NETWORK OPERATING DIVISION Operating Effectiveness

Name: NETWORK OPERATING DIVISION Operating Effectiveness
Uploaded: 2017-07-21T17:19:23+00:00
Duration: PTM31S27
Channel: Daniel Summers
Description: NETWORK OPERATING DIVISION Operating Effectiveness

NETWORK OPERATING DIVISION Operating Effectiveness
Transmission Lines Protection Overview

Transmission Lines LH1 Protection Overview
Operating Effectiveness Training & Development Transmission Lines LH1 Protection Overview  Hydro One Networks Inc 49 Sarjeant Drive Barrie, Ontario Canada, L4N 4V9 Phone (705) Revised: November 4, 2008 The information in this document is for reference and is to be used as a guide only. The OE Training Section makes no representation or warranty, expressed or implied, that the information contained within is current. The information included is subject to change. It is solely your responsibility to ensure that you are using up-to-date documents, prints and information. Please notify the HONOC Operating Effectiveness Training Section of required updates and/or modifications.

Transmission Lines Protection
Objectives Through the use of this presentation participants will learn and understand Transmission Lines Protection. Emphasis is on: Functionality Limitations Instructions and Procedures Support Services. Cont…

This presentation will cover:
Transmission Lines Protection Overview. This presentation will cover: What transmission line protection is, Why the need for line protection Principles of Operation ( Impedance), Different Operational zones Various types or schemes Exceptions and Anomalies Transfer Trip Channels Permissive Echo

This presentation will cover:
Transmission Lines Protection Overview. This presentation will cover: LH1 configuration Micro-wave communications Power Line Carrier communications Fibre-Optic Digital communications Various types or schemes

Transmission Lines Protection Overview.
We first must understand what a transmission line is. A transmission line is a high voltage circuit designed to carry a high amount of power over great distances between points. In some cases, this could be simply between two points as shown. Station ‘A’ ‘B’ Power flow

In more complicated configurations there could be: Multiple terminal stations Multiple tap stations Combinations of both Station ‘D’ Station ‘A’ Station ‘B’ Power flow Station ‘F’ Station ‘E’ Station ‘C’

To begin, we will look at a simple two ended circuit Station 'Y' Station 'Z' Station 'Y' is a terminal that has two breakers on the circuit. Station 'Z' is also a two breaker terminal for the circuit.

Simple two ended circuit
Transmission Lines Protection Overview. Simple two ended circuit Station 'Y' Station 'Z' The circuit that travels between Station 'Y' and Station 'Z' is a high voltage open air transmission line and as such is vulnerable to external influences.

Transmission Lines Protection Overview. Simple two ended circuit Station 'Y' Station 'Z' A fault could develop anywhere along the circuit causing fault current to flow between phases and/or to the ground.

Transmission Lines Protection Overview. Simple two ended circuit Station 'Y' Station 'Z' If there is no way of removing this faulted equipment from service, it will remain faulted eventually causing danger to the public, damage to equipment or even lead to a system wide disturbance.

Simple two ended circuit Station 'Y' How does the protection system see the fault? Station 'Z' Protection systems will sense the fault and clear the circuit removing it from service.

Simple two ended circuit There are many ways in which faults can be detected. For transmission circuits the most common method is by using impedance .

Transmission Lines Protection Overview. Simple two ended circuit Voltage (CVT) Current (CT) Station 'Y' Station 'Z' At each end of the line there are both voltage sensing devices and current sensing devices

Transmission Lines Protection Overview. Simple two ended circuit These sensing devices monitor line voltage and line current on a continuous basis. Under normal circumstances, the current will be at expected normal values and the voltage will be at the system normal.

Transmission Lines Protection Overview. Simple two ended circuit The Impedance is derived by placing the voltage and current into a ratio using OHMS law. Voltage 230,000 Impedance = = 115 ohms Current 2,000 Voltage = 230,000 volts Current = 2,000 amps

Transmission Lines Protection Overview. Simple two ended circuit If a fault occurs then these quantities will be disrupted causing the ratio to greatly change. 150000 230,000 Impedance = = 3 ohms = 115 ohms 50000 2,000 Voltage = 150,000 volts Voltage = 230,000 volts Current = 2,000 amps Current = 50,000 amps

Simple two ended circuit The impedance is set to a certain range. Anything outside of that set range is considered a fault and will trip the circuit. Impedance is outside of preset range – Circuit will trip. Trip Setting range 3 ohms Normal Operating range 115 ohms 50000 Amps 2000 Amps Volts Volts

Transmission Lines Protection Overview. Simple two ended circuit Station 'Y' Station 'Z' The idea is to set the impedance such that for any fault on the line, the protections will see the changes in voltage, current and the ratio between them, covering 100% of the circuit.

