CN104198863A - Sensing technology based online open-type lightning arrester monitoring device and monitoring method - Google Patents

Abstract

The invention relates to an on-line monitoring device and method for an open-type surge arrester based on sensing technology, which includes an open-type current transformer, a mounting bracket and a monitoring host, and the open-type current transformer and the monitoring host are respectively installed on two sides of the installation bracket. terminal, the open-type current transformer is set on the lightning arrester, and communicated with the monitoring host; the open-type current transformer collects the full current information on the lightning arrester in real time and transmits it to the monitoring host in real time, after the monitoring host analyzes Obtain the peak value of the resistive current and compare it with the set threshold, and if it exceeds, an alarm will be issued. Compared with the prior art, the present invention effectively solves the real-time on-line monitoring of the arrester, and truly and effectively solves the electrical installation problem that plagues the on-line monitoring device with the arrester.

Description

On-line monitoring device and monitoring method of open arrester based on sensing technology

technical field

The invention relates to a monitoring device for a lightning arrester, in particular to an on-line monitoring device and a monitoring method for an open lightning arrester based on sensing technology.

Background technique

As the necessary electrical equipment in the substation, the lightning arrester has almost no replacement for its wide application, and it has become one of the main electrical equipment of the electrical substation. Safe operation plays a big protective role. The quality or performance attenuation of the arrester itself directly affects the safety and reliability of the protected equipment. If the arrester is damp for a long time or the valve plate is aging, the resistive current will increase, and the resistive power will be too large. It will generate heat, and the continuous heat will destroy the Or damage the arrester. In order to know in real time whether the arrester is working normally and its damage tendency, special equipment is needed to monitor it. At present, there are many similar products with different technical routes. Most of them analyze their total power, capacitive power, and resistive current through the method of bus voltage reference value to judge their working status in real time. The main problem is: really cause heat The resistive current calculation is not accurate, and the installation of the device must be powered off (high-grade substations have very limited power outages every year). However, the present invention substantially solves the above problems from the calculation model and structural design, not only greatly improves the monitoring accuracy of resistive current, but also effectively solves the problem of live installation, thereby reducing the installation time and enhancing the reliability of the equipment. Reliability and accuracy greatly avoid the waste of manpower, time and cost.

Contents of the invention

The purpose of the present invention is to provide an on-line monitoring device and monitoring method for open arresters based on sensing technology in order to overcome the above-mentioned defects in the prior art.

The purpose of the present invention can be achieved through the following technical solutions:

An on-line monitoring device for an open-type arrester based on sensing technology, characterized in that it includes an open-type current transformer, a mounting bracket and a monitoring host, and the open-type current transformer and the monitoring host are respectively installed at both ends of the installation bracket, The open-type current transformer is sleeved on the lightning arrester and communicated with the monitoring host;

The open-type current transformer collects the full current information on the arrester in real time and transmits it to the monitoring host in real time. The monitoring host analyzes and obtains the peak value of the resistive current and compares it with the set threshold. If it exceeds, an alarm is issued.

The open-type current transformer includes a first arc-shaped component and a second arc-shaped component, one end of the first arc-shaped component and one end of the second arc-shaped component are respectively rotatably connected to the mounting bracket. When the transformer is closed, the other end of the first circular arc component is connected to the other end of the second circular arc component.

The other end of the first arc-shaped component has a convex structure, and the other end of the second arc-shaped component has a concave structure. When the open-type current transformer is closed, the first arc-shaped component The protrusion is inserted into the groove of the second arc-shaped component.

The protrusion of the first arc-shaped component is provided with through holes, and the two sides of the groove of the second arc-shaped component are provided with through holes corresponding to the through holes of the protrusion.

The monitoring host includes a housing and a printed circuit board installed in the housing, and the housing is connected with the mounting bracket.

The printed circuit board includes a CPU circuit, a storage circuit connected to the CPU circuit, a wireless communication circuit, an input interface and an alarm circuit, the input interface is connected to the open-type current transformer, and the wireless communication circuit is connected to the open-type current transformer. Remote terminal connection.

