国外继电保护经验

DONGBEI · 发表于 2007-12-23 23:24:57

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我愿意与大家一起讨论国外继电保护经验。使用GE，SEL，L-PRO 等保护方面经验。

SUN1 · 发表于 2007-12-25 13:37:32

请问国外继电保护有什么特点？

DONGBEI · 发表于 2007-12-27 23:25:12

总体来说，主保护，后备保护，失灵保护等概念是相同的。
北美保护设计比中国要复杂得多。保护与自动化结合在一起设计。设计人员按照保护方案设计逻辑图，而不是由厂家设计。
馈线保护采用反时限曲线，即短路电流越大，跳闸时间越短。
线路保护采用允许式或闭锁式保护方案。
元件保护与国内类似采用差动保护。
我将陆续POST 一些英文资料供大家参考。

DONGBEI · 发表于 2007-12-27 23:29:31

(DIFF) – LINE DIFFERENTIAL SCHEME:

General Information:

High voltage protection on Hydro One lines are presented in a form of protection groups made up of individual schemes, this above scheme is one that is part of the protection group listed for this element.

The LINE DIFFERENTIAL protection scheme is a "zone tight" type of protection where currents at the line terminals are compared to determine if there is an internal fault (trip), or an external fault (no trip).

LINE DIFFERENTIAL protection schemes normally use digital communication channels, over which the set of differential relays send and receive composite signals, in digital format.

Normally, LINE DIFFERENTIAL is used over high speed communication channels.

This protection is a NEW protection standard to Hydro One (2004).

For additional detail in understanding the DIFFERENTIAL philosophy, review the Pilot Wire and Transformer Differential (FUTURE) descriptors.

DONGBEI · 发表于 2007-12-27 23:33:03

(DirC) – DIRECTIONAL COMPARISON SCHEME:

COVERAGE AREA: Zone 2 fault detectors at each line terminal are set to reach about 125% of the line length (or impedance) from the local terminal. Reverse fault detectors, looking back into the terminal, are located at each terminal. Zone 2 therefore covers the full line section and “over-reaches” beyond the remote terminal(s).

FAULT CLEARANCE / TRIPPING: High-speed tripping at the local terminal occurs from Zone 2 directly unless a “blocking” signal is received from the reverse fault detectors at the other terminal(s). Communication (i.e. Blocking) signals are transmitted to the remote terminals to prevent out-of-zone instantaneous Zone 2 tripping from occurring at all remote terminals. When a blocking signal is NOT received, tripping at remote terminal(s) is instantaneous and over-tripping can occur.

EVENTS / SEQUENCE:

1. For external faults, the local terminal reverse looking detectors send a blocking signal to the remote terminals to indicate the fault is beyond the line zone and prevent the remote breaker(s) from instantaneously tripping.
2. The communication (Blocking) signals are sent via the identified COMMUNICATION MEDIUM to the remote terminal(s) as identified in the COMMUNICATION MECHANISM to prevent the tripping relays from energizing.
Note: When NO blocking signal is received, the remote terminals will initiate instantaneous tripping of local breaker(s) and send trip signals to all other terminals immediately.
Note: Removal of the blocking signal transmitter (i.e. T25) at one terminal shall instigate the need to block the corresponding (T25) blocking transmitters at all other terminals to prevent over-tripping. See below for greater detail.
Afternoon
High voltage protection on Hydro One lines are presented in a form of protection groups made up of individual schemes, this above scheme is one that is part of the protection group listed for this element.

The advantage of DIRECTIONAL COMPARISON is high-speed tripping for multiple-ended (i.e. three terminal) circuits in cases that cannot be covered by the Zone 1 or Zone 2 fault detectors (i.e. DUR, POR schemes).

DirC also provides a more reliable (but less secure) instantaneous protection. It is more susceptible to power swings than POR scheme and due to additional equipment within the scheme, is more expensive than POR.

For the DirC scheme to operate correctly, consideration has to be given to the reduction of relay reach (i.e. coverage) due to infeeds from tapped supply station(s) and a third main terminal.