Transmission Lines Protection Overview. Simple two ended circuit Station 'Y' Station 'Z' With this type of impedance detection, it would be very difficult to set the range to exactly cover 100% of the circuit due to tolerances in measuring equipment.

Simple two ended circuit Station 'Y' Station 'Z' The settings could be set: Too short. Under protected Too long. Over protected

Transmission Lines Protection Overview. Simple two ended circuit Station 'Y' Station 'Z' To correct this problem, specific zones of protection have been created.

Simple two ended circuit Station 'Y' Station 'Z' Zone 1 – 80-85% Zone 2 – % Zone 1 – Is set to cover 80-85% of the circuit and is instant. Zone 2 – Is set to cover % of the circuit but is generally a timed protection.

Zone 1 Protection Station 'Y' Station 'Z' Zone 1 – 80-85% Zone 1 – Is set to cover 80-85% of the circuit and is instant. Zone 1 protection is generally known as Direct Underreach

Zone 1 Protection There is a limit to the protection when using Direct Underreach Station 'Y' Station 'Z' This area Instantaneous protection from Station 'Y' only. This area overlaps and is Instantaneous protection from both Station 'Y' and Station 'Z'. This area Instantaneous protection from Station 'Z' only.

To overcome this limit communication is used between ends.
Transmission Lines Protection Overview. Zone 1 Protection To overcome this limit communication is used between ends. Station 'Y' Station 'Z' If a fault occurs here, ‘Y’ Zone 1 will see it and send a trip signal called… Transfer Trip

Transfer Trip Communication is accomplished by a variety of media but will not be discussed right now. Station 'Y' Station 'Z' 1 T/T Rx 2 Transfer Trip At Station 'Y' both Zone 1 and Zone 2 will see the fault. Station 'Y' Zone 1 will trip instantly and send Transfer Trip Station ‘Z' will receive Transfer Trip and trip its terminal breakers instantly.

Simple two ended circuit There is another limit to the protection when using Direct Underreach The answer is to use another zone designed to reach all the way across the circuit. Station 'Y' Station 'Z' How do we protect this area from Station 'Z'? How do we protect this area from Station 'Y'?

Zone 2 Transmission Lines Protection Overview.
Simple two ended circuit Zone 2 Station 'Y' Station 'Z' Zone 2 is set to ‘see’ % of the circuit. The protection will overlook into adjacent zones and could cause erroneous trips for faults outside of the zone. To prevent this Zone 2 protection is generally made to be timed.

Zone 2 Transmission Lines Protection Overview.
We will look at Zone 2 independent of Zone 1 Zone 2 Station 'Y' Station 'Z' Zone 2 is set to ‘see’ % of the circuit. Although Zone 2 is normally timed, there is a need for the Zone 2 protection to be instantaneous in order to satisfy rapid removal of the transmission circuit in a faulted condition.

Zone 2 Protection Station 'Y' Station 'Z' The rapid removal will be by using Zone 2 in a: Permissive Overreach scheme or Directional Comparison scheme

Permissive Overreach Station 'Y' Station 'Z' Zone 1 Limit 2 In Permissive Overreach each Station has a timed Zone 2. If a fault occurs outside of Station 'Z' Zone 1 as shown above, only the Station 'Z' Zone 2 will see it. When the Zone 2 ‘sees’ the fault it starts a timer (400ms).

Permissive Overreach Station 'Y' Station 'Z' Zone 1 Limit 1 2 2 Permissive Signal At Station 'Y' both Zone 1 and Zone 2 will see the fault. Station 'Y' Zone 1 will trip instantly Station 'Y' Zone 2 will see the fault and will send Permission to Station 'Z' Zone 2 to trip instantly instead of timed.

Directional Comparison
Transmission Lines Protection Overview. Directional Comparison Station ‘Y’ Station ‘Z’ Zone 1 Limit 2 In Directional Comparison each Station has Instant Zone 2 coverage. If a fault occurs outside of Station ‘Z’ Zone 1 as shown above, only the Station ‘Z’ Zone 2 will see it. When the Zone 2 ‘sees’ the fault it will trip instantly.

Transmission Lines Protection Overview. Directional Comparison Station ‘Y’ Station ‘Z’ Zone 1 Limit 2 This Instantaneous tripping, however, could pose a problem if the fault is outside of the protected circuit, but still inside the Zone 2 reach. The fault will be seen by the Zone 2 protection and will cause the circuit to erroneously trip for this out of zone fault.

