A DCS control method for main transformer ventilation system

Abstract

The present invention discloses a DCS control method for a main transformer ventilation system, including three single-phase transformers, each of which has four groups of coolers, each of which has three cooling fans, each of which is equipped with an on-site control box, and a logic design strategy for controlling the main transformer ventilation system by a DCS system, which specifically includes: ① the design of the cooler's five operating modes of on-off function; ② the design of the interlocking start-stop function of the four groups of coolers of the transformer under various operating modes; ③ the design of the sequential switching function of the four groups of coolers of the single-phase transformer in the two operating modes of 14-23 and 23-14. The DCS control method for the main transformer ventilation system realizes the functions of DCS remote on-off, interlocking on-off, and sequential switching of the operating modes of the cooler group by setting the control logic of the main transformer cooler in the DCS system, so as to achieve the flexible on-off of the main transformer ventilation system according to the changes in temperature, load, grid connection and other conditions, thereby achieving the purpose of safety and energy saving.

Description

Technical Field

[0001] The invention relates to the technical field of transformer ventilation, and in particular to a DCS control method for a main transformer ventilation system. Background Art

[0002] The main transformer is a step-down transformer in a unit or substation that is mainly used for power transmission and transformation. It is also the core part of the substation and a key equipment to ensure the safe and stable operation of the traction power supply system.

[0003] The capacity of the main transformer is generally large, and the reliability of the work is high. Although the failure rate of the main transformer is not high, once a failure occurs, it will cause significant losses, which may cause equipment failure at the least, or cause a fire at the worst. When the equipment is aging or under load, its internal temperature rises rapidly. If the heat dissipation is not timely, the failure rate will increase. However, if the heat dissipation is continued at a high intensity, the power consumption will increase.

[0004] Therefore, in order to improve equipment safety and avoid excessive energy consumption, we proposed a DCS control method for the main transformer ventilation system. Summary of the invention

[0005] In order to overcome the problems of high temperature and high consumption of the main transformer, the purpose of the present invention is to provide a DCS control method for the main transformer ventilation system, which has the functions of intelligent regulation and reduced consumption.

[0006] The present invention adopts the following technical scheme to achieve the technical purpose: a DCS control method for a main transformer ventilation system, including three single-phase transformers, each of which has four groups of coolers, each group of which has three cooling fans, each of which is equipped with a local control box, and a logic design strategy for controlling the main transformer ventilation system by a DCS system, which specifically includes:

[0007] ① Design of the cooler's five operating modes and start and stop functions;

[0008] ② Design of interlocking start and stop function of four groups of transformer coolers under various operation modes;

[0009] ③ Design of the sequential switching function of the four groups of coolers of the single-phase transformer in the two operating modes of 14-23 and 23-14.

[0010] As an optimization, the design of the five operating modes of the cooler's on / off functions specifically includes:

[0011] Each of the four groups of coolers on the main transformer has five operating modes: working, auxiliary 1, auxiliary 2, standby and manual. In working, auxiliary 1, auxiliary 2 and standby modes, the coolers can only be started and stopped after the interlocking conditions are met. In manual mode, the operator can realize remote manual operation;

[0012] The cooler is selected by the operator, so the KEYBOARD algorithm block is selected. Among the five modes, the manual mode has the highest level. No matter what state the cooler is in, it can be switched to the manual mode at any time to manually intervene to start and stop the cooler;

[0013] Therefore, the logic adopts RS trigger algorithm, and the four modes of working, auxiliary 1, auxiliary 2, and standby are directly selected, while the manual mode is used to reset the four modes of the S end. Through this idea, the basic idea of ​​mode selection is determined;

[0014] Considering that only one operation mode can be selected for the same cooler in the same period of time, when any of the four modes of design work, auxiliary 1, auxiliary 2, and standby is put into operation, it must be confirmed that the cooler is not in the other three modes;

[0015] As an optimization, the logic setting also introduces a cooler mode switching instruction from the main transformer to coordinate the switching of the operating modes of the four coolers.

