Air compressor station control system

Abstract

This invention relates to the field of automatic control technology for air compressor stations, and discloses a control system for an air compressor station, comprising: a main controller, which can control the start-up, shutdown, loading, or unloading of each air compressor in the air compressor group based on a preset pressure value and air pressure feedback in the main pipe; multiple air compressor sub-controllers, which are connected in parallel and electrically connected to the main controller, and each air compressor sub-controller can receive the output signal of the main controller to control the independent start-up, shutdown, loading, or unloading of each air compressor in the air compressor group; and an air compressor, which is electrically connected to each air compressor sub-controller to receive the output signal of the air compressor sub-controller. The control system for the air compressor station of this invention can realize automatic linkage control of the air compressor group, thereby improving the automation level of the air compressor group.

Description

Technical Field

[0001] This invention relates to the field of automatic control technology for air compressor stations, and more specifically to a control system for an air compressor station. Background Technology

[0002] Compressed air is a crucial power source for industrial production, and large factories are equipped with continuously operating air compressor stations to ensure their air supply needs are met. However, the air volume load of large factories is not always constant. In actual production operations, when a large factory's air consumption is low, only a few air compressors may be operating, and the number of operating compressors may be reduced. When a large factory's air consumption increases, multiple air compressors may be needed, and the number of operating compressors may need to be increased. When manually starting or stopping air compressors, the automatic control system is limited to a single unit, and manual monitoring and operation are necessary to achieve overall control of the air compressor group. In particular, the control of external supply pressure and flow mainly relies on the PID control of regulating valves. When the external air supply volume increases or decreases sharply, it cannot be adjusted quickly and accurately, requiring manual operation to start or stop the unit and take over the control system. Summary of the Invention

[0003] The purpose of this invention is to overcome the problem of low automation in air compressor groups in large factories in the prior art, and to provide a control system for an air compressor station. This control system can realize automatic linkage control of air compressor groups to improve the automation level of air compressor groups.

[0004] To achieve the above objectives, the present invention provides a control system for an air compressor station, comprising: a main controller, which is capable of controlling the start-up, shutdown, loading, or unloading of each air compressor in the air compressor group based on a preset pressure value and air pressure feedback in the main pipe; multiple air compressor sub-controllers, which are connected in parallel and electrically connected to the main controller, and each air compressor sub-controller is capable of receiving the output signal of the main controller to control the independent start-up, shutdown, loading, or unloading of each air compressor in the air compressor group; and an air compressor, which is electrically connected to the corresponding air compressor sub-controller to receive the output signal of the air compressor sub-controller.

[0005] Optionally, the control system of the air compressor station includes a load distribution controller electrically connected to the main controller and located upstream of the plurality of air compressor sub-controllers. The load distribution controller can adjust the load of each air compressor in the air compressor group according to the output signal received from the main controller and the load of each air compressor in the air compressor group, so as to balance the load of each air compressor in the air compressor group.

[0006] Optionally, the control system of the air compressor station includes a decoupling controller electrically connected between the air compressor sub-controller and the air compressor. The decoupling controller has a higher operating priority than the anti-surge controller of the air compressor and is configured to simultaneously control the guide vanes of the air compressor and indirectly control the vent valve of the air compressor by controlling the anti-surge controller, so as to prevent the guide vanes and the vent valve from being coupled together.

[0007] Optionally, the main controller is configured to increase the number of operating air compressors via the air compressor sub-controllers by comparing the total load of the operating air compressors in the air compressor group with the maximum limit total load of the operating air compressors, or comparing the air pressure of the main pipe with the minimum air pressure of the main pipe; and / or

[0008] The main controller is configured to reduce the number of working air compressors by comparing the total load of the working air compressors in the air compressor group with the minimum limit total load of the working air compressors or the air pressure of the main pipe with the maximum air pressure of the main pipe.

