CN201266900Y

CN201266900Y - Apparatus for excitation of synchronous generator

Info

Publication number: CN201266900Y
Application number: CNU2008201293974U
Authority: CN
Inventors: E·西兰德
Original assignee: ABB Azipod Oy
Current assignee: ABB Oy; ABB Azipod Oy
Priority date: 2008-08-14
Filing date: 2008-08-14
Publication date: 2009-07-01
Anticipated expiration: 2018-08-14

Abstract

The utility model relates to a device which carries out excitation to a synchronous motor (10) when the voltage of a power grid is reduced to be lower than a preset limited value, wherein, the excitation is carried out to the synchronous motor by an exciting winding. The voltage of the power grid of the synchronous motor is measured and compared with the reference value. According the utility model, at least one current transformer (2) is distributed at power grid leads (R, S and T); a primary winding of the current transformer is connected with the power grid leads in series; and a secondary winding of the current transformer is coupled to an regulating circuit (8). When the voltage of the power grid is reduced to be lower than the reference value, the current of an exciting circuit (6) of the synchronous motor is controlled by the regulating circuit.

Description

Be used for synchronous generator is carried out the device of excitation

Technical field

The utility model relates to a kind of device that is used for synchronous generator is carried out excitation.

Background technology

To the excitation of synchronizer, particularly to the excitation of synchronous generator, be typically designed to brushlessly at present, thus, controlled exciting current is provided for excitation winding by energizing apparatus.For example produce exciting current by the voltage transformer that is coupled to electrical network, the secondary voltage of voltage transformer is controlled by voltage regulator.During abnormal conditions, when particularly being short-circuited in electrical network, the exciting current of Chan Shenging can not be satisfied the demand like this, and this is because line voltage can bust.

Under short-circuit conditions, excitation guarantees by current transformer independently usually, and current transformer is demarcated to big must be enough to guarantee enough excitation energy levels.There is shortcoming in this solution, and promptly this scheme can not be regulated exciting current, but the excitation energy level can limit by the demarcation to current transformer.Because each is used, all case ground designs and makes the instrument transformer that adapts one by one, and under most of situation, such solution does not have competitiveness.

Summary of the invention

The purpose of this utility model is to solve problem described above, and can obtain to have advantage and cost-benefit synchronous generator exciting at the situation of line voltage bust.According to the utility model, provide the line voltage that is used for when synchronous generator to drop to the method for when being lower than the predetermined confined value this synchronous generator being carried out excitation, this synchronous generator carries out excitation via excitation winding, measure line voltage according to method of the present utility model thus, and with the line voltage and the reference value comparison of measuring, at least one current transformer is arranged into the electrical network lead, the elementary winding of current transformer is connected with this electrical network lead, and the secondary winding of current transformer is coupled to regulating circuit, drop to when being lower than limit value electric current at line voltage by the field circuit of this regulating circuit control synchronous generator.

Correspondingly, according to the utility model, provide the line voltage that is used for when synchronous generator to drop to the device that when being lower than the predetermined confined value this synchronous generator is carried out excitation, this device comprises line voltage measurement mechanism and comparison means, this comparison means is used for the measured value and the limit value of comparison line voltage, in series is furnished with at least one elementary winding of current transformer with the electrical network lead of this synchronous generator; And the secondary winding of current transformer is connected with regulating circuit, and this regulating circuit is arranged to drop to when being lower than limit value when line voltage, is used for producing required exciting power.

Employing under short-circuit conditions, can obtain suitable excitation energy level according to solution of the present utility model reliably.Implement simple and profitable according to scheme of the present utility model.Be easy to identical realization is applied to high-power scope, this has reduced design and manufacturing cost.In this case, can use limited group standardized short circuit current instrument transformer, this efficient to production line has remarkable influence.Use scheme of the present utility model in can generator in use, because device of the present utility model energy easily links to each other with existing parts at hand.If it is too much that current transformer is demarcated mistakenly, the function of installing before can also regulating so makes it be in operating point preferably.Except short-circuit conditions, the utility model can also be applied in other the abnormal conditions, as when high capacity motor is activated, makes the voltage of generator be tending towards dropping to below the limit value of permission thus.

