CN100485396C - Method for measuring high voltage by current method and its device - Google Patents

Abstract

The invention relates to a method for measuring high-voltage voltage by current method, which belongs to the field of high-voltage measurement. It connects a primary impedance in parallel at the measured voltage terminal, detects the current I ₁ flowing through the impedance through a current sensor, converts I ₁ into current i ₂ through the current sensor, and sends the current i ₂ into a secondary impedance, in which A standard signal u ₂ proportional to the measured voltage is generated at both ends, and u ₂ is connected to the input terminal of the high-voltage voltage measurement, metering, monitoring or protection device as the voltage signal to be measured for the required voltage detection. The present invention also provides a high-voltage voltage measurement device based on the above method. Since the current method is used to measure high-voltage voltage, many disadvantages brought by the use of electromagnetic voltage transformers are overcome, and the high-voltage voltage measurement of the phases of the three-phase three-wire system or three-phase four-wire system can be easily realized. It can be widely used for High-voltage voltage measurement, electric energy metering, monitoring, and protection devices provide the required voltage signals and other high-voltage voltage measurement fields.

Description

A method and device for measuring high-voltage voltage by current method

technical field

The invention belongs to the field of high-voltage measurement, and in particular relates to a method and a device for measuring high-voltage voltage by detecting the magnitude of the current flowing through a designated load.

Background technique

At present, there are mainly two methods for sampling high-voltage signals required by high-voltage system voltage measurement, electric energy metering, monitoring or protection devices in domestic and foreign power systems:

)，再对其进行电压测量、供保护装置使用或接入电能表进行电能计量，这种方对互感器的输出容量要求较高；(1) Use an electromagnetic voltage transformer (referred to as PT, the same below) to convert the high voltage into a standard low voltage (100 or 100/

), and then measure the voltage, use it for the protection device or connect to the electric energy meter for electric energy measurement. This method has higher requirements on the output capacity of the transformer;

(2) With the improvement of power system automation and the extensive application of microcomputer protection methods, the output capacity requirements of voltage sensors for measurement, measurement, monitoring, and protection have been greatly reduced, so various types of transformers using optical fiber transformers and electronic transformers have emerged. A voltage sampling method and device for a voltage divider, a capacitor voltage divider, and a resistance voltage divider.

Both of the above sampling methods have advantages and disadvantages:

(1) For electromagnetic voltage transformers:

a. PT is large in size and heavy in weight;

b. High cost of manufacture, operation and use;

c. prone to failure.

Electromagnetic resonance, high-order harmonics, and operating overvoltage in the power grid will threaten the safe operation of PTs and become difficult problems to solve; at the same time, the cross-section of PT wires is very small, which is a relatively fragile product among power system application components. When a resonance or odd harmonic source occurs in the system, it is very easy to burn the PT, which affects the safe operation of the power system; moreover, the high energy consumption of the PT is not conducive to energy saving and consumption reduction.

The materials for manufacturing PT mainly include silicon steel sheet, copper, steel, transformer oil and epoxy resin, all of which are non-renewable and indispensable for the development of the national economy.

How to reduce the power loss of the high-voltage metering device itself, reduce its volume, save energy, save materials, save investment, reduce metering costs, ensure its good electromagnetic compatibility, environmental performance, and facilitate product installation, use, and maintenance have all become Practitioners in the insurance industry have been researching and focusing on it.

(2) In order to solve the above problems, a method of voltage sampling using optical fiber transformers, electronic transformers, capacitive voltage dividers, and resistor voltage dividers has emerged, which solves some problems with electromagnetic transformers, but due to its The measurement is based on the principle of voltage divider: U ₁ /U ₂ =Z ₁ /Z ₂ (where Z is the voltage divider impedance), affected by the stability of resistance, distributed capacitance, temperature change, corona, and ground voltage Influenced by many factors, such as measurement accuracy and stability of detection parameters, there are many problems.

