北美继电保护设计经验交流

DONGBEI · 发表于 2007-12-27 23:50:34

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我在北美作过继电保护设计。原与大家分享有关经验。

DONGBEI · 发表于 2007-12-27 23:52:06

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 23:58:54

(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.

LINE / SCHEME DIAGRAM

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.

The advantage of PERMISSIVE OVER-REACHING is high-speed tripping for cases that cannot be covered by the Zone 1 fault detectors (i.e. DUR scheme).

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

For the POR 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).

Faults Within the Circuit Zone (Diagram A):
Faults on any part of the line are located within the Zone 2 fault detectors as they are set to see approximately 125% of the circuit length or impedance. When a fault occurs on the circuit, the Zone 2 fault detectors at each terminal(s) are picked up and they send a “permissive” communication signal to each other. Upon receiving the permissive signal from the remote terminal(s), the local trip relays become energized, tripping the local terminal and clearing the fault.

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

a)
the Zone 2 fault detector at that terminal is picked up
b)
a permissive 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 relays of one of the protected circuit remote terminals and a permissive signal is sent to the local terminal where the fault is beyond. The local terminal’s Zone 2 relays will not be energized (as this terminal does not see the fault outside/beyond the circuit) and NO instantaneous tripping will occur at the local or remote terminal(s). The remote terminal(s) will clear on timed relays after 400ms and send a trip signal to all other terminals to initiate tripping at those terminals.

“Echo” Feature (Diagram C):

When the line disconnect at one terminal is open, its fault detectors will not be able to detect any faults on the circuit and a section of the circuit (i.e. beyond the remote terminal Zone 1 coverage area) would not be covered by instantaneous tripping (i.e. up to the open line disconnect).
To ensure that instantaneous tripping remains in place for the length of line beyond the remote terminal Zone 1 coverage area and the open line disconnect, a feature referred to as “echoing” (also called “line end open” logic) makes up part of the POR scheme.

The sequence of events is such that when a remote terminal Zone 2 relay picks up, it sends a permissive signal to the local terminal. Upon receiving this signal, the local terminal “echoes back" a return permissive signal to the remote terminal to allow instantaneous tripping to 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 2007-12-28 00:03:40

(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 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 2007-12-28 12:45:12

H.V. Static Capacitor & Protection
Shunt capacitor banks used on the H.V. system will deliver reactive power, reducing current, therefore extending transmission capability by reducing system losses.  Shunt capacitor banks help maintain system voltage level and therefore reduce operating costs.  A low voltage level in the power system will cause economic and operational liabilities.
The basic building block of a capacitor bank is the single encapsulated capacitor unit combined in a series-parallel arrangement.  The capacitor bank is made up of a number of series groups and a number of parallel capacitor units in each series group. (see Figure 1).  These individual units are arranged in a single-wye configuration with its neutral left ungrounded.  The capacitor units in these banks are rated at 200 Kvar, 13.8 kV or 14.4 kV and have a capacitance of about 2.9 microfarads.  The various arrangements are listed in Table 1.
Figure 1

Table 1

Bank Rating Capacitor Unit Rating “Phase Leg” Arrangement
Bank Configuration

Type of Fuse
Total Number of Cap. Units
No. kV Mvar kV Kvar S P
1 249 48 14.4 200 10 8 Single-wye Ungrounded Current Limiting in series with expulsion 240
2 249 96 14.4 200 10 16 Single-wye Ungrounded “ 480
3 249 192 14.4 200 10 32 Single-wye Ungrounded “ 960
4 239 192 13.8 200 10 32 Single-wye Ungrounded “ 960
5 119.5 96 13.8 200 5 32 Single-wye Ungrounded “ 480
6 119.5 48 13.8 200 5 16 Single-wye Ungrounded “ 240

S = Number of series groups
P = Number of parallel capacitor units in a series group
There are fuses in series with each capacitor unit to provide overcurrent/overvoltage protection due to the failure of the capacitor unit.  The fuse operation can be observed visually and disconnects the particular capacitor unit that has failed.  As units are removed by blown fuses, the impedance will increase.  As a result, a higher voltage is imposed on the remaining capacitor units in the series section.  If this higher voltage exceeds the rating of the remaining capacitor units, of the series section additional fuse operations can occur.
An important consideration for capacitor bank circuit breakers, during an opening operation, is the possibility of a restrike.  Air-blast and SF6 gas circuit breakers have an inherent restrike-free capability and are therefore better suited for switching capacitors.  Oil breakers unless equipped with resistors specifically for capacitor switching are not suitable.  The problem posed by the inadequacy of the breakers backing up a single capacitor breaker has been overcome by providing two breakers in series for capacitor switching purposes.  The two breakers in series are treated as a single unit by tripping both breakers simultaneously (manual operation will open the circuit breakers individually).  None of the two breakers are equipped with circuit breaker failure protection.  By providing two breakers in series and treating them as a single unit for automatic tripping purposes, the need for another breaker in the adjacent zone to interrupt capacitor current is eliminated for the single contingency of a breaker failure of either one of the two capacitor breakers.
There is reclosure consideration which must be addressed following an automatic or manual trip operation of the capacitor bank.  There is the possibility of equipment damage which could occur due to an overvoltage condition if the capacitor bank is re-energized before its charge has decayed sufficiently.  Therefore, both auto and manual reclose is blocked for five minutes.  Some H.V. bank installations are equipped with rapid discharge reactors which would allow re-energizing sooner.  Therefore, the quoted general reclose time delay of five minutes can be reduced.
For this next section refer to the appendix for the elementary wiring diagrams for both A group and B group H.V. Static Capacitor Protection.