Faults Within the Circuit Zone (Diagram A):

Faults on any part of the line are located within at least one of the Zone 2 fault detectors as they are set to see approximately 125% of the circuit length or impedance, dependent on terminal in-feed. When a fault occurs on the circuit, at least one terminal’s Zone 2 fault detectors are picked up and there is NO “blocking” communication signal sent to all other remote terminal(s). The local trip relays become energized, tripping the local terminal, clearing the fault and tripping signals are instantaneously sent to all other terminals to initiate tripping remotely

In summary, DirC instantaneous tripping can only occur at a terminal when:

a) the Zone 2 fault detector at that terminal is picked up
b) NO blocking signal is received from the remote terminal(s)

Faults Outside the Circuit Zone (Diagram B):

When the fault occurs beyond a local terminal (i.e. on a neighbouring circuit, outside/beyond the protected circuit), it is seen by the Zone 2 reverse looking fault detectors. The local terminal (where the reverse detectors see the external fault) sends a blocking signal to all the other protected circuit remote terminals and prevents over-tripping from occurring at the remote terminals for an out-of-zone fault. The remote terminal’s Zone 2 trip relays will not be energized (as this blocking signal prevents tripping) and instantaneous tripping will NOT occur at the remote terminal(s).

Standard high voltage protection provides high speed tripping at the local and remote line terminals from Zone 1 directly and from Zone 2 via permissive over-reaching or directional comparison, using communication media. Timed and Line Test tripping involve the local terminal only. Reclosing is only provided from the high-speed protection.

DONGBEI · 发表于 2007-12-27 23:35:19

(DOR) - DIRECT OVER-REACHING SCHEME::

COVERAGE AREA: Zone 1 or Zone 2 fault detectors at a line terminal are set to reach about 125% of the line length (or impedance) from the local terminal. The Zone therefore covers the full line section and “over-reaches” beyond the remote terminal(s).

FAULT CLEARANCE / TRIPPING: On radial lines, high-speed tripping at the local terminal occurs from the over-reaching zone. For non-radial lines the of DIRECT OVER-REACHING zone is combined with a of PERMISSIVE OVER-REACHING scheme or DIRECTIONAL COMPARISON Scheme Communication (i.e. Blocking or Permissive) signals are transmitted to the remote terminals to prevent or allow instantaneous Zone tripping at all remote terminals for faults on the line.

High voltage protection on Hydro One lines are presented in a form of protection groups made up of individual schemes, this above scheme is one that is part of the protection group listed for this element.

The advantage of DIRECT OVER-REACHING is high-speed tripping for cases that cannot be covered by the DUR scheme.

DOR also provides an alternate instantaneous protection to the DUR scheme, with separate fault detectors and a separate communication path.

For the DOR scheme to operate correctly, consideration has to be given to the reduction of relay reach (i.e. coverage) due to infeeds from tapped supply station(s).

DONGBEI · 发表于 2007-12-27 23:37:11

(DUR) - DIRECT UNDER-REACHING SCHEME:

COVERAGE AREA: Zone 1 fault detectors at each line terminal are set to reach about 75-80% of the line section from the local terminal. Zone 1 therefore does NOT cover the full line section and “under-reaches” to the remote terminal(s).

FAULT CLEARANCE / TRIPPING: High-speed tripping at the local and remote line terminals occurs from Zone 1 directly. The time of fault clearance depends on the channel time (not more than 20 ms) from one terminal to another.

EVENTS / SEQUENCE:

1. When the Zone 1 fault detector picks up, the local breaker(s) are tripped immediately.
2. Communication signals are sent via the identified COMMUNICATION MEDIUM to the remote terminal(s) as identified in the COMMUNICATION MECHANISM to energize the tripping receive relays.

DONGBEI · 发表于 2007-12-27 23:39:09

(HIR) - HIGH RESISTANCE OPEN PHASE (HIROP) SCHEME:

General Information:

HIGH RESISTANCE (Ground) and OPEN PHASE (HIROP) protection schemes have been installed on HV transmission lines, 500/230kV Autotransformers, 230/115kV Autotransformers, HV Lines terminating in an Autotransformer, Generator Transformers and Bus Tie Breakers to help detect and clear open circuit and high impedance ground fault conditions.