Transmission Lines Protection Overview. Directional Comparison Station ‘Y’ Station ‘Z’ Zone 1 Limit 2 For example: The fault is located on the adjacent circuit. Station ‘Z’ Zone 2 ‘sees’ the fault and will trip instantly Only the circuits breakers of the faulted circuit should trip

Transmission Lines Protection Overview. Directional Comparison The OM3 will sense the fault as well and send a block signal to the opposite Zone 2 preventing it from tripping instantly. Station ‘Y’ Station ‘Z’ OM3 X 2 Block Signal To correct this a 3rd Zone is employed This is the Directional Comparison element which employs a relay known as an OM3 relay and is set to look backwards If a fault occurs out of zone it trips its local breakers. The Zone 2 at Station ‘Z’ will also see the fault and try to trip its breakers instantly.

Protection review Permissive Signal Block Signal Station 'Y' Station 'Z' Transfer Trip Station ‘Z’ Zone 3 OM3 2 Station ‘Z’ Zone 2 1 OM3 Station ‘Z’ Zone 1 OM3 1 2 Station ‘Y’ Zone 1 Station ‘Y’ Zone 2 Transfer Trip Station ‘Y’ Zone 3 OM3 Block Signal Permissive Signal In some cases Zone 2 may be different in each Group, Group A Zone 2 could have Permissive Overreach where Group B could have Directional Comparison The protections will all have a Zone 1 Direct Under reach and Zone 2 will have either Permissive Overreach or Directional Comparison but not both. Directional Comparison is Instant unless it receives a Block Signal from the opposite end Zone 3 OM3 element where it will then trip timed. Permissive Overreach is Timed unless it receives a Permissive Signal from the opposite end Zone 2 protection where it will then trip instantly. These protections are referred to as Groups Each terminal will have duplication of each group and will be known as Group A and Group B. Zone 2 can be Permissive Overreach or Directional Comparison Each Group A and Group B are generally clones of each other with a Zone 1 Direct Underreach and a similar Zone 2. Each Station has Zone 2 covering % of the circuit. Each Station Zone 1 will send Transfer Trip to opposite end station tripping its breakers. Each Station has a Zone 1 Direct Underreach covering 80-85% of the circuit.

Protection review Permissive Signal Block Signal Station 'Y' Station 'Z' Transfer Trip Station ‘Z’ Zone 3 OM3 2 Station ‘Z’ Zone 2 1 OM3 Station ‘Z’ Zone 1 OM3 1 2 Station ‘Y’ Zone 1 Station ‘Y’ Zone 2 Transfer Trip Station ‘Y’ Zone 3 OM3 Block Signal Permissive Signal This is what represents a basic line protection. Two Zones with a dual redundancy built in.

Lets look at when a terminal is Out of Service with its line disconnect open Permissive Signal Block Signal Station 'Y' Station 'Z' Transfer Trip Station ‘Z’ Zone 3 OM3 2 Station ‘Z’ Zone 2 1 OM3 Station ‘Z’ Zone 1 OM3 1 2 Station ‘Y’ Zone 1 Station ‘Y’ Zone 2 Transfer Trip Station ‘Y’ Zone 3 OM3 Block Signal Permissive Signal The line switch at Station ‘Y’ is OPEN As a result, Station ‘Y’ Protections no longer see the circuit.

Lets look at when a terminal is Out of Service Station 'Y' Station 'Z' Transfer Trip 2 Station ‘Z’ Zone 2 Station ‘Z’ Zone 1 1 Transfer Trip is Blocked to opposite terminal breakers If a fault occurs within the Zone 1, both Zone 1 and Zone 2 protections will see the fault and the Zone 1 will high speed trip the terminal at Station ‘Z’.

Lets look at when a terminal is Out of Service ‘B’ Pallets Station 'Y' Station 'Z' Permissive Signal Permissive Echo Signal 2 Station ‘Z’ Zone 2 Station ‘Z’ Zone 1 1 If a fault occurs outside of Zone 1, only Zone 2 protections will see the fault and will timed trip the terminal at Station ‘Z’. To correct this, the Permissive Signal is returned or Echoed back to the sending terminal and it will then trip instantly. This signal is keyed on at all times.

Communication Powerline Carrier Wave Trap Station 'Y' Station 'Z' Fibre-Optic Digital Tele-protection MicroWave 2 1 1 2 In order for the Protection signals to travel from one station to another, a communications medium is required. There are several types used today.

