector Part acquires the resistance R_I0The voltage value at both ends.

6. zero sequence current sensor circuit topology according to claim 1, which is characterized in that the three-phase electricity uses Y shape Wiring.

7. zero sequence current sensor circuit topology according to claim 6, which is characterized in that the three-phase phase-sequence electric current passes Sensor is connected to the neutral point of the Y connection.

8. a kind of zero sequence current sensor circuit topology characterized by comprising

Three-phase phase-sequence current sensor, the phase-sequence current and zero-sequence current of each phase of three-phase electricity share the three-phase phase-sequence electric current and pass One primary current of sensor acquires coil to acquire；

One end of current transformer, the primary side of the current transformer passes through zero sequence output loop and the primary current gathering line Circle connection, the other end ground connection of the primary side of the current transformer, and acquired by phase sequence output loop and the primary current The other end of coil connects；

Resistance R_I0, in parallel with the secondary side of the current transformer；

The three-phase phase-sequence current sensor includes that three primary currents acquire coil, zero-sequence current, the phase-sequence current of each phase The primary current acquisition coil of the three-phase phase-sequence current sensor is shared with zero-sequence current to acquire；

The zero sequence output end a of three primary current acquisition coils₁、b₁、c₁It is connected and constitutes the zero sequence output loop；

The phase sequence output end a of three primary current acquisition coils_h、b_h、c_hIt is separately connected positive sequence sampling resistor R_Ia、R_Ib、R_Ic One end, the positive sequence sampling resistor R_Ia、R_Ib、R_IcThe other end be connected and constitute the phase sequence output loop；

Further include voltage acquisition device, acquires the resistance R_I0The voltage value at both ends；

The three-phase electricity uses Y connection；

The three-phase phase-sequence current sensor is connected to the neutral point of the Y connection.

9. a kind of switch pole, which is characterized in that including the electricity of zero sequence current sensor described in claim 1 to 7 any one Road topology.

10. switch pole according to claim 9, which is characterized in that the zero sequence current sensor circuit topology and institute State switch pole one cast molding.