阅读说明：本技术 一种调速型双四象限变频器的能量回收系统的调速方法 (Speed regulation method of energy recovery system of speed regulation type double four-quadrant frequency converter ) 是由 张俊龙 周根标 李付俊 孙鸿声 柳黎光 李震 贾江平 刘拥军 强科 严伟博 张智 于 2021-01-14 设计创作，主要内容包括：本发明公开了一种调速型双四象限变频器的能量回收系统的调速方法,其中,在降速过程中,第一SHRT中,第一离合器始终处于啮合状态,第一电机拖动第一烧结风机和第一汽轮机同步降速；同时,第一四象限变频器会产生制动转矩,通过第一四象限变频器再反向送至电网；在升速过程中,第一SHRT中,第一离合器脱开,第一电机单独拖动第一烧结风机升至目标转速。本发明采用变速调节的汽电双驱方式,在实现余热能量回收目的的同时,通过调速运行方式提高风机本身的效率,降低风机能耗。并具有发电功能,在回收能量大于风机耗功时向电网送电。(The invention discloses a speed regulation method of an energy recovery system of a speed regulation type double four-quadrant frequency converter, wherein in the speed reduction process, a first clutch is always in a meshing state in a first SHRT, and a first motor drags a first sintering fan and a first turbine to synchronously reduce the speed; meanwhile, the first four-quadrant frequency converter can generate braking torque, and the braking torque is reversely transmitted to the power grid through the first four-quadrant frequency converter; in the speed increasing process, in the first SHRT, the first clutch is disengaged, and the first motor independently drags the first sintering fan to increase to the target rotating speed. The invention adopts a variable-speed regulation steam-electricity dual-drive mode, and improves the efficiency of the fan and reduces the energy consumption of the fan through a speed-regulating operation mode while achieving the purpose of waste heat energy recovery. The wind power generation system has a power generation function, and transmits power to a power grid when the recovered energy is larger than the power consumption of the fan.)

1. A speed regulation method of an energy recovery system of a speed regulation type double four-quadrant frequency converter is characterized by comprising the following steps:

step 1, speed reduction control:

step 30201, a first unit DCS controller (105) and a second unit DCS controller (205) give a frequency converter PLC controller (7) a target rotating speed required to be adjusted, and the frequency converter PLC controller (7) calculates corresponding frequency according to the target rotating speed;

step 30202, sending an instruction through a frequency converter PLC (7), and simultaneously reducing the speed of the first motor (102) and the second motor (202) through the regulation and control of the first four-quadrant frequency converter (3) and the second four-quadrant frequency converter (4);

step 30203, in the speed reduction process, in the first SHRT (1), the first clutch (103) is always engaged, and the first motor (102) drags the first sintering fan (101) and the first turbine (104) to synchronously reduce the speed; meanwhile, the first four-quadrant frequency converter (3) can generate braking torque, and the braking torque is reversely transmitted to the power grid through the first four-quadrant frequency converter (3);

in the deceleration process, the process in the second SHRT (2) is the same as that in the first SHRT (1);

step 30204, until the frequency of the first motor (102) is reduced to a frequency corresponding to the target rotating speed, after stable operation, the braking torque is eliminated, the first turbine (104) and the first motor (102) drive the first fan (101) to operate together, the first SHRT (1) finishes speed reduction adjustment, and the frequency conversion working condition is entered;

when the power of the first turbine (104) is larger than that of the first sintering fan (101), the first motor (102) enters a power generation state, redundant energy is transmitted to a power grid through the first four-quadrant frequency converter (3), and at the moment, the first SHRT (1) is in a variable-frequency power generation state;

the process that the second SHRT (2) enters the frequency conversion working condition and is in the frequency conversion power generation state is the same as that of the first SHRT (1);

step 2, speed raising control:

step 30205, the first unit DCS controller (105) and the second unit DCS controller (205) give a target rotating speed to be adjusted to the frequency converter PLC controller (7), and the frequency converter PLC controller (7) calculates corresponding frequency according to the target rotating speed;

step 30206, sending an instruction through a frequency converter PLC (7), and simultaneously accelerating the first motor (102) and the second motor (202) through regulation and control of the first four-quadrant frequency converter (3) and the second four-quadrant frequency converter (4);

step 30207, in the speed increasing process, in the first SHRT (1), the first motor (102) drags the first sintering fan (101) to increase the speed, because the idling speed increasing rate of the first turbine (104) is greater than the speed increasing rate of the first sintering fan (101), the first speed change clutch (103) is always in a meshed state, the first turbine (104) continuously increases the speed along with the rotating speed of the first motor (102) until the target rotating speed is reached, the first turbine (104) and the first motor (102) jointly drive the first sintering fan (101) to operate, and the speed increasing process is completed;

in the acceleration process, the process in the second SHRT (2) is the same as that in the first SHRT (1);

step 30208, after the first motor (102) is raised to a frequency corresponding to the target rotating speed and stably operates, the first turbine (104) and the first motor (102) drive the first fan (101) to operate together, the first SHRT (1) finishes speed raising adjustment, and the frequency conversion working condition is entered;

when the power of the first turbine (104) is larger than that of the first sintering fan (101), the first motor (102) enters a power generation state, redundant energy is transmitted to a power grid through the first four-quadrant frequency converter (3), and at the moment, the first SHRT (1) is in a variable-frequency power generation state;

the process of the second SHRT (2) entering the frequency conversion working condition and being in the frequency conversion power generation state is the same as that of the first SHRT (1).

