CN107246390A - A kind of control method of large-scale helium compressor station multistage pressure - Google Patents

Abstract

The invention discloses a multi-stage pressure control method for a large-scale helium compressor station. The core control target is to stabilize the three-stage pressure. Aiming at the structure of the two-stage series connection of the main compressor unit to form a three-stage pressure, between two pressure pipelines The channel is set and equipped with a bypass valve to realize the rapid deployment of the internal helium volume of the three-stage pressure, so as to improve the shortcoming of slow response and easy overshoot caused by the long-term lag of the single-use compressor energy slide valve adjustment; store gas at the compressor station Control valves are arranged between the three subsystems of the main compressor system, recovery, and main compressor unit to realize the allocation of helium gas volume between the three-stage pressure pipeline of the main compressor system and the external subsystem, and to suppress pressure fluctuations caused by the imbalance of gas volume inside the system. By decomposing the coupling relationship between the pressures at all levels, a coordinated control method of single-variable multiple actuators for each of the three-level pressures is designed, and a variety of expert rules are combined with dynamic matching of control parameters to realize multi-stage helium compressor stations Real-time adjustment of pressure.

Description

A method for controlling multi-stage pressure of a large helium compressor station

technical field

The invention relates to the field of automatic control methods of compressor stations, in particular to a method for controlling multi-stage pressure of large helium compressor stations.

Background technique

The high-pressure helium required in the helium refrigeration cycle is compressed by a compressor, which is an important power device for a refrigerator system. Large-scale helium refrigerators have large cooling capacity and complex processes, and usually need to be equipped with multi-stage large-scale compressor systems with different flow rates and pressure ratios. The compressor system can be divided into three subsystems: gas storage, recovery, and main compressor units. The gas storage system is composed of multiple medium-pressure cylinders, and the gas storage pressure is between low pressure and medium pressure; the recovery system is composed of a suspended gas cabinet and a recovery compressor; the main compressor is generally composed of multiple large screw compressors connected in series and parallel , The energy slide valve is a commonly used energy adjustment device for screw compressors, which can realize stepless adjustment of the displacement. During steady-state operation, the compressor station provides the appropriate displacement for the refrigerator, and at the same time, it is necessary to ensure that the pressure at each level is stable near the given value required by the system, and it can automatically adjust the operating state in response to load fluctuations and sudden disturbances, and the control effect It directly affects the operating efficiency and safety of the refrigerator system. At present, the existing technology relies too much on the control of the energy slide valve of the compressor. However, the energy slide valve is difficult to locate accurately, and has uncertainty drift and nonlinearity. Time lag and easy to cause overshoot. For complex compressor station systems with multi-variable coupling and frequent switching of multiple operating conditions, simple control rules are difficult to achieve good control effects, resulting in large pressure fluctuations and system shocks.

SUMMARY OF THE INVENTION The purpose of the present invention is to provide a multi-stage pressure control method for a large helium compressor station, which can adjust the operating state according to the load change, has a certain anti-interference ability, suppresses system oscillation, and realizes the automatic control of the pressure at each stage of the compressor station. control.

In order to achieve the above object, the technical scheme adopted in the present invention is:

A multi-stage pressure control method for a large-scale helium compressor station, characterized in that: the core control target is to stabilize the three-stage pressure, aiming at the structure of two stages of the main compressor unit connected in series to form a three-stage pressure, between two pressure pipelines The channel is set and equipped with a bypass valve to realize the rapid deployment of the internal helium volume of the three-stage pressure, so as to improve the shortcoming of slow response and easy overshoot caused by the long-term lag of the single-use compressor energy slide valve adjustment; store gas at the compressor station The control valves are arranged among the three subsystems of the main compressor system, recovery, and main compressor unit to realize the helium volume allocation between the three-stage pressure pipeline of the main compressor system and the external subsystem. By decomposing the coupling relationship between the pressures of each stage, the Coordinated control strategies of multiple actuators for each single variable of the three levels of pressure, where:

