CN111416389A

CN111416389A - Backpressure machine switching system

Info

Publication number: CN111416389A
Application number: CN202010346206.5A
Authority: CN
Inventors: 兀鹏越; 王俊和; 郭霞; 寇水潮; 孙钢虎; 马晋辉; 王小辉; 贺婷; 柴琦; 薛磊; 高峰; 杨沛豪
Original assignee: Thermal Power Research Institute
Current assignee: Xian Thermal Power Research Institute Co Ltd
Priority date: 2020-04-27
Filing date: 2020-04-27
Publication date: 2020-07-14

Abstract

The invention discloses a backpressure machine switching system, which comprises a station service power system and a backpressure machine system; the invention provides a system for supplying power to factory loads of two main machines by one back press, which is characterized in that the system comprises a back press, a quick switching device, a switching device and a switching device, wherein the system comprises a first system for driving two main machines to work, the first system is used for driving two main machines to work, the quick switching device is used for realizing the flexible switching of the back press with three-section and four-section factory section bus loads, and the switching method under various working conditions is provided, so that the repeated construction is avoided, the generated energy of the back press is effectively; the backpressure machine switching system can greatly reduce investment, further reduce energy consumption and plant power consumption rate, and has good economical efficiency and engineering practice value.

Description

Backpressure machine switching system

Technical Field

The invention relates to a backpressure machine, in particular to a backpressure machine switching system.

Background

At present, a cogeneration unit in a power plant directly uses reheated steam for external heat supply, and the condition of high quality and low use exists. This method does not realize cascade utilization of steam, thereby increasing energy consumption. In order to solve the problem, a large number of thermal power generating units fully utilize steam in the heat supply transformation by building a small back pressure machine to drag a generator. The back pressure machine applies work by utilizing steam pumped by the corresponding generator, exhaust is used for heat supply, and the generated electric energy is accessed into a plant power system of the machine set, so that energy loss caused by heating after temperature and pressure reduction by utilizing steam of the large machine set at present is reduced, plant power rate can be further reduced, and the back pressure machine has very good energy-saving benefit and is widely applied. In the heat supply transformation of the domestic thermal power generating unit, the selected back pressure machines have different capacities according to the size of heat supply load, and the capacity of the common back pressure machine is 2000kW-25000 kW. Generally, when the backpressure machine is initially designed, the capacity is small, and a power supply mode that one backpressure machine is used for supplying service power to one host machine or a power supply mode that multiple backpressure machines are used for supplying service power to one host machine is adopted. When the generated energy of the back pressure machine is not more than the station service power of a single host, the back pressure machine can safely, stably and economically operate.

However, with the development of economy, the heat load of many heat supply users of the thermal power plant gradually increases, the power generation amount of the back pressure machine gradually increases, and the power generation amount of the back pressure machine exceeds the service power of a single host machine, so that the service power rate of the host machine is negative. At present, the power supply project of the backpressure unit is realized by reducing the plant power consumption rate to a great extent in the current power grid power generation dispatching mode in a profitable mode, so that more internet electricity quantity is obtained. Once the plant power rate of the unit becomes negative, it is likely that the scheduling mechanism will not allow the unit to generate power. Therefore, the upper limit of the generated energy of the originally designed back press is the service power of the unit. In order to give full play to the energy-saving effect of the back press and absorb the generated energy of the back press, a 'one-to-two' system for supplying power to the service loads of two main machines by one back press at the same time is researched, and the flexible switching method for the service power sections supplied by the service power section is realized by a fast switching device, so that the energy consumption and the service power rate can be further reduced, the investment is greatly reduced, the repeated construction is avoided, and the back press has good economical efficiency and engineering practice value.

Disclosure of Invention

The invention aims to provide a backpressure machine switching system method aiming at the current situations that the heat load of a thermal power plant is gradually increased, the power generation power of a backpressure machine exceeds the service power of a single host machine, the full utilization of energy is not realized, and the service power rate of the host machine is negative.

In order to achieve the purpose, the invention adopts the following technical scheme to realize the purpose:

a backpressure machine switching system comprises a station service power system and a backpressure machine system; the back press machine system is connected to a 6kV station-used 3A section bus, a 6kV station-used 3B section bus, a 6kV station-used 4A section bus and a 6kV station-used 4B section bus of a station-used electric system through a ninth circuit breaker, a tenth circuit breaker, an eleventh circuit breaker and a twelfth circuit breaker respectively.

