KR20190129210A - Apparatus and method for removing resonance current in hvdc system - Google Patents

Abstract

The present invention relates to a device for removing resonance current in a high voltage direct current (HVDC) system. The device for removing resonance current in an HVDC system comprises: a lightning arrester checking and removing resonance current at both ends of an AC system in an HVDC system; and a durable management device continuously and stably removing the resonance current through durable management of the lightning arrester.

Description

Apparatus and method for removing resonance current of HVDC system {APPARATUS AND METHOD FOR REMOVING RESONANCE CURRENT IN HVDC SYSTEM}

The present invention relates to an apparatus and method for removing a resonance current of an HVDC system, and more particularly, to detect and remove a resonance current generated by a frequency difference between AC systems in an HVDC system, and to remove the resonance current through endurance management. The present invention relates to a resonant current removing device and method of the HVDC system that allows for continuous and stable removal.

In general, high voltage direct current (HVDC) systems are widely used at home and abroad due to various advantages such as cost reduction, fault current blocking, and large-scale renewable energy utilization. Another feature of this is that HVDC systems can be linked to systems of different frequencies.

However, as described above, when linked with a system having a different frequency, there is a high probability that resonance occurs in the DC line, and when resonance occurs, there is a possibility that insulation breakdown and valve burnout may occur due to overvoltage.

The HVDC system (for example, current type and voltage type HVDC system) actively utilizes a smooth reactor as a method for preventing such resonance. The smooth reactor generally removes harmonics from the DC line to create the maximum DC current, and has a fault current blocking function of the DC stage, and also moves the resonance point that may occur in the low frequency region. It also has a function to suppress the maximum value.

The current type HVDC system includes a rectifier side for converting AC power to DC power and an inverter side for converting DC power to AC power. That is, the general current type HVDC system is basically configured to be rectified through the AC-DC-AC conversion process based on the line voltage of the AC system.

Since the smooth reactor in the voltage type HVDC system mainly aims at preventing the DC stage failure, a large current can be detected, but it is difficult to detect a resonance current generated when the frequency of the AC voltage is different. However, voltage-type HVDC system technology is rapidly growing, and it is expected to use a lot of voltage type in the future, and there is a high possibility of big problem such as cost to prevent such resonance phenomenon when connecting countries.

Therefore, when linking between countries, resonance may occur due to the frequency difference between the two ends of the AC system in the HVDC system, and when such resonance occurs, the current decreases rapidly and the overvoltage occurs while the impedance decreases, thereby continuously and stably removing the resonance current. There is a need for a way to do this.

Background art of the present invention is disclosed in Republic of Korea Patent Publication No. 10-2013-0083292 (published on July 22, 2013, overvoltage control system of the AC system linked to the HVDC system).

According to an aspect of the present invention, the present invention was created to solve the above problems, in the HVDC system detects and eliminates the resonance current generated by the frequency difference between the AC system, through endurance management It is an object of the present invention to provide a resonant current removing device and method of the HVDC system, which allows to remove the resonant current continuously and stably.

Resonant current removing device of the HVDC system according to an aspect of the present invention, the lightning arrester for checking and removing the resonant current at both ends of the AC system in the HVDC system; And a durable management device for continuously and stably removing the resonant current through the durable management of the arrester.

In the present invention, the arrester includes a resonance detector for detecting the occurrence of resonance by detecting the flow of overvoltage and overcurrent.

In the present invention, the durable management device, the lightning arrester operation detection unit for detecting that the arrester performs a resonance current removal operation; A voltage & current detector for detecting a voltage & current applied during the operation of the arrester; An operation time detector for detecting and accumulating the time that the arrester operates; And calculating the endurance life of the arrester which is extinguished during the operation of the arrester, comparing the endurance of the arrested arrester calculated at the initial endurance of the arrester, calculating the remaining end life and outputting the arrester; Control unit for alarming the reinstallation time; characterized in that it comprises a.

According to the present invention, under the control of the controller, the endurance output unit for outputting the endurance remaining in the initial endurance of the arrester; And an alarm output unit configured to alert the user of the replacement or reinstallation time using visual information or auditory information when the remaining end of life of the arrester reaches a predetermined exchange or reinstallation endurance under control of the controller. It is done.