According to a kind of execution mode that has superiority, adjuster that is connected with current transformer and voltage regulator parallel coupled make these adjusters produce exciting current jointly thus.

Description of drawings

With reference to the accompanying drawings the utility model is described, in the accompanying drawings:

Fig. 1 has disclosed the prior art of synchronous generator being carried out excitation during short circuit.

Fig. 2 has described the indicatrix according to the function of the short circuit current of the synchronous generator of prior art and exciting current.

Fig. 3 has disclosed solution of the present utility model.

Fig. 4 has described the indicatrix according to the function of the short circuit current of synchronous generator of the present utility model and exciting current.

Embodiment

Fig. 1 has described a kind of field circuit of synchronous generator, and it produces excitation and produces excitation according to prior art during short-circuit conditions in normal use.Synchronous generator 10 is by the exciting current Im magnetization that is transmitted to excitation winding 6.Threephase potential transformer T1 is coupled to the phase conductor of generator, and the secondary winding 1 of voltage transformer T1 is arranged to voltage regulator 3 power supplies.Another secondary winding 7 of voltage transformer T1 produces the three-phase measured value of adjuster 3.The current transformer T2 that is coupled to generator S phase measures the current value that also is input to voltage regulator.Under normal mode, the exciting current Im of generator is directed to excitation winding 6 by diode 12.

For short-circuit conditions, three current transformer T3 are arranged into three phase conductor R-S-T with synchronous generator according to prior art.In normal use, secondary winding is by the short circuit by the K switch 2 of voltage regulator control.As selection, above-mentioned switch also can be controlled by the contactor of the output of being coupled to voltage transformer T1.Thus, the contact of K switch 2 is at voltage very big open when making that contactor discharges (open) that descend.This switch also can be controlled by voltage relay.The structure of instrument transformer is simple ring translator structure, and its elementary winding circuit is that the phase conductor by the generator that does not have any adjusting device forms as well known in the art.The secondary winding circuit of current transformer is connected to rectifier 4, and the output of rectifier 4 is connected to by diode 14 and is excitation winding 6 power supplies.Current transformer is demarcated to producing the short circuit current in three seconds, and this is equivalent to three times of rated current.Higher electric current also can damage generator self except that damaging excitation unit.

The characteristic curve of prior art scheme has been described among Fig. 2.Curve 1a has illustrated the functional relation of generator short circuit electric current and exciting current, and curve 2a has illustrated the characteristic curve of current transformer.The operating point setting of generator is at the crosspoint I of generator curve summation current transformer curve _K2The place.Curve 2b has illustrated the characteristic curve of another current transformer, and its operating point has value I _K1

Fig. 3 has described according to solution of the present utility model.Under normal mode, this design is corresponding with the device of Fig. 1, and corresponding part identifies with the Reference numeral identical with Fig. 1.During short-circuit conditions, exciting current produces by a kind of new mode.Correspondingly, regulating circuit 8 is coupled with the secondary winding of current transformer 2, and the output of regulating circuit is connected with the excitation winding 6 of synchronous generator 10.The connection in Fig. 1, measured value is that the secondary winding 7 by the voltage transformer T1 of the phase conductor R, the S that are connected to synchronous generator 10, T obtains.In the comparison circuit in voltage regulator 3, voltage measuring value and predetermined reference value are compared.When voltage is reduced to threshold value when following, adjuster is opened the contact of K2, and current transformer is excitation winding 6 feeds by regulating circuit 8 thus.

Regulating circuit 8 comprises three parts substantially: filter 22, circuits for triggering 42 and 44 and silicon controlled

rectifier

28,30,32,34.The effect of filter 22 is the voltage peaks that exceed that smoothly may cause the damage of rectification part even regulating circuit.Actual control circuit comprises the silicon controlled rectifier of two pairs of reverse parallel connection couplings.Silicon controlled

rectifier

28 and 30 is connected between the

output lead

36 and 38 of current transformer, and respectively, silicon controlled

rectifier

32 and 34 is connected between the

output lead

38 and 40 of current transformer.Circuits for triggering 42 control silicon controlled

rectifiers

28 and 30, and respectively, circuits for triggering 44 control silicon controlled rectifiers 32 and 34.When the line voltage of current transformer surpassed preset value, circuits for triggering made the silicon controlled rectifier conducting.The output lead of current transformer and then be connected with the input of the three-phase of rectifier 46.The direct current output of rectifier is coupled with the excitation winding 6 of synchronous generator.The electric current that regulating circuit is presented current transformer is limited in the aspiration level, can use standardized current transformer thus.

