CN103487721A - Traveling wave distance measuring system based on electronic transformer - Google Patents

Abstract

The invention discloses a traveling wave ranging system based on an electronic transformer, which includes an electronic current transformer, a low-frequency signal acquisition circuit and a secondary processing circuit; The circuit is connected with the secondary processing circuit, and also includes a traveling wave signal high-speed acquisition circuit, a traveling wave signal merging unit, a traveling wave signal processing unit and a 61850 standard traveling wave data transmission unit; The signal high-speed acquisition circuit, the traveling wave signal merging unit, the traveling wave signal processing unit and the 61850 standard traveling wave data transmission unit are connected to output the traveling wave signal. Wherein, the annular air-core coil is a Rogowski annular air-core coil. While maintaining the original structure of the low-frequency signal collection and output circuit, the invention adds a traveling wave signal collection and output circuit to be suitable for the use of electronic current transformers.

Description

Traveling wave ranging system based on electronic transformer

technical field

The invention relates to a traveling wave ranging system based on an electronic transformer.

Background technique

With the development of smart grid, digitization of substation has become a trend. In digital substations, because some primary and secondary equipment and their operation methods are different from conventional substations, some of the original equipment can no longer work normally, and can only continue to be used in digital substations after improvement. There is a problem in this respect in the traveling wave distance measuring device used for line fault distance measurement and location.

In digital substations, the traveling wave ranging device is the same as the traditional substation in terms of ranging principle, the main difference between the two lies in the change of signal extraction and processing methods. In traditional substations, electromagnetic CT/PT is mainly used to obtain traveling wave fault information, while in digital substations, electronic transformers are used, so how to extract available traveling wave fault information from electronic transformers becomes a practical task. The key to wave ranging.

Since the existing electronic transformers mainly meet the functional requirements of protection and other functions in terms of sampling frequency, their sampling frequency is basically within 10kHz. The existing electronic transformer cannot provide the signal, so it cannot meet the requirements of traveling wave ranging. Therefore, in order to realize the traveling wave fault location function in the digital substation, the problem of extracting the traveling wave signal must be solved first.

Contents of the invention

The technical problem to be solved by the present invention is to provide a traveling wave ranging system based on an electronic transformer.

In order to solve the above technical problems, the technical solution adopted by the present invention is: a traveling wave ranging system based on an electronic transformer, including an electronic current transformer, a low-frequency signal acquisition circuit and a secondary processing circuit; the electronic current transformer includes a ring Hollow coil, annular hollow coil is connected with the secondary processing circuit through the low-frequency signal acquisition circuit, and also includes the high-speed acquisition circuit of the traveling wave signal, the combining unit of the traveling wave signal, the processing unit of the traveling wave signal and the 61850 standard traveling wave data transmission unit; the electronic current The annular hollow coil of the transformer is sequentially connected with the traveling wave signal high-speed acquisition circuit, traveling wave signal merging unit, traveling wave signal processing unit and 61850 standard traveling wave data transmission unit to output traveling wave signals (should be not only fault signals, but also normal traveling wave signal).

Preferably, the annular air-core coil is a Rogowski annular air-core coil.

As another preference, the output traveling wave signal is not less than 1 MHz.

The beneficial effects of the present invention are:

While maintaining the original structure of the low-frequency signal acquisition and output circuit, a traveling wave signal acquisition and output circuit is added to suit the use of electronic current transformers.

Description of drawings

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

Fig. 1 is a schematic structural diagram of an embodiment of a traveling wave ranging system based on an electronic transformer according to the present invention.

Detailed ways

Figure 1 is a traveling wave ranging system based on an electronic transformer, which consists of an electronic current transformer, a low-frequency signal acquisition circuit and a secondary processing circuit, a traveling wave signal high-speed acquisition circuit, a traveling wave signal merging unit, and a traveling wave signal processing unit It is composed of 61850 standard traveling wave data transmission unit.

Wherein, the electronic current transformer includes an annular air-core coil, and the annular air-core coil is connected with a secondary processing circuit through a low-frequency signal acquisition circuit for acquisition and transmission of low-frequency signals.

The annular hollow coil of the electronic current transformer is sequentially connected with the traveling wave signal high-speed acquisition circuit, the traveling wave signal merging unit, the traveling wave signal processing unit and the 61850 standard traveling wave data transmission unit and outputs the traveling wave used for traveling wave fault location Signal.

