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The power grid system is the Electrical utility distribution system which provides power to the consumer (end user.) Beginning at the Power Generation Plant , conti…nuing on thru the transmission lines and to the substation and local distribution network, finally to the individual consumer. Power grids are smaller distinct sections of this system which together make up the entire distribution network.
Grid failure in a power system would be when much or all of the high voltage transmission grid was forced out of service, thereby isolating the load it would normally serve. T…otal grid failure, while extremely infrequent, can occur (the Eastern Blackout of August 2003 as an example). Grid failure could also be the result of the almost simultaneous loss of multiple generating units or plants however this is less likely to be the reason for a large grid failure. Grid systems are designed to, at a minimum, survive the loss of the most important element at all times. Indeed, most grid systems have shown the capability to survive the loss of several independent elements simultaneously. All grid apparatus is protected by various overlapping redundant protection schemes so that the failed element is removed from service as quickly as possible (often in as few as 3 cycles - or 1/20 of a second).
its a gogappic number garaph
a grid found on a map
Primary and back-up protection / The reliability of a power system has been discussed in earlier sections. Many factors may cause protection failure and there is always some… possibility of a circuit breaker failure. For this reason, it is usual to supplement primary protection with other systems to 'back-up' the operation of the main system and ensure that nothing can prevent the clearance of a fault from the system. Back-up protection may be obtained automatically as an inherent feature of the main protection scheme, or separately by means of additional equipment. Time graded schemes such as over current or distance protection schemes are examples of those providing inherent back-up protection; the faulty section is normally isolated discriminatively by the time grading, but if the appropriate relay fails or the circuit breaker fails to trip, the next relay in the grading sequence will complete its operation and trip the associated circuit breaker, thereby interrupting the fault circuit one section further back. In this way complete back-up cover is obtained; one more section is isolated than is desirable but this is inevitable in the event of the failure of a circuit breaker. Where the system interconnection is more complex, the above operation will be repeated so that all parallel infeeds are tripped. If the power system is protected mainly by unit schemes, automatic back-up protection is not obtained, and it is then normal to supplement the main protection with time graded over current protection, which will provide local back-up cover if the main protective relays have failed, and will trip further back in the event of circuit breaker failure. Such back-up protection is inherently slower than the main protection and, depending on the power system configuration, may be less discriminative. For the most important circuits the performance may not be good enough, even as a back-up protection, or, in some cases, not even possible, owing to the effect of multiple infeeds. In these cases duplicate high speed protective systems may be installed. These provide excellent mutual back-up cover against failure of the protective equipment, but either no remote back-up protection against circuit breaker failure or, at best, time delayed cover. Breaker fail protection can be obtained by checking that fault current ceases within a brief time interval from the operation of the main protection. If this does not occur, all other connections to the bus bar section are interrupted, the condition being necessarily treated as a bus bar fault. This provides the required back-up protection with the minimum of time delay, and confines the tripping operation to the one station, as compared with the alternative of tripping the remote ends of all the relevant circuits. The extent and type of back-up protection which is applied will naturally be related to the failure risks and relative economic importance of the system. For distribution systems where fault clearance Times are not critical, time delayed remote back-up protection is adequate but for EHV systems, where system stability is at risk unless a fault is cleared quickly, local back-up, as described above, should be chosen. Ideal back-up protection would be completely independent of the main protection. Current trans-formers, voltage transformers, auxiliary tripping relays, trip coils and D.C. supplies would be duplicated. This ideal is rarely attained in practice. The following compromises are typical: a. Separate current transformers (cores and secondary windings only) are used for each protective system, as this involves little extra cost or accommodation compared with the use of common current transformers which would have to be larger because of the combined burden. b. Common voltage transformers are used because duplication would involve a considerable increase in cost, because of the voltage transformers them-selves, and also because of the increased accommodation which would have to be provided. Since security of the VT output is vital, it is desirable that the supply to each protection should be separately fused and also continuously supervised by a relay which will give an alarm on failure of the supply and, where appropriate, prevent an unwanted operation of the protection. c. Trip supplies to the two protections should be separately fused. Duplication of tripping batteries and of tripping coils on circuit breakers is sometimes provided. Trip circuits should be continuously supervised. d. It is desirable that the main and back-up protections (or duplicate main protections) should operate on different principles, so that unusual events that may cause failure of the one will be less likely to affect the other. / Previous Next
power grid is an interconnected system of electrical cable and electrical equipments to transmit electrical power from plant to load centers!
Turning them off? No. DISCONNECTING them? Probably, unless the solar storm is of record-breaking intensity. What happens is that electricity and electromagnetic energy are …interchangeable. A radio station uses electricity to create electromagnetic waves at the transmitter, and a radio antenna converts the electromagnetic waves back into electricity. In a severe solar storm, the "coronal mass ejection" causes disturbances in the Earth's magnetic field, generating a lot of electromagnetic energy. Any electric wire, such as a power wire or a telephone wire, will act as a receiver and will generate a lot of electricity in the wire. In the 1870s, a severe solar storm generated so much energy in telegraph wires that they were able to disconnect the power and continue to transmit. There were even some telegraph stations that burned down because of the "induced voltage" in the telegraph wires!
Circuit Breakers or fuses.
Grids collapse due to two basic reasons. One is the failure of the equipment, like it happened a decade ago in 2002 when the northern grid collapsed, due to fog/pollution. The… second trigger is power suppliers drawing excessive power from the grid. Which results in the balance of power generation and supply goes haywire with a cascading effect. This is probably the reason why the grid failed
Off the grid is a term that is commonly used to describe a home that is off of the main energy grid. In other words, they are homes that provide their own energy from alternat…ive sources and do not rely on power companies. Some alternative home energy sources that people are using to get off the grid can include solar panels and wind turbines. Read more: http://wiki.answers.com/What_is_off_the_grid#ixzz1gGeolgFI
A transformer changes the electricity from one voltage to another, which allows a high voltage power line to be converted down to a voltage suitable for home usage.
To improve the power factor
The advantage of the power grid system is that the electricity can be generated where fuel is available and used where there is demand.
In Solar Flares
There could be several reasons. Two of the possible reasons are: Cost of making the changes to protect the grid could be very costly. They might not believe that a massive sol…ar flare that knocks the grid out will actually happen, so the improvements are not necessary. If you look at hiatory, it jas happened before. Look up the Carrington event back in the 1800's. A solor flare happened and FRIED the telegraph cables, and everything else around them. Just imagine if something happened like that today. Plus, the cost would be "pocket change" compared to how much we spend on needless wars!
it cant protect the system against power surges
What countries do have an isolated power grid (islanded power system) and what are the names of these power grids?
Ireland has an isolated power grid, so does Great Britain.