The invention further improves the following steps: the station service power system comprises a 3 # main transformer, a 3 # generator, a 3 # high-voltage station service transformer, a first circuit breaker, a second circuit breaker, a 6kV station service 3A section bus, a starting standby transformer, a third circuit breaker, a fourth circuit breaker, a fifth circuit breaker, a sixth circuit breaker, a 6kV station service 3B section bus, a 6kV station service 4A section bus, a 4 # main transformer, a 4 # generator, a 4 # high-voltage station service transformer, a seventh circuit breaker, an eighth circuit breaker and a 6kV station service 4B section bus; wherein,

the 3 # generator is connected to a power grid through a 3 # main transformer, the high-voltage side of the 3 # high-voltage station transformer is connected to the end of the 3 # generator, and the two low-voltage sides of the 3 # high-voltage station transformer are respectively connected to a 6kV station 3A section bus and a 6kV station 3B section bus through a first circuit breaker and a second circuit breaker; the high-voltage side of the starting standby transformer is connected to a power grid, one low-voltage side of the starting standby transformer is connected to a 6kV station-used 3A section bus and a 6kV station-used 4A section bus through a third circuit breaker and a fourth circuit breaker respectively, and the other low-voltage side of the starting standby transformer is connected to a 6kV station-used 3B section bus and a 6kV station-used 4B section bus through a fifth circuit breaker and a sixth circuit breaker respectively; no. 4 generator is connected to the electric wire netting through No. 4 main transformer, No. 4 high-voltage mill uses transformer high pressure side access No. 4 generator ends, and its two low-voltage sides insert 6kV mill through seventh circuit breaker and eighth circuit breaker respectively and use 4A section generating line and 6kV mill and use 4B section generating line.

The invention further improves the following steps: the back pressure machine system comprises a back pressure machine, a back pressure asynchronous generator outlet circuit breaker, a current limiter, a ninth circuit breaker, a tenth circuit breaker, an eleventh circuit breaker and a twelfth circuit breaker; wherein,

after the back pressure machine passes through the outlet circuit breaker of the back pressure asynchronous generator and the current limiter, the back pressure machine is connected to a 6kV station-used 3A section bus, a 6kV station-used 3B section bus, a 6kV station-used 4A section bus and a 6kV station-used 4B section bus of a station-used electric system through a ninth circuit breaker, a tenth circuit breaker, an eleventh circuit breaker and a twelfth circuit breaker respectively.

The invention further improves the following steps: when the twelfth circuit breaker is in a closed state, the back pressure machine is connected to the 6kV station 4B section bus, and electric energy generated by the back pressure machine is used for supplying station power of the 6kV station 4B section bus and the 6kV station 4A section bus; when the electric energy that the backpressure machine sent increases to it still can be for 6kV station service 3B section generating line power supply after satisfying 4 # generator's whole station service power demands, under the prerequisite of disconnection second circuit breaker, closed tenth circuit breaker, realize the backpressure machine takes 6kV station service 3B section generating line, 6kV station service 4A section generating line and 6kV station service 4B section generating line to share three-section generating line load purpose of operation.

The invention further improves the following steps: on the basis that the backpressure machine carries a three-section bus load operation shared by a 6kV factory-used 3B-section bus, a 6kV factory-used 4A-section bus and a 6kV factory-used 4B-section bus, if the electric energy sent by the backpressure machine is continuously increased, the backpressure machine can still supply power to the 6kV factory-used 3A-section bus after meeting the factory-used requirements of a No. 4 generator and the 6kV factory-used 3B-section bus, and under the premise of disconnecting the first circuit breaker, the ninth circuit breaker is closed, so that the purpose that the backpressure machine carries a four-section bus load operation shared by a 6kV factory-used 3A-section bus, a 6kV factory-used 3B-section bus, a 6kV factory-used 4A-section bus and a 6kV factory-used 4B-section bus is realized.

The invention further improves the following steps: the backpressure machine is enabled to carry out three-section bus load operation of 6kV factory 3B section buses, 6kV factory 4A section buses and 6kV factory 4B section buses:

switching method under normal working condition

Step 1: in the rated operation process of the No. 3 generator and the No. 4 generator, when the phase sequence, the frequency, the phase and the outlet voltage of the back pressure machine are the same as those of the service system, the twelfth circuit breaker is closed, so that the back pressure machine is connected to a 6kV service 4B section bus;

step 2: increasing the power of the backpressure machine, so that the service load of the No. 4 generator is completely supplied with power by the backpressure machine, and the power of the high-voltage side of the No. 4 high-voltage service transformer is close to 0MW at the moment;

and step 3: switching the load of the 3B section of the bus for the 6kV factory to a back pressure machine in a mode of switching in parallel, namely firstly closing the tenth circuit breaker and then opening the second circuit breaker;

and 4, step 4: the generated energy of the back pressure machine is further increased, the power of the high-voltage side of the No. 4 high-voltage station transformer is close to 0MW again, and the condition that the station power is transmitted to the power grid backwards does not occur;

(2) switching method under abnormal working condition

1) When the No. 3 generator is tripped and shut down, the running mode of the back pressure machine is unchanged, so that the power supply of the 3B section of the 6kV station-used bus is not affected, and the 3A section of the 6kV station-used bus is switched to the starting standby transformer by closing the third breaker;

2) when the No. 4 generator is tripped and shut down, the backpressure machine jointly trips at the moment, and the 6kV factory-used 4A section bus, the 6kV factory-used 3B section bus and the 6kV factory-used 4B section bus are switched to the starting standby transformer by closing a fourth breaker, a fifth breaker and a sixth breaker;

3) when the back press trips and stops, the following two switching methods exist:

the first method is that under the condition that an outlet circuit breaker, a ninth circuit breaker, a tenth circuit breaker, an eleventh circuit breaker and a twelfth circuit breaker of the backpressure asynchronous generator are disconnected, the 6kV station-used 3B section bus is switched to a starting standby transformer by closing a fifth circuit breaker;

the second method is that under the condition that only the outlet circuit breaker of the backpressure asynchronous generator is disconnected, when the capacity of the No. 4 high-voltage station transformer meets the load requirement, the No. 4 high-voltage station transformer is enabled to operate with a 3B section bus for 6kV station, a 4A section bus for 6kV station and a 4B section bus for 6kV station.