[0009] Optionally, when the total load of the air compressors in the air compressor group that are in operation is higher than the maximum limit total load of the air compressors in operation, or when the air pressure of the main pipe is lower than the minimum air pressure of the main pipe, the air compressor sub-controller is configured to control the guide vanes and vent valves of the corresponding air compressors respectively, and simultaneously gradually increase the opening of the guide vanes to be greater than the minimum opening for normal operation of the air compressors and gradually decrease the opening of the vent valves to be less than the maximum opening for normal operation of the air compressors, so as to start the air compressors that are not in operation.

[0010] Optionally, each of the air compressor sub-controllers is configured to gradually reduce the opening of the vent valve of the newly started air compressor to fully close according to the load of the corresponding air compressor and the load of the newly started air compressor, and to adjust the guide vane opening of the newly started air compressor and the air compressor in the working state, so as to balance the load of each air compressor.

[0011] Optionally, when the total load of the air compressors in the air compressor group that are in operation is lower than the minimum limit total load of the air compressors in operation, or when the load of the main pipe is higher than the maximum load of the main pipe, the air compressor sub-controller is configured to control the guide vanes and vent valves of the corresponding air compressors respectively, and simultaneously gradually reduce the opening of the guide vanes to less than the minimum opening for normal operation of the air compressors and gradually increase the opening of the vent valves to greater than the maximum opening for normal operation of the air compressors, so as to shut down the air compressors in operation.

[0012] Through the above technical solution, the present invention has the following beneficial effects:

[0013] The main controller controls the loading and unloading of the air compressors by outputting signals to the air compressor sub-controllers. This can be understood as follows: when it is necessary to increase or decrease the air pressure in the main pipe, the main controller outputs a signal to the air compressor sub-controllers (increasing or decreasing the output of the air compressors, i.e., loading or unloading), causing the output of each air compressor to increase or decrease within the same unit of time, thus further increasing or decreasing the air pressure in the main pipe. When the output of an air compressor within the same unit of time increases to the upper limit or decreases to the lower limit, to protect the air compressors in operation from damage, the main controller outputs a signal to the air compressor sub-controllers to control the start and stop of the air compressors (i.e., increasing or decreasing the number of air compressors).

[0014] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0015] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the following detailed description to explain the invention, but do not constitute a limitation thereof.

[0016] Figure 1 This is a schematic diagram of one implementation of the control system of the air compressor station in this invention;

[0017] Figure 2 This is a schematic diagram of the control principle of the air compressor in this invention;

[0018] Figure 3 This is a schematic diagram of the surge curve of the air compressor in this invention. Detailed Implementation

[0019] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0020] like Figure 1 and Figure 2As shown, the control system of the air compressor station of the present invention includes: a main controller, which can automatically control the start-up, shutdown, loading, or unloading of each air compressor in the air compressor group according to a preset pressure value and air pressure feedback in the main pipe; multiple air compressor sub-controllers, which are connected in parallel and electrically connected to the main controller, and can receive the output signal of the main controller to control the independent start-up, loading, unloading, or shutdown of each air compressor in the air compressor group; and, to protect the safe operation of the equipment, the air compressor sub-controllers simultaneously monitor the operating status in real time. When any interlocking condition is triggered, the air compressor sub-controller will unload and shut down the current compressor and record the first condition that causes the interlocking. An air compressor is electrically connected to the corresponding air compressor sub-controller to receive the output signal of the air compressor sub-controller.

[0021] The main controller controls the loading and unloading of the air compressors by outputting signals to the sub-controllers. This can be understood as follows: when it is necessary to increase or decrease the air pressure in the main pipe (i.e., when the actual air pressure in the main pipe deviates from the preset pressure value), the main controller outputs a signal to each sub-controller (increasing or decreasing the output of the air compressor, i.e., loading or unloading), causing the output of each air compressor to increase or decrease uniformly within the same unit of time. Then, the air pressure in the main pipe is further increased or decreased to stabilize it at the preset pressure value. When the output of an air compressor increases to the upper limit of its normal operating range or decreases to the lower limit within the same unit of time, to protect the operating air compressors from damage, the main controller outputs a signal to the sub-controllers to control the start and stop of the air compressors (i.e., increasing or decreasing the number of operating air compressors).

