CN112751319B - Low-power protection control method for unit starting - Google Patents
Low-power protection control method for unit starting Download PDFInfo
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- CN112751319B CN112751319B CN202011602562.5A CN202011602562A CN112751319B CN 112751319 B CN112751319 B CN 112751319B CN 202011602562 A CN202011602562 A CN 202011602562A CN 112751319 B CN112751319 B CN 112751319B
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- 238000000034 method Methods 0.000 title claims abstract description 13
- 238000012544 monitoring process Methods 0.000 claims description 2
- 230000009471 action Effects 0.000 abstract description 11
- 238000010248 power generation Methods 0.000 abstract description 4
- 230000007547 defect Effects 0.000 abstract description 3
- 238000010586 diagram Methods 0.000 description 9
- 101150117538 Set2 gene Proteins 0.000 description 3
- 238000011217 control strategy Methods 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 101150055297 SET1 gene Proteins 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/08—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric motors
- H02H7/0816—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric motors concerning the starting sequence, e.g. limiting the number of starts per time unit, monitoring speed during starting
Abstract
The invention discloses a low-power protection control method for a unit during starting, and belongs to the field of power generation regulation. When all the circuit breakers on a sending-out line channel are in an off state, when the output power of the unit is smaller than a preset percentage of rated power, the unit enters a protection trip, and a delay trip boiler and a steam turbine are started; and if the current output power of the unit is greater than or equal to the preset percentage of the rated power, the protection trip is exited. The invention overcomes the defect that when the set start does not reach the setting value of the low-power cutting machine, the circuit is in reclosing/tripping working condition, and the single protection device can not realize reliable shutdown through the existing low-power protection action logic.
Description
Technical Field
The invention belongs to the field of power generation regulation, and particularly relates to a low-power protection control method for a unit during starting.
Background
The large-sized steam turbine generator unit has large capacity, high steam parameters and large rotor rotational inertia, a circuit side breaker trips due to faults or power grid fluctuation of a power plant outgoing line during normal operation, and when a power outgoing channel is interrupted (all outgoing lines of the power plant are disconnected from a power grid), the power of a generator cannot be output. At this time, if a series of measures such as closing the main valve, flameout of the boiler, de-excitation of the generator and the like cannot be timely adopted, problems such as overspeed of the steam turbine generator unit, overheat and overpressure of a steam thermodynamic system, overvoltage of a generator transformer unit and faults of other auxiliary equipment can be caused, and serious threat is formed to safe operation of the unit equipment.
At present, the construction and development of the power grid in China are rapid, and ultra-large power grids with regional power grid interconnection, provincial power grid interconnection and national power grid interconnection are built gradually, so that the overall stability of the power grid is high. However, in international projects, some national power grids are still in an operation state with large tidal current fluctuation and high grid vulnerability, and the external delivery conditions of the power plant are extremely unstable. To accommodate such conditions where the outgoing line is subject to tripping, large generators are typically provided with a low power chopper protection, also known as generator forward power dump protection, through which the unit is reliably shut down when the external power source fails (unit output dump).
Referring to FIG. 1, FIG. 1 is a logic diagram of a typical low power cutter guard action; in the figure, deltaU f1 Representing the positive sequence voltage burst increment, delta I of the generator f1 The positive sequence current step-down amount on the generator side is represented by f, the generator side frequency is represented by Δf, the generator side frequency step-up increment is represented by P G Represents generator-side active power, Δp represents generator-side active power sudden drop amount, Δp set Indicating the generator side active power dip setting. I fa 、I fb 、I fc For the generator current, uf1 is the generator side positive sequence voltage and Uf2 is the generator side negative sequence voltage. For low power cut-off protection, the power settings are as follows: (1) Pre-accident power setting value P set1 : the power of the large-scale generator is generally not less than 30% -40% of rated power when the large-scale generator is normally and stably operated, and the power setting value before an accident is 0.3-0.4P n The power setting minimum value is not less than the stable running value of the unit. The stable operation of the unit is a precondition for the protection action of the variable unit (the start-stop protection is put into before the stable operation), and other protection measures for the unit are needed when the fault of the sending-out line occurs during the stable operation. The criterion for the device action is therefore that the pre-accident power measurement is greater than P set1 . (2) Post-accident power setting value P set2 . When the power of the large-scale generator suddenly drops to 2%P during operation n Hereinafter, the generator should be considered to be operated at low power, and the post-accident power setting value P set2 Should be greater than the power zero drift value. For protection action, the starting criterion is that the power measured value is smaller than the setting value P in case of accident set2 . (3) the amount of power change (amount of dip) is an internal fixed value. Based on the setting, the low-power cut-off protection can cope with the power sudden drop condition when the unit stably operates. However, when the set start-up does not reach the setting value of the low-power switching machine, the working condition that reclosing/tripping occurs to the circuit is solved, and the single protection device cannot be protected by the existing low-power switching machineThe protection action logic achieves the aim of reliable shutdown.