[0016] As an optimization, the design of the interlocking start-stop function of the four groups of coolers of the single-phase transformer under various operating modes specifically includes:

[0017] The original local control box of the cooler has no interlocking start and stop logic. After changing to DCS control, the start and stop of the cooler can be set in four ways:

[0018] ① When the generator is connected to the grid, the cooler in working mode starts to operate;

[0019] ② When the load is greater than 150MW after the generator is connected to the grid, the cooler in auxiliary 1 mode is started;

[0020] ③ When the load after the generator is connected to the grid is greater than 300MW or the oil temperature of the main transformer is greater than 60℃, the cooler in auxiliary 2 mode is started;

[0021] ④ When any of the four coolers fails and the oil temperature of the main transformer is greater than 65℃, the cooler in standby mode will be started;

[0022] ⑤ When three of the four coolers are in operation and the oil temperature of the main transformer is less than 60°C and there is no failure in the cooler, the cooler in the joint stop standby mode;

[0023] ⑥ When three of the four coolers are in operation and the oil temperature of the main transformer is less than 52°C, the coolers in auxiliary 2 mode are shut down.

[0024] As an optimization, for each main transformer, the start and stop conditions of its cooler are the same. Since the cooler has four operating modes, the start and stop conditions of the cooler are different in each operating mode. Therefore, when designing the logic, the logical judgment of the interlocking start and stop conditions of the main transformer cooler in the four modes is first performed, and then the judgment conditions in different modes and the conditions of the upper cooler that have been put into use are used as the final instruction to start the cooler.

[0025] As an optimization, the design of the sequential switching function of the four groups of coolers of the single-phase transformer in the two operating modes of 14-23 and 23-14 specifically includes:

[0026] The four groups of coolers equipped with each main transformer are numbered 1, 2, 3, and 4. When the unit is operating normally, the four coolers are put into working, auxiliary 1, auxiliary 2, and standby mode respectively;

[0027] According to the arrangement of the coolers, cooler No. 1 is set to working mode, cooler No. 4 is set to auxiliary mode 1, cooler No. 2 is set to auxiliary mode 2, and cooler No. 3 is set to standby mode, i.e. 14-23 operation mode;

[0028] Set cooler 2 to working mode, cooler 3 to auxiliary mode 1, cooler 1 to auxiliary mode 2, and cooler 4 to standby mode, i.e. 23-14 operation mode;

[0029] During the operation of the unit, in order to improve the utilization rate of each cooler, the 14-23 mode and 23-14 mode need to be switched regularly.

[0030] As an optimization, when configuring the sequential control logic, the passing conditions after each step instruction is issued must be considered. Since the sequential control logic is aimed at changing the operating mode of the cooler, considering that after the operating mode of the cooler is changed, under different load and oil temperature conditions, the cooler may start and stop in a chain manner. In order to ensure the safety of mode switching, the logic is set to switch the mode when the unit load is greater than 150MW, so as to ensure that each main transformer has two coolers in operation.

[0031] The present invention has the following beneficial effects:

[0032] 1. The DCS control method of the main transformer ventilation system realizes the functions of DCS remote start and stop, interlocking start and stop, and sequential switching of the cooler group operation mode by setting the control logic of the main transformer cooler in the DCS system, so that the main transformer ventilation system can be flexibly put into operation and withdrawn according to changes in temperature, load, grid connection and other conditions, thereby achieving the purpose of safety and energy saving.

