GB2290390A - Electrical power supply system - Google Patents
Electrical power supply system Download PDFInfo
- Publication number
- GB2290390A GB2290390A GB9508676A GB9508676A GB2290390A GB 2290390 A GB2290390 A GB 2290390A GB 9508676 A GB9508676 A GB 9508676A GB 9508676 A GB9508676 A GB 9508676A GB 2290390 A GB2290390 A GB 2290390A
- Authority
- GB
- United Kingdom
- Prior art keywords
- program
- power
- equipment
- items
- electrical
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 238000000034 method Methods 0.000 claims description 13
- 238000012544 monitoring process Methods 0.000 claims description 2
- 230000000694 effects Effects 0.000 abstract description 2
- 238000004364 calculation method Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B9/00—Safety arrangements
- G05B9/02—Safety arrangements electric
- G05B9/03—Safety arrangements electric with multiple-channel loop, i.e. redundant control systems
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J1/00—Circuit arrangements for dc mains or dc distribution networks
- H02J1/10—Parallel operation of dc sources
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J1/00—Circuit arrangements for dc mains or dc distribution networks
- H02J1/14—Balancing the load in a network
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/12—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load
- H02J3/14—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load by switching loads on to, or off from, network, e.g. progressively balanced loading
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P9/00—Arrangements for controlling electric generators for the purpose of obtaining a desired output
- H02P9/02—Details of the control
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J2310/00—The network for supplying or distributing electric power characterised by its spatial reach or by the load
- H02J2310/50—The network for supplying or distributing electric power characterised by its spatial reach or by the load for selectively controlling the operation of the loads
- H02J2310/56—The network for supplying or distributing electric power characterised by its spatial reach or by the load for selectively controlling the operation of the loads characterised by the condition upon which the selective controlling is based
- H02J2310/58—The condition being electrical
- H02J2310/60—Limiting power consumption in the network or in one section of the network, e.g. load shedding or peak shaving
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P2101/00—Special adaptation of control arrangements for generators
- H02P2101/30—Special adaptation of control arrangements for generators for aircraft
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Automation & Control Theory (AREA)
- Supply And Distribution Of Alternating Current (AREA)
Abstract
An electrical supply system has two power generators 10 and 20, several items of electrical equipment 101 to 106 and 201 to 206, and a processor 3 that controls disconnection of the equipment if demand should exceed supply. The processor 3 has a hardware switch 35 controlled by outputs from the generators 10 and 20. The processor runs two different programs A and B at the same time but the switch 35 supplies only one of these to the output 34. When equipment needs to be disconnected, for example when one of the generators 10, 20 fails, the switch changes to supply the results of the other program to the output and this effects the disconnection. When sufficient supply is restored, the switch changes back to its original state to supply the results of the first program to the output of the processor. <IMAGE>
Description
ELECTRICAL SYSTEMS
This invention relates to electrical systems.
The power supply in aircraft is provided by several generators to ensure that sufficient power is available for flight-critical equipment in the event that one ofthe generators should fail. When one of the generators fails it is necessary to switch vital equipment that was supplied by the failed generator to supply by a working generator with minimum interruption to the power supply. Although the power generators can tolerate some overloading for short periods, if the generators are overloaded suddenly, excessively or for prolonged periods, it could cause permanent damage to the generator. The generators are, therefore, provided with protection circuits that shut the generator down if it is seriously overloaded.In order to prevent the working generator being overloaded when the new loads are connected, it is necessary to disconnect, or shed, some of the non-critical loads connected to the working generator before the vital equipment is transferred to it.
The control of power supply to the different items of equipment is generally controlled by a processor receiving inputs from the generators and providing outputs controlling the supply of power to the equipment such as via relays or the like. The outputs are provided as a result of an algorithm or other program computed by the processor during normal operation of the generators. The processor re-computes the system commands at regular intervals, that is, at every processing cycle or at multiples of every processing cycle. If one of the generators should fail, this would be signalled to the processor causing it to run a different, load-shedding algorithm so that appropriate items of equipment are shut down to enable power to be supplied to the flight-critical equipment.
The problem with this arrangement is that there is a time delay before the processor instructs load shedding, which can be equal to that of the processing cycle. Because of this delay, overloading of the working generator can only be avoided by delaying the switching of the critical equipment from the failed generator to the working generator until after the processor has had time to shed the load. The vital equipment is, therefore, deprived of power for a considerable period. Although this delay can be reduced by using high speed processors, the delay is still appreciable.
