CN101707467A - Flexible electric braking method of large-sized water turbine generator - Google Patents
Flexible electric braking method of large-sized water turbine generator Download PDFInfo
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- CN101707467A CN101707467A CN200910232777A CN200910232777A CN101707467A CN 101707467 A CN101707467 A CN 101707467A CN 200910232777 A CN200910232777 A CN 200910232777A CN 200910232777 A CN200910232777 A CN 200910232777A CN 101707467 A CN101707467 A CN 101707467A
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Abstract
The invention relates to a flexible electric braking method of a large-sized water turbine generator, which is suitable for a controllable rectification excitation system adopting the parallel running of a plurality of excitation rectification bridges for meeting the capabilities of excitation and excitation forcing. The invention has the core that the complete input of the traditional rectification bridges is improved into partial input. Because the number of the parallel rectification bridges is reduced, the ascension rate of current flowing through thyristors in rectification bridges input in the running is also increased correspondingly, and the current of the thyristors in the controllable rectification bridges exceeds the latching current of the controllable rectification bridges before triggering pulses disappear, thereby solving the problem of braking failure caused by the hysteresis effect of the induction of rotors and the effect of the latching current of the thyristors and ensuring the safe running of a water turbine generator set.
Description
Technical field
The present invention relates to large-sized water turbine generator flexible electric braking technology, belong to generator electric braking technical field.
Background technology
For Large Hydroelectric Set, huge moment of inertia makes the compressor emergency shutdown overlong time.In order to prevent that the long-time slow-speed of revolution from causing the unit thrust bearing to be damaged, and the caused friction smog pollution of minimizing mechanical braking, both at home and abroad Large Hydropower Station adopts machinery and electric associated braking system in recent years: promptly in the compressor emergency shutdown process, when rotating speed drop to rated speed 50% the time carry out electric braking; When rotating speed drop to rated speed 15% or 10% the time, withdraw from electric braking and drop into the mechanical friction braking.
Generator electric braking principle is to set up the three-phase shortcircuit switch at generator outlet, off-the-line and demagnetization are finished under the prerequisite of (generator terminal voltage is less than 5%) at unit, this short switch closes, and apply a constant DC stream again for rotor, make the generator unit stator steady short reach certain certain value (specified or 1.15 times of rated values), utilize the resistance loss of stator winding to absorb rotor kinetic energy, the generating set in the rotation of slowing down.If the controlled excitation unit that adopts generator provides the DC power supply of braking to generator amature, we are called flexible electric braking.
The generator flexible electric braking, adjuster constant current closed loop, the rectifier cabinet separate excitation wiring of many cabinets parallel connection promptly disconnects the interchange input switch that the normal excitation of rectifier cabinet is moved, the interchange input switch of the rectifier cabinet running under braking of closing.Because the hysteresis effect and the thyristor latching current effect of inductor rotor, when adopting a plurality of controlled rectification bridge parallel running, before usually appearing at the disappearance of thyristor trigger impulse, the electric current that flows through thyristor does not still reach its latching current, and cause pulse disappearance back controlled rectification bridge still not have the phenomenon of output, and then cause the failure of unit electric braking, endanger unit thrust bearing safety.
Summary of the invention
Technical problem to be solved by this invention is: overcome the deficiency that existing generator flexible electric braking method causes the braking failure easily, provide a kind of electric braking success rate high flexible electric braking method of large-sized water turbine generator, solve a braking failure difficult problem that produces when a plurality of controlled rectification bridges are in parallel to drop into braking.
In order to solve above technical problem, flexible electric braking method of large-sized water turbine generator of the present invention, its step is as follows:
After a, field regulator enter the electric braking pattern, the permanent exciting current operation with closed ring of adjuster, and put the exciting current set point when equaling short circuit test, the exciting current value of rated secondary current correspondence;
B, the interchange input when closing the rectifier running under braking, direct current output switch and eliminating magnetism of generator switch;
C, give n rectifier bridge trigger impulse, make this n rectifying bridge outputting, i.e. the trigger impulse of all the other N-n of locking rectifier bridge, wherein N is the rectifier bridge sum, n satisfies formula (1),
In the formula, the rotor current when I is electric braking, i are single rectifier bridge rated current;
D, when unit satisfies when withdrawing from the running under braking condition, adjuster withdraws from braking mode.
Because the total quantity N cabinet parallel running of excitation rectifier bridge, be in order to guarantee the ability of encouraging by force of excitation system, and the electric braking operation is in permanent rotor current closed loop, do not need to consider that excitation encourages by force. when excitation unit enters the braking operating state, only give (n of a part, n is referring to formula 1) the rectifier bridge trigger impulse, it is all the other rectifier bridges of locking (N-n 's) trigger impulse, do not allow it participate in braking control, so just increased the thyristor current flows climbing of n the controlled rectification bridge that puts into operation, made before the thyristor trigger impulse disappears, the electric current that flows through thyristor surpasses its latching current, has guaranteed that the controlled rectification bridge can successfully export stable braking exciting current.
As seen, core of the present invention is existing rectifier bridge all to be dropped into be improved to the part input, because the rectifier bridge quantity that operation drops into when having reduced braking, also just flow through the climbing of the electric current of thyristor in the corresponding rectifier bridge that increases the operation input, make thyristor in the controlled rectification bridge before trigger impulse disappears above its latching current, thereby solved the braking failure difficult problem that hysteresis effect and thyristor latching current effect because of inductor rotor cause, guaranteed the safe operation of hydraulic generator unit.
The invention has the beneficial effects as follows, overcome the excitation controlled rectification bridge braking failure defective of many bridges parallel connection, increased the new function of field regulator brake actuating, improved the reliability of generator flexible electric braking.The present invention implements on the excitation unit of certain large-scale unit, has solved an on-the-spot braking failure difficult problem, and method is simple, and effect is obvious.