2. A speed governing method for an energy recovery system of a speed governing type double four quadrant frequency converter according to claim 1, characterized in that the speed raising control process of the steam turbine is as follows:

after a speed governor of the first turbine (104) receives a speed increasing signal, the first turbine (104) is adjusted to a rotating speed control mode, the speed is increased according to an unequal rate of 5% of a target rotating speed and a set speed increasing rate until the target rotating speed, the first clutch (103) is engaged, and the first clutch (103) sends an engaging signal to a first unit DCS controller (105);

after the first unit DCS controller (105) receives the meshing signal and keeps stable, the signal is considered to be true, the first clutch (103) is confirmed to be meshed, the first unit DCS controller (105) sends the meshing signal to a speed regulator of a first steam turbine (104), the first steam turbine (104) is converted into valve position control, and the valve position is manually opened until the current of a first motor (102) is reduced to 10% of the rated current;

the speed raising control process of the second turbine (204) is the same as the speed raising control process of the first turbine (104).

3. A method of regulating speed of an energy recovery system of a double four-quadrant inverter of the speed regulation type according to claim 2, characterized in that the energy recovery system of the double four-quadrant inverter of the speed regulation type comprises a first SHRT (1) and a second SHRT (2);

the first SHRT (1) comprises a first sintering fan (101), a first motor (102), a first speed change clutch (103) and a first turbine (104) which are coaxially connected in sequence, and further comprises a first unit DCS controller (105) which is electrically connected with the first sintering fan (101), the first motor (102), the first speed change clutch (103) and the first turbine (104);

the second SHRT (2) comprises a second sintering fan (201), a second motor (202), a second speed change clutch (203) and a second turbine (204) which are coaxially connected in sequence, and also comprises a second unit DCS controller (205) which is electrically connected with the second sintering fan (201), the second motor (202), the second speed change clutch (203) and the second turbine (204);

the first motor (102) is electrically connected with the first four-quadrant frequency converter (3), and the first four-quadrant frequency converter (3) is respectively electrically connected with the first high-voltage cable (5) and the second high-voltage cable (6);

the second motor (202) is electrically connected with the second four-quadrant frequency converter (4), and the second four-quadrant frequency converter (4) is respectively electrically connected with the first high-voltage cable (5) and the second high-voltage cable (6);

the first four-quadrant frequency converter (3) and the second four-quadrant frequency converter (4) are respectively electrically connected with a frequency converter PLC (programmable logic controller) (7), and the frequency converter PLC (7) is respectively electrically connected with a first unit DCS controller (105) and a second unit DCS controller (205).

4. A method of regulating speed of an energy recovery system of a double four-quadrant inverter of the speed regulation type according to claim 3, characterized in that said first electric machine (102) is also electrically connected directly to the first high voltage cable (5); the second motor (202) is also directly and electrically connected with a second high-voltage cable (6).

Technical Field

The invention belongs to the field of energy recovery, relates to sintering waste heat recovery, and particularly relates to a speed regulation method of an energy recovery system of a speed regulation type double four-quadrant frequency converter.

Background

In recent years, with the rapid development of infrastructure construction in China, the ferrous metallurgy industry has also developed rapidly. The metallurgical industry is a high energy consumption industry, and the pollution to the environment is serious. In the production process of metallurgy, a large amount of waste heat can be generated, and the recovery and utilization of the waste heat have decisive effects on production energy efficiency, product cost, energy conservation and emission reduction; especially, in recent two years, with the production capacity replacement of related regulations in the national steel industry, higher requirements on high efficiency and energy conservation of equipment are provided.

In the sintering process of the current domestic iron and steel industry, two technical schemes are commonly used for the driving form of a sintering fan:

first, a sintering waste heat energy recovery unit (i.e., SHRT):

in the driving form of the existing sintering fan, an SHRT unit adopts an arrangement form of a steam turbine, a clutch, a motor and a fan, and the steam turbine directly recovers the energy of the sintering waste heat steam to drive the sintering fan to operate and drives the sintering fan to operate together with the motor. Compared with the traditional waste heat power generation, the steam-electricity double-drive unit avoids the energy conversion loss of waste heat → mechanical energy → electric energy → mechanical energy, and has the advantages of high recovery efficiency, compact structure and the like; in addition, the investment of user power generation equipment is reduced, and the procedures and approval of power generation grid connection are reduced.

