WO2018006876A1

WO2018006876A1 - Capacitive voltage mutual inductor for transient over-voltage monitoring system

Info

Publication number: WO2018006876A1
Application number: PCT/CN2017/092280
Authority: WO
Inventors: 邹俭; 叶洪波; 李骏; 金珩; 司文荣; 赵文彬; 赵丹丹; 周行星; 黄华
Original assignee: 国网上海市电力公司; 华东电力试验研究院有限公司; 上海赛璞乐电力科技有限公司; 上海电力学院
Priority date: 2016-07-08
Filing date: 2017-07-07
Publication date: 2018-01-11
Also published as: JP6547217B2; CN106199121A; CN106199121B; JP2018532249A

Abstract

A capacitive voltage mutual inductor (2) for a transient over-voltage monitoring system comprises a first capacitor (C1), a second capacitor (C2), a third capacitor (C3), an intermediate transformer (T), a transient over-voltage monitoring unit (M), a grounding switch (K), a compensation reactor (L) and a first lightning arrester (BL1). One end of the first capacitor (C1) is connected to a power grid (1), and the other end is respectively connected to one end of the second capacitor (C2) and one end of a primary winding in the intermediate transformer (T). The other end of the second capacitor (C2) is respectively connected to one end of the transient over-voltage monitoring unit (M) and one end of the compensation reactor (L). The other end of the primary winding of the intermediate transformer (T) is respectively connected to the other end of the compensation reactor (L) and one end of the first lightning arrester (BL1). The other end of the transient over-voltage monitoring unit (M) and the other end of the first lightning arrester (BL1) are both grounded. The grounding switch (K) is connected in parallel at the two ends of the transient over-voltage monitoring unit (M). One end of the third capacitor (C3) is connected to the other end of the second capacitor (C2), and the other end of the third capacitor (C3) is grounded. A voltage bearable by the first capacitor (C1) is greater than a voltage bearable by the second capacitor (C2), and the voltage bearable by the second capacitor (C2) is greater than a voltage bearable by the third capacitor (C3).

Description

Capacitive voltage transformer for transient overvoltage monitoring system

Technical field

The present disclosure relates to the field of electrical engineering, for example, to a capacitive voltage transformer for a transient overvoltage monitoring system.

Background technique

The transient state of the power grid is an important indicator of the operating state of the power grid. For the transient overvoltage in the power grid (operating overvoltage, temporary overvoltage and undervoltage caused by the DC transmission system), there is still no effective measurement and monitoring means at home and abroad. For new equipment, only some power companies in China have tested the overvoltage of the 500kV system before it is officially put into operation. Generally, transient measurement is performed when switching the no-load line, main transformer, low-voltage reactor or capacitor, as the charging test of the new equipment.

For operating equipment, conventional protection and recording devices can only record power frequency overvoltage information and cannot record the transient process of the system. The monitoring system, intelligent monitoring and early warning system and power grid wide-area real-time dynamic monitoring system that the dispatching department has used mainly monitor the power running characteristics from the perspective of dynamic stability and static stability of the entire power grid, and then predict the power grid in the future. Steady state, although the sampling frequency is relatively high, but since the primary signal is collected from the capacitor voltage transformer (CVT) ferromagnetic unit, the high frequency signal has a large degree of distortion, so it cannot truly reflect the system. The process of rapid change of medium voltage can not achieve comprehensive monitoring of the operating state of the power system.

The capacitive voltage transformer used in the transient over-voltage monitoring system is a new type of electrical equipment that meets the functional requirements of AC/DC hybrid power grid and smart grid informationization, and conforms to the development direction of overvoltage and insulation coordination technology.

Summary of the invention

The present disclosure provides a capacitive voltage transformer for a transient over-voltage monitoring system, which has high operating frequency, high precision of measurement data, and wide application range.

The present disclosure provides a capacitive voltage transformer for a transient overvoltage monitoring system, including a first capacitor, a second capacitor, a third capacitor, a transient overvoltage monitoring unit, an intermediate transformer, a grounding knife, and a compensation reactor. And the first arrester, one end of the first capacitor is set to be connected to the power grid, and the other end is Connecting one end of the second capacitor and one end of the primary winding in the intermediate transformer respectively, and the other end of the second capacitor is respectively connected to one end of the transient overvoltage monitoring unit and one end of the compensating reactor, and the other of the intermediate windings in the intermediate transformer One end of the compensating reactor and one end of the first arrester are respectively connected to one end, the other end of the transient over-voltage monitoring unit and the other end of the first arrester are grounded, and the grounding switch is connected in parallel to the transient over-voltage monitoring unit. The two ends of the third capacitor are connected to the other end of the second capacitor, and the other end of the third capacitor is grounded, and the voltage that the first capacitor can bear is greater than the voltage that the second capacitor can bear. The voltage that the second capacitor can bear is greater than the voltage that the third capacitor can bear.