[0022] Among them, the pressure preset value, as a core control parameter, can be understood as: the pressure value that the gas pressure in the main pipe is to be set. For example, if it is necessary to change the gas pressure in the main pipe from low pressure to high pressure, this value (high pressure) is the pressure preset value.

[0023] The control system of the air compressor station can automatically control the start-up, shutdown, loading, or unloading of the air compressors, further improving the automation level of the air compressor station. In particular, it can automatically increase or decrease the number of operating air compressors according to the air pressure demand of the main pipeline, so as to achieve unmanned operation.

[0024] A detailed explanation of the air compressor's start-up, shutdown, loading, or unloading process:

[0025] Start-up: When the air compressor receives a start signal from the main controller to the air compressor sub-controller, the auxiliary oil pump automatically starts and establishes oil pressure conditions. Once the oil pressure conditions are met, the air compressor sub-controller automatically resets the unit interlock and starts the air compressor's main motor, thus starting the air compressor. The air compressor's main motor operating signal and current signal are fed back to the main controller, which determines whether the air compressor in the unit has started normally. If the air compressor starts normally, the air compressor sub-controller enters a loading state, uniformly increasing the air compressor's output. When the air compressor's outlet pressure reaches the same level as the main pipe pressure, the main controller automatically takes over control of this air compressor, controlling it in parallel with the other operating air compressors. If the air compressor does not start normally, the main controller sends a start signal to the next air compressor sub-controller until the air compressor starts normally.

[0026] The principle of 2 out of 3: To prevent air compressor malfunctions or shutdowns due to instrument failures or data transmission loss, key monitoring parameters of the air compressor, such as vibration, current, and oil pressure, are each equipped with 3 online monitoring meters. The sub-controller will only trigger the interlock action when the values ​​of 2 or more online monitoring meters reach the interlock setting value.

[0027] Shutdown: When the air compressor receives a shutdown signal from the main controller to the air compressor sub-controller, this air compressor exits the parallel control of the main controller. The air compressor sub-controller gradually adjusts the guide vane valve to its minimum opening and the vent valve to its fully open state, making the air compressor ready for shutdown. During the shutdown process, the main controller synchronously adjusts the load of other parallel-operating units according to the changes in the main pipe pressure.

[0028] Automatic loading and unloading:

[0029] a. Start-up phase: After the air compressor starts normally, the air compressor sub-controller controls the air compressor guide vanes, causing the guide vanes to climb from zero opening to the minimum normal operating opening of the air compressor guide vanes (the minimum opening is different for each air compressor, and the minimum opening is mainly determined based on the air compressor's performance test results, measured surge curves, and other factors), and allows the air compressor to maintain no-load operation for a certain period of time (the no-load operation time is mainly determined based on the air compressor's performance test results and other factors).

[0030] b. Air compressor connection to the pipeline network stage: After the air compressor's no-load time ends, the vent valve will gradually close from fully open within a certain period of time. For the purpose of energy saving and consumption reduction, the sub-controller will try to adjust the vent valve to the fully closed state (but if the air volume gap is not large, the air compressor output can meet the demand when the vent valve is not fully closed. Continuing to close the vent valve will cause the main pipe pressure to be higher than the preset pressure value). When the air compressor outlet pressure is consistent with the main pipe pressure, it starts to connect to the pipeline network (main pipe).