The actuators of the three-stage pressure medium and low pressure pressure LP control loop are bypass valves V1 and V2 connected to the high pressure pipeline, protection valve V3 connected to the recovery system, and energy slide valve C1 of the low pressure stage screw compressor unit, of which the bypass valve V1 , V2 and protection valve V3 are all controlled by PID controller;

The low-pressure pressure LP control strategy takes the low-pressure pressure LP as a single controlled variable: when the low-pressure pressure LP>set value LP_SP1, the opening of the bypass valve V1 is controlled to decrease, where LP_SP1 is; when the opening of the bypass valve V1 is lower than the lower When the limit value is reached, the C1 energy slide valve of the low-pressure stage screw compressor unit performs a load-increasing action; when the low pressure LP<set value LP_SP1, the opening of the bypass valve V1 is controlled to increase, and when the opening of the bypass valve V1 is higher than the upper limit When the low-pressure stage screw compressor unit C1 is unloaded; if the low-pressure pressure LP continues to drop to the low-pressure pressure LP<set value LP_SP2, the bypass valve V2 is controlled to open the auxiliary adjustment; when the low-pressure pressure LP>upper limit value LP_HI, the control protection Valve V3 opens to release pressure to the recovery system;

The actuators of the three-stage pressure medium pressure pressure MP control circuit are the bypass valve V4 connected with the high pressure pipeline, the bypass valve V5 connected with the low pressure pipeline, and the bypass valve V6 connected with the C2 inlet of the high pressure stage screw compressor unit , wherein the bypass valves V4, V5, and V6 are all controlled by the PID controller;

The medium pressure MP control strategy is to use the medium pressure MP as a single controlled variable, and the bypass valve V4 and bypass valve V6 perform reverse split-range control. The PID controller of the bypass valve V4 reacts in reverse, and the PID controller of the bypass valve V6 The controller is positive, and the bypass valve V4 is interlocked with the bypass valve V6. Only when one of them is closed, the other is controlled to adjust; when MP>upper limit MP_HI, the bypass valve V5 is controlled to open to the low pressure LP pipeline pressure relief;

The actuators of the three-stage pressure, medium and high pressure HP control loop are the gas collection valves V7 and V8 connected to the gas storage system, and the bypass valve V2 connected to the low pressure pipeline, and the gas collection valves V7 and V8 are controlled by the PID controller. ;

The control strategy of the high pressure HP is: when the high pressure HPHP>the set value HP_SP1, control the air collection valve V7 to open to collect air from the gas storage system, when the air collection valve V7 is too late to collect air, the high pressure HP continues to rise to the high pressure HP >Setting value HP_SP2, start the control of gas receiving valve V8; when the high pressure HP>upper limit value HP_HI, the bypass valve V2 is forced to open to release pressure to the low pressure circuit.

The multi-stage pressure control method of a large helium compressor station is characterized in that: in the low pressure LP control strategy, the set value LP_SP1 is the set value of the PID controller of the bypass valve V1, and the bypass valve The PID controller of V1 is a dynamic PID controller, and its parameters are dynamically adjusted according to the system working conditions;

The set value LP_SP2 is the set value of the PID controller of the bypass valve V2, and the PID controller of the bypass valve V2 is a PID controller with expert rules;

The upper limit LP_HI is the setting value of the PID controller of the protection valve V3.

The multi-stage pressure control method of a large helium compressor station is characterized in that: in the medium pressure pressure MP control strategy, the upper limit value MP_HI is the set value in the PID controller of the bypass valve V5.

The multi-stage pressure control method of a large-scale helium compressor station is characterized in that: in the control strategy of the high pressure HP, the set value HP_SP1 is the set value in the PID controller of the air intake valve V7, and the set value HP_SP2 is the setting value of the PID controller of the intake valve V8, and the upper limit HP_HI is the limit setting value of the PID controller of the bypass valve V2.