Optionally, a second arrester is further included, and the second arrester is connected in parallel at both ends of the transient overvoltage monitoring unit.

Optionally, wherein the compensating reactor is a resistor with adjustable reactance value.

Optionally, a damper is also provided, the damper being disposed on the secondary winding of the intermediate transformer.

Optionally, a protection gap is further included, and the protection gap is connected in parallel at both ends of the transient overvoltage monitoring unit.

Compared with the related art, the present disclosure provides a capacitive voltage transformer for a transient overvoltage monitoring system:

1) High operating frequency and high precision of measurement data: not only has the functions of conventional capacitive voltage transformers, for example, for voltage measurement and relay protection, but also for measuring harmonics on high voltage and ultra high voltage power grids. Real-time observation and measurement of grid voltage waveforms. By setting the first arrester and the second arrester, the damage caused by the overvoltage can be prevented, and the transient overvoltage monitoring unit can be protected, which can be used as a sensor for coupling the overvoltage of the 500 kV transmission line in the transient overvoltage monitoring system.

2) Stable work: Due to the design concept of permanent outdoor equipment, the CVT referred to in this disclosure is a device that can work in the power grid for a long time, rather than a temporary facility or measure.

DRAWINGS

1 is a schematic structural diagram of a circuit of a capacitive voltage transformer according to the embodiment;

2A is a schematic structural view of a lower bottom plate of a third capacitor C3 in the embodiment;

2B is a schematic top plan view of the upper bottom plate of the third capacitor C3 in the embodiment;

FIG. 3 is a schematic structural diagram of a transient overvoltage monitoring system in the embodiment.

In the figure: 1, power grid, 2, capacitive voltage transformer, 3, transmission cable, 4, protector, 5, pass Letter optical cable, 6, transient voltage collector, 7, communication cable, 8, industrial computer 9, non-inductive capacitive components, C1, first capacitor, C2, second capacitor, C3, third capacitor, M, transient Voltage monitoring unit, T, intermediate transformer, K, grounding knife, L, compensating reactor, ZD, damper, P, protection gap, BL1, first arrester, BL2, second arrester.

detailed description

The present disclosure will be described below in conjunction with the accompanying drawings and embodiments. The features of the following embodiments and embodiments may be combined with each other without conflict.

As shown in FIG. 1 , a capacitive voltage transformer 2 for a transient over-voltage monitoring system includes a first capacitor C1, a second capacitor C2, a third capacitor C3, an intermediate transformer T, and a transient over-voltage monitoring unit. M, grounding knife gate K, compensating reactor L, damper ZD, protection gap P, first arrester BL1 and second arrester BL2, one end of the first capacitor C1 is connected to the grid 1, and the other end is connected to one end of the second capacitor C2 And one end of the primary winding in the intermediate transformer T, the other end of the second capacitor C2 is respectively connected to one end of the transient overvoltage monitoring unit M and one end of the compensating reactor L, and the other end of the primary winding of the intermediate transformer T is respectively connected with the compensating reactor The other end of the L and one end of the first arrester BL1, the other end of the transient overvoltage monitoring unit M and the other end of the first arrester BL1 are grounded, and the grounding knife K, the protection gap P and the second arrester BL2 are respectively connected in parallel. The two ends of the transient over-voltage monitoring unit M, the damper ZD is disposed on the secondary winding of the intermediate transformer T, wherein U1 is the voltage of the grid 1, and the compensating reactor L can be a resistor with adjustable reactance value, compensation Electricity The reactance value of the L is equal to the capacitive reactance of the equivalent capacitor of the capacitive voltage transformer 2 at the rated frequency, so that the primary voltage (the voltage of the high voltage terminal connected to the first capacitor C1) and the second voltage are different under different secondary loads. The correct phase and ratio can be obtained between the secondary voltage (the voltage across the third capacitor C3 or the voltage output from the intermediate transformer T). Among them, the phase difference and the ratio should be stable, do not drift with voltage changes, the phase difference is preferably zero, or remain constant for calibration. In Fig. 1, N is the low voltage end of the second capacitor C2, and 1a, 1n, 2a, 2n, da1, da2, dan are the secondary winding output ends of the intermediate transformer T. The second arrester BL2, the protection gap P and the damper ZD are optional devices, and may not be present in the capacitive voltage transformer 2.