[0033] 2. The DCS control method of the main transformer ventilation system. The DCS control of the main transformer ventilation system improves the safe operation of the main transformer cooler on the one hand. At the same time, the load and oil temperature interlocking start and stop cooler function is designed, which effectively reduces the plant power consumption rate during unit operation and improves energy saving efficiency. On the other hand, by realizing DCS remote control, the operating personnel can monitor and control the main transformer ventilation system equipment more intuitively and conveniently, effectively improving the reliability of the main transformer equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is the control diagram of the main transformer ventilation system of the present invention. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] See also Figure 1 A DCS control method for a main transformer ventilation system includes three single-phase transformers, each of which has four groups of coolers, each group of which has three cooling fans, and each of which is equipped with a local control box. The logic design strategy for controlling the main transformer ventilation system by the DCS system specifically includes:

[0037] ① Design of the cooler's five operating modes and start and stop functions;

[0038] ② Design of interlocking start and stop function of four groups of transformer coolers under various operation modes;

[0039] ③ Design of the sequential switching function of the four groups of coolers of the single-phase transformer in the two operating modes of 14-23 and 23-14.

[0040] The design of the five operating modes of the cooler's on / off functions specifically includes:

[0041] Each of the four groups of coolers on the main transformer has five operating modes: work (WORK), auxiliary 1 (AUX1), auxiliary 2 (AUX2), standby (SPARE) and manual (MAN). In the work, auxiliary 1, auxiliary 2 and standby modes, the coolers can only be started and stopped after the interlocking conditions are met. In the manual mode, the operator can realize remote manual operation;

[0042] The cooler is selected by the operator, so the KEYBOARD algorithm block is selected. Among the five modes, the manual mode has the highest level. No matter what state the cooler is in, it can be switched to the manual mode at any time to manually intervene to start and stop the cooler;

[0043] Therefore, the logic adopts RS trigger algorithm, and the four modes of work (WORK), auxiliary 1 (AUX1), auxiliary 2 (AUX2), and spare (SPARE) are directly selected, and the manual (MAN) mode is used to reset the four modes of the S end. Through this idea, the basic idea of ​​mode selection is determined;

[0044] Considering that only one operation mode can be selected for the same cooler in the same time period, when any of the four modes (WORK, AUX1, AUX2, and SPARE) is put into operation, it must be confirmed that the cooler is not in the other three modes;

[0045] When designing the logic for each mode, the other three modes are negated to achieve the interlocking function of the four modes, ensuring the uniqueness of the cooler mode.

[0046] Taking into account the uniqueness of the cooler mode selection, the command from the mode switching first resets the original cooler mode and then switches the mode, thus avoiding the confusion that the cooler may start and stop in two modes at the same time.

[0047] The logic setting also introduces a mode switching instruction from the main transformer cooler (switching working mode and auxiliary 2 mode), which cooperates with the switching of the operating modes of the four coolers to achieve the change of the unit operation mode.

[0048] The design of the interlocking start-stop function of the four groups of coolers of the single-phase transformer under various operation modes specifically includes:

[0049] The original local control box of the cooler has no interlocking start and stop logic. After changing to DCS control, the start and stop of the cooler can be set in four ways:

[0050] ① When the generator is connected to the grid, the cooler in working mode starts to operate;

[0051] ② When the load is greater than 150MW after the generator is connected to the grid, the cooler in auxiliary 1 mode is started;

[0052] ③ When the load after the generator is connected to the grid is greater than 300MW or the oil temperature of the main transformer is greater than 60℃, the cooler in auxiliary 2 mode is started;

[0053] ④ When any of the four coolers fails and the oil temperature of the main transformer is greater than 65℃, the cooler in standby mode will be started;

[0054] ⑤ When three of the four coolers are in operation and the oil temperature of the main transformer is less than 60°C and there is no failure in the cooler, the cooler in the joint stop standby mode;

[0055] ⑥ When three of the four coolers are in operation and the oil temperature of the main transformer is less than 52°C, the coolers in auxiliary 2 mode are shut down.

[0056] It can be seen from the above start and stop conditions that as the unit starts and is connected to the grid, the load increases, and the oil temperature changes, the four coolers are started and stopped in sequence. This minimizes the number of operating coolers while ensuring the safe operation of the main transformer equipment, thereby achieving the purpose of energy saving for the unit.

