A method, system and controller for automatic loading and grid connection of a compressor unit

Abstract

The application discloses a kind of compressor unit automatic loading and grid-connected method, system and controller, it is applied to controller, controller is respectively with the high load unit of compressor unit, low load unit and station backflow valve communication.The method comprises: when low load unit is in low-speed warm-up state, whether the deviation value of the running working point of high load unit and anti-surge control line is greater than first margin;When the deviation value of the running working point of high load unit and anti-surge control line is greater than first margin, control high load unit to reduce speed, to provide gas volume for low load unit;In the case where low load unit is in automatic loading state, according to the deviation value of the working point of high load unit and anti-surge control line control station backflow valve opening valve or valve;In the case where it is detected that low load unit completes loading, to low load unit and high load unit are grid-connected control.The application is suitable for various working conditions to reduce unnecessary energy consumption in the process of unit grid connection, increase the success rate of unit grid connection.

Description

Technical Field

[0001] This application relates to the field of natural gas compressor unit grid connection technology, specifically to a method, system and controller for automatic grid connection of compressor units. Background Technology

[0002] In compressor stations with multiple electrically driven centrifugal compressor units operating in parallel, significant manual intervention is required for load loading and grid connection operations, which is prone to misoperation and misjudgment. Existing control strategies cannot adapt to abnormal operating conditions of low flow and low load, resulting in the inability to load the units after startup and causing energy waste. When starting a unit individually, operators need to manually and gradually increase the output of the speed controller and set the anti-surge controller to complete the unit loading. Furthermore, when multiple units are connected to the grid, the later-starting unit is limited by the back pressure of the already connected high-load units, preventing the anti-surge valve from closing and the loading control from being achieved by increasing the speed. When facing insufficient gas supply to the compressor station, even manually reducing the speed of high-load units and increasing the speed of low-load units cannot complete the unit loading; it is necessary to manually open the station return valve to provide sufficient natural gas flow and perform load distribution control. Summary of the Invention

[0003] The purpose of this application is to provide a method, system, and controller for automatic loading and grid connection of compressor units, in order to solve the problem that in the prior art, the loading and grid connection of unit loads requires manual intervention, which poses a risk of misoperation and prediction errors, resulting in high energy consumption of the compressor unit.

[0004] To achieve the above objectives, the first aspect of this application provides a method for automatic loading and grid connection of a compressor unit, applied to a controller. The controller includes a pressure controller, a performance controller, an anti-surge controller, a speed controller, and an equal margin controller. The controller communicates with the high-load unit, the low-load unit, and the station return valve of the compressor unit, respectively. The method includes:

[0005] When the low-load unit is in a low-speed warm-up state, determine whether the deviation between the operating point of the high-load unit and its own anti-surge control line is greater than the first margin.

[0006] If the deviation between the operating point of the high-load unit and its own anti-surge control line is greater than the first margin, the high-load unit is controlled to reduce its speed in order to provide gas volume to the low-load unit.

[0007] When the low-load unit is in automatic loading mode, the control station return valve is opened or closed according to the deviation between the operating point of the high-load unit and its own anti-surge control line.

[0008] When it is detected that the low-load unit has completed loading, equal margin grid connection control is performed on the low-load unit and the high-load unit.

[0009] In this embodiment of the application, when the low-load unit is in automatic loading state, controlling the station return valve to open based on the deviation between the operating point of the high-load unit and its own anti-surge control line includes:

[0010] When the low-load unit is in automatic loading state, determine whether the amount of gas swallowed by the low-load unit and discharged by the high-load unit is greater than the preset amount of gas, and whether the deviation between the operating point of the high-load unit and its own anti-surge control line is greater than the second margin.

[0011] When the gas volume is not greater than the preset gas volume and the deviation between the operating point of the high-load unit and its own anti-surge control line is not greater than the second margin, the control station return valve opens to provide gas volume to the low-load unit.

[0012] In this embodiment of the application, when the low-load unit is in automatic loading mode, controlling the station return valve to close based on the deviation between the operating point of the high-load unit and its own anti-surge control line includes:

[0013] During the process of the station return valve supplying gas to the low-load unit, if the deviation between the operating point of the high-load unit and its own anti-surge control line is detected to be greater than the third margin, the station return valve will be closed.

[0014] In this embodiment of the application, controlling the high-load unit to reduce its speed to provide gas volume to the low-load unit includes:

[0015] The high-load unit exits the equal margin control state of the load distribution control and begins to reduce its speed to provide gas to the low-load unit.

[0016] During the deceleration process of a high-load unit, if the deviation between the operating point of the high-load unit and its own anti-surge control line is less than the first margin, the high-load unit is controlled to stop decelerating.

[0017] In this embodiment of the application, when it is detected that the low-load unit has completed loading, the grid connection control of the low-load unit and the high-load unit includes:

[0018] Switch low-load units to grid-connected control mode;

[0019] Switch high-load units to grid-connected control mode;

[0020] Equal margin control is implemented for low-load and high-load units operating online.