In addition, the above products due to:

A. The voltage is taken out by means of voltage division;

B. At present, the products can only measure the voltage relative to the ground;

C. Measuring the voltage of the opposite phase needs to be equipped with two products at the same time to measure;

D. The divided voltage is greatly affected by the distributed capacitance to the ground, the measurement error is unstable, and it cannot be well adapted to the power system with various wiring schemes;

E. The performance is unstable under outdoor conditions, and the test run effect is not ideal.

Therefore the popularization and application of its product is unsatisfactory.

Contents of the invention

The technical problem to be solved by the present invention is to provide a method and device for measuring high-voltage voltage, which overcomes many disadvantages caused by the use of electromagnetic voltage transformers, and can well adapt to the power supply with various wiring schemes. The system can conveniently realize the phase-to-phase high-voltage voltage measurement of the three-phase three-wire system or three-phase four-wire system, meet the signal sampling requirements of differential protection and zero-sequence protection devices, and meet the requirements of metering, measurement, monitoring and protection regulations , the whole device not only saves energy, saves installation space, saves production materials, but also greatly reduces the cost of metering, facilitates the installation, use and maintenance of metering, measurement, monitoring or protection devices, and more importantly, it can improve the safe operation factor and improve Power quality.

The technical solution of the present invention is to provide a method for measuring high-voltage voltage using the current method, including a voltage terminal to be measured and a voltage signal input terminal of a voltage measurement, metering, monitoring or protection device, characterized in that:

(1) A primary impedance Z ₁ with a standard/fixed impedance is connected in parallel at the measured voltage end;

(2) A current sensor is set to detect the current I ₁ flowing through the primary impedance Z ₁ ;

(3) Transform I ₁ into current i ₂ by a current sensor;

(4) Send the current i ₂ into a secondary impedance Z ₂ with a standard/fixed impedance, and generate a standard signal u ₂ proportional to the measured voltage at its two ends;

(5) Connect u ₂ as the voltage signal to be measured to the input terminal of a voltage measurement, measurement, monitoring or protection device with high input impedance for the required measurement, measurement, monitoring or protection detection.

The above-mentioned current i ₂ is sent to a voltage measurement, metering, monitoring or protection device after high/low voltage isolation.

The present invention also provides a device for measuring high-voltage voltage with the current method based on the above-mentioned scheme, including a measured voltage terminal and a voltage signal input terminal of a voltage measurement, metering, monitoring or protection device, characterized in that: at the measured voltage terminal Between the voltage signal input terminal of the voltage measurement, metering, monitoring or protection device, a high-voltage sensor consisting of at least one primary impedance with standard/fixed impedance, a secondary impedance with standard/fixed impedance and a current sensor is set ; Among them, after the primary impedance is connected in series with the input end of the current sensor, it is connected to the two ends of the measured voltage; the output end of the current sensor is connected in parallel with the secondary impedance; the two ends of the current sensor are connected to the voltage measurement, metering, monitoring or protection The voltage signal input terminal of the device is connected.

The output terminal of the above-mentioned current sensor is connected with the voltage signal input terminal of the voltage measurement, metering, monitoring or protection device through the high/low voltage isolation unit.

Its high/low voltage isolation unit can be a photoelectric, optical fiber, electromagnetic, gas-insulated, oil-insulated or solid-insulated isolation device.

Its primary impedance and secondary impedance can be resistive load, capacitive load, inductive load or a combination thereof.

The current sensor is a photoelectric current sensor, an optical fiber current sensor, an electromagnetic current sensor, a miniature current transformer or a penetrating miniature current transformer, and its primary side current input terminal is connected in series between the primary impedance and the measured voltage terminal; or , one connection end of the primary impedance passes through the through-type miniature current transformer; its secondary current output end is connected to the voltage signal input end of the voltage measurement, metering, monitoring or protection device.

Its voltage measurement, metering, monitoring or protection devices are voltmeters, digital voltmeters, electric energy metering devices, power system monitoring devices or protection devices.

The electric energy metering device can be a mechanical electric energy meter, an electronic electric energy meter, a penetrating electric energy meter or an electronic electric energy metering module.

