CN219046470U - De-excitation system of steam turbine generator - Google Patents
De-excitation system of steam turbine generator Download PDFInfo
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- CN219046470U CN219046470U CN202223279140.6U CN202223279140U CN219046470U CN 219046470 U CN219046470 U CN 219046470U CN 202223279140 U CN202223279140 U CN 202223279140U CN 219046470 U CN219046470 U CN 219046470U
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- 238000004804 winding Methods 0.000 claims abstract description 33
- 230000005284 excitation Effects 0.000 claims abstract description 25
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 23
- 230000008033 biological extinction Effects 0.000 claims abstract description 23
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 23
- 239000010703 silicon Substances 0.000 claims abstract description 23
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical group [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 claims description 16
- 239000011787 zinc oxide Substances 0.000 claims description 8
- 230000005347 demagnetization Effects 0.000 abstract description 7
- 238000000034 method Methods 0.000 abstract description 6
- 230000002159 abnormal effect Effects 0.000 abstract description 2
- 238000010248 power generation Methods 0.000 abstract description 2
- 230000008569 process Effects 0.000 abstract description 2
- 238000010521 absorption reaction Methods 0.000 description 4
- 230000007547 defect Effects 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical group [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 230000005856 abnormality Effects 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000006978 adaptation Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
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Abstract
The utility model belongs to the technical field of power generation, and discloses a de-excitation system of a steam turbine generator. In the system, a silicon controlled rectifier bridge and an excitation winding are electrically connected to form an excitation direct current loop; the magnetic extinction switch is connected in series in the excitation direct current loop, the first nonlinear resistor and the diode are connected in series and then connected across the two ends of the excitation winding, and the conduction direction of the diode is opposite to the direct current direction generated by the silicon controlled rectifier bridge; and after being connected in series with the direct-current contactor, the linear resistor is connected across the two ends of the exciting winding so that under the state of demagnetization, when the difference between the arc-building voltage at the two ends of the demagnetization switch and the direct-current side voltage at the two ends of the silicon controlled rectifier bridge is greater than 0, the linear resistor starts to freewheel and demagnetize. The utility model reduces the voltage conditions which need to be met in the energy-transfer de-excitation process, thereby avoiding the limitation of the existing voltage conditions and the de-excitation failure caused by abnormal closing of the multi-fracture de-excitation switch derived from the existing voltage conditions, and improving the de-excitation reliability of the steam turbine generator.
Description
Technical Field
The utility model relates to the technical field of power generation, in particular to a de-excitation system of a steam turbine generator.
Background
In order to avoid damage to the turbo generator when faults such as short circuit or grounding occur outside or inside the turbo generator, a corresponding de-excitation system needs to be configured for the turbo generator.
The de-excitation system needs to realize the following two functions simultaneously: on the one hand, the exciting winding of the generator is rapidly cut off; on the other hand, the magnetic field energy stored in the field winding is rapidly consumed. Based on this, the conventional de-excitation system of the turbo generator is mostly composed of a de-excitation switch connected in series in the exciting dc loop, and a nonlinear resistor connected across the two ends of the exciting winding. At this time, if the generator normally operates, the magnetic extinction switch is closed, the voltage of the nonlinear resistor is smaller, the nonlinear resistor is in a high-resistance state, and the excitation direct current loop is conducted; when an arc occurs, the magnetic extinction switch is disconnected, the arc voltage at two ends of the magnetic extinction switch is increased, the exciting winding is electrically reversed, and then the voltage at two ends of the nonlinear resistor is increased until the voltage is larger than the residual voltage, the nonlinear resistor is turned into a conducting state, and the magnetic field energy in the exciting winding is rapidly consumed by the auxiliary magnetic extinction switch; thereby realizing the purpose of protecting the steam turbine generator.
From the above, the key point of the conduction of the nonlinear resistor in the existing demagnetizing system is that the difference between the arc voltage at the two ends of the demagnetizing switch and the dc side voltage in the exciting dc circuit needs to be larger than the residual voltage of the nonlinear resistor; so that rapid de-excitation cannot be realized. And the existing solution to meet the voltage condition is to make the magnetic-killing switch have enough breaks, and the breaks are simultaneously opened to provide high enough arc-building voltage. However, in practical use, the possibility that a plurality of fractures in the magnetic-killing switch are absolutely simultaneously broken is extremely low, so that the arc-building voltage is greatly reduced when the magnetic-killing switch is disconnected, and the reliability of demagnetization is affected. In more serious cases, one or a part of the fracture fails to break, so that energy-moving de-excitation cannot be realized.