[0031] c. Successful grid connection of the air compressor: During the grid connection process, the air compressor sub-controller adjusts the guide vanes and vent valve simultaneously according to the preset outlet pressure value. This ensures that while the vent valve is lowered, the outlet pressure of the air compressor remains at the predetermined pressure. The controller also synchronously adjusts the output of other operating air compressors, ensuring that the vent valve of the started air compressor is fully closed as much as possible. Ultimately, the air compressor is successfully connected to the grid.

[0032] like Figure 1 As shown, the control system of the air compressor station of the present invention includes a load distribution controller electrically connected to the main controller and located upstream of the plurality of air compressor sub-controllers. The load distribution controller can adjust the load of each air compressor in the air compressor group according to receiving the output signal of the main controller and the load of each air compressor in the air compressor group, so as to balance the load of each air compressor in the air compressor group.

[0033] When the air pressure in the main pipeline needs to be adjusted to increase or decrease, the outlet pressure of each air compressor in the air compressor group also needs to be adjusted accordingly. During this process, the pressure of some air compressors cannot be adjusted to the required air pressure of the main pipeline in a timely manner, resulting in variations in the outlet pressure and operating conditions of the air compressors. Secondly, when the air pressure in the main pipeline needs to be adjusted to increase or decrease, the number of air compressors in the air compressor group needs to be increased or decreased. Due to changes in the number of air compressors connected to the pipeline network (main pipeline), the pressure of some air compressors may also fail to be adjusted to the required air pressure of the main pipeline in a timely manner, leading to variations in the outlet pressure and operating conditions of the air compressors. Therefore, this invention uses a load distribution controller to adjust the load of each air compressor in the air compressor group to achieve load balance among the air compressors. Specifically, after each air compressor in the air compressor group is automatically connected to the pipeline network, the air compressors are automatically put into parallel operation mode. The main controller sends a signal (output pressure setpoint) to the air compressor sub-controller of each unit. The air compressor sub-controller then adjusts the load of its own air compressor based on the comparison between the load of the individual air compressor and the load of other parallel air compressors. While controlling the main pipeline pressure to reach the set value, the load of each air compressor is adjusted to achieve load balance control (the load of each air compressor is the same or the output of each air compressor is the same), which achieves the effect of energy saving and consumption reduction.

[0034] like Figure 3As shown, the function of the anti-surge controller is to prevent surge during air compressor operation. This controller requires input of the measured surge data of the air compressor, generating a measured surge line with current as the x-axis and outlet pressure as the y-axis. The measured surge line is then shifted to the right by different widths on the x-axis to generate a quick-opening line and a control line. The current and outlet pressure of the air compressor during operation are represented on this coordinate axis as the operating point. Under normal circumstances, the operating point is to the right of the control line. When the operating point is about to touch the control line, the anti-surge controller will preemptively activate to prevent the operating point from approaching. When external operating conditions change abruptly and the operating point crosses the quick-opening line, the anti-surge controller will quickly open the vent valve to a certain opening degree (depending on the air compressor performance and surge test data), ensuring that the vent valve opens in time when the air compressor is about to surge, while not significantly affecting the mains pressure.

[0035] like Figures 1 to 3 As shown, the control system of the air compressor station of the present invention includes a decoupling controller electrically connected between the air compressor sub-controller and the air compressor. The decoupling controller has a higher working priority than the anti-surge controller of the air compressor and is configured to simultaneously control the guide vanes of the air compressor and indirectly control the vent valve of the air compressor by controlling the anti-surge controller, so as to prevent the guide vanes and the vent valve from being coupled together.

[0036] Both the inlet guide vane and the vent valve can regulate the outlet pressure. When controlled separately, there is a coupling relationship between the anti-surge controller and the outlet pressure controller, ultimately leading to unstable operation of the air compressor. To avoid this, the decoupling module separates the air compressor sub-controller and the anti-surge controller, ensuring that they do not simultaneously regulate the vent valve and the inlet guide vane.