The multi-stage pressure control method of a large-scale helium compressor station is characterized in that: when the load suction volume is greater than the return gas volume, the helium volume in the compressor station system decreases so that the medium pressure MP and high pressure HP drop, When the medium pressure MP<air supply value MP_S and the high pressure HP<air supply value HP_S, it is judged that the system enters the air supply state, and the air supply valve V9 connected to the gas storage system is opened to supply air to the system from the low pressure pipeline;

The expert rule of air supply control is: when the air supply conditions are met, set the PID controller setting value of the air supply valve V9 to LP_SP_S to raise the low pressure LP for air supply. The increase of the air volume leads to the increase of the medium pressure MP, and the increase of the medium pressure MP increases the displacement of the high-pressure compressor unit, which leads to the increase of the high pressure HP; The PID controller of the valve V9 is reduced to LP_SP_D, so as to control the air supply valve V9 to close quickly to end the air supply. The PID controller setting value LP_SP_S of the air supply valve V9 is dynamically given according to the load change. When the load suction speed increases , increase the air supply speed correspondingly by increasing the PID controller setting value LP_SP_S of the air supply valve V9.

The multi-stage pressure control method of a large-scale helium compressor station is characterized in that: the control system is realized by a PLC system or a DCS control framework, and the field equipment layer is composed of measuring instruments and actuators, and the I/O card and The control layer is connected, and the control layer is the control card of PLC or DCS; the upper computer system of PLC or DCS communicates with the control layer through the control network to realize monitoring signal acquisition and control configuration download.

The advantage of the present invention is that it provides a multi-stage pressure control method for a large-scale helium compressor station, converts multi-variable control into single-variable control by decomposing the coupling relationship, and designs multi-actuator coordinated control strategy and control strategy for each control variable. Expert rules, and dynamically adjust controller parameters according to the operating status, overcome the shortcomings of simple control rules, such as large lag and easy overshoot, and can intelligently cope with the variable operating conditions of the system.

Description of drawings

Fig. 1 is a flow chart of a large helium screw compressor station according to the method embodiment of the present invention.

Fig. 2 is a control block diagram of LP in the method of the present invention.

Fig. 3 is a control block diagram of MP in the method of the present invention.

Fig. 4 is a control block diagram of HP in the method of the present invention.

Fig. 5 is a schematic diagram of air supplement control in the method of the present invention.

detailed description

As shown in Figure 1, a multi-stage pressure control method for a large-scale helium compressor station, aiming at the structure of two stages in series of the main compressor unit to form a three-stage pressure, a passage is provided between two pressure pipelines and a bypass valve is equipped In the compressor station, protection valves, gas collection and supply valves are arranged between the three subsystems of gas storage, recovery, and main compressor unit. Through the control of these control valves and compressor energy slide valves, the adjustment of pressure at all levels and the gas volume of the system are realized. The balance to achieve the goal of controlling the pressure stability.

As shown in Figure 2, a multi-stage pressure control method for a large helium compressor station, the LP control strategy is: V1 is controlled by dynamic PID, when LP>LP_SP1, the opening of V1 decreases; when the low pressure LP< LP_SP1, The opening of V1 increases. V2 is controlled by expert PID, if LP continues to drop to LP< LP_SP2, and HP does not exceed the upper limit value HP_HI, V2 auxiliary regulation will be started. V3 is controlled by PID. When LP>LP_HI, V3 is controlled to release pressure to the recovery system. The C1 energy slide valve is controlled by expert rules. When the opening of V1 is lower than the lower limit, the load of the main tune C1 energy slide valve is increased; when the opening of V1 is higher than the upper limit, the load of the main tune C1 energy slide valve is reduced. The position change of the energy slide valve acts on the low-pressure stage compressor unit to change the displacement, thereby further adjusting LP.

As shown in Figure 3, a multi-stage pressure control method for a large helium compressor station, the MP control strategy is: V4 and V6 perform reverse split-range control, the PID controller of V4 acts in reverse, and the PID controller of V6 acts positively. And V4 and V6 are interlocked; V5 is controlled by PID, and the set value of PID controller is MP_HI.