In recent years, the gas-electricity double-drive coaxial unit is adopted by more and more users with the advantages of considerable energy recovery benefit, good operation performance and the like, and has huge market space.

For a sintering waste heat energy recovery unit (SHRT), the existing steam-electricity double-drive coaxial unit can only realize steam-electricity double-drive coaxial operation with a fixed rotating speed (power frequency 50 Hz); when the load of the process system changes, only the mode of the air adjusting door is adopted for adjustment.

As shown in fig. 1, before changing the working condition, the performance curve of the fan is at 50Hz, the characteristic curve of the pipe network is 1, and the intersection point B is the operating point of the fan; when the working condition changes and the air door is closed, the resistance of the pipe network is increased, the characteristic curve of the pipe network is changed to be steep (1 → 2), the performance curve of the fan is still at the rotating speed of 50Hz, the operating point is changed to be B ', and the energy consumption is saved by S after the operating point of the fan is changed from B to B' as can be seen from the figure_A’-A-B-DAt the same time, but increaseAdd fortune S_{B’-C’-C-D}Part of the energy consumption, whether energy can be saved or not, also depends on S_A’-A-B-DAnd S_{B’-C’-C-D}The size of the area of (c).

Therefore, the technical defects of the steam-electric double-drive unit in the scheme are mainly as follows: the function of variable speed operation is not provided; the energy-saving effect of the traditional steam-electricity double-drive coaxial unit is not ideal when the unit operates under variable working conditions.

Secondly, the motor and the fan are operated in a frequency conversion mode:

another common driving mode is that the motor drives the sintering fan independently and a two-quadrant frequency converter is used to regulate the speed. The fan adopts a mode of combining variable speed and air door adjustment, and the rotating speed of the fan is adjusted according to the working condition change of the sintering process line. The arrangement form is simple, the running state of the fan can be flexibly adjusted according to the actual running working condition, and particularly, the energy-saving effect of the fan is very obvious when the fan runs at a variable rotating speed.

Although the driving mode can realize the frequency-conversion speed-regulation operation of the fan, the fan can achieve the purpose of energy conservation when the process is in a variable working condition. However, the single-drive form of the motor does not have the function of waste heat recovery, and the energy recovery efficiency of the whole sintering system is low; meanwhile, the user needs to increase the procedures of waste heat power generation and grid connection independently, and the initial investment of equipment is large and the procedures are complex.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a speed regulation method of an energy recovery system of a speed regulation type double four-quadrant frequency converter, so as to solve the technical problem that energy recovery efficiency and variable speed regulation are difficult to be considered in the prior art.

In order to solve the technical problems, the invention adopts the following technical scheme:

a speed regulation method of an energy recovery system of a speed regulation type double four-quadrant frequency converter comprises the following steps:

step 1, speed reduction control:

step 30201, the first unit DCS controller and the second unit DCS controller provide a target rotating speed to be adjusted for the frequency converter PLC controller, and the frequency converter PLC controller calculates corresponding frequency according to the target rotating speed;

step 30202, sending an instruction through a frequency converter PLC controller, and simultaneously reducing the speed of the first motor and the second motor through regulation and control of the first four-quadrant frequency converter and the second four-quadrant frequency converter;

step 30203, in the deceleration process, in the first SHRT, the first clutch is always engaged, and the first motor drags the first sintering fan and the first turbine to synchronously decelerate; meanwhile, the first four-quadrant frequency converter can generate braking torque, and the braking torque is reversely transmitted to the power grid through the first four-quadrant frequency converter;

in the speed reduction process, the process in the second SHRT is the same as that in the first SHRT;

step 30204, until the first motor decreases to the frequency corresponding to the target rotating speed, after stable operation, eliminating the braking torque, driving the first fan to operate by the first turbine and the first motor together, completing the speed reduction adjustment of the first SHRT, and entering a frequency conversion working condition;

when the power of the first turbine is larger than that of the first sintering fan, the first motor enters a power generation state, redundant energy is transmitted to a power grid through the first four-quadrant frequency converter, and the first SHRT is in a variable-frequency power generation state;

the process that the second SHRT enters the frequency conversion working condition and is in the frequency conversion power generation state is the same as that of the first SHRT;

step 2, speed raising control:

step 30205, the first unit DCS controller and the second unit DCS controller provide a target rotating speed to be adjusted for the frequency converter PLC controller, and the frequency converter PLC controller calculates corresponding frequency according to the target rotating speed;

step 30206, sending an instruction through a frequency converter PLC controller, and simultaneously accelerating the first motor and the second motor through regulation and control of the first four-quadrant frequency converter and the second four-quadrant frequency converter;

step 30207, in the speed increasing process, in the first SHRT, the first motor drags the first sintering fan to increase the speed, because the no-load speed increasing rate of the first turbine is greater than the speed increasing rate of the first sintering fan, the first speed change clutch is always in a meshing state, the first turbine continuously increases the speed along with the rotating speed of the first motor until the target rotating speed is reached, the first turbine and the first motor jointly drive the first sintering fan to operate, and the speed increasing process is completed;

in the acceleration process, the process in the second SHRT is the same as the process in the first SHRT;

step 30208, after the first motor is increased to a frequency corresponding to the target rotating speed and stably operates, the first turbine and the first motor jointly drive the first fan to operate, the first SHRT speed increase adjustment is completed, and the frequency conversion working condition is entered;

when the power of the first turbine is larger than that of the first sintering fan, the first motor enters a power generation state, redundant energy is transmitted to a power grid through the first four-quadrant frequency converter, and the first SHRT is in a variable-frequency power generation state;

the process of the second SHRT entering the frequency conversion working condition and being in the frequency conversion power generation state is the same as that of the first SHRT.