[0021] In this application implementation, the method further includes:

[0022] When the compressor unit reaches its minimum operating speed, switch the individual pressure controller to automatic mode;

[0023] The set value of the single-unit pressure controller is higher than the first gradient value of the compressor unit outlet pressure, so that the operating point of the compressor unit is located to the right of the anti-surge line.

[0024] A second aspect of this application provides a controller, the controller comprising:

[0025] The memory is configured to store instructions; and

[0026] The processor is configured to retrieve instructions from memory and to enable automatic loading and grid connection of the compressor unit while executing the instructions.

[0027] A third aspect of this application provides a system for automatic grid connection of a compressor unit, comprising:

[0028] According to the above controller, the controller includes a pressure controller, a performance controller, an anti-surge controller, a speed controller, and an equal margin controller;

[0029] High-load units communicate with the controller;

[0030] Low-load units communicate with the controller;

[0031] The station's return valve communicates with the controller.

[0032] A fourth aspect of this application provides a machine-readable storage medium storing instructions for causing a machine to execute a method for automatically matching loading and grid connection according to the opening degree of a station return valve as described above.

[0033] The above technical solution establishes communication between the controller and the high-load and low-load units of the compressor group, as well as the station return valve. When the low-load unit is in a low-speed warm-up state, the controller checks if the deviation between the operating point of the high-load unit and its anti-surge control line exceeds a first margin. If it does, the high-load unit exits the equal-margin control state of load distribution control and begins to reduce its speed to provide gas to the low-load unit. When the low-load unit is in automatic loading mode, the controller opens or closes the station return valve based on the deviation between the high-load unit's operating point and its own anti-surge control line. This process continues until the low-load unit completes loading. Then, both the low-load and high-load units are switched to grid-connected control mode, and equal-margin control under load distribution control is restarted for all online units. This application automatically loads and connects the compressor unit to the grid through a controller, ensuring that low-load units have sufficient gas volume to quickly complete the loading process, while also ensuring the safe operation of high-load units. It can also avoid additional energy consumption by providing only the necessary return gas volume through the feed station return valve. This control method can realize the function of efficient automatic loading and grid connection of low-load units under operating conditions such as low flow rate and high pressure ratio, reducing the risk of misoperation and prediction errors, and reducing the energy consumption of the compressor unit.

[0034] Other features and advantages of the embodiments of this application will be described in detail in the following detailed description section. Attached Figure Description

[0035] The accompanying drawings are provided to further illustrate the embodiments of this application and form part of the specification. They are used together with the following detailed description to explain the embodiments of this application, but do not constitute a limitation on the embodiments of this application. In the drawings:

[0036] Figure 1 A flowchart illustrating an automatic grid connection method for a compressor unit according to an embodiment of this application is shown schematically;

[0037] Figure 2 This schematic diagram illustrates a structural block diagram of a controller according to an embodiment of the present application;

[0038] Figure 3 The illustration schematically depicts a system capable of performing an automatic loading and grid connection method for a compressor unit according to an embodiment of this application.

[0039] Explanation of reference numerals in the attached figures

[0040] 210 memory, 220 processor Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only for illustration and explanation of the embodiments of this application and are not intended to limit the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0042] It should be noted that if the embodiments of this application involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0043] Furthermore, if the embodiments of this application involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, features defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed in this application.

[0044] Figure 1 A flowchart illustrating an automatic grid connection method for a compressor unit according to an embodiment of this application is shown schematically. Figure 1 As shown in the embodiment of this application, a method for automatic loading and grid connection of a compressor unit is applied to a controller. The controller includes a pressure controller, a performance controller, an anti-surge controller, a speed controller, and an equal margin controller. The controller communicates with the high-load unit, the low-load unit, and the station return valve of the compressor unit, respectively. The method may include the following steps:

[0045] Step 101: When the low-load unit is in a low-speed warm-up state, determine whether the deviation between the operating point of the high-load unit and its own anti-surge control line is greater than the first margin.

[0046] Step 102: When the deviation between the operating point of the high-load unit and its own anti-surge control line is greater than the first margin, control the high-load unit to reduce its speed so as to provide gas volume to the low-load unit.

[0047] Step 103: When the low-load unit is in automatic loading mode, control the station return valve to open or close according to the deviation value between the operating point of the high-load unit and its own anti-surge control line.

[0048] Step 104: When it is detected that the low-load unit has completed loading, perform equal margin grid connection control on the low-load unit and the high-load unit.

[0049] This application discloses a method for automatic grid connection of a compressor unit, which is applied to a system for automatic grid connection of a compressor unit. The system may include a controller, a high-load compressor unit, a low-load compressor unit, and a station return valve. The controller communicates with the high-load compressor unit, the low-load compressor unit, and the station return valve. The controller may include a pressure controller, a performance controller, an anti-surge controller, a speed controller, and an equal margin controller.

[0050] In this embodiment, when the compressor unit needs to be connected to the grid, it is necessary to reduce the speed of the high-load unit that starts first and increase the speed of the low-load unit that starts later. Existing technology requires manually reducing the speed of the high-load unit and increasing the speed of the low-load unit. When the gas supply from the compressor station is insufficient, it is often impossible to complete the unit loading, and the station return valve needs to be manually opened. Therefore, this easily leads to the risk of misoperation or misjudgment, and the station return valve cannot be opened and closed precisely, resulting in high energy consumption of the compressor unit. Therefore, this embodiment provides a method for the controller to automatically load and connect the low-load unit to the grid, achieving automatic loading of the low-load unit by precisely controlling the opening or closing of the return valve.