In the present invention, the control unit, in order to calculate the endurance life, refers to the lightning arrester endurance DB, the lightning arrester endurance DB, stores at least one or more information that affects the endurance endurance for each arrester in the form of a lookup table Characterized in that.

Resonance current removal method of the HVDC system according to another aspect of the present invention, the HRR system to continuously and stably remove the resonant current through the endurance management of the arrester and the arrester to check and remove the resonant current at both ends of the AC system. Checking, by the controller of the resonant current removing device of the HVDC system, comprising a durable management device to enable the arrester to perform the resonant current removing operation; Detecting, by the controller, a voltage & current applied to the arrester when the arrester is operated; Checking, by the controller, a time period during which the arrester operates for the resonance current removing operation; Calculating, by the controller, the endurance life of the arrester that is extinguished upon operation of the arrester; Calculating, by the control unit, the remaining end life of the lightning arrester by comparing the endurance life of the extinguished lightning arrester calculated at the initial end life of the arrester; And outputting, by the controller, the remaining service life of the arrester, and also alarming a time of replacing or reinstalling the arrester.

In the present invention, in order to calculate the endurance endurance or the remaining endurance of the arrester, the control unit refers to the DB of the lightning arrester, the arrester endurance DB, at least one or more affecting the durability of the lightning arrester The information is stored in the form of a lookup table.

According to an aspect of the present invention, the present invention detects and removes the resonance current generated by the frequency difference across the AC system in the HVDC system, and allows the continuous and stable removal of the resonance current through endurance management. .

1 is an exemplary view showing a configuration and installation position of a resonance current removing device of an HVDC system according to an embodiment of the present invention.
2 is an exemplary view schematically showing an internal configuration of the arrester in FIG. 1.
3 is an exemplary view showing a characteristic curve of the arrester in FIG.
4 is an exemplary view showing a schematic configuration of a management device built in the resonance current removing device of the HVDC system in FIG.
FIG. 5 is a flowchart illustrating a control method of a management device built in the resonance current removing device of the HVDC system in FIG. 1.

Hereinafter, an embodiment of a resonant current removing device and method of an HVDC system according to the present invention will be described with reference to the accompanying drawings.

In this process, the thickness of the lines or the size of the components shown in the drawings may be exaggerated for clarity and convenience of description. In addition, terms to be described below are terms defined in consideration of functions in the present invention, which may vary according to the intention or convention of a user or an operator. Therefore, the definitions of these terms should be made based on the contents throughout the specification.

1 is an exemplary view showing a configuration and an installation position of a resonance current removing device of an HVDC system according to an embodiment of the present invention.

As shown in FIG. 1, an apparatus for removing resonance current of an HVDC system includes an arrester 100 that checks and removes a resonance current at both ends of an AC system in an HVDC system (eg, a voltage type HVDC system), and the arrester 100. It includes a durable (or life) management device 200 to be able to continuously and stably remove the resonant current through the durable (or life) management of the.

FIG. 2 is an exemplary view schematically illustrating an internal configuration of the arrester in FIG. 1. The arrester 100 includes a resonance detector 110 that detects the occurrence of an overvoltage and an overcurrent to detect a resonance.

The other components of the arrester 100 except for the resonance detector 110 are components of a conventional general arrester (eg, a pressure plate O-ring, a spring, a ZnO element, an insulation tube, a voltage divider capacitor, an insulator, a gas guide, and a seal). Terminals, etc.), so a detailed description thereof will be omitted.

The arrester 100 installed at both ends of the AC system in the HVDC system detects resonance by checking a rapidly increasing amount of current and a current waveform when resonance occurs (or detecting a resonance occurrence through the resonance detector 110). can do.

In general, when resonance occurs, the amount of current rapidly increases beyond the reference, and the current waveform is distorted beyond the reference (or allowable range).

When the resonance occurs as described above, the arrester 100 operates, and the arrester operation detector 210 of FIG. 4 detects (or detects) the operation of the arrester 100. That is, when resonance occurs and overvoltage occurs, a rapid current is generated.

When a sudden current occurs as described above, the arrester 100 operates, and when the resonance occurs, the overcurrent is removed through the arrester 100. That is, referring to FIG. 3, when the voltage flowing into the arrester 100 enters the second region (II zone), the current is rapidly removed in a short time due to the non-linear characteristic.