The invention also has the following technical characteristics:

the speed raising control process of the steam turbine comprises the following steps:

after receiving the speed increasing signal, a speed regulator of the first turbine adjusts the first turbine into a rotating speed control mode, the first turbine increases the speed according to the unequal rate of 5% of the target rotating speed and the set speed increasing rate until the target rotating speed, the first clutch is meshed, and the first clutch sends a meshing signal to a first unit DCS controller;

after the first unit DCS controller receives the meshing signal and keeps stable, the signal is considered to be true, the first clutch is confirmed to be meshed, the first unit DCS controller sends the meshing signal to a speed regulator of a first turbine, the first turbine is converted into valve position control, and the valve position is manually opened until the current of a first motor is reduced to 10% of the rated current;

the speed raising control process of the second turbine is the same as that of the first turbine.

Specifically, the energy recovery system of the speed-regulating double four-quadrant frequency converter comprises a first SHRT and a second SHRT;

the first SHRT comprises a first sintering fan, a first motor, a first speed change clutch and a first turbine which are coaxially connected in sequence, and further comprises a first unit DCS controller which is electrically connected with the first sintering fan, the first motor, the first speed change clutch and the first turbine;

the second SHRT comprises a second sintering fan, a second motor, a second speed change clutch and a second turbine which are coaxially connected in sequence, and further comprises a second unit DCS controller which is electrically connected with the second sintering fan, the second motor, the second speed change clutch and the second turbine;

the first motor is electrically connected with the first four-quadrant frequency converter, and the first four-quadrant frequency converter is respectively electrically connected with the first high-voltage cable and the second high-voltage cable;

the second motor is electrically connected with a second four-quadrant frequency converter, and the second four-quadrant frequency converter is respectively electrically connected with the first high-voltage cable and the second high-voltage cable;

the first four-quadrant frequency converter and the second four-quadrant frequency converter are also respectively electrically connected with a frequency converter PLC controller, and the frequency converter PLC controller is respectively electrically connected with the first unit DCS controller and the second unit DCS controller.

Preferably, the first motor is also directly electrically connected with a first high-voltage cable; the second motor is also directly and electrically connected with a second high-voltage cable.

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

in the production process of a user, due to the deviation of a sintering design and an actual operation condition, production scheduling and adjusting and the like, the fan needs to be operated under variable working conditions frequently. Aiming at the defects of the existing steam-electricity double-drive unit in the aspect of adjusting the working condition, the low waste heat recovery efficiency of the motor single-drive unit and the like, the invention adopts a variable-speed adjusting steam-electricity double-drive mode, achieves the purpose of waste heat energy recovery, and simultaneously improves the efficiency of the fan and reduces the energy consumption of the fan through a speed-adjusting operation mode. The wind power generation system has a power generation function, and transmits power to a power grid when the recovered energy is larger than the power consumption of the fan.

(II) the invention configures two SHRT sets for each sintering line, which can adopt a mode of 'two driving two' of frequency converter and motor as main and standby, and improves the reliability of the whole energy recovery system: under normal conditions, the two variable frequencies respectively drive the units to operate in a speed-regulating mode; when one of the frequency converters fails, the other frequency converter can ensure that the unit is smoothly started to a power frequency state without influencing the normal production of the sintering process line.

Drawings

FIG. 1 is a graph of known damper mode operation.

Fig. 2 is a frequency conversion adjustment mode operation curve of the present invention.

Fig. 3 is a schematic diagram of an energy recovery system of a speed-regulating type double four-quadrant frequency converter.

The meaning of the individual reference symbols in the figures is: 1-a first SHRT, 2-a second SHRT, 3-a first four-quadrant frequency converter, 4-a second four-quadrant frequency converter, 5-a first high-voltage cable, 6-a second high-voltage cable and 7-a frequency converter PLC controller;

101-a first sintering fan, 102-a first motor, 103-a first speed change clutch, 104-a first turbine and 105-a first unit DCS controller;

201-a second sintering fan, 202-a second motor, 203-a second speed change clutch, 204-a second turbine, 205-a second unit DCS controller.

The present invention will be explained in further detail with reference to examples.

Detailed Description

It is to be noted that all components in the present invention, unless otherwise specified, are all those known in the art. For example, the frequency converter PLC controller, the first unit DCS controller, and the second unit DCS controller are all known products in the prior art.