The advantage of HIROP protection scheme is that it can help to detect both the open phase conditions associated with load-carrying broken conductor (or malfunctioning switches/breakers) as well as extremely high impedance faults which may not have been detected by other `conventional' relays. In general, it is intended to improve the selectivity and coordination of power system operations

Whenever an OPEN PHASE occurs, load current creates an imbalance in the system phases and in the neutral (ground), compared to a PHASE GROUND when fault current creates an imbalance in the system phases and neutral (ground).

Note: Only those open circuit or high impedance ground fault conditions in which the necessary minimum pickup current exists will be detected.

Principle of Operation:

The protection is designed to detect current imbalance situations and initiate the removal of affected apparatus from service. The Hydro One system configuration is such that the terminals of the element affected by HIROP detectable conditions will be subject to more imbalance current than any other element. Thus, it follows that relays on all terminals set with the same pick-up and time settings would support selective removal of the faulted element. In situations where this selectivity can be compromised (e.g. so much fault current that a difference in relay operating time is virtually non-existent), additional features have been provided to enhance selectivity.

Actions Upon Loss of HIROP:

HIROP is normally a duplicated protection (i.e. installed on both `A' and `B' schemes), therefore:
- Loss of both HIROP protections would require the immediate removal of the related element from service. (This is necessary in order to prevent uncoordinated operation of other HIROP protections for faults/open phases on the `unprotected' element.)
- Loss of both permissive tones/channels (where such are used) could result in timed clearance of high impedance in-zone faults; this may involve a second element.

Note: Most 115 kV circuits do NOT have duplicated `A' & `B' protections. Thus, the single 115 kV System HIROP may be considered the duplicate protection.

Sequence of Events / HIROP Components:

Basic HIROP consists of:

Timed Trip: an inverse time ground overcurrent relay (51N, 500ms pickup @ 360 a; the greater the current, the faster the operation). This will detect open phase conditions and very high impedance faults on a per element basis provided the imbalance current is >360 amps. This annunciates separately. Inverse Time tripping will trip locally and send transfer trip for 35 s; reclosure is blocked.

This is due to the fact that the inverse time relay could, for light-current conditions, take longer than 10 seconds to operate, and breaker reclose capability takes only 10 seconds to recover after a breaker is closed (or recloses); thus, the breaker could reclose after being tripped and be closed for 10 seconds before the inverse time protection operated again, which would allow reclosure again after the next trip, etc.

Instantaneous Trip: an instantaneous ground overcurrent relay (50N) is used to detect high impedance ground faults on a per element basis provided the imbalance current is >1000 amps. Instantaneous tripping will trip locally and send communication signals to the remote end, allowing reclosure.

In some cases, the level of current could be so high that a number of different relays could all operate with virtually the same speed. To prevent this, HIROP will include a permissive directional ground relay (67N) supervising the instantaneous ground
overcurrent relay (50N), operating through a 120 ms timer, as follows:

(i) If a fault is detected (67N and 50N operate) and the associated timer times-out, permissive signals are sent to the other terminal. If permissive is not received, no tripping occurs. This allows for clearance of out-of- zone HIROP faults via protections associated with the other zones.

(ii) If a fault is detected and permissive is received, both local and transfer tripping are initiated.

Bus HIROP:

When the other bus tie breaker is closed, the imbalance is contained within the station buses. HIROP will detect this situation if the current is greater than 360 amps and
annunciates ONLY.

When the other bus tie breaker is open (or is opened), the imbalance currents could impact on the system (i.e. unwanted protection operations, voltage imbalance, etc); HIROP will detect this situation if the current is greater than 360 amps and will trip the breaker and initiate breaker failure. A similar set-up is used for very short lines (e.g. Bruce `A' X Bruce `B'.)