A monitoring method of an on-line monitoring device for a vented arrester based on sensing technology, characterized in that it comprises the following steps:

1) The open current transformer collects the full current information on the arrester and transmits it to the monitoring host in real time;

2) Monitor the full current of the host sampling a cycle;

3) Take the extreme point within half a cycle as the capacitive current extreme point;

4) Simulating a capacitive current based on the capacitive current extreme point;

5) Subtracting the simulated capacitive current from the full current to achieve the resistive current waveform;

6) Determine whether the peak value of resistive current and capacitive current satisfies the following formula, if so, perform step 7), otherwise perform step 2)

iX=iC+iR, where iX is the full current, iC is the capacitive current, and iR is the resistive current

7) Determine the voltage reference extreme value point based on the resistive current extreme value moment;

8) The sampling value of the corresponding point on the waveform of the full current is the peak value of the resistive current.

The simulated capacitive current waveform is a standard sine wave waveform.

Compared with the prior art, the present invention has the following advantages:

1) It does not need to be disassembled and modified, which reduces the complexity of the work for the first time, and also avoids the adjustment of the voltage phase sequence. More importantly, it can carry out live work, which will simplify the engineering installation and avoid affecting the data due to construction reasons. accuracy.

2) It effectively solves the real-time online monitoring of the arrester, and truly and effectively solves the electrical installation problem that plagues the online monitoring device with the arrester.

Description of drawings

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

Fig. 2 is method flowchart of the present invention;

Fig. 3 is the equivalent circuit diagram of the lightning arrester;

Figure 4 is a vector diagram of the leakage full current.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

Example

As shown in Figure 1, an on-line monitoring device for open-type surge arresters based on sensing technology includes an open-type current transformer 1, a mounting bracket 2 and a monitoring host 3, and the open-type current transformer 1 and the monitoring host 3 are respectively Installed at both ends of the mounting bracket 2, the open-type current transformer 1 is set on the arrester 4 and communicated with the monitoring host 3; the open-type current transformer 1 collects the full current information on the arrester 4 in real time And real-time transmission to the monitoring host 3, the monitoring host 3 obtains the resistive current peak value after analysis, and compares it with the set threshold value, and if exceeds, an alarm is given.

The open-type current transformer 1 includes a first circular arc component 11 and a second circular arc component 12, one end of the first circular arc component 11 and one end of the second circular arc component 12 rotate with the mounting bracket 2 respectively Connection, when the open-type current transformer is closed, the other end of the first circular arc component 11 is connected to the other end of the second circular arc component 12 .

The other end of the first circular arc component 11 has a convex structure, and the other end of the second circular arc component 12 has a concave structure. When the open-type current transformer is closed, the first circular arc The protrusion of the shape component is inserted into the groove of the second arc-shaped component. The protrusion of the first arc-shaped component 11 is provided with through holes, and the two sides of the groove of the second arc-shaped component 12 are provided with through holes corresponding to the through holes of the protrusions.

The monitoring host 3 includes a housing and a printed circuit board installed in the housing, and the housing is connected to the mounting bracket. The printed circuit board includes a CPU circuit, a storage circuit connected to the CPU circuit, a wireless communication circuit, an input interface and an alarm circuit, the input interface is connected to the open-type current transformer, and the wireless communication circuit is connected to the open-type current transformer. Remote terminal connection.

As shown in Figure 2, the monitoring method of the present invention comprises the following steps:

1) The open current transformer collects the full current information on the arrester and transmits it to the monitoring host in real time;

2) Monitor the full current of the host sampling a cycle;

3) Take the extreme point within half a cycle as the capacitive current extreme point;

4) Simulating a capacitive current based on the capacitive current extreme point;

5) Subtracting the simulated capacitive current from the full current to achieve the resistive current waveform;

6) Determine whether the peak value of resistive current and capacitive current satisfies the following formula, if so, perform step 7), otherwise perform step 2)

iX=iC+iR, where iX is the full current, iC is the capacitive current, and iR is the resistive current

7) Determine the voltage reference extreme value point based on the resistive current extreme value moment;

8) The sampling value of the corresponding point on the waveform of the full current is the peak value of the resistive current.

The simulated capacitive current waveform is a standard sine wave waveform.