[0051] In this embodiment, the low-load unit initially operates in a low-speed warm-up state. When the low-load unit is in this state and the deviation between the operating point of the high-load unit and the controller's anti-surge control line exceeds a first margin, the high-load unit is controlled to exit the grid, i.e., it exits the equal margin control state of load distribution control and begins automatic speed reduction. While the high-load unit is slowing down, it can supply gas to the low-load unit. The anti-surge control line refers to the operating point that maintains the safe operation of the compressor unit, determined by detecting the compressor unit's pressure and flow rate and based on a preset control strategy. The first margin refers to the margin required to determine whether the high-load unit should exit the grid. The margin refers to the deviation between the compressor unit's operating point and its own anti-surge control line. When the deviation between the high-load unit's operating point and the controller's own anti-surge control line exceeds the first margin, it indicates that the high-load unit's operating point maintains sufficient margin with the controller's anti-surge control line; therefore, the high-load unit can be controlled to exit the grid.

[0052] In this embodiment, after the low-load unit completes the low-speed warm-up state, it enters the automatic loading state. During the automatic loading process of the low-load unit, if the low-load unit cannot complete the loading even after absorbing the gas volume discharged by the high-load unit (i.e., the anti-surge valve is closed), and the operating point of the high-load unit cannot maintain the minimum safety margin of its own anti-surge control line, the controller can control the automatic opening of the station return valve. This provides sufficient gas volume for the automatic loading process of the low-load unit, ensuring that the low-load unit can quickly complete the loading process, while also ensuring that the high-load unit does not reduce its own load to an unsafe range when discharging gas.

[0053] In this embodiment, during the automatic opening of the station return valve to supply gas to the low-load unit, if the deviation between the operating point of the high-load unit and the controller's anti-surge line is too large, it indicates that the station return valve opening is too large, resulting in excessive return flow and increased energy consumption. Therefore, the controller can automatically close the station return valve to reduce energy loss caused by excessive opening of the station return valve during the gradual increase of the low-load unit load.

[0054] Once the low-load units have completed loading, the controller can automatically switch the low-load units to grid-connected control mode. At the same time, it can automatically switch the high-load units that were temporarily disconnected from the grid during the low-load unit loading process to grid-connected control mode. After that, it can control all online units to restart equal margin control under load distribution control.

[0055] This application embodiment automatically loads and connects the compressor unit to the grid through the controller, ensuring that the low-load unit has sufficient gas volume to quickly complete the loading, while also ensuring the safe operation of the high-load unit. It can also avoid additional energy consumption by providing only the necessary return gas volume through the feed station return valve. This control method can realize the function of efficient automatic loading and grid connection of low-load units under operating conditions such as low flow rate and high flow rate and high pressure ratio, reducing the risk of misoperation and prediction errors and reducing the energy consumption of the compressor unit.

[0056] In this embodiment of the application, the method further includes:

[0057] When the compressor unit reaches its minimum operating speed, switch the individual pressure controller to automatic mode;

[0058] The set value of the single-unit pressure controller is higher than the first gradient value of the compressor unit outlet pressure, so that the operating point of the compressor unit is located to the right of the anti-surge line.

[0059] When starting the first compressor unit, a booster pump is used to pressurize it, increasing its speed from 0 to minimum. Afterward, the first compressor unit's speed is independently supplied internally. Once the first compressor unit reaches its minimum operating speed, the individual unit pressure controller switches to automatic mode, and its setpoint is always set at a gradient value higher than the compressor unit's outlet pressure. This gradient value depends on the outlet pressure under different conditions. The performance controller outputs to the speed controller and anti-surge controller, enabling the unit to simultaneously increase speed and close the anti-surge valve. This function positions the first compressor unit's operating point to the right of the anti-surge line, making it a high-load compressor unit. The high-load unit switches to grid-connected control mode, initiating equal-margin control under load distribution control. This achieves rapid valve closure and rapid speed increase, reducing energy consumption.

[0060] In this embodiment of the application, step 102, controlling the high-load unit to reduce its speed to provide gas volume to the low-load unit, may include:

[0061] The high-load unit exits the equal margin control state of the load distribution control and begins to reduce its speed to provide gas to the low-load unit.

[0062] In actual production environments, if a single compressor unit cannot supply enough natural gas, multiple compressor units will be activated in parallel to boost the natural gas pipeline and provide the required natural gas pressure. Starting with the second compressor unit, once the booster pump provides the compressor unit with the minimum operating speed for the low-load unit, that compressor unit will remain in a low-speed warm-up state, functioning as a low-load unit. The first compressor unit is the high-load unit. At this time, the controller determines whether to reduce the speed of the high-load unit by judging whether the deviation between the operating point of the first compressor unit and its own anti-surge control line is consistently greater than the first margin. The first margin is the margin required to determine whether the high-load unit needs to be reduced in speed. If the operating point of the high-load unit (i.e., the first compressor unit) consistently deviates from its own anti-surge control line by more than the first margin, then this high-load unit exits the equal margin control state of load distribution control and begins automatic speed reduction to provide gas volume and increase the speed of the low-load unit. The operating point and anti-surge control line corresponding to each compressor unit may be different; therefore, the specific first margin needs to be determined for each specific compressor unit. This allows the low-load unit to draw in additional air volume from the high-load unit during low-speed warm-up, thus accelerating the loading process of the low-load unit.

