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| Transmission line Protection Relay panel-1A
transmission line, installed in wide area for its
characteristics, is a power system facility that
transfers power from generation to a customer. |
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| Thus, compared to other power system facilities,
transmission lines face more frequent accident rate
due to natural disasters such as thunder and snow
storm. It is important due to its effect on power
transfer and degree of stability when there are
changes of power flows. Thus it needs a protection
function with stability of protective system. |
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| In Korea, transmission line voltage levels are mainly
154 kV and 354 kV. In order to support development
of the industry which needs electrical power, 756 kV
line also constructed and operated. |
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| In transmission line protection panel, there is a
function that uses PCM current differential function
(87T) and back-up function which uses 3 steps
(zone 1, 2, 3) distance protection scheme. |
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| GABO’s transmission line protection panel has a
combination of main protection relay (7SD522) and
back-up protection relay (7SA522) made from
SIEMENS. |
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PCM COMMUNICATION FUNCTION |
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| Through communication between relays at both ends, it
checks differential current of transmission lines, deciding
any existence of accidents. |
| Therefore multi-functional support of communication is a
very important factor to support flexible application of current
differential protection function. |
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REDUNDANCY OF COMMUNICATION LINE |
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| Local/Remote communication
line enables redundancy. In 2
terminal systems, it offers as
main/ back-up line. In 3 or
more terminals it offers Ring/
Chain Topology. |
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| chain topology |
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MULTI TERMINAL TRANSMISSION LINE PROTECTION FUNCTION |
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| By providing general 2 terminal transmission line protections
and multi terminals more than 3 terminals protection function,
we provide facility’s credibility and efficiency in operation. |
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345 [KV] TRANSMISSION LINE PROTECTION PANEL |
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345 [kv] transmission line
protection panel
Due to high voltage level,
345 [kv] transmission line
protection panel is applied
with duplication system. |
| In order to guarantee
credible function, it has
redundancy by having two
transmission lines.
(Protection panel
composed of current
differential relay and
distance relay) |
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SHORT TRANSMISSION LINE PROTECTION PANEL |
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Along with development of the industry and
urban areas, transmission lines have been
buried in underground as built in short
distance. That could cause problems of
independence characteristics setting and
disturbance in credibility of function. |
| Hence, a short transmission line protection
panel has two types of protection relays, main
and back-up. Like main protection relay, it
uses current differential functions. And backup
protection relay uses distance protection
function and current differential function. |
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DIFFERENTIAL CURRENT RELAY(7SD5x) |
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| - For a remote PCM communication between relays located at both ends, CCITTG. 703 and IEEE C37.94 standard applied. |
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| - Designed to meet redundancy communication function for maintenance of protection function when a communication error occurs. |
| - In 3 or more terminals, a redundancy communication function offers Ring/Chain Topology. |
| - In multi terminal differential current protection, it supports up to 6 terminals. |
| - Differential current protection could be applied also on transmission line including a transformer. |
| - Built in high sensitive protection function for detecting high impendence ground fault. |
| - Applied with synchronizing differential protection through communication delaytime compensation between relays located in remote ends. |
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CHARACTERISTICS OF CURRENT DIFFERENTIAL PROTECTION |
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| According to the ratio of restraint current and
differential current, it is divided into trip area and
non-trip area. In restraint current, it offers stable
restraint current factor by considering current
transformer error, synchronization error and CT
saturation. |
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| - Current differential function (an independent protection function on each phase) |
| - Auto compensation function on difference between CT ratios |
| - Current transformer open detection possible both in one pole/ three pole |
| - Fault location function |
| - Function to prevent mal-function through many fault detection |
| - Selection of one pole/three pole trip function |
| - Event recording function (trip, alarm, fail, etc) |
| - Using any portable computing device, setting and fault analysis function(Analysisprogram(DIGSI),comradefileconversionfunctionispossible) |
| - PCM telecommunication function between remote end relays. |
| - Charging current compensation function |
| - Auto-reclosing function |
| - User defined logic (CFC-continuous function chart) |
| - Self diagnosis function |
| - Metering function (current, voltage, active power, reactive power) |
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CHARACTERISTICS OF DISTANCE RELAY (7SA5x) |
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| - Distance protection which could be applied up to 3 terminals transmission lines network |
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| - Distance protection having 5+1 zone which could be set as forward/reverse and non- directional protection zone |
| - Polygonal characteristics and MHO characteristics selection |
| - Prevention of impedance over-reach by heavy load current |
| - Selection of mutual impedance compensation on parallel transmission line |
| - Built in high sensitive protection function for detecting high impedance ground fault |
| - Detection of current transformer saturation and compensation of errors occurring |
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CHARACTERISTICS OF 5+1 ZONE IMPEDANCE |
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By calculating impedance using voltage and
current, 5+1 impedance zone which divided
into forward and reverse direction could be
provided. Also as characteristic curve, both
polygonal characteristics and MHO
characteristics are built-in to provide selections
to users. |
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- 5+1 step distance protection function (independent protection function on each phase) |
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- Auto reclosing function |
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- Weak source protection function |
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- Power Swing Blocking/ Out of Step Tripping |
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- STUB protection function |
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- Synchronization detection function and single pole/multi pole auto reclosing function |
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- Single pole/ multi pole current transformer open detection function |
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- Additional various fault detection functions |
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- Selectable One pole/ 3 poles Trip function |
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- Metering function (current, voltage, active/reactive power, etc) |
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- Event recording function (Trip, Alarm, Fail, etc) |
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- Using any portable computing device, setting and fault analysis function(Analysis program (DIGSI), comrade file conversion function is possible) |
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- Out of step detection |
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- Directional comparison protection |
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- Switch-onto-fault protection |
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- User defined logic (CFC-continuous function chart). |
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- Fault location function |
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- Self diagnosis function |
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TRANSMISSION LINE PROTECTION PANEL TECHNICAL SPECIFICATION/STANDARD |
| Index |
Item |
Specification |
| Current differential ralay |
Distance relay |
| Rating |
Power Supply |
Voltage Input |
DC : 125[V], AC : 230[V] (Frequency 50/60[hz]) |
| Power Consumption |
12[W], 17[VA] |
| Analog |
Current |
1[A], Burden : 0.05[VA] |
| 5[A], Burden : 0.3[VA] |
| Power |
80/125[V], Power Consumption ≤ 0.1[VA] |
| Digital input |
Number of digital input : 8/16/24
Voltage Range : 88~300[VDC] |
8/16/22/24 |
| Digital output |
Number of digital output : 7~31
Allowable Current : Continus(5[A]), 30[A](0.5[sec]) |
15~43 |
| Communication |
Communication Port |
RS-232, RS-485, Ethernet, FO(Fiber Optic) |
| Protocol |
Profibus , DNP3.0, IEC61850, TCP/IP |
| Time Synchronization |
DCF77/IRIG-B/SNTP |
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