Disclosure of Invention
The invention aims to overcome the defect that a single protection device cannot realize reliable shutdown through the existing low-power protection action logic when the set start does not reach the setting value of a low-power switching machine and the working condition of reclosing/tripping of a circuit occurs, and provides a low-power protection control method when the set is started.
In order to achieve the purpose, the invention is realized by adopting the following technical scheme:
a low-power protection control method for starting a unit uses the position state quantity of a unit side isolating switch as a unit input criterion, and judges whether the unit is ready to be input or not through the position state of the unit side isolating switch.
Furthermore, the position state quantity of the line side isolating switch is used as an operation mode criterion, and whether the line in the transformer substation is put into and sent out is judged through the position state of the line side isolating switch.
Further, when all the circuit breakers on the outgoing line channel are in an off state and the output power of the unit is smaller than the preset percentage of rated power, a protection tripping control strategy is started, and the boiler and the steam turbine are tripped in a delay mode;
and if the current output power of the unit is greater than or equal to the preset percentage of the rated power, the protection trip is exited.
Further, the preset percentage is 40%.
Further, the boiler and the steam turbine are tripped by delaying for 1s through a computer monitoring system.
Further, the protection trip control strategy starting condition is a logic combination of all switch and breaker position states on the power output channel.
Compared with the prior art, the invention has the following beneficial effects:
the low-power protection control method for the unit starting provided by the invention has the advantages that the protection tripping enters the delay tripping boiler and the steam turbine, so that the problems that the electric low-power protection device does not reach the action condition at the moment when the circuit breaker is disconnected and the output power of the unit is smaller than the preset percentage of the rated power in the unit starting stage, the whole stop cannot be started, and the main valve is closed are solved.
Drawings
FIG. 1 is a logic diagram of a typical low power cutter protection action;
FIG. 2 is an electrical main wiring of a power generation project of an embodiment;
FIG. 3 is a schematic diagram of the control logic wiring of the embodiment #1 unit at start-up;
FIG. 4 is a schematic diagram of the control logic wiring of the embodiment #2 unit at start-up;
FIG. 5 is a schematic diagram of the control box wiring;
fig. 6 is a diagram of the control box trip and reclose latch exit.
Detailed Description
In order that those skilled in the art will better understand the present invention, a technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in which it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, shall fall within the scope of the present invention.
It should be noted that the terms "first," "second," and the like in the description and the claims of the present invention and the above figures are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that the embodiments of the invention described herein may be implemented in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
The invention is described in further detail below with reference to the attached drawing figures:
examples
In a certain power generation project, 2x660MW units are newly built, 2 units are connected into a 500kV power distribution device in a factory through generator-transformer unit wiring, three-half wiring is adopted by the 500kV power distribution device, the power distribution device is sent out through two lines, and the main wiring schematic diagram is shown in figure 2. Because of poor stability of the power grid, a situation that line reclosing/tripping occurs in the unit load lifting process may exist. In this case, if all the outgoing line breakers trip, the main operation conditions of the electrical protection are generally based on the premise of stable operation, and the related protection is difficult to be implemented by the simple electrical protection, then the low-power protection logic needs to be added in the DCS, and the related protection function of the unit during starting is completed in cooperation with the characteristics of the unit itself and the related control strategy.