For reference, FIG. 3 is an exemplary view showing a characteristic curve of the arrester in FIG. 2, and the characteristics of the zones of the arrester 100 will be described as follows.

인데, 여기서 I는 전류, V는 전압, C는 커패시턴스를 의미하며, a는 40 또는 그이상이 된다. 제3 영역(Ⅲ zone)(또는 대전류 영역)은, 전류밀도가 더 커지면 ZnO의 결정의 비저항 성분(R_z)이 지배적이고, 이 영역에서 a는 거의 1에 가까워진다.Referring to FIG. 3, when the electric field is applied, the first region (I zone) (or the yield region) is lowered by the electric field when the boundary potential barrier between the ZnO crystal and the critical layer is flowed by the electric field and the current flows as the hot electrons jump over the barrier. . In the second zone (or the zone of breakdown), when the electric field becomes larger, the electrons trapped at the boundary surface exit the barrier due to the tunnel effect. This causes a sharp increase in current and large non-linearity. The formula applied here

Where I is the current, V is the voltage, C is the capacitance, and a is 40 or more. In the third region (III zone) (or a large current region), when the current density becomes larger, the resistivity component R _z of the crystal of ZnO is dominant, and in this region, a becomes close to one.

As described above, the arrester 100 operates according to its own characteristic to operate when the resonance current occurs at both ends of the AC system of the HVDC system to remove the resonance current. However, the lightning arrester 100 may vary in speed (or duration) in which endurance (life) decreases according to an operation time or a magnitude (or amount) of a resonant current to be removed.

As described above, as the end of life (life) ends, the performance of eliminating resonance current decreases, and when the end of life (life) ends during elimination of the resonance current, insulation breakdown and valve burnout occur due to overvoltage caused by resonance. Can be generated. Therefore, it is necessary to manage such that the performance of the arrester 100 is not degraded or the endurance (life) is not terminated during the removal of the resonance current.

The endurance (or life) management apparatus 200 may continuously and stably remove the resonance current through the endurance (or life) management of the arrester 100.

FIG. 4 is an exemplary view showing a schematic configuration of a management device built in the resonance current removing device of the HVDC system in FIG. 1.

As shown in FIG. 4, the management device implemented in the resonant current removing device of the HVDC system according to the present embodiment includes an arrester operation detector 210, a voltage & current detector 220, an operation time detector 230, and a controller. 240, a lightning arrester durable DB 250, a durable (life) output unit 260, and an alarm output unit 270.

The arrester operation detection unit 210 detects that the arrester 100 that detects the lightning arrester 100 performs the resonance current removal operation as an overvoltage caused by resonance in the HVDC system generates a sudden current (that is, a resonance current). .

The voltage & current detector 220 detects the voltage & current applied to the arrester 100 (ie, the overvoltage generated by resonance and the resonance current accordingly) when the arrester 100 operates.

The operation time detector 230 detects and accumulates the time that the arrester 100 operates.

The controller 240 calculates the endurance (life) of the arrester based on the information detected by the arrester operation detector 210, the voltage & current detector 220, and the operation time detector 230. .

The controller 240 may refer to the lightning arrester DB 250 to calculate the service life (life).

The lightning arrester endured DB 250 stores at least one or more pieces of information affecting the endurance (life) of each arrester in the form of a lookup table. For example, the information stored in the DB 250 built into the arrester includes a capacitance, a voltage, and a current of the arrester.

The control unit 240 compares the endurance (life) of the extinguished lightning arrester calculated from the original endurance (initial endurance) of the arrester 100, calculates and outputs the remaining endurance (life) of the arrester. Alarm (100) replacement (or reinstallation) time in advance.

The endurance (life) output unit 260 outputs the endurance life remaining in the original endurance (initial endurance) of the arrester 100 under the control of the controller 140.

The alarm output unit 270 is exchanged (or reinstalled) under the control of the controller 140 when the remaining life (life) of the arrester 100 becomes a predetermined exchange (or reinstallation). ) Alarm the user (or administrator) with time or hearing information.

FIG. 5 is a flowchart illustrating a control method of the management device built in the resonance current removing device of the HVDC system in FIG. 1.

As shown in FIG. 5, as the controller 240 generates an overvoltage due to resonance in the HVDC system and generates a sudden current (that is, a resonance current), the arrester 100 that detects this operates to remove the resonance current. It is checked whether the operation is performed (S101).