[0063] In this embodiment of the application, the method further includes:

[0064] During the deceleration process of a high-load unit, if the deviation between the operating point of the high-load unit and its own anti-surge control line is less than the first margin, the high-load unit is controlled to stop decelerating.

[0065] If, during the process of reducing speed and discharging output, the deviation between the operating point and its own anti-surge control line of the high-load unit is not greater than the first margin, then the high-load unit will no longer reduce speed and discharge output, and will maintain the current speed to ensure the normal operation of the high-load unit.

[0066] In this embodiment of the application, step 103, when the low-load unit is in automatic loading state, controlling the station return valve to open based on the deviation between the operating point of the high-load unit and its own anti-surge control line may include:

[0067] When the low-load unit is in automatic loading state, determine whether the amount of gas swallowed by the low-load unit and discharged by the high-load unit is greater than the preset amount of gas, and whether the deviation between the operating point of the high-load unit and its own anti-surge control line is greater than the second margin.

[0068] When the gas volume is not greater than the preset gas volume and the deviation between the operating point of the high-load unit and its own anti-surge control line is not greater than the second margin, the control station return valve opens to provide gas volume to the low-load unit.

[0069] In this embodiment, the low-load unit enters an automatic loading process after ingesting the reduced-speed exhaust volume of the high-load unit (i.e., the first compressor unit). If the low-load unit still cannot complete loading after ingesting the exhaust volume of the high-load unit, the anti-surge valve closes, and the deviation between the operating point of the high-load unit and its own anti-surge line is no greater than the second margin. The anti-surge control line refers to the operating point that maintains the safe operation of the compressor unit, determined by detecting the pressure and flow rate of the compressor unit and according to a preset control strategy. The second margin refers to the minimum safety margin that the high-load unit's operating point can maintain relative to its own anti-surge control line. At this time, the station return valve automatically opens.

[0070] Specifically, the control station's return valve opening is performed in the following ways:

[0071] If the station return valve control output is less than 15%, and the station return valve is triggered to open, then the station return valve controller will automatically step control to 15%.

[0072] The station return valve controller is in automatic mode. The station return valve is triggered to open if the following conditions are met: (1# unit needs to open its return valve while waiting for subsequent units; 2# unit needs to open its return valve while waiting for subsequent units; 3# unit needs to open its return valve while waiting for subsequent units; 4# unit needs to open its return valve while waiting for subsequent units; or 1# unit needs to open its return valve during high-load discharge; or 2# unit needs to open its return valve during high-load discharge; or 3# unit needs to open its return valve during high-load discharge; or 4# unit needs to open its return valve during high-load discharge; or 1# unit needs to open its return valve as a subsequent start-up unit; or 2# unit needs to open its return valve during high-load discharge; or 3# unit needs to open its return valve during high-load discharge; or 4# unit needs to open its return valve during high-load discharge).

[0073] If the station return valve control output is ≥15%, and (after triggering the station return valve to open, Unit 1 needs to re-open the station return valve to enable it; or after triggering the station return valve to open, Unit 2 needs to re-open the station return valve to enable it; or after triggering the station return valve to open, Unit 3 needs to re-open the station return valve to enable it; or after triggering the station return valve to open, Unit 4 needs to re-open the station return valve to enable it), then the station return valve controller will automatically increment the step control by 15%.

[0074] If the station return valve control output is ≥15%, the station return valve is triggered to open. If the above conditions are met, the station return valve controller automatically increments by 1% in a step control cycle of 5 seconds.

[0075] After the station reflux valve opens, the inlet gas volume of the low-load compressor unit increases, while the outlet gas volume decreases, resulting in an overall increase in the gas volume of the low-load compressor unit. Specifically, the station reflux valve opens in a step-like manner by gradually increasing the opening degree per unit time. Closed-loop control and automatic matching of the operating point margins of each compressor unit are achieved by combining the detection of whether the low-load unit has completed loading with a comparison of the deviation between the high-load unit's operating point and its own anti-surge line with the second margin. The automatic opening of the station reflux valve provides sufficient gas volume for the low-load unit during loading, ensuring that the low-load unit can quickly complete loading, while also ensuring that the high-load unit does not drop its own load to an unsafe range when discharging.

[0076] In this embodiment of the application, step 103, when the low-load unit is in automatic loading state, controlling the station return valve to close based on the deviation between the operating point of the high-load unit and its own anti-surge control line may include:

[0077] During the process of the station return valve supplying gas to the low-load unit, if the deviation between the operating point of the high-load unit and its own anti-surge control line is detected to be greater than the third margin, the station return valve will be closed.