One alternative way of producing a more rapid response is to interrupt the processing cycle of the processor immediately a fault is detected, suspending the normal program and executing the new load-shedding program with minimal delay. Although this can reduce the delay, the interrupt is non-deterministic since it can occur at any point in the processor program. This makes it difficult to prove that the interrupt will always be serviced correctly and that, after servicing the interrupt, the processor will always return to its normal program in an orderly manner, whatever point the interrupt occurs in the processing cycle.
There are other systems, as well as aircraft power systems, where it is desirable to be able to respond reliably to change in an external stimulus more rapidly than the processing time of a program.
It is an object of the present invention to provide an improved electrical system.
According to one aspect of the present invention there is provided an electrical system including processor means having input means and output means, the processor means being arranged to run first and second different programs at the same time and the input means having switching means operable in response to change in an input signal, to switch the result of a different one of the first and second programs to the output.
The system preferably includes a power generator, the input signal being indicative of whether or not the power generator provides sufficient power for the system. The system preferably includes a plurality of items of electrical equipment, the equipment being supplied with power from the power generator and the second program being arranged to control disconnection of one or more items of electrical equipment in response to loss of power from the generator. Each item of electrical equipment may be connected to the power generator via a respective relay, the second program controlling operation of the relays. The system may include two power generators, the input signal being indicative of correct operation of the two generators.The system may include two power buses connected to respective ones of the generators, some of the items of equipment being connected to one bus and others being connected to the other bus, and the two buses being interconnected by a switch that is normally open but is closed in response to operation ofthe second program. The results ofthe first program are preferably normally connected to the output means and the results of the second program are connected to the output means when the switching means is operated, the first program remaining running after operation ofthe switching means so that the results ofthe first program can be connected to the output means when the input signal reverts to its original state.
According to another aspect of the present invention there is provided a method of controlling an electrical system in response to a first or second program including the steps of running both the first and second programs at the same time, providing control for the system by only one of the programs and subsequently switching control of the system to the other of the programs in response to change in an external stimulus.
Control ofthe system is preferably switched to the other program by operation of a hardware switch. Both programs preferably continue to run following switching, the one program being switched back to control the system when the external stimulus reverts to its original state.
According to a further aspect of the present invention there is provided a method of controlling an electrical power supply system including a power generator and a plurality of items of electrical equipment connected to be supplied with power from the generator, the method including the steps of monitoring operation of the power generator, running a first program enabling supply of power to each item of equipment, running a second program at the same time as the first program, the second program enabling supply of power to only selected items of said equipment, supplying the results of only the first program via a hardware switch to control of the system when the operation of the power generator is sufficient to supply all items of equipment, and changing the state of the switch when operation of the power generator is insufficient to supply all items of equipment so that the results of the second program are instead supplied to control of the system.
The first program may be maintained running after change in the state of the switch, the switch being changed back to its original state when operation of the power generator is sufficient to supply all the items of equipment so that the results of the first program are again supplied to control of the system.
An aircraft power supply system and its method of control, in accordance with the present invention, will now be described, by way of example, with reference to the accompanying drawing which shows the system schematically.
The aircraft power supply system has two power generators 10 and 20 both rated at i20kVA for continuous operation. The generators 10 and 20 can be operated at higher power without damage for short periods. In particular, they can be operated at up to 160kVA for up to 5 minutes and at between 160kVA and 1 80kVA for 5 seconds. The generators can only be operated above 1 80kVA for very short periods of Sms or less.
The generators 10 and 20 are connected to respective power buses 11 and 21, which are electrically isolated from one another but which can be interconnected via a tie 1 and a switch 2
The system also includes various items of electrical equipment, of which only twelve are shown, six items 101 to 106 being connected to the left-hand bus 11 and the remaining six items 201 to 206 being connected to the right-hand bus 21. Each item of equipment 101 to 106, 201 to 206 is connected to its respective bus 11 and 21 via a respective relay 111 to 116 and 211 to 216. Each relay is connected to a processing unit 3, which provides appropriate control to maintain the relays open or closed as desired. The processing unit 3 is also connected via line 30 to the tie switch 2 to control operation of this switch.