According to the electric main wiring, taking the #1 unit as an example, the following control scheme is given for realizing the low-power protection function when the unit is started by comparing the position state of the breaker during reclosing/tripping of the outgoing line:
1. control logic
1) The isolating switch B1Q10 is at a closing position, the circuit breaker B1Q2 and the circuit breaker B1Q3 are at an opening position, the circuit breaker B2Q1 and the circuit breaker B2Q3 are at an opening position, the output power of the unit does not exceed 40% of rated power at the moment, the condition is met, and the boiler and the steam turbine are tripped through DCS delay 1 s;
2) The isolating switch B1Q10 is at a closing position, the circuit breaker B1Q20 is at an opening position (the series ring), the circuit breaker B2Q1 and the circuit breaker B2Q3 are at an opening position, the output power of the unit does not exceed 40% of rated power at the moment, the condition is met, and the boiler and the steam turbine are tripped through DCS delay 1 s;
3) The isolating switch B1Q10 is at a closing position, the circuit breaker B2Q10 is at an opening position (other serial rings), the output power of the unit does not exceed 40% of rated power at the moment, the condition is met, and the boiler and the steam turbine are tripped through DCS delay for 1 s.
Corresponding to the position state of the disconnecting switch B1Q10, the starting condition control logic wiring schematic diagram is shown in fig. 3, the disconnecting switch B1Q10 on the #1 unit side is in a closing state, and at this time, if the circuit breaker B1Q2, the circuit breaker B1Q3, the circuit breaker B2Q1 and the circuit breaker B2Q3 are all in an opening state, or when the disconnecting switch B1Q20 on the line side, the circuit breaker B2Q1 and the circuit breaker B2Q3 are all in an opening state, or when the disconnecting switch B2Q10 on the line side, the circuit breaker B1Q2 and the circuit breaker B1Q3 are all in an opening state, the #1 unit low-power protection sends a tripping instruction.
Similarly, when the corresponding #2 unit is started, the corresponding disconnecting switch B2Q20 is in a position state, a starting condition control logic wiring schematic diagram is shown in fig. 4, the #2 unit side disconnecting switch B2Q20 is in a closing state, and at this time, if the circuit breaker B1Q2, the circuit breaker B1Q3, the circuit breaker B2Q1 and the circuit breaker B2Q3 are all in an opening state, or if the circuit side disconnecting switch B1Q20, the circuit breaker B2Q1 and the circuit breaker B2Q3 are all in an opening state, or if the circuit side disconnecting switch B2Q10, the circuit breaker B1Q2 and the circuit breaker B1Q3 are all in an opening state, the #2 unit low-power protection issues a trip instruction.
4) And when the output power of the unit exceeds 40% of rated power, exiting the DCS tripping condition corresponding to the logic.
The invention provides a relay lap joint scheme, which comprises the following steps:
for a running unit with a defect in low-power protection when the unit is started, if related logic of a computer control system is directly modified, the running of the unit is possibly influenced, so that a relay lap joint scheme is provided, the control box is matched with logic of the computer control system to realize the requirement of low-power protection, and the modification of the control system is reduced, wherein the control logic of the scheme is shown in figure 5. The intermediate relay (ZJ) expands the circuit breakers B1Q2, B1Q3, B2Q1 and B2Q3 respectively, and the disconnecting positions of the disconnecting switches B1Q20 and B2Q10 are respectively connected with the hard-wired loop of the control box by using the intermediate relay (ZJ) and the expanded normally open auxiliary contact according to the control logic.
In order to reduce external wiring, the scheme is expanded by using an intermediate relay (ZJ) as much as possible, logic lap joint is completed in the control box, necessary external outlet and reclosing locking logic are provided, and as shown in fig. 6, the tripping outlet of the control box is connected into a tripping circuit of a circuit breaker in a unit-side circuit breaker sink control cabinet, so that low-power protection and reliable action are realized.