As shown in Figure 4, a control method for multi-stage pressure in a large helium compressor station, the HP control strategy is: V2, V7, V8 as the actuator, where V7, V8 are controlled by PID, and the set values of the controllers are respectively It is HP_SP1, HP_SP2. V2 not only serves as a bypass valve to assist in regulating LP, but also acts as a protection valve to prevent HP from being too high. When HP>HP_HI, V2 is forced to open to release pressure to the low-pressure circuit. At this time, V2 is not used as an actuator for the LP process.

As shown in Figure 5, a multi-stage pressure control method for a large-scale helium compressor station, the HP control strategy is: judge whether the system needs to replenish gas by MP and HP comprehensively, when MP<MP_S and HP<HP_S, judge the system Enter the gas supplement state. At this time, set the PID controller setting value of V9 to LP_SP_S to raise the LP for gas supplement. When the gas supplement condition is not satisfied, its setting will be reduced to LP_SP_D, so as to control V9 to shut down quickly and end the gas supplement. LP_SP_S is dynamically set according to the load change. When the load suction speed increases, the air supply speed is correspondingly increased by increasing LP_SP_S.

The above-mentioned control loops are realized by the PLC system or DCS control framework. The pressure transmitter measures the gas pressure, and the pressure signal is input to the control layer through the I/O card. The PLC or DCS control card in the control layer performs corresponding calculations. And through the I/O card, the obtained control quantity is output to the control valve, and the control valve executes the control action for adjustment.

Claims (6)