The first steam turbine and the second steam turbine are both provided with speed regulators, and the speed regulators have three functions of rotating speed control, valve position control and front pressure control. The governor is also a product known in the art.

Note that, in the present invention, SHRT refers to a sintering waste heat energy recovery unit.

As shown in FIG. 2, when the working condition changes, the frequency of the fan is changed from 50HzRun to 40Hz speed with performance curves from n₁Is changed into n₂(ii) a The resistance of the pipe network system is not changed, and the characteristic curve of the pipe network is still a curve 1; therefore, the operating point of the fan is changed from B to B', and the power consumption of the fan is changed from S from the curve_O-A-B-CIs reduced to S_{O-A’-B’-C’}，S_{A’-A-B-C-C’-B’}The corresponding areas are energy-saving parts with variable working conditions, and compared with an air adjusting door mode, the air adjusting door has absolute technical advancement.

The invention adopts the arrangement form of a steam turbine, a speed change clutch, a motor generator and a fan and adopts a four-quadrant frequency converter, can realize the speed regulation operation of a unit on the basis of the steam-electricity double-drive coaxial operation, and has the power generation function, thereby achieving the purpose of more efficient energy conservation.

The four-quadrant frequency converter is key equipment for realizing speed regulation operation of the unit, and has the following technical characteristics:

firstly, the torque borne by a motor rotor is taken as an axis Y, the electric state is positive, and the braking state is negative; taking the running direction as an X axis, wherein positive rotation is positive and negative rotation is negative; then the four quadrants of the frequency converter are in the forward braking power generation state.

Secondly, the power unit adopts an advanced IGBT module as a rectifying device, so that bidirectional circulation of energy can be realized, and regenerated energy can be fed back to a power grid under the condition of not needing any additional device, so that the energy-saving operation effect is achieved;

when the production process needs to reduce the load operation, the frequency of the frequency converter can be adjusted according to the load, and the rotating speed of the fan is reduced:

during the speed reduction process, the clutch is always in an engaged state; at the moment, the steam turbine inlet valve does not act, the rotating speed is forced to be reduced, the power grid applies braking torque to the steam turbine, and the torque is used as regenerative energy and is fed back to the power grid through the four-quadrant frequency converter, so that reverse power transmission is realized, and the energy-saving operation effect is achieved;

secondly, after speed regulation is finished, the unit stably operates, and when the power of the steam turbine is smaller than the operating power of the fan, the steam turbine and the motor jointly drive the fan to operate, so that steam-electricity dual-drive operation is realized;

when the steam quantity of the waste heat system is sufficient and the output power of the steam turbine is greater than the power of the fan, the steam turbine drives the fan to operate independently, redundant power can be fed back to a power grid through the four-quadrant frequency converter, and power generation is achieved while driving.

It should be noted that, for a large-capacity four-quadrant frequency converter, each frequency converter is connected in parallel by 2 small power modules, and both the two frequency converters are added to have faults, so that when the unit is stopped, the rotary inertia of a sintering fan is large, so that direct starting cannot be met, and frequency conversion starting is needed; at this moment, as long as any one of the 4 power modules in the two frequency converters can normally operate and corresponds to half of the power of a single fan, the power module can be used for respectively starting two sets of units and entering a power frequency state, so that the normal production of a sintering process is ensured, and the reliability of the units is improved.

The present invention is not limited to the following embodiments, and all equivalent changes based on the technical solutions of the present invention fall within the protection scope of the present invention.

Example 1:

the embodiment provides an energy recovery system of a speed-regulating double four-quadrant frequency converter, as shown in fig. 3, including a first SHRT1 and a second SHRT 2;

the first SHRT1 comprises a first sintering fan 101, a first motor 102, a first speed change clutch 103 and a first turbine 104 which are coaxially connected in sequence, and also comprises a first unit DCS controller 105 which is electrically connected with the first sintering fan 101, the first motor 102, the first speed change clutch 103 and the first turbine 104;

the second SHRT2 comprises a second sintering fan 201, a second motor 202, a second speed change clutch 203 and a second turbine 204 which are coaxially connected in sequence, and also comprises a second unit DCS controller 205 which is electrically connected with the second sintering fan 201, the second motor 202, the second speed change clutch 203 and the second turbine 204;

the first motor 102 is electrically connected with the first four-quadrant frequency converter 3, and the first four-quadrant frequency converter 3 is respectively electrically connected with the first high-voltage cable 5 and the second high-voltage cable 6;

the second motor 202 is electrically connected with the second four-quadrant frequency converter 4, and the second four-quadrant frequency converter 4 is electrically connected with the first high-voltage cable 5 and the second high-voltage cable 6 respectively;

the first four-quadrant frequency converter 3 and the second four-quadrant frequency converter 4 are also electrically connected with a frequency converter PLC controller 7 respectively, and the frequency converter PLC controller 7 is electrically connected with the first unit DCS controller 105 and the second unit DCS controller 205 respectively.

