Method for regulating opening of IGV and hot gas bypass valve of large pressure ratio heat pump unit

Abstract

The application discloses a large-pressure-ratio heat pump unit starting IGV and hot gas bypass valve regulation method, comprising the following steps: S1: parameter initialization configuration; S2: initial state setting; S3: starting delay and compressor starting; S4: IGV opening degree dynamic adjustment; S5: hot gas bypass valve working condition judgment and adjustment; S6: inverse ratio control mode execution; S7: running state continuous monitoring and steady state transition. The application realizes accurate linkage control of IGV and hot gas bypass valve when the large-pressure-ratio centrifugal heat pump unit starts, meets the requirement that IGV is fully closed or nearly fully closed to reduce starting current when the fixed-frequency unit starts, accurately avoids the surge risk in the starting stage through dynamic adaptive adjustment of the hot gas bypass valve, effectively avoids the problems of condenser without liquid refrigerant, further caused cooling system failure and oil system or motor over-temperature shutdown due to the hot gas bypass valve being fully opened, and in addition, the liquid pipe electric valve can be accurately controlled.

Description

Technical Field

[0001] This invention relates to the field of high-pressure-ratio centrifugal heat pump units, and in particular to a method for regulating the start-up IGV and hot gas bypass valve of a high-pressure-ratio heat pump unit. Background Technology

[0002] When starting a fixed-frequency centrifugal air conditioning unit, in order to reduce the starting current, the inlet guide vane IGV of the unit is usually required to be fully closed or nearly fully closed. However, during the start-up phase, the operating point of the unit is close to the surge zone. Therefore, in order to prevent surge from occurring, the hot gas bypass valve is usually required to be fully open to prevent the unit from surging. For high-pressure-ratio heat pump units, if the operating conditions of the evaporator and condenser deviate significantly, especially when the evaporator pressure is low while the condenser pressure is high, the compressor discharge pressure will be difficult to rise quickly when the guide vane opening is small during startup. This can lead to a situation where the refrigerant inside the condenser cannot be condensed. If the hot gas bypass valve is fully open at this time, this phenomenon will be exacerbated, resulting in no liquid refrigerant at the bottom of the condenser. If this continues for a while, the unit's cooling system will malfunction, and in severe cases, it may cause the oil system or motor to overheat and shut down. Therefore, the control of the hot gas bypass valve is crucial. Opening it too little will cause the unit to surge, while opening it too much will cause problems with the unit's cooling system. Existing technologies cannot precisely control the inlet guide vane, hot gas bypass valve, and liquid line electric valve. In light of the above, this application proposes a method for controlling the IGV and hot gas bypass valve during startup of high-pressure-ratio heat pump units. Summary of the Invention

[0003] Based on the technical problems existing in the background technology, the present invention proposes a method for regulating the start-up IGV and hot gas bypass valve of a high-pressure ratio heat pump unit.

[0004] The method for regulating the IGV and hot gas bypass valve during the start-up of a high-pressure-ratio heat pump unit proposed in this invention includes the following steps: S1: Parameter initialization configuration: Before the unit is started, all settings data are pre-configured to ensure that key parameters match the surge characteristics and operating standards of the current model; at the same time, the data acquisition system is started to collect parameters in real time. S2: Start initial state setting: After the unit start command is issued, two initial controls are executed simultaneously: (1) Control the opening degree of the inlet guide vane IGV to 0% to minimize the start current and ensure start safety; (2) Control the opening degree of the hot gas bypass valve to the preset initial opening degree SP-HvI to build the initial anti-surge condition. S3: Start-up delay and compressor start-up: Start a 120-second delay program, maintaining the initial state set in step S2 during the delay; after the delay ends, start the compressor and enter the dynamic adjustment stage of operating conditions; S4: Dynamic adjustment of IGV opening: Real-time monitoring of compressor current Icomp, and adjustment of IGV opening according to set logic, followed by continuous adjustment of IGV opening according to soft loading rules: Every 60 seconds, the IGV opening is incremented by 1 second until the IGV reaches the target operating opening to achieve stable loading; S5: Hot gas bypass valve condition judgment and adjustment: After the compressor starts, the condensing temperature Tcond and the condenser outlet water temperature Tcw are collected in real time, and the pressure ratio Pr is calculated according to the formula Pr = absolute pressure value of condenser / absolute pressure value of evaporator, and the hot gas bypass valve is adjusted based on the operating conditions. S6: Hot gas bypass valve inverse proportional control mode execution: When entering the inverse proportional control mode, the real-time opening degree of IGV is further determined by the following logic: If the real-time opening degree of IGV Igvop ≥ the set opening value: the hot gas bypass valve is completely closed to avoid energy consumption increase due to ineffective bypass; if Igvop < the set opening value: the real-time opening degree of hot gas bypass valve Hvop is calculated, and the flow rate is kept stable through the inverse proportional relationship to prevent surge. The calculation formula is: Hvop=(SP-Hvst–Igvop) / SP-Hvst*SP-Hvmax; S7: Continuous monitoring of operating status and steady-state transition: After the IGV gradually reaches the target opening degree according to the soft loading rule, it continuously monitors the pressure ratio Pr, compressor current Icomp and various temperature parameters. If the unit's parameters are stable within the rated operating range, it maintains the current control state and enters the normal operating mode. If the operating conditions fluctuate, it returns to steps S4 and S5 to re-execute the corresponding adjustment logic to ensure that the unit is always away from the surge zone and to ensure operational stability.