[0078] During the process of supplying gas to low-load units by opening the station return valve, if the deviation between the operating point of the high-load unit and its own anti-surge line exceeds the third margin, it indicates that the station return valve is opened too wide, resulting in excessive return flow and increased energy consumption. The anti-surge control line refers to the operating point that maintains the safe operation of the compressor unit, determined by detecting the compressor unit's pressure and flow rate and based on a preset control strategy. The third margin refers to the deviation between the high-load unit's operating point and its own anti-surge control line exceeding a certain value due to the station return valve opening being too large, i.e., excessive natural gas return flow. At this point, the station return valve begins to close, and the controller detects the average operating margin of each unit. If the average operating margin is already greater than the preset third margin, the station return valve performs step-by-step valve closing control by gradually decreasing its opening within a unit time. Closed-loop control and automatic matching of the operating point margin of each compressor unit are achieved by detecting whether the low-load unit has completed loading and combining the control method of real-time margin detection of each compressor unit.

[0079] Specifically, the following conditions must be met for the station return valve to close:

[0080] If Unit #1 is started as the first unit when multiple units are started, and the number of units started does not reach the preset value, and the margin of Unit #1 is greater than or equal to the set value of the station shutdown return valve margin (14%), then the enablement of the station shutdown return valve for Unit #1 during the waiting period for subsequent units is triggered. If the margin of Unit #1 is less than the set value of the stop station shutdown return valve margin (13%), then the enablement of the station shutdown return valve for Unit #1 during the waiting period for subsequent units is canceled.

[0081] If Unit #1 is started as the second unit during a multi-unit startup operation, and the number of units started does not reach the preset value, and the margin of Unit #1 is greater than or equal to the set value of the station shutdown return valve margin (14%), then the enablement for Unit #1 to agree to close the station return valve during the waiting period for subsequent units is triggered. If the margin of Unit #1 is less than the set value of the stop-shutdown return valve margin (13%), then the enablement for Unit #1 to agree to close the station return valve during the waiting period for subsequent units is canceled.

[0082] If the margin of Unit 1 is greater than or equal to the set value of the station shut-off return valve margin (14%), the load distribution of Unit 1 is allowed to be put into operation, and the equal margin controller of Unit 1 is put into operation, then the enable of allowing the station shut-off return valve during the high-load unit output process of Unit 1 will be triggered. If the margin of Unit 1 is less than the set value of the stop-continue station shut-off return valve margin (13%), then the enable of allowing the station shut-off return valve during the high-load unit output process of Unit 1 will be canceled.

[0083] If Unit #2 is started as the first unit in a multi-unit startup scenario, and the number of units started does not reach the preset value, and the margin of Unit #2 is greater than or equal to the set value of the station shutdown return valve margin (14%), then the enablement for Unit #2 to agree to close the station return valve during the waiting period for subsequent units is triggered. If the margin of Unit #2 is less than the set value of the stop-shutdown return valve margin (13%), then the enablement for Unit #2 to agree to close the station return valve during the waiting period for subsequent units is canceled.

[0084] If Unit #2 is started as the second unit during a multi-unit startup operation, and the number of units started does not reach the preset value, and the margin of Unit #2 is greater than or equal to the set value of the station shutdown return valve margin (14%), then the enablement for Unit #2 to agree to close the station return valve during the waiting period for subsequent units is triggered. If the margin of Unit #2 is less than the set value of the stop-shutdown return valve margin (13%), then the enablement for Unit #2 to agree to close the station return valve during the waiting period for subsequent units is canceled.

[0085] If the margin of Unit 2 is greater than or equal to the set value of the station shut-off return valve margin (14%), the load distribution of Unit 2 is allowed to be put into operation, and the equal margin controller of Unit 2 is put into operation, then the enable of allowing the station shut-off return valve during the high-load unit output process of Unit 2 will be triggered. If the margin of Unit 2 is less than the set value of the stop-continue station shut-off return valve margin (13%), then the enable of allowing the station shut-off return valve during the high-load unit output process of Unit 2 will be canceled.

[0086] If Unit #3 is started as the first unit when multiple units are started, and the number of units started does not reach the preset value, and the margin of Unit #3 is greater than or equal to the set value of the station shutdown return valve margin (14%), then the enablement of the station shutdown return valve for Unit #3 during the waiting period for subsequent units is triggered. If the margin of Unit #3 is less than the set value of the stop station shutdown return valve margin (13%), then the enablement of the station shutdown return valve for Unit #3 during the waiting period for subsequent units is canceled.

[0087] If Unit #3 is started as the second unit during a multi-unit startup operation, and the number of units started does not reach the preset value, and the margin of Unit #3 is greater than or equal to the set value of the station shutdown return valve margin (14%), then the enablement for Unit #3 to agree to close the station return valve during the waiting period for subsequent units is triggered. If the margin of Unit #3 is less than the set value of the stop-shutdown return valve margin (13%), then the enablement for Unit #3 to agree to close the station return valve during the waiting period for subsequent units is canceled.