Micro-Wave Communication Station 'Y' Station 'Z' Microwave signals are transmitted between points. These are known as Guard Tones The Guard Tones typically consist of Transfer Trip Tones and 2 Permissive / Blocking Tones We will call them… A large microwave transmission tower is built at each end of the circuit

Micro-Wave Communication Station 'Y' Station 'Z' Transfer Trip Channel #1 Transfer Trip Channel #2 Transfer Trip Channel #3 Transfer Trip Channel #4 Permissive / Block Channel #1 Permissive / Block Channel #2

Micro-Wave Communication
Transmission Lines Protection Overview. Micro-Wave Communication Station 'Y' The question arises. Why so many Tones? Station 'Z' Here’s why…. Microwave is: - influenced by external forces - a line of sight communication

Micro-Wave Communication Station 'Y' Station 'Z' Microwave is a radio signal and uses air to travel through. When the air changes properties, it distorts the path of the microwave This is known as- Microwave Fading

Micro-Wave Communication Station 'Y' Distortions in the air can be caused by changes in: Temperature Pressure Humidity Precipitation Fog and many other atmospheric factors. Station 'Z'

Transmission Lines Protection Overview. Micro-Wave Communication Station 'Z' Microwave is also a “Line of Sight” communications Station 'Y' Trees Buildings Any type of physical obstruction will affect the path of the signal

Transmission Lines Protection Overview. Micro-Wave Communication Station 'Z' Station 'Y' To correct for these limits. Pathways are carefully determined to minimize external influences.

Transmission Lines Protection Overview. Micro-Wave Communication Station 'Z Station 'Y' Main Pathway Bodies of Water Hills and Mountains Tall Buildings Another method to secure transmission of the signal is sending along redundant pathways Pathways will go around avoiding large obstacles Alternate Pathway

Transmission Lines Protection Overview. Micro-Wave Communication Station 'Z Station 'Y' Main Pathway T/T ch#1 T/T ch#2 Perm#1 Bodies of Water Hills and Mountains Tall Buildings Sometimes signals will be split. 2 T/T ch’s, 1 Perm on Main path 2 T/T ch’s, 1 Perm on Alt Path T/T ch#3 T/T ch#4 Perm#2 Alternate Pathway

Power Line Carrier - PLC Power Line Carrier employs a high frequency signal injected into the transmission circuit. At each end of the circuit, wave traps are employed which are tuned to trap the frequency and shunt it away to communications equipment. Transmission Circuit Wave Trap Wave Trap 60hz passes, high hz does not CVT shunts signal to communications equipment

Digital Tele-protection – Fibre Optic
Transmission Lines Protection Overview. Digital Tele-protection – Fibre Optic Digital Tele-protection had once utilized microwave tone equipment for the LH1 configuration but for the most part has since been replaced with all digital equipment. This is a true Digital Tele-Protection scheme and is beyond the scope of this presentation. Digital Tele-protection employs light signal injected into fibre optic cable. The fibre could be buried or even in the sky wire of a transmission circuit. Fibre Optic Fibre Optic SkywireShield Wires

Micro-Wave Communication Station 'Y' Station 'Z' Frequency Shift T1 G1 T2 G2 T3 G3 T4 G4 T5 G5 T6 G6 Fault TRIP R1 G1 R2 G2 R3 G3 R4 G4 R5 G5 R6 G6 Watch carefully how this works Relay/Microwave buildings

‘A’ Battery DC + ‘A’ Protection ‘B’ Battery DC + ‘B’ Protection LH1 Configuration CH #1 CH #3 CH #2 CH #3 CH #2 CH #4 CH #1 CH #4 Permissive ‘A’ Logic Permissive ‘B’ Logic Disconnect Switch ‘A’ Pallet Supervision Click These Trip Circuit Fail Fail Fail Disconnect Switch Fail Fail Fail Close Trip #1 Guard #1 Trip #2 Guard #2 Trip #3 Guard #3 Trip #4 Guard #4 Perm #1 Guard #1 Perm #2 Guard #2 Open Transfer Trip Channels Permissive Channels

To conclude you learned:
Transmission Lines Protection Overview. To conclude you learned: What a circuit is What circuit protections are and why they are needed The different zones of protection and how they work Transfer Trip, Permissive & Block signals Microwave, Power Line Carriers and Fibre-Optic Digital Tele-Protections communications LH1 configuration for protection tripping

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NETWORK OPERATING DIVISION Operating Effectiveness

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