Embodiment
The present invention implements on certain Large Hydropower Station, has solved a part of generating units long-term immobilization failure difficult problem.
Example: certain Large Hydropower Station, rated exciting current 4000A, 5 rectifier bridge parallel connections, single bridge rated output 1800A are adopted in the excitation design.During electric braking, the exciting current set point is 1900A, during electric braking, can select to drop into the rectifier bridge number and is
Substitution numerical value draws n=2,3,4, and the rectifier bridge quantity that participation is exerted oneself is few more, and its thyristor current flows climbing is high more, and the braking success rate is also just high more, and in this example, n gets 2, and (smallest positive integral of formula 1 is separated, and also can directly adopt
Finding the solution smallest positive integral separates), therefore when braking, can realize the operation of 2 cabinets by the mode of excising other 3 bridge pulses, adopt this scheme after, the electric braking success rate brings up to 100%.
Its concrete steps are as follows:
When meeting the following conditions simultaneously, field regulator enters the electric braking pattern:
1, generator speed＜50% rated speed, electricity generator monitoring system are sent generator outlet three-phase shortcircuit switch command combined floodgate and are thrown brake command;
2, compound rectifier excitation operation interchange input switch disconnects;
3, excitation unit is without any fault;
4, generator does not have the electric accident trip signal;
5, generator terminal voltage＜5% rated voltage;
6, generator outlet three-phase shortcircuit switch closes.
After entering electric braking, excitation begins to carry out:
After a, field regulator enter the electric braking pattern, the permanent exciting current operation with closed ring of adjuster, and put the exciting current set point when equaling short circuit test, the exciting current value of rated secondary current correspondence;
B, the interchange input when closing the rectifier running under braking, direct current output switch and eliminating magnetism of generator switch;
C, give any 2 rectifier bridge trigger impulses, make this 2 rectifying bridge outputtings, i.e. the trigger impulse of all the other 3 rectifier bridges of locking, the number of the rectifier bridge of wherein exerting oneself can be found the solution acquisition according to formula (1),
In the formula, n is for handling the rectifier bridge number, and N is the rectifier bridge sum, and the rotor current when I is electric braking, i are single rectifier bridge rated current;
D, when unit satisfies when withdrawing from the running under braking condition, adjuster withdraws from braking mode.
Withdraw from running under braking condition following (establishment is arranged in following five, promptly withdraw from the running under braking condition and satisfy):
1, the emergency stop valve trip signal appears in generator;
2, the non-Light Condition of generator;
3, generator speed＜15% rated speed;
4, electric braking overrun;
5, receive computer supervisory control system and move back brake command.
In case adjuster withdraws from braking mode, remove locking immediately to aforementioned 3 rectifier bridge trigger impulses.
In addition to the implementation, the present invention can also have other execution modes.All employings are equal to the technical scheme of replacement or equivalent transformation formation, all drop on the protection range of requirement of the present invention.
Claims (3)
1. flexible electric braking method of large-sized water turbine generator, its step is as follows:
After a, field regulator enter the electric braking pattern, the permanent exciting current operation with closed ring of adjuster, and put the exciting current set point when equaling short circuit test, the exciting current value of rated secondary current correspondence;
B, the interchange input when closing the rectifier running under braking, direct current output switch and eliminating magnetism of generator switch;
C, give n rectifier bridge trigger impulse, make this n rectifying bridge outputting, i.e. the trigger impulse of all the other N-n of locking rectifier bridge, wherein N is the rectifier bridge sum, n satisfies formula (1),
In the formula, the rotor current when I is electric braking, i are single rectifier bridge rated current;
D, when unit satisfies when withdrawing from the running under braking condition, adjuster withdraws from braking mode.
2. according to the described flexible electric braking method of large-sized water turbine generator of claim 1, it is characterized in that: described n satisfies formula (2)
3. according to the described flexible electric braking method of large-sized water turbine generator of claim 2, it is characterized in that: in the steps d, after adjuster withdraws from braking mode, remove locking immediately described N-n rectifier bridge trigger impulse.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200910232777A CN101707467A (en) | 2009-12-01 | 2009-12-01 | Flexible electric braking method of large-sized water turbine generator |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200910232777A CN101707467A (en) | 2009-12-01 | 2009-12-01 | Flexible electric braking method of large-sized water turbine generator |
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| CN101707467A true CN101707467A (en) | 2010-05-12 |
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| CN200910232777A Pending CN101707467A (en) | 2009-12-01 | 2009-12-01 | Flexible electric braking method of large-sized water turbine generator |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109361329A (en) * | 2018-11-29 | 2019-02-19 | 华自科技股份有限公司 | Medium-and-large-sized braking system system and method |
| CN112952784A (en) * | 2021-02-24 | 2021-06-11 | 国网浙江省电力有限公司电力科学研究院 | Excitation becomes overload limiter suitable for flexible excitation system |
| CN112952784B (en) * | 2021-02-24 | 2024-05-10 | 国网浙江省电力有限公司电力科学研究院 | Excitation variable overload limiter applicable to flexible excitation system |
-
2009
- 2009-12-01 CN CN200910232777A patent/CN101707467A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109361329A (en) * | 2018-11-29 | 2019-02-19 | 华自科技股份有限公司 | Medium-and-large-sized braking system system and method |
| CN112952784A (en) * | 2021-02-24 | 2021-06-11 | 国网浙江省电力有限公司电力科学研究院 | Excitation becomes overload limiter suitable for flexible excitation system |
| CN112952784B (en) * | 2021-02-24 | 2024-05-10 | 国网浙江省电力有限公司电力科学研究院 | Excitation variable overload limiter applicable to flexible excitation system |
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Open date: 20100512 |