The invention further improves the following steps: the backpressure machine is enabled to carry out load operation on four sections of buses including a 3A section bus for a 6kV factory, a 3B section bus for a 6kV factory, a 4A section bus for a 6kV factory and a 4B section bus for a 6kV factory:

switching method under normal working condition

and step 3: switching the load of the 3A section of bus for the 6kV factory and the load of the 3B section of bus for the 6kV factory to the back pressure machine in a mode of switching in parallel, namely firstly closing the ninth circuit breaker and the tenth circuit breaker and then disconnecting the first circuit breaker and the second circuit breaker;

and 4, step 4: the generated energy of the back pressure machine is further increased, the power of the high-voltage side of the No. 4 high-voltage station transformer is close to 0MW again, and the condition that the station power is transmitted to the power grid in a backward mode does not occur;

(2) switching method under abnormal working condition

1) When the No. 3 generator is tripped and shut down, the running mode of the back pressure machine is unchanged, so that the power supply of the 3A section of bus for 6kV factories and the 3B section of bus for 6kV factories is not affected;

2) when the No. 4 generator trips and stops, the back pressure machine jointly trips at the moment, and the 6kV factory-used 3A section bus, the 6kV factory-used 4A section bus, the 6kV factory-used 3B section bus and the 6kV factory-used 4B section bus are switched to the starting standby transformer by closing the third breaker, the fourth breaker, the fifth breaker and the sixth breaker;

the first method is that under the condition of disconnecting the outlet circuit breaker of the backpressure asynchronous generator, the ninth circuit breaker, the tenth circuit breaker, the eleventh circuit breaker and the twelfth circuit breaker, the third circuit breaker and the fifth circuit breaker are closed to switch the 3A section bus of the 6kV factory and the 3B section bus of the 6kV factory to the starting standby transformer;

the second method is that under the condition that only the outlet circuit breaker of the backpressure asynchronous generator is disconnected, when the capacity of the No. 4 high-voltage station transformer meets the load requirement, the No. 4 high-voltage station transformer is enabled to operate with a 3A section bus for 6kV station, a 3B section bus for 6kV station, a 4A section bus for 6kV station and a 4B section bus for 6kV station.

Compared with the prior art, the invention has at least the following beneficial technical effects:

1. the system has clear structure and simple wiring, can realize a one-to-two system that one back press supplies power for factory loads of two hosts at the same time through simple wiring, avoids repeated construction and reduces investment cost;

2. the energy-saving effect of the back press can be fully exerted, the generated energy of the back press is consumed, the energy consumption and the plant power consumption rate are greatly reduced, and the economical efficiency of unit operation is improved;

3. according to the invention, the flexible switching of the station service power sections supplied by the back press can be realized through the fast cutting device, so that the flexibility of system operation is improved;

4. the invention has simple and clear switch switching under normal working conditions and various accident conditions, and improves the safety and the reliability of the operation of the switching system.

In conclusion, the invention avoids repeated construction, reduces investment, has strong practicability and is convenient for popularization and use.

Drawings

Fig. 1 is a schematic wiring diagram of a switching system of a back pressure machine.

FIG. 2 is a diagram of the switching of the switch during normal operation of the load with three bus bars, namely, a 3B bus bar with 6kV service, a 4A bus bar with 6kV service and a 4B bus bar with 6kV service.

FIG. 3 is a switch switching diagram of a #3 machine tripping and stopping in the load operation process with 6kV factory-used 3B section bus, 6kV factory-used 4A section bus and 6kV factory-used 4B section bus.

FIG. 4 is a switch switching diagram of a #4 machine tripping and stopping in the load operation process with 6kV factory-used 3B section bus, 6kV factory-used 4A section bus and 6kV factory-used 4B section bus.

Fig. 5 is a switching diagram of a switch when a back pressure machine is tripped and stopped in a load operation process with 6kV station 3B section buses, 6kV station 4A section buses and 6kV station 4B section buses (fig. 5(a) shows a first switching method, and fig. 5(B) shows a second switching method).

FIG. 6 is a switch switching diagram when the load of the 3A section bus, the 6B section bus, the 4A section bus and the 4B section bus with 6kV factory is normally operated/the switch switching diagram when the #3 machine trips to stop in the process of the load operation of the 3A section bus, the 6B section bus, the 4A section bus and the 4B section bus with 6kV factory.