[0088] If the margin of Unit 3 is greater than or equal to the set value of the station shut-off return valve margin (14%), the load distribution of Unit 3 is allowed to be put into operation, and the equal margin controller of Unit 3 is in operation, then the enable of allowing the station shut-off return valve during the high-load unit output process of Unit 3 will be triggered. If the margin of Unit 3 is less than the set value of the stop-continue station shut-off return valve margin (13%), then the enable of allowing the station shut-off return valve during the high-load unit output process of Unit 3 will be canceled.

[0089] If Unit #4 is started as the first unit when multiple units are started, and the number of units started does not reach the preset value, and the margin of Unit #4 is greater than or equal to the set value of the station shutdown return valve margin (14%), then the enablement of the station shutdown return valve for Unit #4 during the waiting period for subsequent units is triggered. If the margin of Unit #4 is less than the set value of the stop station shutdown return valve margin (13%), then the enablement of the station shutdown return valve for Unit #4 during the waiting period for subsequent units is canceled.

[0090] If Unit #4 is started as the second unit during a multi-unit startup operation, and the number of units started does not reach the preset value, and the margin of Unit #4 is greater than or equal to the set value of the station shutdown return valve margin (14%), then the enablement for Unit #4 to agree to close the station return valve during the waiting period for subsequent units is triggered. If the margin of Unit #4 is less than the set value of the stop-shutdown return valve margin (13%), then the enablement for Unit #4 to agree to close the station return valve during the waiting period for subsequent units is canceled.

[0091] If the margin of Unit 4 is greater than or equal to the set value of the station shut-off return valve margin (14%), the load distribution of Unit 4 is allowed to be put into operation, and the equal margin controller of Unit 4 is in operation, then the permission to close the station return valve during the high-load output process of Unit 4 will be triggered. If the margin of Unit 4 is less than the set value of the stop-continue station shut-off return valve margin (13%), then the permission to close the station return valve during the high-load output process of Unit 4 will be canceled.

[0092] Specifically, the station return valve closing control is executed in the following steps:

[0093] ① If the load distribution of Unit 1 is permitted to be put into operation, and Unit 1 is in the process of discharging at high load, the request to shut down the station return valve is approved; if the load distribution of Unit 1 is not permitted to be put into operation, and Unit 1 is in the process of waiting for subsequent units, the request to shut down the station return valve is approved.

[0094] Alternatively, Unit 1 may be in a standby state.

[0095] Or Unit 1 is in a fault shutdown state.

[0096] Or Unit 1 is in a normal shutdown state.

[0097] ② If the load distribution of Unit 2 is permitted to be put into operation, and Unit 2 is in the process of discharging at high load, the request to shut down the station return valve is approved; if the load distribution of Unit 2 is not permitted to be put into operation, and Unit 2 is in the process of waiting for subsequent units, the request to shut down the station return valve is approved.

[0098] Alternatively, Unit 2 may be in a standby state.

[0099] Alternatively, Unit 2 may be in a fault shutdown state.

[0100] Alternatively, Unit 2 may be in a normal shutdown state.

[0101] ③ If the load distribution of Unit 3 is permitted to be put into operation, and Unit 3 is in the process of discharging at high load, the request to shut down the station return valve is approved; if the load distribution of Unit 3 is not permitted to be put into operation, and Unit 3 is waiting for subsequent units, the request to shut down the station return valve is approved.

[0102] Alternatively, Unit 3 may be in a standby state.

[0103] Or Unit 3 is in a fault shutdown state.

[0104] Or Unit 3 is in a normal shutdown state.

[0105] ④ If the load distribution of Unit 4 is permitted to be put into operation, and Unit 4 is in the process of discharging at high load, the request to shut down the station return valve is approved; if the load distribution of Unit 4 is not permitted to be put into operation, and Unit 4 is in the process of waiting for subsequent units, the request to shut down the station return valve is approved.

[0106] Alternatively, Unit 4 may be in a standby state.

[0107] Or Unit 4 is in a fault shutdown state.

[0108] Alternatively, Unit 4 may be in a normal shutdown state.

[0109] ①②③④ generate a request to close a station return valve. If the average distance from the operating point to the control line is greater than 30%, the station return valve is activated to close after a 10-second delay. Every 30 seconds, the station return valve controller automatically decrements by 1% in a step control manner.

[0110] ①②③④ generate a request to close a station return valve. If 14% < the average distance from the operating point to the control line ≤ 30%, the station return valve is activated to close after a 60-second delay. If 14% < the average distance from the operating point to the control line ≤ 30%, the station return valve controller automatically decrements by 1% every 60 seconds; if 13% < the average distance from the operating point to the control line ≤ 14%, the station return valve controller automatically decrements by 1% every 120 seconds.

[0111] If the station return valve controller is set to automatic mode, and the station return valve is triggered to close, and the station return valve position feedback is ≤5%, then the automatic step control of the station return valve controller is 0, and the station return valve control output is 0.

[0112] When the station return valve controller is set to automatic mode, the station return valve is triggered to close. The start-up quantity setting is 0. The speeds of Unit 1, Unit 2, Unit 3, and Unit 4 are all less than 3100 rpm. If all of the above conditions are met simultaneously, the automatic step control of the station return valve controller is 0, and the station return valve control output is 0.