The control unit 240 detects the voltage & current (that is, the overvoltage generated by resonance and the resonance current accordingly) applied to the arrester 100 when the arrester 100 operates (YES in S101). ).

The controller 240 checks (or detects) a time during which the arrester 100 operates for the resonance current removing operation (S103).

The controller 240 is extinguished based on the information (eg, lightning arrester operating time, voltage, and current) detected by the arrester operation detector 210, the voltage & current detector 220, and the operation time detector 230. The durability (life) of the arrester 100 to be calculated is calculated (S104).

The controller 240 compares the endurance life (life) of the extinguished lightning arrester calculated from the original endurance life (initial endurance life) of the arrester 100, and calculates the remaining endurance life (life).

At this time, the control unit 240 may refer to the DB 250 in the lightning arrester in order to calculate the endurance (life).

In addition, the control unit 240 outputs the remaining life (life) of the calculated lightning arrester 100, and also alarms the time of replacement (or reinstallation) of the arrester 100 (S106).

Accordingly, the user has an effect of continuously and stably removing the resonance current by replacing or reinstalling the arrester 100 before the performance degradation of the arrester 100 or the end of service life (end of life) is terminated.

Although the present invention has been described with reference to the embodiments illustrated in the drawings, this is merely exemplary, and various modifications and equivalent other embodiments are possible for those skilled in the art to which the art pertains. I will understand the point. Therefore, the technical protection scope of the present invention will be defined by the claims below.

100: lightning arrester 110: resonance detector
200: durable management device 210: lightning arrester motion detection unit
220: voltage & current detector 230: operation time detector
240: control unit 250: lightning arrester durable DB
260: durable output unit 270: alarm output unit

Claims (7)

Lightning arrester for checking and removing the resonant current across the AC system in the HVDC system; And
And a durable management device for continuously and stably removing the resonant current through endurance management of the arrester.
The lightning arrester of claim 1,
Resonance detector for detecting the over-voltage and over-current to detect the occurrence of the resonance; resonance current removal device of the HVDC system comprising a.
According to claim 1, wherein the durable management device,
An arrester operation detector for detecting that the arrester performs a resonance current removing operation;
A voltage & current detector for detecting a voltage & current applied during the operation of the arrester;
An operation time detector for detecting and accumulating the time that the arrester operates; And
Calculate the endurance life of the arrester that is extinguished during the operation of the arrester, compare the endurance of the lightning arrester calculated at the initial endurance of the arrester, calculate the remaining end life and output it, and replace or reinstall the arrester Resonant current removing device of the HVDC system comprising a; control unit for alarming the timing.
The method of claim 3,
An endurance output unit configured to output the endurance limit remaining from the initial endurance end of the arrester under the control of the controller; And
Under the control of the control unit, if the remaining end of life of the arrester is a predetermined exchange or reinstallation endurance life, the alarm output unit for alarming the user using visual information or auditory information when the replacement or reinstallation; Resonant current removal device of the HVDC system.
The method of claim 3, wherein the control unit,
In order to calculate the endurance life, refer to the arrester endurance DB,
The lightning arrester endured DB, at least one or more information that affects the endurance endurance for each arrester, the resonant current removing device of the HVDC system, characterized in that for storing in the form of a look-up table.
Resonant current elimination of HVDC system including lightning arrester for checking and removing resonance current at both ends of AC system in HVDC system and durable management device for continuously and stably removing resonance current through endurance management of the arrester Checking, by the controller of the device, whether the arrester performs a resonance current removing operation;
Detecting, by the controller, a voltage & current applied to the arrester when the arrester is operated;
Checking, by the controller, a time period during which the arrester operates for the resonance current removing operation;
Calculating, by the controller, the endurance life of the arrester that is extinguished upon operation of the arrester;
Calculating, by the control unit, the remaining end life of the lightning arrester by comparing the endurance life of the extinguished lightning arrester calculated at the initial end life of the arrester; And
And outputting, by the controller, the remaining service life of the arrester, and also alarming a time when the arrester is replaced or reinstalled.
The method of claim 6,
In order to calculate the endurance endurance or remaining endurance of the arrester,
The control unit refers to the DB of the lightning arrester,
The lightning arrester endured DB stores at least one or more pieces of information affecting the endurance endurance for each arrester in the form of a lookup table.

Images