FIG. 7 is a switch switching diagram of a #4 machine tripping and stopping in the load operation process of a 3A section bus with 6kV factory, a 3B section bus with 6kV factory, a 4A section bus with 6kV factory and a 4B section bus with 6kV factory.

Fig. 8 is a switching diagram of the switch when the back pressure machine is tripped and stopped in the load operation process with 6kV station 3A section bus, 6kV station 3B section bus, 6kV station 4A section bus and 6kV station 4B section bus (fig. 8(a) shows a first switching method, and fig. 8(B) shows a second switching method).

Description of reference numerals:

1-a service power system; 2-backpressure machine system; 1-3 main transformer; 1-2-3 generators; 1-3 high-voltage station transformer; 1-4 — a first circuit breaker; 1-5-second circuit breaker; 1-6 kV factory 3A section bus; 1-7-starting the standby transformer; 1-8-third circuit breaker; 1-9-fourth circuit breaker; 1-10-fifth circuit breaker; 1-11-sixth circuit breaker; 1-12-6 kV factory 3B section bus; 4A section of bus for 1-13-6 kV factories; 1-14-4 main transformer; 1-15-4 generators; 1-16-4 high-voltage station transformer; 1-17-seventh circuit breaker; 1-18 — eighth circuit breaker; 4B section buses for 1-19-6 kV factories; 2-1-back press; 2-back pressure asynchronous generator outlet breaker; 2-3-current limiter; 2-4 — ninth circuit breaker; 2-5-tenth circuit breaker; 2-6-eleventh circuit breaker; 2-7 — twelfth breaker.

Detailed Description

The technical solution of the present invention is further described in detail by the accompanying drawings and embodiments.

As shown in fig. 1, the backpressure machine switching system provided by the present invention includes an auxiliary power system 1 and a backpressure machine system 2; the back press machine system 2 is connected to 6kV station-used 3A section buses 1-6, 6kV station-used 3B section buses 1-12, 6kV station-used 4A section buses 1-13 and 6kV station-used 4B section buses 1-19 of the station-used electrical system 1 through ninth circuit breakers 2-4, tenth circuit breakers 2-5, eleventh circuit breakers 2-6 and twelfth circuit breakers 2-7 respectively. The plant power system 1 comprises a No. 3 main transformer 1-1 (a plant system generally comprises a main transformer and a generator), a No. 3 generator 1-2, a No. 3 high-voltage plant transformer 1-3, a first circuit breaker 1-4, a second circuit breaker 1-5, a 6kV plant 3A section bus 1-6, a starting standby transformer 1-7, a third circuit breaker 1-8, a fourth circuit breaker 1-9 and a fifth circuit breaker 1-10, the power supply comprises a sixth circuit breaker 1-11, a 6kV factory 3B section bus 1-12, a 6kV factory 4A section bus 1-13, a No. 4 main transformer 1-14, a No. 4 generator 1-15, a No. 4 high-voltage factory transformer 1-16, a seventh circuit breaker 1-17, an eighth circuit breaker 1-18 and a 6kV factory 4B section bus 1-19; the No. 3 generator 1-2 is connected to a power grid through a No. 3 main transformer 1-1, the high-voltage side of a No. 3 high-voltage station transformer 1-3 is connected to the end of the No. 3 generator 1-2, and the two low-voltage sides of the No. 3 high-voltage station transformer are respectively connected to a 6kV station 3A section bus 1-6 and a 6kV station 3B section bus 1-12 through a first circuit breaker 1-4 and a second circuit breaker 1-5; the high-voltage side of the starting standby transformer 1-7 is connected to a power grid, one low-voltage side is connected to 6kV station-used 3A section buses 1-6 and 6kV station-used 4A section buses 1-13 through a third circuit breaker 1-8 and a fourth circuit breaker 1-9 respectively, and the other low-voltage side is connected to 6kV station-used 3B section buses 1-12 and 6kV station-used 4B section buses 1-19 through a fifth circuit breaker 1-10 and a sixth circuit breaker 1-11 respectively; the No. 4 generator 1-15 is connected to a power grid through a No. 4 main transformer 1-14, the high-voltage side of a No. 4 high-voltage station transformer 1-16 is connected to the end of the No. 4 generator 1-15, and the two low-voltage sides of the No. 4 high-voltage station transformer are respectively connected to a 6kV station 4A section bus 1-13 and a 6kV station 4B section bus 1-19 through a seventh circuit breaker 1-17 and an eighth circuit breaker 1-18. The backpressure machine system 2 comprises a backpressure machine 2-1, a backpressure asynchronous generator outlet circuit breaker 2-2, a current limiter 2-3, a ninth circuit breaker 2-4, a tenth circuit breaker 2-5, an eleventh circuit breaker 2-6 and a twelfth circuit breaker 2-7; the back pressure machine 2-1 is connected to 6kV station-used 3A section buses 1-6, 6kV station-used 3B section buses 1-12, 6kV station-used 4A section buses 1-13 and 6kV station-used 4B section buses 1-19 of the station-used power system 1 through a ninth circuit breaker 2-4, a tenth circuit breaker 2-5, an eleventh circuit breaker 2-6 and a twelfth circuit breaker 2-7 respectively after passing through a back pressure asynchronous generator outlet circuit breaker 2-2 and a current limiter 2-3. When the twelfth circuit breaker 2-7 is in a closed state, the back press 2-1 is connected to the 6kV station 4B section bus 1-19 in a grid-connected mode, and electric energy generated by the back press 2-1 can be supplied to the 6kV station 4B section bus 1-19 and the 6kV station 4A section bus 1-13 for station service; when the electric energy generated by the back press machine 2-1 is increased, so that the back press machine can still supply power to the 6kV station 3B section bus 1-12 after meeting all the station power requirements of the No. 4 generator 1-15, the tenth circuit breaker 2-5 can be closed on the premise of disconnecting the second circuit breaker 1-5, and the purpose of three-section bus load operation of the back press machine 2-1 with the 6kV station 3B section bus 1-12, the 6kV station 4A section bus 1-13 and the 6kV station 4B section bus 1-19 is achieved. On the basis of the load operation of three sections of bus bars, namely, a 6kV factory 3B section bus bar 1-12, a 6kV factory 4A section bus bar 1-13 and a 6kV factory 4B section bus bar 1-19, of the back pressure machine 2-1, if the electric energy generated by the back pressure machine is continuously increased, so that when the power supply can still supply power to the 6kV station 3A section bus 1-6 after meeting the station power demand of the No. 4 generator 1-15 and the 6kV station 3B section bus 1-12, the ninth circuit breaker 2-4 can be closed on the premise of disconnecting the first circuit breaker 1-4, so that the purpose that the back press 2-1 with 6kV station-used 3A section bus 1-6, 6kV station-used 3B section bus 1-12, 6kV station-used 4A section bus 1-13 and 6kV station-used 4B section bus 1-19 are operated under four sections of bus loads is achieved.