The processing unit 3 has various inputs 31 to 33 such as, for example, temperature sensors, fire sensors and current sensors associated with the different items of equipment. The signals from the inputs 31 to 33 are used in an algorithm or other program run by the processing unit and indicated by the block A. The algorithm computes which of the relays 111 to 116 to 211 to 216 should be open and which should be closed and supplies appropriate signals to an output stage 34 in the unit by which the relays are powered. The time period for the processing cycle of the algorithm might typically be about 20ms. In addition to the algorithm A, the processing unit 30 also runs a second algorithm B at the same time.This algorithm computes what outputs should be supplied to the relays 111 to 116 to 211 to 216 if one ofthe generators 10 or 20 should fail, such that only a single generator is available to supply the loads. The results of these computations are, however, not utilised during normal operation, with both generators in correct operation. The processing unit 3 also includes a hardware switch 35 connected to receive outputs from the two generators 10 and 20. The hardware switch 35 has two states. In the state shown, it connects the results of the algorithm
A to the output stage 34. If one of the generators 10 or 20 should fail, the switch 35 rapidly changes state and connects the other algorithm B to the output stage 34.Switching of the hardware switch 35 can be achieved in about 1 to 3 ms, that is, considerably quicker than the processing cycle of the processor unit 3. The second algorithm B also receives the inputs 31 to 33 and performs different calculations from the first algorithm. Algorithm B is initially set to command all non-essential loads to be shed such that, as soon as the generator fails and the switch 35 selects algorithm B to the output, all the non-essential loads are immediately disconnected. A command is then issued to close the switch 2, so that the tie 1 links the two buses 11 and 21, thereby enabling equipment connected to both buses to be supplied by the single, operational generator 10 or 20.The shedding ofthe non-essential loads ensures that the total load after tie 1 has closed will always be within the capability ofthe working generator.
Algorithm B then compares the connected loads with the power available from the working generator and restores as many non-essential loads as possible without causing an overload.
During this period of operation, when load has been shed, the first algorithm A continues to be run in the processing unit. In this way, if the failed generator should become operational again, the switch 35 would revert to its original state and connect the first algorithm
A to control of the relays.
The present invention enables power to be restored to essential equipment very quickly following a generator failure, without the risk of overloading the working generator, and without the need to provide excessively large generators each capable of driving all the loads by itself. It also permits restoration of non-essential loads if spare power is available. Because both programs in the processing unit 3 are run at the same time, there is no need to interrupt the non-operational program when it is switched out of control, since it can be allowed to continue running but without having any control effect, thereby ensuring that the process is entirely deterministic.
The invention is not confined to aircraft power systems but can be used in other applications where it is necessary to produce a rapid changeover between different control algorithms or other programs. The invention is not limited to use with two programs but could be used with three or more programs.
Claims (16)
1. An electrical system including processor means having input means and output means,
wherein the processor means is arranged to run first and second different programs at
the same time, and wherein the processor means has switching means operable in
response to change in an input signal, to switch the result of a different one of the first
and second programs to the output means.
2. An electrical system according to Claim 1, wherein the system includes a power
generator, and wherein the input signal is indicative of whether or not the power
generator provides sufficient power for the system.
3. An electrical system according to Claim 2, wherein the system includes a plurality of
items of electrical equipment, wherein the equipment is supplied with power from the
power generator, and wherein the second program is arranged to control disconnection
of one or more items of electrical equipment in response to a loss of power from the
generator.
4. An electrical system according to Claim 3, wherein each item of electrical equipment is
connected to the power generator via a respective relay, and wherein the second
program controls operation of the relays.
5. An electrical system according to any one of claims 2 to 4, wherein the system includes
two power generators, and wherein the input signal is indicative of correct operation of
the two generators.
6. An electrical system according to Claim 5 and including a plurality of items of
electrical equipment, wherein the system includes two power buses connected to
respective ones of the generators, wherein some of the items of equipment are
connected to one bus and others are connected to the other bus, and wherein the two
buses are interconnected by a switch that is normally open but is closed in response to
operation of the second program.
7. An electrical system according to any one of the preceding claims, wherein the results
of the first program are normally connected to the output means and the results of the
second program are connected to the output means when the switching means is
operated, and wherein the first program remains running after operation ofthe switching means so that the results of the first program can be connected to the output
means when the input signal reverts to its original state.