[0057] For each main transformer, the start and stop conditions of its cooler are the same. Since the cooler has four operating modes, the start and stop conditions of the cooler are different in each operating mode. Therefore, when designing the logic, the logical judgment of the interlocking start and stop conditions of the main transformer cooler in the four modes is first performed, and then the judgment conditions in different modes and the conditions of the upper cooler that have been put into use are used as the final instruction to start the cooler.

[0058] The design of the sequential switching function of the four groups of coolers of the single-phase transformer in the two operation modes of 14-23 and 23-14 specifically includes:

[0059] The four groups of coolers equipped with each main transformer are numbered 1, 2, 3, and 4. When the unit is operating normally, the four coolers are put into working (WORK), auxiliary 1 (AUX1), auxiliary 2 (AUX2), and standby (SPARE) modes respectively;

[0060] According to the arrangement of the coolers, cooler No. 1 is set to working mode, cooler No. 4 is set to auxiliary mode 1, cooler No. 2 is set to auxiliary mode 2, and cooler No. 3 is set to standby mode, i.e. 14-23 operation mode;

[0061] Set cooler 2 to working mode, cooler 3 to auxiliary mode 1, cooler 1 to auxiliary mode 2, and cooler 4 to standby mode, i.e. 23-14 operation mode;

[0062] During the operation of the unit, in order to improve the utilization rate of each cooler, the 14-23 mode and 23-14 mode need to be switched regularly.

[0063] The most direct configuration solution is to implement the switching function by configuring sequential control logic.

[0064] When configuring the sequential control logic, the passing conditions after each step instruction is issued must be considered. Since the sequential control logic is aimed at changing the operating mode of the cooler, considering that after the operating mode of the cooler is changed, under different load and oil temperature conditions, the cooler may start and stop in a chain manner. In order to ensure the safety of mode switching, the logic is set to switch the mode when the unit load is greater than 150MW, so as to ensure that each main transformer has two coolers in operation.

[0065] Taking the main transformer phase A as an example, the mode switching is performed when the unit load is greater than 150MW. When switching from the 14-23 mode to the 23-14 mode,

[0066] The first step is to issue a command to switch cooler No. 2 to the working mode. This command is sent to the mode switching logic of cooler No. 2, so that cooler No. 2 is switched to the working position. At the same time, the mode switching logic delays 15 seconds to determine that cooler No. 2 is running.

[0067] Enter the second step, issue a command to switch the No. 1 cooler to auxiliary 2 mode, delay 15 seconds after the No. 1 cooler is in auxiliary 2 mode,

[0068] Enter the third step and issue a command to switch the No. 3 cooler to auxiliary 1 mode. After a delay of 15 seconds, when the No. 3 cooler has been running,

[0069] That is, enter the fourth step, issue a command to switch the No. 4 cooler to the standby mode, and when the No. 4 cooler is in the standby mode after a delay of 15 seconds, the mode switching sequence is completed.