As shown in fig. 2, in this example, the back press 2-1 with 6kV station-used 3B segment bus 1-12, 6kV station-used 4A segment bus 1-13, and 6kV station-used 4B segment bus 1-19 normally operate, and the switching can be realized by the following steps:

step 1: in the rated operation process of the No. 3 generator 1-2 and the No. 4 generator 1-15, when the phase sequence, the frequency, the phase and the outlet voltage of the back press machine 2-1 are the same as those of the service electric system 1, the twelfth circuit breaker 2-7 can be closed, so that the back press machine 2-1 is connected to 6kV service 4B section bus 1-19 in a grid-connected mode;

step 2: increasing the power of a back press machine 2-1, so that the service load of a No. 4 generator 1-15 is completely supplied with power by the back press machine 2-1, and the power of the high-voltage side of a No. 4 high-voltage service transformer 1-16 is close to 0MW at the moment;

and step 3: switching the load of a 6kV factory 3B section bus 1-12 to a back press machine 2-1 in a mode of switching in parallel, namely firstly closing a tenth circuit breaker 2-5 and then disconnecting a second circuit breaker 1-5;

and 4, step 4: the generated energy of the back press 2-1 is further increased, the power of the high-voltage side of the No. 4 high-voltage station transformer 1-16 is close to 0MW again, and the condition that station power is transmitted to a power grid reversely is avoided.

As shown in fig. 3, in this embodiment, in the operation process of the back-pressing machine 2-1 with the 6kV station-used 3B segment bus 1-12, the 6kV station-used 4A segment bus 1-13, and the 6kV station-used 4B segment bus 1-19, the generator 1-2 No. 3 is tripped and shut down, because the operation mode of the back-pressing machine 2-1 is not changed, the power supply of the 6kV station-used 3B segment bus 1-12 is not affected, and the 6kV station-used 3A segment bus 1-6 is switched to the starting backup transformer 1-7 by closing the third circuit breaker 1-8.

As shown in fig. 4, in this embodiment, in the operation process of the back press 2-1 with the 6kV station 3B segment bus 1-12, the 6kV station 4A segment bus 1-13 and the 6kV station 4B segment bus 1-19, the No. 4 generator 1-15 trips, and at this time, the back press 2-1 jointly trips, and the 6kV station 4A segment bus 1-13, the 6kV station 3B segment bus 1-12 and the 6kV station 4B segment bus 1-19 can be switched to the starting backup transformer 1-7 by closing the fourth breaker 1-9, the fifth breaker 1-10 and the sixth breaker 1-11.