The output of regulating circuit 8 and voltage regulator 3 are connected in parallel, and think that excitation winding 6 provides exciting current.Like this, the electric current of current transformer so the voltage regulator of not flowing through, thereby under any circumstance, it can not cause damage to voltage regulator.On the other hand, current transformer 2 and regulating circuit 8 can produce whole exciting currents under the voltage regulator fault or the out-of-work state of emergency.

On the other hand, under short-circuit conditions, exciting current must be enough high, to obtain the suitable current relay operation.Yet exciting current can not increase De Taigao, to avoid field circuit and generator undermined.Typically, operation is designed, so that the short circuit current I of generator _k(Fig. 4) approximately be three times in rated value I _nWhen the electric current of current transformer is limited in desired value I _MhThe time, the characteristic curve of current transformer (Fig. 4, curve 2c) has provided short-circuit current value I _Kb, and short circuit current can be limited in desired value I _KaAccording to the utility model, the maximum of exciting current can be regulated (Fig. 4, straight line 3a) by the trigger voltage of suitably choosing circuits for triggering.Can adopt mode to realize in the practical application as jumper.Limit the preset value of exciting voltage and adjuster setting according to design evaluation, and before generator is carried out, finish short circuit test, regulate the desired value of exciting voltage in view of the above.After this, the jumper of circuits for triggering is set on the respective voltage level position, to obtain appropriate short circuit excitation.Because this is the problem of equipment concrete property, so just need not to change set point in actual applications.

When using the utility model, except that the brushless excitation of generally using at present, generator excitation can also particularly be realized in small generator in brush excitation connection is arranged.When using the utility model, the realization of excitation does not produce materially affect under normal mode.Although under short-circuit conditions, normal excitation is especially unavailable in aforementioned improved, still can adopt the utility model under the interim situation about descending of voltage when starting such as high capacity motor.In this case, use normal excitation, and the additional excitation that is produced and controlled by adjuster by current transformer will add according to the needs of load.

Hereinbefore, utilized an execution mode that the utility model is described.But these descriptions are not to be restriction to claim, can have various modification of the present utility model within the scope of the appended claims on the contrary.

Claims

1. the line voltage when synchronous generator drops to the device that when being lower than the predetermined confined value this synchronous generator is carried out excitation, this device comprises line voltage measurement mechanism and comparison means, this comparison means is used for the relatively measured value and the limit value of this line voltage, it is characterized in that: in series be furnished with at least one elementary winding of current transformer (2) with the electrical network lead of this synchronous generator; And the secondary winding of current transformer (2) is connected with regulating circuit (8), and this regulating circuit (8) is arranged to drop to when being lower than limit value when line voltage, is used for producing required exciting power.

2. device as claimed in claim 1 is characterized in that, the short circuit excitation can be in parallel with normal excitation, and total excitation of synchronous generator is the combination of short circuit excitation and normal excitation thus.

3. device as claimed in claim 1 is characterized in that described regulating circuit comprises the adjusting parts, makes that by described adjusting parts the amount of short circuit excitation is controlled as the function of the exciting voltage of synchronous generator.

4. device as claimed in claim 3 is characterized in that, described adjusting parts are realized with jumper, make that by described jumper the level of exciting voltage is controlled.

5. as each described device of claim 1-4, it is characterized in that excitation is controlled by the secondary voltage of regulating current transformer.

6. as each described device of claim 1-4, it is characterized in that described device also comprises the device (T1,7) that is used to measure three-phase voltage.

7. device as claimed in claim 5 is characterized in that, described device also comprises the device (T1,7) that is used to measure three-phase voltage.