The first electric machine 102 is also electrically connected directly to the first high voltage cable 5; the second electrical machine 202 is also in direct electrical connection with the second high voltage cable 6.

Example 2:

this embodiment provides a speed regulation method for an energy recovery system of a speed regulation type double four-quadrant frequency converter, where the speed regulation method employs the energy recovery system of the speed regulation type double four-quadrant frequency converter in embodiment 1. Specifically, the method comprises the following steps:

step 1, speed reduction control:

step 30201, the first unit DCS controller 105 and the second unit DCS controller 205 provide a target rotation speed to be adjusted to the frequency converter PLC controller 7, and the frequency converter PLC controller 7 calculates a corresponding frequency according to the target rotation speed;

step 30202, sending an instruction through the frequency converter PLC controller 7, and simultaneously slowing down the first motor 102 and the second motor 202 through the regulation and control of the first four-quadrant frequency converter 3 and the second four-quadrant frequency converter 4;

step 30203, in the speed reduction process, in the first SHRT1, the first clutch 103 is always engaged, and the first electric machine 102 drags the first sintering fan 101 and the first turbine 104 to synchronously reduce the speed; meanwhile, the first four-quadrant frequency converter 3 can generate braking torque, and the braking torque is reversely transmitted to the power grid through the first four-quadrant frequency converter 3;

during the deceleration process, the process in the second SHRT2 is the same as the process in the first SHRT 1;

step 30204, until the frequency of the first motor 102 is reduced to a frequency corresponding to the target rotating speed, after stable operation, the braking torque is eliminated, the first turbine 104 and the first motor 102 drive the first fan 101 to operate together, the first SHRT1 finishes speed reduction adjustment, and the variable frequency operating mode is entered;

when the power of the first turbine 104 is greater than that of the first sintering fan 101, the first motor 102 enters a power generation state, redundant energy is sent to a power grid through the first four-quadrant frequency converter 3, and at the moment, the first SHRT1 is in a variable-frequency power generation state;

the process that the second SHRT2 enters the frequency conversion working condition and is in the frequency conversion power generation state is the same as that of the first SHRT 1;

step 2, speed raising control:

step 30205, the first unit DCS controller 105 and the second unit DCS controller 205 provide a target rotation speed to be adjusted to the frequency converter PLC controller 7, and the frequency converter PLC controller 7 calculates a corresponding frequency according to the target rotation speed;

step 30206, sending an instruction through the frequency converter PLC controller 7, and simultaneously accelerating the first motor 102 and the second motor 202 through the regulation and control of the first four-quadrant frequency converter 3 and the second four-quadrant frequency converter 4;

step 30207, in the speed increasing process, in the first SHRT1, the first motor 102 pulls the first sintering fan 101 to increase the speed, because the idling speed increasing rate of the first turbine 104 is greater than the speed increasing rate of the first sintering fan 101, the first speed change clutch 103 is always engaged, the first turbine 104 continuously increases the speed along with the rotating speed of the first motor 102 until the target rotating speed is reached, the first turbine 104 and the first motor 102 jointly drive the first sintering fan 101 to operate, and the speed increasing process is completed;

during the ramp-up process, the process in the second SHRT2 is the same as the process in the first SHRT 1;

step 30208, after the first motor 102 is increased to a frequency corresponding to the target rotating speed and stably operates, the first turbine 104 and the first motor 102 jointly drive the first fan 101 to operate, the speed increase adjustment of the first SHRT1 is completed, and the frequency conversion working condition is entered;

when the power of the first turbine 104 is greater than that of the first sintering fan 101, the first motor 102 enters a power generation state, redundant energy is sent to a power grid through the first four-quadrant frequency converter 3, and at the moment, the first SHRT1 is in a variable-frequency power generation state;

the process of the second SHRT2 entering the variable frequency working condition and being in the variable frequency power generation state is the same as that of the first SHRT 1.

As a preferable scheme of this embodiment, the turbine speed-up control process includes:

after receiving the speed increasing signal, the speed regulator of the first turbine 104 firstly adjusts the first turbine 104 into a rotating speed control mode, and increases the speed according to the unequal rate of 5% of the target rotating speed and the set speed increasing rate until the target rotating speed, the first clutch 103 is engaged, and the first clutch 103 sends an engaging signal to the first unit DCS controller 105;

after the first unit DCS controller 105 receives the meshing signal and keeps stable, the signal is considered to be true, the first clutch 103 is confirmed to be meshed, the first unit DCS controller 105 sends the meshing signal to the speed regulator of the first turbine 104, the first turbine 104 is converted into valve position control, and the valve position is manually opened until the current of the first motor 102 is reduced to 10% of the rated current;

the speed-up control process of the second turbine 204 is the same as that of the first turbine 104.