As shown in fig. 5, in this embodiment, when the back press 2-1 with 6kV station-used 3B segment bus 1-12, 6kV station-used 4A segment bus 1-13, and 6kV station-used 4B segment bus 1-19 runs, the back press 2-1 is tripped and shut down, and there are the following two switching methods: the first method as shown in fig. 5(a) is that in the case of opening the backpressure asynchronous generator outlet circuit breaker 2-2, the ninth circuit breaker 2-4, the tenth circuit breaker 2-5, the eleventh circuit breaker 2-6 and the twelfth circuit breaker 2-7, the 6kV station 3B section bus 1-12 can be switched to the starting backup transformer 1-7 by closing the fifth circuit breaker 1-10; the second method as shown in fig. 5(B) is to make the No. 4 high-voltage station transformer 1-16 with 6kV station 3B bus 1-12, 6kV station 4A bus 1-13 and 6kV station 4B bus 1-19 run when the No. 4 high-voltage station transformer 1-16 capacity meets the load requirement only by disconnecting the back pressure asynchronous generator outlet breaker 2-2.

As shown in fig. 6, in this embodiment, the back press 2-1 has 6kV station-used 3A segment bus 1-6, 6kV station-used 3B segment bus 1-12, 6kV station-used 4A segment bus 1-13, and 6kV station-used 4B segment bus 1-19 to operate normally. The handover may be achieved by:

and step 3: switching the load of a 3A section of bus 1-6 for 6kV factories and a 3B section of bus 1-12 for 6kV factories to a back press 2-1 in a mode of firstly closing a ninth circuit breaker 2-4 and a tenth circuit breaker 2-5 and then opening the first circuit breaker 1-4 and the second circuit breaker 1-5 through parallel switching;

and 4, step 4: the generated energy of the back press 2-1 is further increased, the power of the high-voltage side of the No. 4 high-voltage station transformer 1-16 is close to 0MW again, and the condition that station power is transmitted to a power grid in a reverse mode does not occur.

Meanwhile, as shown in fig. 6, in the embodiment, when the back press 2-1 is provided with 6kV station 3A section buses 1-6, 6kV station 3B section buses 1-12, 6kV station 4A section buses 1-13 and 6kV station 4B section buses 1-19 in the operation process, the generator 1-2 of number 3 is tripped and shut down, and because the operation mode of the back press 2-1 is not changed, the power supply of the 6kV station 3A section buses 1-6 and the 6kV station 3B section buses 1-12 is not affected.

As shown in fig. 7, in this embodiment, when the back press 2-1 with 6kV station-used 3A segment bus 1-6, 6kV station-used 3B segment bus 1-12, 6kV station-used 4A segment bus 1-13, and 6kV station-used 4B segment bus 1-19 operates, the No. 4 generator 1-15 trips, and at this time, the back press 2-1 trips jointly, and the 6kV station-used 3A segment bus 1-6, 6kV station-used 4A segment bus 1-13, 6kV station-used 3B segment bus 1-12, and 6kV station-used 4B segment bus 1-19 can be switched to the starting backup transformer 1-7 by closing the third breaker 1-8, the fourth breaker 1-9, the fifth breaker 1-10, and the sixth breaker 1-11.

As shown in fig. 8, in this embodiment, when the back press 2-1 has 6kV station-used 3A segment bus 1-6, 6kV station-used 3B segment bus 1-12, 6kV station-used 4A segment bus 1-13, and 6kV station-used 4B segment bus 1-19, the back press 2-1 is tripped and shut down, there are two switching methods: the first method as shown in fig. 8(a) is that in the case of opening the backpressure asynchronous generator outlet circuit breaker 2-2, the ninth circuit breaker 2-4, the tenth circuit breaker 2-5, the eleventh circuit breaker 2-6 and the twelfth circuit breaker 2-7, the 6kV station 3A section bus 1-6 and the 6kV station 3B section bus 1-12 can be switched to the starting backup transformer 1-7 by closing the third circuit breaker 1-8 and the fifth circuit breaker 1-10; the second method as shown in fig. 8(B) is to make the No. 4 high-voltage station transformer 1-16 with 6kV station 3A section bus 1-6, 6kV station 3B section bus 1-12, 6kV station 4A section bus 1-13 and 6kV station 4B section bus 1-19 run when the No. 4 high-voltage station transformer 1-16 capacity meets the load requirement only by disconnecting the back pressure asynchronous generator outlet breaker 2-2.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and all simple modifications, changes and equivalent structural changes made to the above embodiment according to the technical spirit of the present invention still belong to the protection scope of the technical solution of the present invention.

Claims

1. A backpressure machine switching system is characterized in that: the system comprises a plant power system (1) and a back pressure machine system (2); wherein,

the back pressure machine system (2) is connected to a 6kV station-used 3A section bus (1-6), a 6kV station-used 3B section bus (1-12), a 6kV station-used 4A section bus (1-13) and a 6kV station-used 4B section bus (1-19) of a station-used electrical system (1) through a ninth circuit breaker (2-4), a tenth circuit breaker (2-5), an eleventh circuit breaker (2-6) and a twelfth circuit breaker (2-7) respectively.