1. A method for controlling the multi-stage pressure of a large helium compressor station, characterized in that: taking the stability of the three-stage pressure as the core control target, aiming at the structure of two stages of the main compressor unit connected in series to form a three-stage pressure, in two pressure pipelines A passage is set between them and a bypass valve is used to realize the rapid deployment of the internal helium volume of the three-stage pressure, so as to improve the shortcomings of slow response and easy overshoot caused by the long-term lag of the single-use compressor energy slide valve adjustment; in the compressor station Control valves are arranged between the three subsystems of gas storage, recovery, and main compressor unit to realize the allocation of helium volume between the three-stage pressure pipeline of the main compressor system and the external subsystem. By decomposing the coupling relationship between the pressures of each stage, A coordinated control strategy of multiple actuators with univariate pressures for each of the three levels of pressure is designed, in which: The actuators of the three-stage pressure medium and low pressure pressure LP control loop are bypass valves V1 and V2 connected to the high pressure pipeline, protection valve V3 connected to the recovery system, and energy slide valve C1 of the low pressure stage screw compressor unit, of which the bypass valve V1 , V2 and protection valve V3 are all controlled by PID controller; The low-pressure pressure LP control strategy takes the low-pressure pressure LP as a single controlled variable: when the low-pressure pressure LP>set value LP_SP1, the opening of the bypass valve V1 is controlled to decrease, where LP_SP1 is; when the opening of the bypass valve V1 is lower than the lower When the limit value is reached, the C1 energy slide valve of the low-pressure stage screw compressor unit performs a load-increasing action; when the low pressure LP<set value LP_SP1, the opening of the bypass valve V1 is controlled to increase, and when the opening of the bypass valve V1 is higher than the upper limit When the low-pressure stage screw compressor unit C1 is unloaded; if the low-pressure pressure LP continues to drop to the low-pressure pressure LP<set value LP_SP2, the bypass valve V2 is controlled to open the auxiliary adjustment; when the low-pressure pressure LP>upper limit value LP_HI, the control protection Valve V3 opens to release pressure to the recovery system; The actuators of the three-stage pressure medium pressure pressure MP control circuit are the bypass valve V4 connected with the high pressure pipeline, the bypass valve V5 connected with the low pressure pipeline, and the bypass valve V6 connected with the C2 inlet of the high pressure stage screw compressor unit , wherein the bypass valves V4, V5, and V6 are all controlled by the PID controller; The medium pressure MP control strategy is to use the medium pressure MP as a single controlled variable, and the bypass valve V4 and bypass valve V6 perform reverse split-range control. The PID controller of the bypass valve V4 reacts in reverse, and the PID controller of the bypass valve V6 The controller is positive, and the bypass valve V4 is interlocked with the bypass valve V6. Only when one of them is closed, the other is controlled to adjust; when MP>upper limit MP_HI, the bypass valve V5 is controlled to open to the low pressure LP pipeline pressure relief; The actuators of the three-stage pressure, medium and high pressure HP control loop are the gas collection valves V7 and V8 connected to the gas storage system, and the bypass valve V2 connected to the low pressure pipeline, and the gas collection valves V7 and V8 are controlled by the PID controller. ; The control strategy of the high pressure HP is: when the high pressure HPHP>the set value HP_SP1, control the air collection valve V7 to open to collect air from the gas storage system, when the air collection valve V7 is too late to collect air, the high pressure HP continues to rise to the high pressure HP >Setting value HP_SP2, start the control of gas receiving valve V8; when the high pressure HP>upper limit value HP_HI, the bypass valve V2 is forced to open to release pressure to the low pressure circuit. 2. The method for controlling the multi-stage pressure of a large helium compressor station according to claim 1, characterized in that: in the low pressure LP control strategy, the set value LP_SP1 is the setting of the PID controller of the bypass valve V1 value, and the PID controller of the bypass valve V1 is a dynamic PID controller, whose parameters are dynamically adjusted according to the system working conditions; The set value LP_SP2 is the set value of the PID controller of the bypass valve V2, and the PID controller of the bypass valve V2 is a PID controller with expert rules; The upper limit LP_HI is the setting value of the PID controller of the protection valve V3. 3. The method for controlling the multi-stage pressure of a large helium compressor station according to claim 1, characterized in that: in the medium pressure MP control strategy, the upper limit MP_HI is set in the PID controller of the bypass valve V5 Value. 4. The method for controlling the multi-stage pressure of a large helium compressor station according to claim 1, characterized in that: in the control strategy of the high pressure HP, the set value HP_SP1 is set in the PID controller of the gas collection valve V7 Fixed value, the set value HP_SP2 is the set value in the PID controller of the air intake valve V8, and the upper limit HP_HI is the limit set value of the PID controller of the bypass valve V2. 5. A method for controlling multi-stage pressure of a large helium compressor station according to claim 1, characterized in that: when the load suction volume is greater than the return gas volume, the helium volume in the compressor station system decreases so that the medium pressure MP And the high pressure HP drops, when the medium pressure MP<gas supply value MP_S and the high pressure HP<gas supply value HP_S, it is judged that the system enters the gas supply state, and the gas supply valve V9 connected to the gas storage system is opened to supply the system with the low pressure pipeline. gas; The expert rule of air supply control is: when the air supply conditions are met, set the PID controller setting value of the air supply valve V9 to LP_SP_S to raise the low pressure LP for air supply. The increase of the air volume leads to the increase of the medium pressure MP, and the increase of the medium pressure MP increases the displacement of the high-pressure compressor unit, which leads to the increase of the high pressure HP; The PID controller of the valve V9 is reduced to LP_SP_D, so as to control the air supply valve V9 to close quickly to end the air supply. The PID controller setting value LP_SP_S of the air supply valve V9 is dynamically given according to the load change. When the load suction speed increases , increase the air supply speed correspondingly by increasing the PID controller setting value LP_SP_S of the air supply valve V9. 6. A method for controlling multi-stage pressure of a large helium compressor station according to claim 1, characterized in that: the control system is implemented by a PLC system or a DCS control framework, and the field equipment layer is composed of measuring instruments and actuators, through The I/O card is connected to the control layer, and the control layer is the control card of PLC or DCS; the PLC or DCS upper computer system communicates with the control layer through the control network to realize monitoring signal acquisition and control configuration download.