When the first capacitor C1, the second capacitor C2, and the third capacitor C3 are connected in series, the first capacitor C1 (also referred to as a high voltage arm) is connected to the high voltage terminal, and the third capacitor C3 (also referred to as a low voltage arm) is connected to the ground. Since the capacitive voltage transformer of the embodiment can be applied to the power grid of different voltage levels, the voltages of the first capacitor C1, the second capacitor C2, and the third capacitor C3 are also different. Generally, the first capacitor C1> The second capacitor C2>the third capacitor C3. For example, in a 500kV voltage class system, the first capacitor C1 (high voltage arm) It bears most of the voltage drop, while the third capacitor C3 (low-voltage arm) only takes about one-tenth to two-thousands of voltage; in a 35kV voltage-class system, the low-voltage arm will take about two-thousandths to three-thousands. In engineering applications, the value of the third capacitor C3 is usually fine-tuned to stabilize the maximum operating voltage across C3 at around 100V.

Alternatively, referring to FIG. 2A and FIG. 2B, the third capacitor C3 is composed of a plurality of non-inductive capacitive elements 9 connected in parallel with each other, and all of the non-inductive capacitive elements 9 are arranged in a coaxial circumferential structure. The transient overvoltage monitoring unit M is connected in parallel with the third capacitor C3. The high voltage end of the transient overvoltage monitoring unit M is connected in series with the low voltage terminal N of the second capacitor C2 inside the CVT, the ground terminal of the third capacitor C3 is grounded with a copper or copper strip, and the measuring terminal of the third capacitor C3 is based on the same standard. The shaft cable sends the voltage signal at both ends of C3 to the digital collector (ie, transient over-voltage monitoring unit M).

As shown in FIG. 3, the embodiment provides a transient over-voltage monitoring system for monitoring various forms of transient voltages appearing on power system operating equipment, including power frequency over-voltage, operating over-voltage, and lightning over-voltage. Wait. The transient over-voltage monitoring system includes a capacitive voltage transformer 2, a protector 4, a transient voltage collector 6 and an industrial computer 8, and the capacitive voltage transformer 2 is connected with a transmission line or a bus of the power grid 1, and the capacitive voltage transformer 2 is connected to the protector 4 via the transmission cable 3, the protector 4 is connected to the transient voltage collector 6 via the communication cable 5, and the transient voltage collector 6 is connected to the industrial computer 8 via the communication cable 7. On-line monitoring of transient over-voltage is to monitor the voltage disturbance of the grid system in real time by means of signal-dividing sensors, and to record and store the amplitude of each phase voltage, the waveform before and after the fault, and various kinds of waveforms. Parameters, with signal processing and parameter extraction, application and analysis (for example, alarms, historical data queries and statistics, etc.).

Industrial applicability

The present invention provides a capacitive voltage transformer for a transient over-voltage monitoring system, which has high operating frequency, high precision of measurement data, wide application range, can adapt to the functional requirements of intelligent grid informationization and automation, and is compatible with overvoltage and insulation. Cooperate with the requirements of technological development.

Claims

A capacitive voltage transformer for a transient overvoltage monitoring system, comprising a first capacitor, a second capacitor, a third capacitor, a transient overvoltage monitoring unit, an intermediate transformer, a grounding knife gate, a compensating reactor, and a a lightning arrester, one end of the first capacitor is disposed to be connected to the power grid, and the other end is respectively connected to one end of the second capacitor and one end of the primary winding in the intermediate transformer, and the other end of the second capacitor is respectively connected to the transient overvoltage monitoring unit One end of the compensating reactor and one end of the compensating reactor, wherein the other end of the primary winding of the intermediate transformer is respectively connected to the other end of the compensating reactor and one end of the first arrester, the other end of the transient overvoltage monitoring unit and the first arrester The other end is grounded, the grounding switch is connected in parallel at both ends of the transient overvoltage monitoring unit, one end of the third capacitor is connected to the other end of the second capacitor, and the other end of the third capacitor is grounded. The voltage that the first capacitor can bear is greater than the voltage that the second capacitor can bear, and the voltage that the second capacitor can bear is greater than the third The container can assume voltage.
The capacitive voltage transformer according to claim 1, further comprising a second arrester, the second arrester being connected in parallel at both ends of the transient overvoltage monitoring unit.
The capacitive voltage transformer according to claim 1, wherein the compensating reactor is a resistor having an adjustable reactance value.
The capacitive voltage transformer of claim 1 further comprising a damper disposed on the secondary winding of the intermediate transformer.
The capacitive voltage transformer of claim 1 further comprising a guard gap connected in parallel across the transient overvoltage monitoring unit.