DONGBEI · 发表于 2007-12-28 12:51:52

The goal of troubleshooting is to return defective equipment to service in a timely and cost effective manner. There are a variety of tools and techniques available to staff performing these activities. Tools include voltmeters, ammeters and ohmmeters.
The five step approach to troubleshooting is:
1. Observe
2. Define the problem area
3. Identify the possible causes
4. Determine the most probable cause
5. Test
Once repairs have been completed, inform the Controlling Authority the equipment is available for service and file a defect report.
Above all, understand what the problem is, plan your work, use the correct drawings and test equipment and strive to work safely.

DONGBEI · 发表于 2007-12-28 13:02:26

Zone Instantaneous Tripping [results in: 1) Local Tripping, 2) TT Send (T11/T12), 3) Initiate B/F, 4) Initiate Reclosing]
- Zone 1 Direct Underreaching (MHO) Phase & Ground + Line DS Close,
- Zone 2 Overreaching (MHO) Phase & Ground (+ Line DS Close) with Perm. Signal,
- Long Line HIROP (51NT),
Zone Timed Tripping [results in: 1) Local Tripping, 2) Initiate B/F]
- Zone 2 Overreaching (MHO) Phase & Ground (+ Line DS Close)with Definite Time
- Line Test 1) Three Phase Undervoltage + Time + High Set Phase O/C, 2) Line DS OPEN + High Set O/C
Permissive send[Result in sending (T11/T12) Signals],
- Zone 2 Phase & Ground (+ Line DS Close) + Manual Transfer or Selector Device signal

1. MER is revised to correct multiple event report triggers.
2. Previously MER=M2P*!LP3+Z2G*!LP3+50H+LOP is to be revised to MER=M2P*!LP3+Z2G*!LP3+50H*X+LOP.
3. No other change to settings.
4. Reviewed setting associated with ZLOAD30 (NERC 8A recommendations). Do not need to add it.

ywhywh · 发表于 2007-12-28 13:09:31

感谢楼主！只是现在没有时间详读。忙过这一阵一定好好读一下

DONGBEI · 发表于 2007-12-28 13:10:40

1 DISTANCE RELAY FEATURES AND CHARACTERISTICS

The new generation of micro-processor-based distance relays perform numerical algorithms to achieve the required relaying functions.  These devices usually not only provide a choice of distance measuring elements, i.e., mho or quadrilateral, but they also embody much more than just distance elements, e.g., over-current supervision elements, over-current elements for auxiliary functions, directional supervision elements, shaping elements for load encroachment, out-of-step supervision elements, switch-on-to-fault protection elements, stub bus protection elements, phase selection logic (faulted phase identification), as well as programmable logic and communication interfaces.  Despite the inclusion of a comprehensive list of features, the complete device is still commonly referred to as a ‘distance relay’.  Hence, in the context of this guide, a ‘distance relay’ consists of more than just distance measuring elements and, hence, will pay appropriate attention to setting of all the normally used elements.

2 SETTING REQUIREMENTS

The basic requirements for setting distance relays that have been used as guidelines over a number of years are outlined below.

Settings that are ideal for a line protection, satisfy the following requirements:

(a) A distance relay must detect any fault on the protected portion of the line.

(b) A distance relay must not operate for system swings that the power system can withstand.

(c) A distance relay must not limit the load carrying capability of the line.

To satisfy (a), a distance relay line protection will have over-reaching zones that are set to operate for faults beyond the protected line.  The over-reaching zones are coordinated to respond by permission or time.
Establishing settings in accordance with the guidelines above, in general requires information on the characteristics of the protected line, i.e., positive sequence line impedance and zero sequence compensation factor, as well as the maximum apparent impedance on three-phase faults (ZMA(THP)) and phase-ground faults (ZMA(SLG)).  The apparent impedances as ‘seen’ by a distance relay element are required for certain line configurations and are obtained from fault studies on the power system that represents the protected line and an appropriate network of surrounding lines.  The apparent impedance generally depends on the line configuration (e.g., tapped, multi-terminal), and the source impedance behind the relay terminal.  Hence, in order that apparent impedances are representative, it is important that the power system model used in the fault studies is as accurate as possible.  Usually, a model of the entire utility network is available to perform the studies.

DONGBEI · 发表于 2008-1-1 23:18:05

COVERAGE AREA: Local Terminal of circuit between breakers and line disconnect switch.

FAULT CLEARANCE / TRIPPING: High-speed tripping at the local terminal only, to cover three-phase close-in faults

EVENTS / SEQUENCE:

1. When the Line Test over-current relays pick up, the local breaker(s) are tripped immediately.
2. No communication signals are sent, local tripping only.

High voltage protection on 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 the LINE TEST scheme is high-speed tripping for when grounding devices have been left on at the local line terminal.

LINE TEST scheme is intended to cover three-phase and line-to-ground faults when NO voltage can be derived from either the potential transformers (PT or CVT or through memory action of the respective phase or ground distance relays to operate.

When the line is de-energized or if the potential transformer happens to be on the line side, the LINE TEST protection is useful in protecting that portion of the bus between the breakers and the line disconnect switch, as shown in Diagram A

When maintenance is done on the line, grounding devices are applied to all three phases of the line and the memory action of the distance relay is no longer in effect since the line has been de-energized for some time.

If the line is energized again with the grounds on, a severe three-phase fault occurs. Without the LINE TEST scheme, this serious accident CANNOT be covered.

The Line Test scheme’s measuring element is an overcurrent relay and the logic is provided by an undervoltage relay with time delay. The undervoltage relay puts the LINE TEST protection scheme in service when the line is de-energized but only after a delay of ~ 2.0 seconds to ensure the drop in voltage is not of a transient nature.

LINE TEST protection scheme time delay shall exceed the timed backup time or else there is a risk of clearing under LINE TEST non-directionally for external faults that have delayed clearing.

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.

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北美继电保护设计经验交流

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