Example 3:

this embodiment provides a control method for an energy recovery system of a speed-regulating double four-quadrant frequency converter, where the method employs the energy recovery system of the speed-regulating double four-quadrant frequency converter in embodiment 1. Specifically, the method comprises the following steps:

step one, starting to power frequency rated speed working condition control:

101, when starting, a first unit DCS controller 105 and a second unit DCS controller 205 send starting instructions to a frequency converter PLC controller 7, the frequency converter PLC controller 7 controls the starting instructions, the air doors of a second sintering fan 201 are firstly closed to the opening degree of 5% -10% through the regulation and control of the second unit DCS controller 205, and then the first sintering fan 101 is started;

102, according to a speed increasing rate set by a frequency converter PLC (programmable logic controller) 7, a first motor 102 is increased to a power frequency of 50Hz to operate through regulation and control of a first four-quadrant frequency converter 3, a first unit DCS (distributed control System) controller 105 controls a first turbine 104 to increase the speed, when the speed is increased to the vicinity of a rated rotating speed, the speed of the speed increase is controlled to be no more than 5rpm, a first speed change clutch 103 is stably meshed, and the first turbine 104 and the first motor 102 are driven together to enable the first sintering fan 101 to operate at the rated rotating speed;

103, after the first sintering fan 101 operates stably, according to the speed-up rate set by the frequency converter PLC controller 7, the second motor 202 is controlled to operate at the power frequency of 50Hz by the regulation and control of the second four-quadrant frequency converter 4, the second set DCS controller 205 controls the second turbine 204 to operate at the speed-up rate, when the speed-up rate is increased to the vicinity of the rated rotational speed, the speed-up rate is controlled to not more than 5rpm, the second speed-change clutch 203 is engaged stably, and the second turbine 204 and the second motor 202 are driven together, so that the second sintering fan 201 operates at the rated rotational speed;

step two, controlling the working condition with low energy loss:

after the first sintering fan 101 and the second sintering fan 201 operate stably, the energy recovery system of the speed-regulating type double-four-quadrant frequency converter operates at a rated rotating speed, the first four-quadrant frequency converter 3 exits from the first high-voltage cable 5, and the first motor 102 directly takes power from the first high-voltage cable 5 of the power grid to drag the first motor 102 to operate; the second four-quadrant frequency converter 4 exits the second high-voltage cable 6, and the second motor 202 directly takes power from the second high-voltage cable 6 of the power grid to drive the second motor 202 to operate;

step three, frequency conversion working condition control:

step 301, when the working conditions of the first SHRT1 and the second SHRT2 change, the first sintering fan 101 and the second sintering fan 201 need to operate at a speed regulation, the first unit DCS controller 105 and the second unit DCS controller 205 send speed regulation instructions to the frequency converter PLC controller 7, the first four-quadrant frequency converter 3 cuts into the first high-voltage cable 5, and the first motor 102 takes power from the first high-voltage cable 5 of the power grid through the first four-quadrant frequency converter 3 to drag the first motor 102 to operate; the second four-quadrant frequency converter 4 cuts into the second high-voltage cable 6, and the second motor 202 takes power from the second high-voltage cable 6 of the power grid through the second four-quadrant frequency converter 4 to drag the second motor 202 to operate;

step 302, a target rotating speed required to be adjusted is given to the frequency converter PLC controller 7 by the first unit DCS controller 105 and the second unit DCS controller 205, the frequency converter PLC controller 7 calculates corresponding frequency according to the target rotating speed, an instruction is sent by the frequency converter PLC controller 7, the first motor 102 and the second motor 202 are simultaneously regulated and controlled by the first four-quadrant frequency converter 3 and the second four-quadrant frequency converter 4, so that the first motor 102 and the second motor 202 reach frequencies corresponding to the target rotating speed, and the first SHRT1 and the second SHRT2 enter a frequency conversion working condition;

step four, controlling the working condition of non-stop rotating speed reduction when the single four-quadrant frequency converter breaks down suddenly:

step 401, the first SHRT1 and the second SHRT2 operate under a frequency conversion working condition, when the first four-quadrant frequency converter 3 or the second four-quadrant frequency converter 4 suddenly fails, the corresponding first motor 102 or the corresponding second motor 202 is powered off and loses driving force, and the corresponding first SHRT1 or the corresponding second SHRT2 is driven by the first turbine 104 or the second turbine 204 alone;

step 402, when the power of the first turbine 104 or the second turbine 204 is greater than the power of the corresponding first sintering fan 101 or the second sintering fan 201, the first electric motor 102 or the second electric motor 202 is in a power generation state, the first SHRT1 or the second SHRT2 continuously increases the speed under the driving of the first turbine 104 or the second turbine 204, and in order to prevent the first SHRT1 or the second SHRT2 from exceeding the speed, 108% of rated speed is set in the first set DCS controller 105 or the second set DCS controller 205 as a turbine overspeed protection interlocking shutdown value;