Compared with prior art, the advantages of the present invention are:

1. Using the current method to measure high-voltage voltage, it solves many problems such as electromagnetic resonance, high-order harmonics, and operating overvoltage in electromagnetic transformers that threaten safe operation, and fully meets the requirements of metering, measurement, monitoring and protection;

2. Avoid the common voltage sensor that adopts the voltage-dividing measurement method to be greatly affected by the distributed capacitance to the ground. The measurement error deviation is different in power systems with different topological structures, and it cannot be well adapted to the situation with various wiring schemes. problems with the electrical system;

3. It can conveniently realize the high-voltage voltage measurement of the phases of the three-phase three-wire system or the three-phase four-wire system;

4. It can not only adopt the conventional wiring method to meet the signal sampling requirements of the zero-sequence protection device, but also form an open triangle connection method to meet the signal sampling requirements of the differential protection device;

5. It can adapt to the needs of power grid automation, and can provide voltage signals that meet the various needs of metering, measurement, monitoring or protection systems at the same time, making its measurement simple;

6. The sampling method not only saves energy, saves installation space, saves production materials, but also greatly reduces the cost of measurement, is environmentally friendly, and is convenient for the installation, use and maintenance of measurement, measurement or protection devices, and plays a key role in improving the quality of power supply.

Description of drawings

Fig. 1 is a schematic diagram of circuit structure of the present invention;

Fig. 2 is the circuit diagram of one of embodiment;

Fig. 3 is the circuit diagram of embodiment two;

Fig. 4 is the circuit diagram of embodiment three;

Fig. 5, 6, 7 are the appearance diagrams of the products of above-mentioned three embodiments.

In the figure, 1 and 2 are high-voltage measurement terminals, 3 and 4 are voltage signal output terminals of high-voltage sensors, Z ₁ , Z ₁ ′, Z ₁ ″ are first impedances, CS, CS ′, and CS ″ are current sensors, Z ₂ , Z ₂ ′, Z ₂ ″ are the second impedances.

Detailed ways

The method for measuring high voltage of the present invention is:

(1) A primary impedance Z ₁ with a standard/fixed impedance is connected in parallel at the measured voltage end;

(2) A current sensor is set to detect the current I ₁ flowing through the primary impedance Z ₁ ;

(3) Transform I ₁ into current i ₂ by a current sensor;

(4) Send the current i ₂ into a secondary impedance Z ₂ with a standard/fixed impedance, and generate a standard signal u ₂ proportional to the measured voltage at its two ends;

(5) Connect u ₂ as the voltage signal to be measured to the input terminal of a voltage measurement, measurement, monitoring or protection device with high input impedance for the required measurement, measurement, monitoring or protection detection.

The above-mentioned current i ₂ is sent to the voltage measurement, metering, monitoring or protection device after high/low voltage isolation.

By formula, then the measurement principle of the present invention can be expressed as follows:

Set the primary impedance Z ₁ with standard/fixed impedance at both ends of the measured voltage U, then:

U/Z ₁ = I ₁

Among them, U—measured voltage, Z ₁ —primary impedance I ₁ —current flowing through the primary impedance;

The current I1 passes through the primary side of the current sensor (for example: current transformer), forms a current on its secondary side, and i ₂ flows through the secondary impedance Z ₂ connected to the output terminal of the current sensor to form the secondary voltage u ₂ , u ₂ Connect to the input ports of voltmeters, digital voltmeters, energy metering, power system monitoring or protection devices.

The ratio k of U and _u2 constitutes the transformation ratio of the current sensor:

k=U/u ₂

Among them, k—the transformation ratio of the current sensor, U—the measured voltage, u ₂ —the secondary voltage;

Then u ₂ ×k is the measured voltage.

The circuit structure that can realize the above-mentioned method is shown in Fig. 1 .