2. The backpressure machine switching system of claim 1, wherein:

the station power system (1) comprises a No. 3 main transformer (1-1), a No. 3 generator (1-2), a No. 3 high-voltage station power transformer (1-3), a first circuit breaker (1-4), a second circuit breaker (1-5), a 6kV station 3A section bus (1-6), a starting standby transformer (1-7), a third circuit breaker (1-8), a fourth circuit breaker (1-9), a fifth circuit breaker (1-10), a sixth circuit breaker (1-11), a 6kV station 3B section bus (1-12), a 6kV station 4A section bus (1-13), a No. 4 main transformer (1-14), a No. 4 generator (1-15), a No. 4 high-voltage station power transformer (1-16), a seventh circuit breaker (1-17), An eighth breaker (1-18) and a 6kV station 4B section bus (1-19); wherein,

the No. 3 generator (1-2) is connected to a power grid through a No. 3 main transformer (1-1), the high-voltage side of the No. 3 high-voltage station transformer (1-3) is connected to the end of the No. 3 generator (1-2), and the two low-voltage sides of the No. 3 high-voltage station transformer are respectively connected to a 6kV station 3A section bus (1-6) and a 6kV station 3B section bus (1-12) through a first circuit breaker (1-4) and a second circuit breaker (1-5); the high-voltage side of the starting standby transformer (1-7) is connected to a power grid, one low-voltage side is connected to a 6kV station-used 3A section bus (1-6) and a 6kV station-used 4A section bus (1-13) through a third circuit breaker (1-8) and a fourth circuit breaker (1-9), and the other low-voltage side is connected to a 6kV station-used 3B section bus (1-12) and a 6kV station-used 4B section bus (1-19) through a fifth circuit breaker (1-10) and a sixth circuit breaker (1-11); no. 4 generator (1-15) is connected to the electric wire netting through No. 4 main transformer (1-14), No. 4 high-voltage for plant transformer (1-16) high pressure side access No. 4 generator (1-15) terminal, its two low-voltage sides access 6kV for plant 4A section generating line (1-13) and 6kV for plant 4B section generating line (1-19) through seventh circuit breaker (1-17) and eighth circuit breaker (1-18) respectively.

3. A backpressure machine switching system as claimed in claim 2, wherein:

the back pressure machine system (2) comprises a back pressure machine (2-1), a back pressure asynchronous generator outlet circuit breaker (2-2), a current limiter (2-3), a ninth circuit breaker (2-4), a tenth circuit breaker (2-5), an eleventh circuit breaker (2-6) and a twelfth circuit breaker (2-7); wherein,

the back pressure machine (2-1) is connected to a 6kV station-used 3A section bus (1-6), a 6kV station-used 3B section bus (1-12), a 6kV station-used 4A section bus (1-13) and a 6kV station-used 4B section bus (1-19) of a station-used electrical system (1) through a ninth circuit breaker (2-4), a tenth circuit breaker (2-5), an eleventh circuit breaker (2-6) and a twelfth circuit breaker (2-7) after passing through a back pressure asynchronous generator outlet circuit breaker (2-2) and a current limiter (2-3).

4. A backpressure machine switching system as claimed in claim 3, wherein:

when the twelfth circuit breaker (2-7) is in a closed state, the back pressure machine (2-1) is connected to the 6kV station 4B section bus (1-19), and the electric energy generated by the back pressure machine (2-1) is supplied to the station power of the 6kV station 4B section bus (1-19) and the 6kV station 4A section bus (1-13); when the electric energy generated by the back pressure machine (2-1) is increased so that the back pressure machine can still supply power to the 3B section bus (1-12) for 6kV factories after meeting all the requirements of the No. 4 generator (1-15) for the factory power, the tenth circuit breaker (2-5) is closed on the premise of disconnecting the second circuit breaker (1-5), and the purpose of the back pressure machine (2-1) with three sections of bus load operation, namely the 3B section bus (1-12) for 6kV factories, the 4A section bus (1-13) for 6kV factories and the 4B section bus (1-19) for 6kV factories is achieved.

5. A backpressure machine switching system as claimed in claim 3, wherein:

on the basis of the back pressure machine (2-1) with three-section bus load operation of 6kV factory 3B section buses (1-12), 6kV factory 4A section buses (1-13) and 6kV factory 4B section buses (1-19), if the electric energy generated by the back pressure machine is continuously increased, so that when the power supply can still supply power to the 6kV station 3A section bus (1-6) after meeting the station power demand of the No. 4 generator (1-15) and the 6kV station 3B section bus (1-12), on the premise of disconnecting the first circuit breaker (1-4), closing the ninth circuit breaker (2-4) to achieve the purpose that the back press (2-1) is provided with four sections of bus load operation, namely a 6kV factory 3A section bus (1-6), a 6kV factory 3B section bus (1-12), a 6kV factory 4A section bus (1-13) and a 6kV factory 4B section bus (1-19).