when the power of the first turbine 104 or the second turbine 204 is not enough to drive the corresponding first sintering fan 101 or the second sintering fan 201, the first sintering fan 101 or the second sintering fan 201 is idled under the action of inertia, the rotating speed is reduced to reach the rotating speed corresponding to the equilibrium state of the first turbine 104 or the second turbine 204, and the first SHRT1 or the second SHRT2 is driven by the first turbine 104 or the second turbine 204 alone;

step five, controlling the working condition of non-stop rotation speed rise when a single four-quadrant frequency converter breaks down suddenly:

step 501, when the first SHRT1 is driven by the first turbine 104 alone, the second SHRT2 increases the power frequency of the second motor 202 to 50Hz to operate under the control of the second four-quadrant frequency converter 4, so that the second sintering fan 201 operates at the rated speed, and the second four-quadrant frequency converter 4 exits the second high-voltage cable 6;

step 502, feeding back the current rotating speed of the first turbine 104) to a frequency converter PLC controller 7 by the first unit DCS controller 105), controlling the second four-quadrant frequency converter 4 to cut into the first high-voltage cable 5 by the frequency converter PLC controller 7, adjusting the output frequency of the second four-quadrant frequency converter 4 by the frequency converter PLC controller 7 according to the target rotating speed, and starting the first motor 102 under the output frequency;

step 503, the first motor 102 drags the first sintering fan 101 to increase the speed, the no-load speed increasing rate of the first turbine 104 is greater than the speed increasing rate of the first sintering fan 101, the first speed change clutch 103 is always in a meshing state, the first turbine 104 continuously increases the speed along with the rotating speed of the first motor 102 until the rotating speed reaches a rated rotating speed, and the first turbine 104 and the first motor 102 jointly drive the first sintering fan 101 to operate;

step 504, the second four-quadrant frequency converter 4 exits the first high-voltage cable 5, so that the first sintering fan 101 operates at a rated rotation speed;

505, enabling the first SHRT1 and the second SHRT2 to run in a power frequency 50Hz state corresponding to the rated rotation speed, and adjusting the working conditions by adjusting the opening degrees of air doors of the first sintering fan 101 and the second sintering fan 201;

and step 506, when the second SHRT2 is driven by the second turbine 204 alone, the same method as the steps 501 to 505 is adopted, so that the second SHRT1 and the first SHRT2 both enter the power frequency 50Hz state corresponding to the rated rotation speed to operate.

As a preferable scheme of this embodiment, in step 302, the speed regulation includes speed reduction control and speed increase control, and the speed regulation method in embodiment 2 is specifically adopted.

(A) When the unit operates under variable working conditions, the larger the speed regulation range is, the higher the energy saving rate of the variable-frequency speed regulation steam-electric double-drive unit is compared with the traditional steam-electric double-drive unit.

(B) When the unit operates at the rated rotating speed, the two motors directly take power from the power grid, so that energy loss of about 3% of the frequency converter is avoided, and the operating efficiency of the unit at the rated rotating speed is improved.

(C) The control method of the invention can effectively reduce the shutdown of the system, make the sintering process more stable, and simultaneously improve the energy utilization rate of the system to the maximum extent, so that the operation efficiency of the unit reaches the best.

Application example:

taking two sets of steam-electricity double-drive coaxial sintering fans configured on a certain sintering line as an example for explanation, the calculation parameters of a single fan are as follows:

under the design working condition: the air input is Q₀＝19800m³Min, pressure rise P0 is 20500Pa, full-pressure efficiency eta 0 of the fan is 0.85, and the shaft power N0 under the design working condition of the fan is 7959 kW;

when the working condition changes and the air inflow is adjusted to be 80% to operate, the air adjusting door shown in figure 1 is adopted to adjust the air inflow Q₁＝15840m³Min, checking the performance curve of the fan and increasing the pressure P₂2450 Pa, full pressure efficiency η₁The shaft power N of the fan operation can be calculated as 0.83₁7792kW, the energy saving rate of the unit is about 2%.

Similarly, when the working condition changes and the air intake quantity is adjusted to be 80% to operate, the variable frequency speed regulation mode as shown in fig. 2 is adopted for regulation, and the air intake quantity Q₂＝15840m³Min; by the characteristics Q of the fan₀/Q₂＝n₀/n₂、N₀/N₂＝(n₀/n₂)³It can be known that when the frequency converter is reduced from 50Hz to 40Hz, the power N of the fan shaft₂As 4075kW, the fan power can be reduced by about 49% in theory. In the actual operation process, the efficiency of the fan is reduced to a certain extent along with the reduction of the rotating speed, the power consumption of the frequency converter is considered by 3%, and the actual energy saving rate is comprehensively considered and can be expected to reach more than 30%. Compared with the traditional steam-electricity double-drive coaxial unit, the energy-saving effect has qualitative change.

Therefore, it can be concluded that when the system operating condition is changed to below 80% air volume, the energy saving rate of the variable-frequency speed-regulating steam-electric double-drive unit is higher than that of the traditional steam-electric double-drive unit by more than 30%, so that the energy recovery efficiency of the invention is higher, and the technical advantages are more prominent.