In Fig. 1, between the measured voltage terminals 1, 2 and the voltage signal input terminals 3, 4 of voltage measuring, metering, monitoring or protection devices, at least one primary impedance Z ₁ with standard/fixed impedance, two A high-voltage sensor composed of a secondary impedance Z ₂ and a current sensor CS; among them, the primary impedance is connected in series with the input end of the current sensor, and connected to both ends of the measured voltage, and the output end of the current sensor is connected in parallel with the secondary impedance, and its current The two ends of the sensor are connected with the voltage signal input terminals of the voltage measurement, metering, monitoring or protection device.

Its primary impedance and secondary impedance are resistive load, capacitive load, inductive load or a combination thereof.

The current sensor is a photoelectric current sensor, an optical fiber current sensor, an electromagnetic current sensor, a miniature current transformer or a penetrating miniature current transformer, and its primary side current input terminal is connected in series between the primary impedance and the measured voltage terminal; or, One connection end of the primary impedance passes through the through-type miniature current transformer; its secondary current output end is connected with the voltage signal input end of the voltage measurement, metering, monitoring or protection device.

Since the current sensor used has no iron core, it is used to provide a protection signal for the protection circuit, and its input/output ratio is completely linear, which can solve the sensitivity reduction caused by magnetic saturation and the malfunction of the protection circuit caused by it, and save energy. Large quantities of the aforementioned valuable or non-renewable materials.

Since the output voltage signal is a standard level voltage signal, it can be easily matched with existing metering, measurement, monitoring or protection devices without further transformation, which is conducive to simplifying the circuit structure and reducing intermediate links, improving metering and measurement. , Monitoring and protection accuracy.

The above-mentioned voltage measuring, metering, monitoring or protection devices can be voltmeters, digital voltmeters, electric energy metering devices, power system monitoring devices or protection devices, and the electric energy metering devices can be mechanical electric energy meters, electronic electric energy meters, through-type The electric energy meter or the electronic electric energy metering module are all well-known technologies in the art, and will not be described here.

Since the symbols, numbering, and naming methods of each device or component in the figure are the same as those of the current power transformation and distribution system, the specific meanings of each letter and symbol can be fully understood by those skilled in the art and will not be described in detail.

Example 1:

Voltage measurements on single-phase high voltage circuits:

Using the circuit shown in Figure 2, the output terminal of the current sensor CS is connected to the voltage signal input terminals 3 and 4 of the voltage measurement, metering or protection device after high/low voltage isolation.

Its high/low voltage isolation unit can choose photoelectric, optical fiber, electromagnetic, gas-insulated, oil-insulated or solid-insulated isolation devices.

High/low voltage isolation units are used to process the collected voltage signals, which can simultaneously meet the requirements of high and low voltage isolation, electromagnetic shielding (electromagnetic compatibility), ratio difference and angle difference of measurement accuracy, and sampling signals of voltage protection circuits. .

Since the high/low voltage isolation is a prior art, it will not be described here.

The rest are the same as in Figure 1.

Example 2:

Phase voltage measurement on three-phase three-wire lines:

Using the circuit shown in Figure 3, two sets of high-voltage sensors are connected between the A-B and B-C phases of the power supply to measure the phase-to-phase voltage, and output standard-level voltage detection signals through V-v wiring.

For the sake of brevity, the high/low voltage isolation unit is not shown in the figure (the same below).

All the other are with Fig. 1 or embodiment 1.

Example 3:

Voltage measurements on three-phase three-wire lines:

Using the circuit shown in Figure 4, use three sets of high-voltage sensors to connect between the A, B, and C phases of the power supply and their center point O to measure the voltage, and use Y-y wiring to connect with voltage measurement, measurement, monitoring or protection. device to connect.

All the other are with Fig. 1 or embodiment 1.

In addition, zero-sequence or open triangle connection can also be used to connect with the protection device. Since the above connection method, working principle and high-voltage protection device are prior art, they will not be described here.

Figures 5, 6, and 7 are the outline drawings of products with single-phase, three-phase V-v wiring and three-phase Y-y wiring, respectively.