[0037] The decoupling module manages and determines when the inlet guide vanes and vent valve should be adjusted. For example, when the outlet pressure measurement increases, the compressor sub-controller maintains pressure stability by reducing the inlet guide vane opening. Before the anti-surge controller controls the vent valve (excessively reducing the inlet guide vane opening will eventually lead to compressor surge), the decoupling module uses the compressor sub-controller to open the vent valve, preventing the anti-surge controller from controlling it.

[0038] like Figure 1As shown, the main controller of this invention is configured to increase the number of operating air compressors by comparing the total load of the air compressors in operation with the maximum limit total load of the air compressors in operation, or comparing the air pressure of the main pipe with the minimum air pressure of the main pipe. Specifically, the main controller has a load calculation function. When it is determined that the load of the operating air compressor group is close to the maximum limit or the main pipe pressure is lower than the minimum limit, the main controller automatically sends a start command to the first-priority air compressor according to the priority judgment module. The first-priority air compressor sub-controller executes the start procedure after receiving the command. If the first-priority air compressor is operating normally, but the load of the operating air compressor group is still close to the maximum limit or the main pipe pressure is lower than the minimum limit, then the main controller automatically sends a start command to the second-priority air compressor according to the priority judgment module. The second-priority air compressor sub-controller executes the start procedure after receiving the command.

[0039] Furthermore, the main controller is configured to reduce the number of operating air compressors by comparing the total load of the operating air compressors in the air compressor group with the minimum limit total load of the operating air compressors, or comparing the air pressure of the main pipe with the maximum air pressure of the main pipe, through the air compressor sub-controllers. Specifically, the main controller has a load calculation function. When it is determined that the load of the operating air compressor group is close to the minimum limit or the main pipe pressure is higher than the minimum limit of the index, the main controller sends a shutdown command to the first air compressor in the operating air compressor group to unload it. After unloading, the air compressor maintains the minimum opening of the guide vanes (the minimum opening is different for each air compressor, and the minimum opening size is mainly determined based on factors such as the performance of the air compressor) and the full opening of the vent valve. That is, the air compressor is kept in the operating state. If the load of the operating air compressor group is not close to the minimum limit or the main pipe pressure is not higher than the minimum limit of the index, the main controller sends a loading command to the unloaded air compressor so that the outlet pressure of the air compressor group meets the pressure requirement of the main pipe. This can be understood as follows: the system will reload the unloaded air compressors to avoid repeatedly starting them. If the load on the operating air compressor group is still close to the minimum limit or the main pipe pressure is still higher than the lower limit of the indicator, the unloaded air compressors will be shut down.

[0040] When the total load of the air compressors in the air compressor group that are in operation exceeds the maximum limit total load of the air compressors in operation, or when the air pressure of the main pipeline is lower than the minimum air pressure of the main pipeline, the air compressor sub-controller is configured to control the guide vanes and vent valves of the corresponding air compressors respectively. Simultaneously, the opening of the guide vanes is gradually increased to be greater than the minimum opening for normal operation of the air compressor, and the opening of the vent valve is gradually decreased to be less than the maximum opening for normal operation of the air compressor, in order to start the air compressors that are not in operation. During the start-up phase, the air compressor guide vanes are at zero opening and the vent valves are at full opening. However, during normal operation, both the guide vanes and the vent valves have standard operating conditions. To ensure normal operation and successful connection to the pipeline network, the opening of the air compressor guide vanes must be greater than the minimum opening for normal operation, while the opening of the vent valves must be less than the maximum opening for normal operation.

[0041] The individual air compressor controllers in this invention are configured to gradually reduce the opening of the vent valve of the newly started air compressor to full closure based on the load of the corresponding air compressor and the load of the newly started air compressor. They also adjust the guide vane opening of the newly started and operating air compressors to ensure load balance among the air compressors. When the number of air compressors increases, to maintain load balance, the loads of newly connected air compressors and operating air compressors are adjusted to ensure that the loads or outputs of all air compressors in the pipeline network are the same.