Principle analysis of the present invention is as follows:

The on-line monitoring of the zinc oxide arrester is the leakage current in its operating state. Call it leakage full current (referred to as full current) iX. A zinc oxide arrester is equivalent to a parallel connection of a capacitor and a nonlinear resistor. The current flowing through the capacitor is called capacitive leakage current (capacitive current for short) iC, and the current flowing through the nonlinear resistor is called resistive leakage current. (referred to as resistive current) iR. Figure 3 is the equivalent circuit diagram of the arrester, and Figure 4 is the leakage current vector diagram.

Since the measurement can only obtain the full current of the arrester, the more traditional arrester monitor generally monitors the effective value of the full current. But the full current is not enough to completely and clearly reflect the internal insulation performance of the arrester.

In the full current, the capacitive current dominates, and the resistive current only accounts for 5-20% of the full leakage current. The capacitive current depends on the dielectric constant of the metal oxide, the stray capacitance and the internal balancing capacitance.

Resistive leakage current is a concentrated reflection of the operating state of the arrester:

Under the normal operating voltage state, the proportion of resistive current to the total current will not exceed 5-20%, and the resistive leakage current is much smaller than the capacitive leakage current, so even if the resistive component is doubled, the change of the total current will not exceed 5.0%.

A large change in the resistive current can cause a change in the full current. The resistive current is the most direct response of the volt-ampere characteristic curve of the metal oxide arrester. It is also a direct response to the internal insulation state of the arrester.

During the operation of the arrester, due to the deterioration of the internal components, the resistive current increases and the active power loss continues to increase. After a certain degree, it will lead to the thermal collapse of the arrester. If the abnormal arrester cannot be withdrawn from operation in time, it is likely to be Explosion occurs within a period of time (months, days or hours), causing large-scale electrical accidents.

Based on the above reasons, many manufacturers at home and abroad have begun to develop on-line monitors with resistive current measurement. However, due to the limitation of various conditions, so far there are few products that monitor the resistive leakage current of arresters online, and even fewer good products, and most of them are concentrated on the following technical bottlenecks that are difficult to break through:

The lack of effective high-voltage measurement means cannot meet the safety level and anti-interference requirements of the monitor.

The lack of new measurement and calculation methods cannot improve the measurement accuracy and stability of the monitor.

Generally speaking, due to the defects in the traditional resistive current measurement method, no cost-effective product has been formed.

Two-component component analysis method:

The leakage current of the arrester is superimposed and synthesized by two components, which are the linear capacitive current and the nonlinear resistive current component of the 90° leading voltage. The expression is as follows:

iX=iC+iR

The full current iX is formed by superimposing the capacitive current iC and the resistive current iR. Since the capacitive current iC is a linear function, it is a sinusoidal waveform like the voltage waveform, but the phase is advanced by 90°.

Since the resistive current iR is a nonlinear function, it is no longer a sinusoidal waveform, but a pulse waveform with the same phase and frequency as the voltage waveform, and its amplitude depends on the volt-ampere characteristics of the arrester. Its maximum value occurs at the same moment as the voltage maximum value.

(1) The measured full current iX is formed by the superposition of capacitive current iC and resistive current iR. Its relationship is:

iX=iC+iR

(2) The sinusoidal waveform of the capacitive current can be uniquely determined, its frequency is 50Hz at the power frequency, the phase is ahead of the non-sinusoidal waveform of the resistive current by 90°, the amplitude satisfies the above formula, and the equivalent capacitance of the arrester is uniquely determined.

(3) The non-sinusoidal waveform of resistive current can be uniquely determined. Its frequency is power frequency 50Hz, and the 90° amplitude of the sinusoidal waveform of capacitive current behind the phase satisfies the above formula, and the volt-ampere characteristics of the arrester are uniquely determined.

(4) The maximum value of the sinusoidal waveform of the capacitive current is ahead of the maximum value of the non-sinusoidal waveform of the resistive current by 1/4 cycle, which determines the maximum value of the non-sinusoidal waveform of the resistive current, which is equivalent to the maximum value of the voltage, which is equivalent to Since the voltage reference point is found, the desired peak resistive leakage current can be directly found on the full current waveform.