It can be seen from the embodiment that, in the starting stage of the unit, if the external network is powered off (all circuit breakers are opened), the electric low-power protection device does not reach the action condition, and cannot start to stop completely, and the main valve is closed, so that the low-power protection of the unit needs to be completed through the logic control scheme set forth in the invention.
The above is only for illustrating the technical idea of the present invention, and the protection scope of the present invention is not limited by this, and any modification made on the basis of the technical scheme according to the technical idea of the present invention falls within the protection scope of the claims of the present invention.
Claims (1)
1. The low-power protection control method for the starting of the unit is characterized by comprising a bus I, a bus II, a bus B1 string and a bus B2 string;
the B1 string includes a #1 generator connected to the outgoing line I, and the B2 string includes a #2 generator connected to the outgoing line II; the generator #1 and the generator #2 are respectively connected to the low-voltage sides of the two main transformers, isolating switches B1Q10 and B2Q20 are arranged on the inlet wire sides of the main transformers of the B1 string and the B2 string, and isolating switches B1Q20 and B2Q10 are arranged on the outlet wire sides of the B1 string and the B2 string;
the disconnecting switch B1Q10 is connected to the bus I through a breaker interval B1Q1, the B1Q20 is connected to the bus II through a breaker interval B1Q2, the #1 transformer group incoming line and the outgoing line I are connected through a breaker interval B1Q3, and the breaker interval B1Q3 is connected in series between the breaker interval B1Q1 and the breaker interval B1Q 2;
the isolating switch B2Q20 is connected to the bus I through the breaker interval B2Q1, the isolating switch B2Q10 is connected to the bus II through the breaker interval B2Q2, the #2 transformer group incoming line is connected with the outgoing line II through the breaker interval B2Q3, and the breaker interval B2Q3 is connected in series between the breaker interval B2Q1 and the breaker interval B2Q 2;
taking the position state quantity of the unit side isolating switch B1Q20 or B2Q10 as a unit input criterion, and judging whether the unit is ready to be input or not through the position state of the unit side isolating switch B1Q20 or B2Q10;
taking the position state quantity of the line side isolating switches B1Q10 and B2Q20 as an operation mode criterion, and judging whether the line in the transformer substation is put into and sent out or not through the position states of the line side isolating switches B1Q10 and B2Q 20;
when all the circuit breakers on the outgoing line channel are in an off state and the output power of the unit is smaller than the preset percentage of rated power, the protection trip is carried out, and the boiler and the steam turbine are tripped in a delay manner;
if the current output power of the unit is greater than or equal to the preset percentage of the rated power, the protection trip is exited; the preset percentage is 40%;
delaying 1s trip of the boiler and the steam turbine through a computer monitoring system;
and selecting the position state of the circuit breaker and establishing control logic.
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| CN202011602562.5A CN112751319B (en) | 2020-12-29 | 2020-12-29 | Low-power protection control method for unit starting |
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| CN202011602562.5A CN112751319B (en) | 2020-12-29 | 2020-12-29 | Low-power protection control method for unit starting |
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| CN112751319B true CN112751319B (en) | 2024-01-30 |
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|---|---|---|---|---|
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| CN109286174A (en) * | 2017-07-20 | 2019-01-29 | 北京华清燃气轮机与煤气化联合循环工程技术有限公司 | A kind of control device and power guard method for Gas Turbine Generating Units |
| CN209896703U (en) * | 2019-04-22 | 2020-01-03 | 协鑫能源工程有限公司 | Anti-reverse power automatic control device and new energy power generation system |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9496707B2 (en) * | 2014-12-22 | 2016-11-15 | Schweitzer Engineering Laboratories, Inc. | Generator protection element |
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2020
- 2020-12-29 CN CN202011602562.5A patent/CN112751319B/en active Active
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| US4832898A (en) * | 1987-11-25 | 1989-05-23 | Westinghouse Electric Corp. | Variable delay reactor protection system |
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| CN209896703U (en) * | 2019-04-22 | 2020-01-03 | 协鑫能源工程有限公司 | Anti-reverse power automatic control device and new energy power generation system |
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