6. A backpressure machine switching system as claimed in claim 3, wherein:

the back pressure machine (2-1) is enabled to carry out load operation on three sections of buses including a 6kV factory 3B section bus (1-12), a 6kV factory 4A section bus (1-13) and a 6kV factory 4B section bus (1-19):

switching method under normal working condition

Step 1: in the rated operation process of the No. 3 generator (1-2) and the No. 4 generator (1-15), when the phase sequence, the frequency, the phase and the outlet voltage of the back press machine (2-1) are the same as those of the station power system (1), the twelfth circuit breaker (2-7) is closed, so that the back press machine (2-1) is connected to a 6kV station power 4B section bus (1-19);

step 2: increasing the power of the back pressure machine (2-1) to ensure that the service load of the No. 4 generator (1-15) is completely supplied with power by the back pressure machine (2-1), and the power of the high-voltage side of the No. 4 high-voltage service transformer (1-16) is close to 0MW at the moment;

and step 3: switching the load of a 6kV factory 3B section bus (1-12) to a back pressure machine (2-1) in a mode of switching in parallel, namely firstly closing a tenth circuit breaker (2-5) and then opening a second circuit breaker (1-5);

and 4, step 4: the power generation capacity of the back press (2-1) is further increased, the high-voltage side power of the No. 4 high-voltage station transformer (1-16) is close to 0MW again, and the condition that station power is transmitted to a power grid reversely is avoided;

(2) switching method under abnormal working condition

1) When the No. 3 generator (1-2) is tripped and shut down, the running mode of the back pressure machine (2-1) is unchanged, so that the power supply of the 6kV station 3B section bus (1-12) is not affected, and the 6kV station 3A section bus (1-6) is switched to the starting standby transformer (1-7) by closing the third circuit breaker (1-8);

2) when the No. 4 generator (1-15) is tripped and shut down, the back press machine (2-1) is tripped jointly, and the 6kV factory 4A section bus (1-13), the 6kV factory 3B section bus (1-12) and the 6kV factory 4B section bus (1-19) are switched to the starting standby transformer (1-7) by closing the fourth breaker (1-9), the fifth breaker (1-10) and the sixth breaker (1-11);

3) when the back press (2-1) is tripped and stopped, the following two switching methods are adopted:

the first method is that under the condition of opening a backpressure asynchronous generator outlet circuit breaker (2-2), a ninth circuit breaker (2-4), a tenth circuit breaker (2-5), an eleventh circuit breaker (2-6) and a twelfth circuit breaker (2-7), the 6kV factory 3B section bus (1-12) is switched to a starting standby transformer (1-7) by closing a fifth circuit breaker (1-10);

the second method is that under the condition that only the outlet circuit breaker (2-2) of the backpressure asynchronous generator is disconnected, when the capacity of the No. 4 high-voltage station transformer (1-16) meets the load requirement, the No. 4 high-voltage station transformer (1-16) is enabled to operate with 6kV station 3B section buses (1-12), 6kV station 4A section buses (1-13) and 6kV station 4B section buses (1-19).

7. A backpressure machine switching system as claimed in claim 3, wherein:

the method comprises the following steps of enabling a back press (2-1) to carry four bus loads of 6kV factory-used 3A section buses (1-6), 6kV factory-used 3B section buses (1-12), 6kV factory-used 4A section buses (1-13) and 6kV factory-used 4B section buses (1-19) to operate:

switching method under normal working condition

and step 3: loads of 3A section buses (1-6) and 3B section buses (1-12) for 6kV factories are switched to a back pressure machine (2-1) in a mode of switching in parallel, namely, firstly closing a ninth breaker (2-4) and a tenth breaker (2-5) and then opening a first breaker (1-4) and a second breaker (1-5);

(2) switching method under abnormal working condition

1) When the No. 3 generator (1-2) is tripped and shut down, the running mode of the back pressure machine (2-1) is unchanged, so that the power supply of the 3A section of bus (1-6) for 6kV factories and the 3B section of bus (1-12) for 6kV factories is not affected;

2) when the No. 4 generator (1-15) is tripped and shut down, the back press machine (2-1) is tripped jointly, and the 6kV factory-used 3A section bus (1-6), the 6kV factory-used 4A section bus (1-13), the 6kV factory-used 3B section bus (1-12) and the 6kV factory-used 4B section bus (1-19) are switched to the starting standby transformer (1-7) by closing the third breaker (1-8), the fourth breaker (1-9), the fifth breaker (1-10) and the sixth breaker (1-11);

the first method is that under the condition of disconnecting an outlet circuit breaker (2-2), a ninth circuit breaker (2-4), a tenth circuit breaker (2-5), an eleventh circuit breaker (2-6) and a twelfth circuit breaker (2-7) of the backpressure asynchronous generator, the 6kV factory-used 3A section bus (1-6) and the 6kV factory-used 3B section bus (1-12) are switched to a starting standby transformer (1-7) by closing a third circuit breaker (1-8) and a fifth circuit breaker (1-10);

the second method is that under the condition that only an outlet breaker (2-2) of the backpressure asynchronous generator is disconnected, when the capacity of the No. 4 high-voltage station transformer (1-16) meets the load requirement, the No. 4 high-voltage station transformer (1-16) is enabled to operate with 6kV station 3A section buses (1-6), 6kV station 3B section buses (1-12), 6kV station 4A section buses (1-13) and 6kV station 4B section buses (1-19).