The installation of the arrester on-line monitoring device is mainly divided into instrument in-place installation, signal line installation and grounding line installation. Due to the limited operational conditions of on-site installation, the additional wiring installation of voltage signals in the installation of signal lines increases the complexity of the project implementation. At the same time, it is necessary to adjust the phase sequence of the voltage, which also increases the technical difficulty of the work. up. Once there is a change in the phase sequence of the bus, a lot of repetitive work will be generated, and whether it is an open arrester, a switch cabinet or an arrester in a GIS, the space left for the monitor is limited, basically no more than 130× In the space of 130×100mm, secondly, it is necessary to remove and modify the grounding bronze plate of the arrester. First of all, for substations with higher grades, the power outage time is very limited, and secondly, construction in such a small space is very inconvenient to operate.

The design of the present invention does not need to be disassembled and refitted first, which reduces the complexity of the work for the first time, and at the same time avoids the adjustment of the voltage phase sequence. Causes affect the accuracy of the data.

Claims (8)

1. An on-line monitoring device for open-type surge arresters based on sensing technology, characterized in that it includes an open-type current transformer, a mounting bracket and a monitoring host, and the open-type current transformer and the monitoring host are respectively installed on two sides of the mounting bracket. end, the open-type current transformer is sleeved on the arrester, and communicated with the monitoring host; The open-type current transformer collects the full current information on the arrester in real time and transmits it to the monitoring host in real time. The monitoring host analyzes and obtains the peak value of the resistive current and compares it with the set threshold. If it exceeds, an alarm is issued. 2. An on-line monitoring device for open-type surge arresters based on sensing technology according to claim 1, wherein the open-type current transformer includes a first arc-shaped component and a second arc-shaped component, the One end of the first arc-shaped component and one end of the second arc-shaped component are respectively rotatably connected to the mounting bracket. When the open-type current transformer is closed, the other end of the first arc-shaped component and the second arc-shaped component are separately Connected at one end. 3. An on-line monitoring device for open-type surge arresters based on sensing technology according to claim 2, wherein the other end of the first circular arc-shaped component has a convex structure, and the second circular arc The other end of the arc-shaped component has a concave structure. When the open-type current transformer is closed, the protrusion of the first arc-shaped component is inserted into the groove of the second arc-shaped component. 4. An on-line monitoring device for open-type surge arresters based on sensing technology according to claim 3, characterized in that, said first circular-arc component protrusion is provided with a through hole, and said second circular Through holes corresponding to the through holes of the protrusion are provided on both sides of the groove of the arc-shaped component. 5. The on-line monitoring device for open-type surge arresters based on sensing technology according to claim 1, wherein the monitoring host includes a housing and a printed circuit board installed in the housing, and the housing Connect with mounting bracket. 6. The on-line monitoring device for open-type surge arresters based on sensing technology according to claim 5, wherein the printed circuit board includes a CPU circuit, a storage circuit and a wireless communication circuit respectively connected to the CPU circuit . An input interface and an alarm circuit, wherein the input interface is connected to the open-type current transformer, and the wireless communication circuit is connected to the remote terminal. 7. A monitoring method implementing the open-type surge arrester online monitoring device based on sensing technology claimed in claim 1, is characterized in that, comprises the following steps: 1) The open current transformer collects the full current information on the arrester and transmits it to the monitoring host in real time; 2) Monitor the full current of the host sampling a cycle; 3) Take the extreme point within half a cycle as the capacitive current extreme point; 4) Simulating a capacitive current based on the capacitive current extreme point; 5) Subtracting the simulated capacitive current from the full current to achieve the resistive current waveform; 6) Determine whether the peak value of resistive current and capacitive current satisfies the following formula, if so, perform step 7), otherwise perform step 2) iX=iC+iR, where iX is the full current, iC is the capacitive current, and iR is the resistive current 7) Determine the voltage reference extreme value point based on the resistive current extreme value moment; 8) The sampling value of the corresponding point on the waveform of the full current is the peak value of the resistive current. 8 . The monitoring method of an on-line monitoring device for open-type surge arresters based on sensing technology according to claim 7 , wherein the simulated capacitive current waveform is a standard sine wave waveform.