[0042] When the total load of the air compressors in the air compressor group that are in operation is lower than the minimum limit total load of the air compressors in operation, or when the load of the main pipe is higher than the maximum load of the main pipe, the air compressor sub-controller is configured to control the guide vanes and vent valves of the corresponding air compressors respectively, and simultaneously gradually reduce the opening of the guide vanes to less than the minimum opening for normal operation of the air compressors and gradually increase the opening of the vent valves to greater than the maximum opening for normal operation of the air compressors, so as to shut down the air compressors in operation.

[0043] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various specific technical features in any suitable manner. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately. However, these simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A control system for an air compressor station, characterized in that, include: The main controller is capable of controlling the start-up, shutdown, loading, or unloading of each air compressor in the air compressor group based on the preset pressure value and the air pressure feedback in the main pipe. Multiple air compressor sub-controllers are connected in parallel and electrically connected to the main controller. Each air compressor sub-controller can receive the output signal of the main controller to control each air compressor in the air compressor group to start, stop, load or unload independently. An air compressor, which is electrically connected to the air compressor sub-controller to receive the output signal of the air compressor sub-controller; A load distribution controller is electrically connected to the main controller and located upstream of the plurality of air compressor sub-controllers. The load distribution controller can adjust the load of each air compressor in the air compressor group according to the output signal received from the main controller and the load of each air compressor in the air compressor group, so as to balance the load of each air compressor in the air compressor group. A decoupling controller is electrically connected between the air compressor sub-controller and the air compressor. The decoupling controller has a higher operating priority than the anti-surge controller of the air compressor. It is configured to simultaneously control the guide vanes of the air compressor and indirectly control the vent valve of the air compressor by controlling the anti-surge controller, so as to prevent the guide vanes and the vent valve from being coupled together.

2. The control system for the air compressor station according to claim 1, characterized in that, The main controller is configured to increase the number of operating air compressors via the air compressor sub-controllers by comparing the total load of the operating air compressors in the air compressor group with the maximum limit total load of the operating air compressors, or by comparing the air pressure of the main pipe with the minimum air pressure of the main pipe; and / or The main controller is configured to reduce the number of working air compressors by comparing the total load of the working air compressors in the air compressor group with the minimum limit total load of the working air compressors or the air pressure of the main pipe with the maximum air pressure of the main pipe.

3. The control system for the air compressor station according to claim 2, characterized in that, When the total load of the air compressors in the air compressor group that are in operation is higher than the maximum limit total load of the air compressors in operation, or when the air pressure of the main pipe is lower than the minimum air pressure of the main pipe, the air compressor sub-controller is configured to control the guide vanes and vent valves of the corresponding air compressors respectively, and simultaneously gradually increase the opening of the guide vanes to be greater than the minimum opening for normal operation of the air compressors and gradually decrease the opening of the vent valves to be less than the maximum opening for normal operation of the air compressors, so as to start the air compressors that are not in operation.

4. The control system of the air compressor station according to claim 3, characterized in that, Each of the air compressor sub-controllers is configured to gradually reduce the opening of the vent valve of the newly started air compressor to full closure according to the load of the corresponding air compressor and the load of the newly started air compressor, and to adjust the guide vane opening of the newly started air compressor and the air compressor in operation state, so as to balance the load of each air compressor.

5. The control system of the air compressor station according to claim 2, characterized in that, When the total load of the air compressors in the air compressor group that are in operation is lower than the minimum limit total load of the air compressors in operation, or when the load of the main pipe is higher than the maximum load of the main pipe, the air compressor sub-controller is configured to control the guide vanes and vent valves of the corresponding air compressors respectively, and simultaneously gradually reduce the opening of the guide vanes to less than the minimum opening for normal operation of the air compressors and gradually increase the opening of the vent valves to greater than the maximum opening for normal operation of the air compressors, so as to shut down the air compressors in operation.

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