[0113] If the station return valve controller is set to automatic mode, and the station return valve is triggered to close, and the station return valve position feedback is ≤5%, then the station return valve control output = the station return valve controller automatic step control, and the station return valve controller automatic step control range is between 0% and 50%.

[0114] If the station return valve controller is set to manual mode, the station return valve control output equals the output value written to the unit's host computer.

[0115] The automatic closing of the station return valve reduces energy loss caused by excessive opening of the station return valve during the gradual increase of load on low-load units.

[0116] In this embodiment of the application, step 104, when it is detected that the low-load unit has completed loading, the grid connection control of the low-load unit and the high-load unit may include:

[0117] Switch low-load units to grid-connected control mode;

[0118] Switch high-load units to grid-connected control mode;

[0119] Equal margin control is implemented for low-load and high-load units operating online.

[0120] In this application, after the low-load unit completes loading, the controller automatically switches the low-load unit to grid-connected control mode, and at the same time automatically switches the high-load unit that was temporarily disconnected from the grid during the loading process to grid-connected control mode. After that, all online units resume equal margin control under load distribution control.

[0121] Figure 2 A schematic block diagram of a controller according to an embodiment of this application is shown. Figure 2 As shown in the figure, this application embodiment provides a controller, which may include:

[0122] Memory 210 is configured to store instructions; and

[0123] The processor 220 is configured to retrieve instructions from memory 210 and to implement a method for automatically loading and connecting the compressor unit to the grid when executing the instructions.

[0124] Specifically, in this embodiment of the application, the processor 220 can be configured to:

[0125] When the compressor unit reaches its minimum operating speed, switch the individual pressure controller to automatic mode;

[0126] The set value of the pressure controller of the single unit is higher than the first gradient value of the compressor unit outlet pressure so that the operating point of the compressor unit is located to the right of the anti-surge line;

[0127] When the low-load unit is in a low-speed warm-up state, determine whether the deviation between the operating point of the high-load unit and its own anti-surge control line is greater than the first margin.

[0128] If the deviation between the operating point of the high-load unit and its own anti-surge control line is greater than the first margin, the high-load unit is controlled to reduce its speed in order to provide gas volume to the low-load unit.

[0129] When the low-load unit is in automatic loading mode, the control station return valve is opened or closed according to the deviation between the operating point of the high-load unit and its own anti-surge control line.

[0130] When it is detected that the low-load unit has completed loading, equal margin grid connection control is performed on the low-load unit and the high-load unit.

[0131] Furthermore, the processor 220 can also be configured to:

[0132] When the low-load unit is in automatic loading state, determine whether the amount of gas swallowed by the low-load unit and discharged by the high-load unit is greater than the preset amount of gas, and whether the deviation between the operating point of the high-load unit and its own anti-surge control line is greater than the second margin.

[0133] When the gas volume is not greater than the preset gas volume and the deviation between the operating point of the high-load unit and its own anti-surge control line is not greater than the second margin, the control station return valve opens to provide gas volume to the low-load unit.

[0134] During the process of the station return valve supplying gas to the low-load unit, if the deviation between the operating point of the high-load unit and its own anti-surge control line is detected to be greater than the third margin, the station return valve is controlled to close.

[0135] The high-load unit exits the equal margin control state of the load distribution control and begins to reduce its speed to provide gas to the low-load unit.

[0136] During the deceleration process of a high-load unit, if the deviation between the operating point of the high-load unit and its own anti-surge control line is less than the first margin, the high-load unit will be controlled to stop decelerating.

[0137] Switch low-load units to grid-connected control mode;

[0138] Switch high-load units to grid-connected control mode;

[0139] Equal margin control is implemented for low-load and high-load units operating online.

[0140] By automatically loading and connecting the compressor unit to the grid through the controller, it is ensured that the low-load unit has sufficient gas volume to quickly complete the loading, while also ensuring the safe operation of the high-load unit. It can also avoid additional energy consumption by providing only the necessary return gas volume through the feed station return valve. This control method can realize the function of efficient automatic loading and grid connection of low-load units under operating conditions such as low flow rate and high pressure ratio, reducing the risk of misoperation and prediction errors, and reducing the energy consumption of the compressor unit.

[0141] Figure 3 The diagram schematically illustrates the structure of a compressor automatic loading and grid connection system according to an embodiment of this application. Figure 3 As shown in the figure, this application provides a system for automatic grid connection of a compressor unit, which may include:

[0142] According to the controller 310 described above, the controller 310 includes a pressure controller, a performance controller, an anti-surge controller, a speed controller, and an equal margin controller.

[0143] High-load unit 320 communicates with controller 310;

[0144] Low-load unit 330 communicates with controller 310;

[0145] Station return valve 340 communicates with controller 310.