As shown in Figures 5, 6, and 7, it can be seen that with the above technical solutions, the primary and secondary impedances, current transformers, high/low voltage isolation units and other components can be packaged as a whole, which is convenient for product design, installation and maintenance , and can form a standardized series of products with uniform installation dimensions, which brings great convenience to product promotion, installation, use and maintenance.

Since the present invention uses the current method to measure the high-voltage voltage, it overcomes the many disadvantages brought by the use of electromagnetic voltage transformers, can well adapt to power systems with various wiring schemes, and can conveniently realize three-phase three-wire systems or The phase-to-phase high-voltage voltage measurement of the three-phase four-wire system meets the signal sampling requirements of differential protection devices and zero-sequence protection devices, and meets the requirements of metering, measurement, monitoring and protection regulations. The entire device saves energy and installation space. , save production materials, and can greatly reduce the cost of measurement, and facilitate the installation, use and maintenance of measurement, measurement, monitoring or protection devices.

The invention can be widely used in high-voltage voltage measurement fields such as high-voltage voltage measurement and electric energy measurement, or providing required voltage signals for power system monitoring and protection devices.

Claims (8)

1. measure the method for high tension voltage with current method for one kind, comprise the voltage signal input end of tested voltage end and voltage measurement, metering, monitoring or protective device, it is characterized in that:

(1) has an impedance Z of standard/blocked impedance in tested voltage end parallel connection one ₁

(2) current sensor is set, detects and flow through impedance Z one time ₁Electric current I ₁

(3) by current sensor with I ₁Be transformed to current i ₂

(4) with current i ₂Send into a secondary impedance Z with standard/blocked impedance ₂, produce a standard signal u who is proportional to tested voltage at its two ends ₂

(5) with u ₂Insert the input end of voltage measurement, metering, monitoring or protective device as voltage signal to be measured, carry out usefulness of required measurement, metering, monitoring or protection detection for it with high input impedance.

2. the method with current method measurement high tension voltage as claimed in claim 1 is characterized in that described current i ₂Through sending into voltage measurement, metering, monitoring or protective device again after the high/low pressure isolation.

3. measure the device of high tension voltage with current method for one kind, comprise the voltage signal input end of tested voltage end and voltage measurement, metering, monitoring or protective device, it is characterized in that:

Between the voltage signal input end of tested voltage end and voltage measurement, metering, monitoring or protective device, setting has an impedance of standard/blocked impedance, a secondary impedance with standard/blocked impedance and the high pressure sensor that current sensor constitutes by one;

Wherein, an impedance is connected with the two ends of tested voltage with after the input end of current sensor is connected;

The output terminal of current sensor is in parallel with secondary impedance;

The two ends of current sensor are connected with the voltage signal input end of voltage measurement, metering, monitoring or protective device.

4. the device with current method measurement high tension voltage as claimed in claim 3 is characterized in that the output terminal of described current sensor is connected with the voltage signal input end of voltage measurement, metering, monitoring or protective device through high/low pressure isolated location.

5. the device with current method measurement high tension voltage as claimed in claim 4 is characterized in that described high/low pressure isolated location is photo-electric, optical fiber type, electromagnetic type, gas-insulating type, oil-insulation formula or solid insulation formula spacer assembly.

6. the device with current method measurement high tension voltage as claimed in claim 3 is characterized in that a described impedance, secondary impedance are resistive load, capacity load, inductive load or its combination.

7. the device of measuring high tension voltage with current method as claimed in claim 3, it is characterized in that described current sensor is photo-electric current sensor, fibre optic current sensor, electromagnetic type current sensor or penetration type micro-transformer of current, its primary side current input terminal is serially connected between an impedance and the tested voltage end; Perhaps, an impedance link passes the penetration type micro-transformer of current; Its secondary side current output terminal is connected with the voltage signal input end of voltage measurement, metering, monitoring or protective device.

8. the device with current method measurement high tension voltage as claimed in claim 3 is characterized in that described voltage measurement, metering, monitoring or protective device are voltage table, electric power meter, power system monitor or protective device.

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