Disclosure of Invention
The utility model aims to provide a de-excitation system of a steam turbine generator, which aims to solve the technical problems that the existing de-excitation system of the steam turbine generator is limited by nonlinear resistance conduction conditions and the energy transfer de-excitation cannot be effectively performed due to abnormal fracture disconnection when a derivative multi-fracture de-excitation switch provides arc-building voltage.
In order to achieve the above purpose, the present utility model proposes the following technical scheme:
a de-excitation system for a turbo generator, comprising: the device comprises a silicon controlled rectifier bridge, an excitation winding, a magnetic extinction switch, a first nonlinear resistor, a diode, a linear resistor and a direct current contactor; the silicon controlled rectifier bridge and the exciting winding are mutually and electrically connected to form an exciting direct current loop; the magnetic extinction switch is connected in series in the excitation direct current loop, the first nonlinear resistor and the diode are connected in series and then connected across the two ends of the excitation winding, and the conduction direction of the diode is opposite to the direction of direct current generated by the silicon controlled rectifier bridge; and the linear resistor is connected with the direct current contactor in series and then connected across the two ends of the exciting winding so that under the state of de-excitation, when the difference between the arc-establishing voltage at the two ends of the de-excitation switch and the direct current side voltage at the two ends of the silicon controlled rectifier bridge is greater than 0, the linear resistor starts to de-excite the flywheel.
Further, in the no-load running state, the voltage of the direct current side of the silicon controlled rectifier bridge is 95V; in a rated load running state, the direct-current side voltage of the controllable silicon rectifier bridge is 245V; in the forced excitation running state, the direct-current side voltage of the silicon controlled rectifier bridge is 440V.
Further, the magnetic extinction switch comprises a first fracture and a second fracture, and the first fracture and the second fracture are connected in series and then are connected in series in the excitation direct current loop.
Further, the first fracture and the second fracture comprise 28 arc extinguishing grids, and the arc voltage range provided by each arc extinguishing grid is 30-35V.
Further, the first nonlinear resistor is a zinc oxide de-excitation resistor; the residual voltage of the zinc oxide de-excitation resistor is 1000V.
Further, the resistance value of the linear resistor is 0.8Ω.
Further, the method comprises the steps of: and the first fuse is connected across the two ends of the thyristor rectifier bridge.
Further, the method comprises the steps of: and the second nonlinear resistor is connected with the first fuse in series and then is connected across the two ends of the silicon controlled rectifier bridge.
Further, the method comprises the steps of: and the second fuse is connected in series between the diode and the first nonlinear resistor.
Further, the method comprises the steps of: and the third nonlinear resistor, the second fuse and the first nonlinear resistor are connected in series and then connected across the two ends of the exciting winding.
The beneficial effects are that:
according to the technical scheme, the current turbonator de-excitation system is improved, so that the defect that the current de-excitation system cannot be rapidly subjected to arc extinction and the arc extinction reliability is poor is overcome.
The de-excitation system comprises: the device comprises a silicon controlled rectifier bridge, an excitation winding, a magnetic extinction switch, a first nonlinear resistor, a diode, a linear resistor and a direct current contactor; the silicon controlled rectifier bridge and the exciting winding are mutually and electrically connected to form an exciting direct current loop; the magnetic extinction switch is connected in series in the excitation direct current loop, the first nonlinear resistor and the diode are connected in series and then connected across the two ends of the excitation winding, and the conduction direction of the diode is opposite to the direction of direct current generated by the silicon controlled rectifier bridge; and the linear resistor is connected with the direct current contactor in series and then connected across the two ends of the excitation winding.