8. An electrical system substantially as hereinbefore described with reference to the
accompanying drawing.
9. A method of controlling an electrical system in response to a first or second program
including the steps of running both the first and second programs at the same time,
providing control for the system by only one ofthe programs and subsequently
switching control of the system to the other of the programs in response to change in
an external stimulus.
10. A method according to Claim 9, wherein control ofthe system is switched to the other
program by operation of a hardware switch.
11. A method according to Claim 9 or 10, wherein both programs continue to run
following switching, and wherein the one program is switched back to control the
system when the external stimulus reverts to its original state.
12. A method of controlling an electrical power supply system including a power generator
and a plurality of items of electrical equipment connected to be supplied with power
from the generator, wherein the method includes the steps of monitoring operation of
the power generator, running a first program enabling supply of power to each item of
equipment, running a second program at the same time as the first program, the second
program enabling supply of power to only selected items of said equipment, supplying
the results of only the first program via a hardware switch to control of the system
when the operation of the power generator is sufficient to supply all items of
equipment, and changing the state of the switch when operation of the power
generator is insufficient to supply all items of equipment so that the results of the
second program are instead supplied to control of the system.
13. A method according to Claim 12, wherein the first program is maintained running after
change in the state of the switch, and wherein the switch is changed back to its original
state when operation of the power generator is sufficient to supply all the items of
equipment so that the results of the first program are again supplied to control of the
system.
14. A method substantially as hereinbefore described with reference to the accompanying
drawing.
15. A system for carrying out a method according to any one of Claims 9 to 14.
16. Any novel feature or combination of features as hereinbefore described.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9508676A GB2290390B (en) | 1994-06-18 | 1995-04-28 | Electrical systems |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9412261A GB9412261D0 (en) | 1994-06-18 | 1994-06-18 | Electrical systems |
| GB9508676A GB2290390B (en) | 1994-06-18 | 1995-04-28 | Electrical systems |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB9508676D0 GB9508676D0 (en) | 1995-06-14 |
| GB2290390A true GB2290390A (en) | 1995-12-20 |
| GB2290390B GB2290390B (en) | 1998-07-08 |
Family
ID=26305083
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9508676A Expired - Lifetime GB2290390B (en) | 1994-06-18 | 1995-04-28 | Electrical systems |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2290390B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1260885A2 (en) * | 2001-05-25 | 2002-11-27 | Siemens Aktiengesellschaft | Control or regulation method |
| FR2911442A1 (en) * | 2007-01-16 | 2008-07-18 | Airbus France Sas | POWER SUPPLY SYSTEM AND METHOD FOR ACTUATORS ON BOARD AN AIRCRAFT |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4351023A (en) * | 1980-04-11 | 1982-09-21 | The Foxboro Company | Process control system with improved system security features |
| GB2104247A (en) * | 1981-07-13 | 1983-03-02 | Nissan Motor | Automatic control of i c engines in vehicles |
-
1995
- 1995-04-28 GB GB9508676A patent/GB2290390B/en not_active Expired - Lifetime
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4351023A (en) * | 1980-04-11 | 1982-09-21 | The Foxboro Company | Process control system with improved system security features |
| GB2104247A (en) * | 1981-07-13 | 1983-03-02 | Nissan Motor | Automatic control of i c engines in vehicles |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1260885A2 (en) * | 2001-05-25 | 2002-11-27 | Siemens Aktiengesellschaft | Control or regulation method |
| EP1260885A3 (en) * | 2001-05-25 | 2003-08-06 | Siemens Aktiengesellschaft | Control or regulation method |
| FR2911442A1 (en) * | 2007-01-16 | 2008-07-18 | Airbus France Sas | POWER SUPPLY SYSTEM AND METHOD FOR ACTUATORS ON BOARD AN AIRCRAFT |
| US7923857B2 (en) | 2007-01-16 | 2011-04-12 | Airbus France | System and method for supplying power for actuators on board an aircraft |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2290390B (en) | 1998-07-08 |
| GB9508676D0 (en) | 1995-06-14 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| 732E | Amendments to the register in respect of changes of name or changes affecting rights (sect. 32/1977) | ||
| PE20 | Patent expired after termination of 20 years |
Expiry date: 20150427 |