[0070] When switching from 23-14 to 14-23 mode, the logic step setting idea is the same. Although the embodiments of the present invention have been shown and described, it is understandable to those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A DCS control method for a main transformer ventilation system, comprising three single-phase transformers, each of which has four groups of coolers, each group of which has three cooling fans, and each of which is equipped with a local control box, characterized in that: Including the logic design strategy of DCS system controlling the main transformer ventilation system, which is as follows: ① Design of the cooler's five operating modes and start and stop functions; ② Design of interlocking start-stop function under various operation modes of four groups of coolers of single-phase transformer; ③ Design of the sequential switching function of the four groups of coolers of the single-phase transformer in the two operating modes of 14-23 and 23-14; The design of the five operating modes of the cooler's on / off functions specifically includes: The four groups of coolers on the main transformer are each set with five operating modes: working, auxiliary 1, auxiliary 2, standby and manual. In working, auxiliary 1, auxiliary 2 and standby modes, the coolers can only be started and stopped after the interlocking conditions are met. In manual mode, the operator can realize remote manual operation; the cooler is selected by the operator, so the KEYBOARD algorithm block is selected. Among the five modes, the manual mode has the highest level. No matter what state the cooler is in, it can be exited and switched to manual mode at any time for manual intervention to start and stop the cooler; therefore, the logic adopts the RS trigger algorithm, and the four modes of working, auxiliary 1, auxiliary 2 and standby are directly selected, and the manual mode is used to reset the four modes of the S end; considering that only one operating mode can be selected for the same cooler in the same time period, when any of the four modes of working, auxiliary 1, auxiliary 2 and standby are put into use, it must be confirmed that the cooler is not in the other three modes; The interlocking start-stop function design of the four groups of coolers of the single-phase transformer under various operation modes specifically includes: The original local control box of the cooler has no interlocking start-stop logic. After changing to DCS control, the start-stop of the cooler is set in four modes: ① When the generator is connected to the grid, the cooler in the working mode starts and runs; ② When the load is greater than 150MW after the generator is connected to the grid, the cooler in the interlocking auxiliary 1 mode is started; ③ When the load is greater than 300MW after the generator is connected to the grid or the oil temperature of the main transformer is greater than 60℃, the cooler in the interlocking auxiliary 2 mode is started; ④ When any of the four coolers fails and the oil temperature of the main transformer is greater than 65℃, the cooler in the interlocking standby mode is started; ⑤ When three of the four coolers are running and the oil temperature of the main transformer is less than 60℃ when there is no failure in the cooler, the cooler in the interlocking standby mode is stopped; ⑥ When three of the four coolers are running and the oil temperature of the main transformer is less than 52℃, the cooler in the interlocking auxiliary 2 mode is stopped; The design of the sequential switching function of the four groups of coolers of the single-phase transformer in the two operation modes of 14-23 and 23-14 specifically includes: The four groups of coolers equipped with each main transformer are numbered 1, 2, 3 and 4 respectively. When the unit is operating normally, the four coolers are put into working, auxiliary 1, auxiliary 2 and standby modes respectively; according to the layout of the coolers, cooler No. 1 is set to working mode, cooler No. 4 is set to auxiliary 1 mode, cooler No. 2 is set to auxiliary 2 mode, and cooler No. 3 is set to standby mode, that is, 14-23 operating mode; cooler No. 2 is set to working mode, cooler No. 3 is set to auxiliary 1 mode, cooler No. 1 is set to auxiliary 2 mode, and cooler No. 4 is set to standby mode, that is, 23-14 operating mode; during the operation of the unit, in order to improve the utilization rate of each cooler, the 14-23 mode and the 23-14 mode need to be switched regularly.

2. A DCS control method for a main transformer ventilation system according to claim 1, characterized in that: The logic setting also introduces a cooler mode switching instruction from the main transformer to coordinate the switching of the operating modes of the four coolers.

3. A DCS control method for a main transformer ventilation system according to claim 1, characterized in that: For each main transformer, the start and stop conditions of its cooler are the same. Since the cooler has four operating modes, the start and stop conditions of the cooler are different in each operating mode. Therefore, when designing the logic, first perform logical judgment on the interlocking start and stop conditions of the main transformer cooler in the four modes, and then use the judgment conditions in different modes and the conditions of the upper cooler that have been put into use as the final instruction to start the cooler.

4. A DCS control method for a main transformer ventilation system according to claim 1, characterized in that: When configuring the sequential control logic, the passing conditions after each step instruction is issued must be considered. Since the sequential control logic is aimed at changing the operating mode of the cooler, considering that after the operating mode of the cooler is changed, the cooler will start and stop in a chain under different load and oil temperature conditions, in order to ensure the safety of mode switching, the logic is set to switch the mode when the unit load is greater than 150MW.

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