Notes: While Bus HIROP could detect open phase conditions anywhere on a ring bus, the likelihood of such a condition occurring on a bus is minimal. Terminal In bus
(circuit or transformer) breakers are the most likely location for an open condition to occur. Circuit or transformer HIROP protects the respective circuit terminal and transformer breakers/buses and both are coordinated to operate for in-zone HIROP conditions before Bus HIROP. The operation of Bus HIROP by itself indicates an open phase on either the bus tie breakers or those portions of the bus not contained within the circuit or transformer zones (i.e. the main buses).

Bus or Line-Connected Autotransformers HIROP:

HIROP protection will detect on-load open phase conditions. Conventional differential protections take care of internal high impedance faults.

115 kV Circuits:

Most 115 kV circuits have a low-set ground overcurrent protection that will clear most open phase or high impedance ground faults. Thus, they will not be provided with HIROP. (Note: Some critical 115 kV systems do have duplicated HIROP, e.g., Leaside, Buchanan and will be noted in the “Key Info” field.

In such cases, in order to provide coordinated backup protection for 115 kV systems (much of which does not have duplicated line protection groups) a 115 kV system `group' HIROP protection will be provided with CT’s connected at the secondary of the autotransformer. This timed residual ground relay will provide the backup protection by tripping all autotransformer LV breakers.

HIROP Operating Considerations:

Some directional comparison schemes will have their timed (.4 s) feature removed since this could operate faster than HIROP's inverse timed (500ms) feature. This means that the only tripping from conventional directional comparison schemes will be in the instantaneous mode (when the block signal has not been received).

BACKGROUND:

High voltage protection on Hydro One lines are presented in a form of protection groups made up of individual schemes, this above scheme is one that is part of the protection group listed for this element.

Both open phase and high resistance grounds produce zero sequence currents manifested as ground or neutral currents. They circulate in the power system and are distributed across all system elements in inverse proportion to their sequence impedance. The affected element carries most of the zero sequence current since it is the “source” of this current. Therefore, inverse time overcurrent based protection in the neutral, set with the same pick up current and time characteristics for all power system elements, provides selective isolation of the affected system element.

Identical inverse time characteristics for all HIROP protection ensures that the faulted element is cleared first since it carries higher zero sequence current than adjacent (non-faulted_ elements. Existing transfer trip facilities are used for fast clearing of the remote end of the faulted element.

To further ensure proper coordination, sufficient margin has been incorporated in the settings, minor variations have been introduced in the nominal pick-up setting of the overcurrent relay (set for 360A primary in the neutral) and instantaneous and directional protections have been employed where appropriate.

Existing (or lack of) open phase and ground fault protections may not detect the above abnormal conditions. The wide implementation has raised some questions whose answers may have implication for system operations in the following areas.

Standard high voltage protection provides high speed tripping at the local and remote line terminals from Zone 1 directly and from Zone 2 via permissive over-reaching or directional comparison, using communication media. Timed and Line Test tripping involve the local terminal only. Reclosing is only provided from the high-speed protection.

DONGBEI · 发表于 2007-12-27 23:40:55

(POR) - PERMISSIVE OVER-REACHING SCHEME:

COVERAGE AREA: Zone 2 fault detectors at each line terminal are set to reach about 125% of the line length (or impedance) from the local terminal. Zone 2 therefore covers the full line section and “over-reaches” beyond the remote terminal(s).

FAULT CLEARANCE / TRIPPING: High-speed tripping at the local terminal occurs from Zone 2 directly. Communication (i.e. Permissive) signals are transmitted to the remote terminals to allow instantaneous Zone 2 tripping to occur at all remote terminals. When a permissive signal is NOT received, tripping at remote terminal(s) becomes timed and occurs after 400ms.

EVENTS / SEQUENCE:

1. When the Zone 2 fault detector picks up, the local breaker(s) are tripped immediately.
2. Communication (Permissive) signals are sent via the identified COMMUNICATION MEDIUM to the remote terminal(s) as identified in the COMMUNICATION MECHANISM to energize the tripping receive relays.
3. When the permissive signal is received (or after 400ms), the remote terminal(s) are tripped from the Zone 2 timed tripping relays.

lbsjx519 · 发表于 2008-2-17 17:49:18

Thanks a lot!

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国外继电保护经验

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