At this time, when the magnetic-killing switch trips to de-magnetic, the magnetic-killing switch performs arc-pulling voltage-building, and when the difference between the arc-building voltage at two ends of the magnetic-killing switch and the direct-current side voltage at two ends of the silicon-controlled rectifier bridge is greater than 0, that is, when the exciting winding is back-pressed, the linear resistor starts to freewheel to de-magnetic. The magnetic field current is firstly transferred from the demagnetizing switch to the linear resistor; and in the transfer process, when the voltage at two ends of the linear resistor exceeds the residual voltage of the first nonlinear resistor, the first nonlinear resistor participates in de-excitation and energy absorption. And then the magnetic field current is transferred in a segmented way through the linear resistor and the first nonlinear resistor so as to jointly perform the de-excitation and energy absorption, so that the de-excitation performance is effectively improved, the de-excitation efficiency is improved, and the de-excitation reliability is ensured.
It should be understood that all combinations of the foregoing concepts, as well as additional concepts described in more detail below, may be considered a part of the inventive subject matter of the present disclosure as long as such concepts are not mutually inconsistent.
The foregoing and other aspects, embodiments, and features of the present teachings will be more fully understood from the following description, taken together with the accompanying drawings. Other additional aspects of the utility model, such as features and/or advantages of the exemplary embodiments, will be apparent from the description which follows, or may be learned by practice of the embodiments according to the teachings of the utility model.
Drawings
The drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component that is illustrated in various figures may be represented by a like numeral. For purposes of clarity, not every component may be labeled in every drawing. Embodiments of various aspects of the utility model will now be described, by way of example, with reference to the accompanying drawings, in which:
fig. 1 is a schematic structural diagram of a de-excitation system of a turbo generator according to the present utility model.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present utility model more clear, the technical solutions of the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. It will be apparent that the described embodiments are some, but not all, embodiments of the utility model. All other embodiments, which can be made by a person skilled in the art without creative efforts, based on the described embodiments of the present utility model fall within the protection scope of the present utility model. Unless defined otherwise, technical or scientific terms used herein should be given the ordinary meaning as understood by one of ordinary skill in the art to which this utility model belongs.
The terms "first," "second," and the like in the description and in the claims, are not used for any order, quantity, or importance, but are used for distinguishing between different elements. Also, unless the context clearly indicates otherwise, singular forms "a," "an," or "the" and similar terms do not denote a limitation of quantity, but rather denote the presence of at least one. The terms "comprises," "comprising," or the like are intended to cover a feature, integer, step, operation, element, and/or component recited as being present in the element or article that "comprises" or "comprising" does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. "up", "down", "left", "right" and the like are used only to indicate a relative positional relationship, and when the absolute position of the object to be described is changed, the relative positional relationship may be changed accordingly.
In the prior art, when the direct current de-excitation is carried out on the exciting winding of the steam turbine generator, energy-shifting de-excitation structures are adopted. The structure needs to take the residual voltage that the difference between the arc voltage at two ends of the magnetic extinction switch and the voltage at the direct current side is larger than the nonlinear resistor (namely the first nonlinear resistor in fig. 1) as a necessary condition; in order to meet the foregoing requirements, it is generally required that multiple breaks of the magnetic switch are simultaneously opened to provide a high enough arc voltage, but in practice, multiple breaks cannot be simultaneously opened, which results in that the actual arc voltage is lower than the required arc voltage. The two points not only bring inconvenience for quick de-excitation; and has the defect of poor de-excitation reliability. Particularly, when an extreme abnormality occurs that a part of the fracture cannot be broken, energy-moving and de-excitation cannot be performed. Based on this, the present embodiment provides a de-excitation system of a steam turbine generator to improve the above-mentioned existing drawbacks.
The de-excitation system of the steam turbine generator disclosed by the utility model is further specifically described below with reference to the embodiment shown in the drawings.
As shown in fig. 1, the de-excitation system mainly includes: the DC contactor comprises a silicon controlled rectifier bridge LP, an excitation winding LQ, a magnetic extinction switch MK, a first nonlinear resistor RV1, a diode D, a linear resistor Rm and a DC contactor ZLC.
In a specific connection, the scr bridge LP and the excitation winding LQ are electrically connected to each other to form an excitation dc loop. The magnetic extinction switch MK is connected in series in the exciting direct current loop, the first nonlinear resistor RV1 and the diode D are connected in series and then connected across the two ends of the exciting winding LQ, and the conducting direction of the diode D is opposite to the direction of the direct current generated by the thyristor rectifier bridge LP. The linear resistor Rm is connected with the direct current contactor ZLC in series and then connected across the two ends of the exciting winding LQ.