[0146] The controller 310 communicates with the high-load unit 320, the low-load unit 330, and the station return valve 340. When the low-load unit 330 is in a low-speed warm-up state, if the operating point of the high-load unit 320 consistently deviates from its anti-surge control line by more than the first margin, the controller 310 controls the high-load unit 320 to disconnect from the grid, i.e., exit the equal margin control state of the load distribution control of the controller 310, and the high-load unit 320 begins to decelerate. If, during the deceleration process, the operating point of the high-load unit 320 deviates from its anti-surge control line by less than the first margin, the controller 310 controls the high-load unit 320 to stop decelerating and maintain its current speed. During the automatic loading process of the low-load unit 330 controlled by the controller 310, if the low-load unit 330 cannot complete the loading even after absorbing the gas discharged from the high-load unit 320, the anti-surge valve will be closed. Furthermore, if the deviation between the operating point of the high-load unit 320 and its own anti-surge control line is no greater than the second margin, the controller 310 will automatically open the control station return valve 340 to ensure that the low-load unit 330 can quickly complete the loading process and to prevent the high-load unit 320 from dropping its load to an unsafe range. During the process of the controller 310 controlling the control station return valve 340 to supply gas to the low-load unit 330, if the deviation between the operating point of the high-load unit 320 and its own anti-surge control line is greater than the third margin, the controller 310 will close the control station return valve 340 to reduce energy loss caused by excessive opening of the return valve 340. After the low-load unit 330 completes loading, the controller 310 automatically switches the low-load unit 330 to grid-connected control mode. At the same time, the high-load unit 320, which was temporarily disconnected from the grid during the loading process of the low-load unit 330, is automatically switched to grid-connected control mode. After that, all online compressor units resume equal margin control under load distribution control.

[0147] The above technical solutions ensure that low-load units have sufficient gas volume to quickly complete loading, while also ensuring the safe operation of high-load units. Furthermore, by providing only the necessary return gas volume through the feed station return valve, additional energy consumption can be avoided. This control method can achieve efficient automatic loading and grid connection of low-load units under operating conditions such as low flow rate and high pressure ratio, and high flow rate and high pressure ratio.

[0148] This application also provides a machine-readable storage medium storing instructions for causing a machine to execute the above-described method for automatically loading and connecting a compressor unit to the grid.

[0149] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0150] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0151] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0152] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0153] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0154] Memory may include non-persistent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0155] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0156] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0157] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A method for automatic grid connection of a compressor unit, characterized in that, The method is applied to a controller, which includes a pressure controller, a performance controller, an anti-surge controller, a speed controller, and an equal margin controller. The controller communicates with the high-load unit, the low-load unit, and the station return valve of the compressor unit, respectively. When the low-load unit is in a low-speed warm-up state, determine whether the deviation between the operating point of the high-load unit and its own anti-surge control line is greater than the first margin. If the deviation between the operating point of the high-load unit and its own anti-surge control line is greater than the first margin, the high-load unit is controlled to reduce its speed in order to provide gas volume to the low-load unit. When the low-load unit is in automatic loading mode, it is determined whether the amount of gas consumed by the low-load unit from the high-load unit is greater than the preset amount of gas, and whether the deviation between the operating point of the high-load unit and its own anti-surge control line is greater than the second margin; the second margin is the minimum safety margin that the operating point of the high-load unit can maintain from its own anti-surge control line. When the gas volume is not greater than the preset gas volume and the deviation between the operating point of the high-load unit and its own anti-surge control line is not greater than the second margin, the station return valve is opened to provide gas volume to the low-load unit. During the process of the station return valve supplying gas to the low-load unit, if the deviation between the operating point of the high-load unit and its own anti-surge control line is detected to be greater than the third margin, the station return valve is controlled to close. When it is detected that the low-load unit has completed loading, equal margin grid connection control is performed on the low-load unit and the high-load unit; Specifically, during the deceleration process of the high-load unit, if the deviation between the operating point of the high-load unit and its own anti-surge control line is less than a first margin, the high-load unit is controlled to stop decelerating.

2. The method according to claim 1, characterized in that, Controlling the high-load unit to reduce its speed in order to supply gas volume to the low-load unit includes: The high-load unit is controlled to exit the equal margin control state of load distribution control and begin to reduce speed in order to provide gas volume to the low-load unit.

3. The method according to claim 1, characterized in that, When the low-load unit is detected to have completed loading, the grid connection control of the low-load unit and the high-load unit includes: Switch the low-load unit to grid-connected control mode; Switch the high-load unit to grid-connected control mode; Equal margin control is performed on the low-load and high-load units operating online.

4. The method according to claim 1, characterized in that, The method further includes: When the compressor unit reaches its minimum operating speed, switch the individual pressure controller to automatic mode; The set value of the single-unit pressure controller is controlled to be higher than the first gradient value of the compressor unit outlet pressure, so that the operating point of the compressor unit is located to the right of the anti-surge line.

5. A controller, characterized in that, include: The memory is configured to store instructions; as well as The processor is configured to retrieve the instructions from the memory and, when executing the instructions, to implement the method for automatic grid connection of the compressor unit according to any one of claims 1 to 4.

6. A system for automatic grid connection of a compressor unit, characterized in that, include: The controller according to claim 5, wherein the controller comprises a pressure controller, a performance controller, an anti-surge controller, a speed controller, and an equal margin controller; High-load units communicate with the controller; Low-load units communicate with the controller; The station's return valve communicates with the controller.

7. A machine-readable storage medium, characterized in that, The machine-readable storage medium stores instructions for causing the machine to perform a method for automatically loading and connecting a compressor unit to the grid according to any one of claims 1 to 4.

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