Coil-type electronic current transformers are commonly known as Rogowski coil-type electronic current transformers, which induce primary current through Rogowski ring-shaped hollow coils, and then convert the induced current signals into optical signals through the electronic circuit board set on the high-voltage side After that, it is transmitted to the secondary system. Compared with the traditional electromagnetic current transformer, it realizes the isolation of high and low voltage terminals, and its principle is still the principle of electromagnetic induction. The sampling frequency of the electronic current transformer in this way is basically within 10kHz. In order to realize the output of the traveling wave fault signal of the electronic transformer, the following changes are made to it:

As shown in Figure 1, without changing the characteristics of the transformer and without affecting the original data collection, a high-speed data acquisition unit is added to collect the data of the Rogowski coil at the same time, and the two acquisition modules do not affect each other. , which can not only ensure the output of low frequency signals, but also satisfy the collection of traveling wave fault signals.

The technical requirements of traveling wave ranging for electronic transformers mainly include the following four points:

1) Provide sampling signals above 500KHZ;

2) The sampling signal bandwidth is above 100KHZ;

3) The sampling accuracy is not less than 12 bits;

4) The communication with the traveling wave ranging device is reliable.

In response to the above requirements, in order to collect the data of Rogowski coils in the transformation of the digital substation, the following changes were made to the existing electronic transformer collector:

1) Add a hardware integration link in the collector for signal conditioning, and select the operational amplifier required by the integration circuit to meet the requirements of bandwidth and response speed;

2) Select an A/D chip with a high sampling rate in the collector;

3) Select the corresponding MCU that controls the high-speed A/D chip.

On the premise that the existing protection signal output remains unchanged, an additional signal output suitable for traveling wave fault location is added, and its sampling is preferably not less than 1MHz. The specially added module in the Rogowski coil type electronic current transformer outputs a signal with a sampling frequency of 500KHz. Since this frequency is still less than 1MHz, further processing of this signal is required to meet the reliability and reliability of traveling wave fault location. precision.

Processing of Traveling Wave Fault Information and Realization of Ranging Function

The signal collected from the electronic current transformer is input into the traveling wave fault location device through the optical fiber. Different from the analog signal collected by the traveling wave distance measuring device in the conventional station, the digital signal is collected from the electronic transformer now. Therefore, the signal input module of the original fault distance measuring device should be changed to be suitable for electronic Digital signal input module of type transformer.

In order to ensure the reliability of ranging, the information collected by the electronic transformer is sent to the traveling wave fault distance measuring device in real time, but the traveling wave distance measuring device is activated only when a fault is detected. In order to realize the dual-terminal ranging function, the traveling wave ranging device needs to access the time synchronization signal just like the device in the conventional station.

Due to the limitation of the acquisition signal frequency, it is necessary to process the traveling wave fault signal differently from the conventional station, so that the final data is the same as the traveling wave fault location data in the conventional substation, so as to realize the analysis function of double-ended ranging and single-ended ranging. At the same time, the ranging accuracy is guaranteed.

The embodiments of the present invention described above are not intended to limit the protection scope of the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the claims of the present invention.

Claims (3)

1. the travelling wave ranging system based on electronic mutual inductor, comprise electronic current mutual inductor, low frequency signal Acquisition Circuit and secondary treating circuit; Described electronic current mutual inductor comprises annular air core coil, described annular air core coil is connected with the secondary treating circuit by the low frequency signal Acquisition Circuit, it is characterized in that: also comprise travelling wave signal high speed acquisition circuit, travelling wave signal merge cells, travelling wave signal processing unit and 61850 standard row wave datum transmission units; The annular air core coil of described electronic current mutual inductor is connected with travelling wave signal high speed acquisition circuit, travelling wave signal merge cells, travelling wave signal processing unit and 61850 standard row wave datum transmission units successively and exports travelling wave signal.

2. the travelling wave ranging system based on electronic mutual inductor according to claim 1 is characterized in that: described annular air core coil is Rogowski annular air core coil.

3. the travelling wave ranging system based on electronic mutual inductor according to claim 1, it is characterized in that: the travelling wave signal of described output is not less than 1MHz.

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