In specific implementation, when the turbo generator is in normal operation, the magnetic extinction switch MK is closed, and the scr bridge LP outputs the dc side voltage Ud, and the dc side voltage Ud is recorded as positive voltage (i.e. the voltage Ud is positive and negative in fig. 1). And the direct-current side voltage Ud provides exciting voltage Uf for the exciting winding LQ, and the exciting voltage Uf is positive (i.e. the voltage Uf is positive and negative in fig. 1) at this time; under the isolation action of the diode D and the direct current contactor ZLC, no direct current corresponding to the direct current side voltage Ud passes through the first nonlinear resistor RV1 and the linear resistor Rm.
When faults such as short circuit or grounding occur outside or inside the turbo generator, the magnetic extinction switch MK is opened and arc-drawing voltage establishment is carried out, and once exciting voltage Uf is back-pressure (namely, the voltage Uf is negative and positive in the figure 1), namely Uk-Ud is more than 0, the linear resistor Rm starts to freewheel and demagnetize. The magnetic field current in the exciting winding LQ is firstly transferred to the linear resistor Rm by the demagnetizing switch MK, namely, the linear resistor Rm is used for energy transfer and demagnetization; then when the voltage at two ends of the linear resistor Rm exceeds the residual voltage of the first nonlinear resistor RV1, the first nonlinear resistor RV1 starts to participate in de-excitation and energy absorption, and the excitation voltage is limited to be the residual voltage. And further, the voltage threshold condition of energy transfer and demagnetization is reduced, and the limitation of residual voltage of the first nonlinear resistor RV1 on demagnetization and current conversion is avoided. In addition, the de-excitation at this time is not only dependent on the first nonlinear resistor RV1, so that the number of breaks of the de-excitation switch and whether the breaks are simultaneously disconnected are not necessary.
In this embodiment, the cable used in the de-excitation system is 95mm 2 A single core copper core cable.
As a specific embodiment, the dc-side voltage Ud under different conditions is defined as follows: in the no-load operation state, the direct-current side voltage ud=95v of the thyristor rectifier bridge; in a rated load operation state, the direct-current side voltage ud=245V of the thyristor rectifier bridge; in the forced operation state, the dc side voltage ud=440V of the thyristor rectifier bridge.
Based on this, in order to reduce the de-excitation time, the first nonlinear resistor RV1 is set to be a zinc oxide de-excitation resistor. Specifically, the zinc oxide de-excitation resistor is formed by connecting 19 zinc oxide valve plates in parallel, and the residual voltage of the zinc oxide de-excitation resistor is 1000V.
Meanwhile, the magnetic extinction switch MK is set to include two fractures: a first fracture and a second fracture. Specifically, the first fracture and the second fracture are connected in series and then connected in series in the excitation direct current loop. Specifically, the first fracture and the second fracture comprise 28 arc-extinguishing grids, and the arc voltage range provided by each arc-extinguishing grid is 30-35V. At this time, the arc-forming voltage normally provided by the magnetic extinction switch MK is 1680-1960V. As an alternative embodiment, the model number of the magnetic extinction switch MK is DM4-2500.
At this time, when the fault is caused under the most serious working condition, namely the strong excitation running state, and when the magnetic extinction switch MK is disconnected, the follow current demagnetization can be started by the linear resistor Rm only by enabling Uk-440V to be larger than 0, namely Uk > 440V; and when the voltage at two ends of the linear resistor Rm is larger than 1000V, the first nonlinear resistor RV1 participates in de-excitation and energy absorption. Compared with the prior art, uk-440V is more than 1000V, namely Uk is more than 1440V, the energy transfer and de-excitation can be performed more quickly, so that the fault expansion is avoided, and the damage of the turbogenerator under the fault condition is reduced.
In this embodiment, the resistance of the linear resistor is 0.8Ω.
As an alternative embodiment, the de-excitation system is provided for protecting the dc supply side and further comprises a first fuse FU1. The first fuse FU1 is connected across the scr bridge LP. Preferably, the second nonlinear resistor RV2 is further included, and the second nonlinear resistor RV2 is connected in series with the first fuse FU1 and then connected across the two ends of the scr bridge LP.
As a further alternative embodiment, the de-excitation system is provided for protecting the field winding side with a second fuse FU2. The second fuse FU2 is connected in series between the diode D and the first nonlinear resistor RV 1. Preferably, the circuit further comprises a third nonlinear resistor RV3, and the third nonlinear resistor RV3, the second fuse FU2 and the first nonlinear resistor RV1 are connected in series and then connected across the two ends of the exciting winding LQ.
Furthermore, in order to measure the current in the de-excitation system and relay protection, the de-excitation system is provided with a current transformer CT. One end of the current transformer CT is connected with the thyristor rectifier bridge LP and the exciting winding LQ at the same time, and the other end of the current transformer CT is connected with the first nonlinear resistor RV1 and the second nonlinear resistor RV2 at the same time.
Meanwhile, the de-excitation system further comprises a time relay and an intermediate relay controlled by the ECS device to automatically control switching of the de-excitation resistor formed by the first nonlinear resistor RV1 and the linear resistor Rm according to the state of the de-excitation switch MK.
While the utility model has been described with reference to preferred embodiments, it is not intended to be limiting. Those skilled in the art will appreciate that various modifications and adaptations can be made without departing from the spirit and scope of the present utility model. Accordingly, the scope of the utility model is defined by the appended claims.
Claims (10)
1. A de-excitation system for a turbo generator, comprising: the device comprises a silicon controlled rectifier bridge, an excitation winding, a magnetic extinction switch, a first nonlinear resistor, a diode, a linear resistor and a direct current contactor; the silicon controlled rectifier bridge and the exciting winding are mutually and electrically connected to form an exciting direct current loop; the magnetic extinction switch is connected in series in the excitation direct current loop, the first nonlinear resistor and the diode are connected in series and then connected across the two ends of the excitation winding, and the conduction direction of the diode is opposite to the direction of direct current generated by the silicon controlled rectifier bridge; and the linear resistor is connected with the direct current contactor in series and then connected across the two ends of the exciting winding so that under the state of de-excitation, when the difference between the arc-establishing voltage at the two ends of the de-excitation switch and the direct current side voltage at the two ends of the silicon controlled rectifier bridge is greater than 0, the linear resistor starts to de-excite the flywheel.
2. The de-excitation system of claim 1, wherein the dc side voltage of the scr bridge is 95V in an idle operating condition; in a rated load running state, the direct-current side voltage of the controllable silicon rectifier bridge is 245V; in the forced excitation running state, the direct-current side voltage of the silicon controlled rectifier bridge is 440V.
3. The de-excitation system of claim 2, wherein the de-excitation switch comprises a first break and a second break, the first break and the second break being connected in series and then in series in the excitation dc loop.
4. A de-excitation system for a turbo-generator according to claim 3, wherein the first and second interruptions each comprise 28 arc-suppressing grids, each providing an arc voltage in the range of 30-35V.
5. The de-excitation system of a turbo generator of claim 4, wherein the first non-linear resistor is a zinc oxide de-excitation resistor; the residual voltage of the zinc oxide de-excitation resistor is 1000V.
6. The de-excitation system of a turbo generator of claim 5, wherein the linear resistor has a resistance of 0.8Ω.
7. The de-excitation system of a turbo-generator of claim 1, comprising: and the first fuse is connected across the two ends of the thyristor rectifier bridge.
8. The de-excitation system of a turbo-generator of claim 7, comprising: and the second nonlinear resistor is connected with the first fuse in series and then is connected across the two ends of the silicon controlled rectifier bridge.
9. The de-excitation system of a turbo-generator of claim 1, comprising: and the second fuse is connected in series between the diode and the first nonlinear resistor.
10. The de-excitation system of a turbo-generator of claim 9, comprising: and the third nonlinear resistor, the second fuse and the first nonlinear resistor are connected in series and then connected across the two ends of the exciting winding.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202223279140.6U CN219046470U (en) | 2022-12-08 | 2022-12-08 | De-excitation system of steam turbine generator |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202223279140.6U CN219046470U (en) | 2022-12-08 | 2022-12-08 | De-excitation system of steam turbine generator |
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| CN219046470U true CN219046470U (en) | 2023-05-19 |
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| CN202223279140.6U Active CN219046470U (en) | 2022-12-08 | 2022-12-08 | De-excitation system of steam turbine generator |
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