[0005] Preferably, in step S1, the data is set as shown in the table below:

[0006] Preferably, in step S1, the collected data is shown in the following table:

[0007] Preferably, the logic set in S4 is as follows: (1) If the compressor current Icomp > the compressor rated current SP-Ir×0.8, keep the IGV opening at 0% to avoid further increase in current, where 0.8 is the overload judgment threshold; (2) If the compressor current Icomp ≤ the compressor rated current SP-Ir×0.8, immediately increase the IGV opening to the preset minimum opening SP-Igvmin to get out of the extremely low flow risk zone.

[0008] Preferably, in step S5, the logic for adjusting the hot gas bypass valve based on operating conditions is as follows: (1) Operating condition judgment a: If the condenser outlet water temperature Tcw > condensing temperature Tcond and the pressure ratio Pr < the normal control start pressure ratio SP-Prsp, control the hot gas bypass valve to close quickly to the fully closed state to avoid excessive loss of refrigerant in the condenser and ensure the normal operation of the cooling system. (2) Operating condition judgment b: If the condenser outlet water temperature Tcw ≤ condensing temperature Tcond or the pressure ratio Pr > the normal control start pressure ratio SP-Prsp, switch to the hot gas bypass valve inverse ratio control mode.

[0009] Preferably, in S6, the adjustment logic makes the opening of the hot gas bypass valve larger as the opening of the IGV decreases, so as to always maintain the compressor inlet flow rate within the safe range.

[0010] Preferably, in step S3, after the compressor starts, the control process of the liquid line electric valve is as follows: S301: Control the liquid line electric valve to the initial opening degree 1, the initial opening degree 1 is SP-Epvl-1; S302: The condition for determining that the liquid pipe electric valve has reached the initial opening degree 2 is: lgvop>SP-lgvmin or Pevap≤SP-EvPlow; S303: Determines that the initial opening time of the liquid line electric valve has reached the set value, which is SP-TepvITm; S304: When the initial opening time of the S303 hydraulic valve reaches the set value, it switches to the normal control mode of the hydraulic valve.

[0011] Preferably, the conventional control mode of the liquid pipe electric valve is as follows: after the initial opening time of the liquid pipe electric valve is reached, the liquid pipe electric valve is controlled by PID to keep the evaporator Ltd always stable within 0.2℃ above or below the target Ltd of the evaporator. PID stands for Proportional-Integral-Derivative, which is a widely used industrial control algorithm and controller.

[0012] Compared with existing technologies, the beneficial effects of this invention are: This invention achieves precise linkage control of the IGV and hot gas bypass valve during the startup of a high-pressure-ratio centrifugal heat pump unit. This not only meets the requirement of the IGV being fully or nearly fully closed during the startup of a fixed-frequency unit to reduce the starting current, but also precisely avoids the surge risk during the startup phase through the dynamic adaptation and adjustment of the hot gas bypass valve. This effectively prevents the cooling system failure and oil system or motor overheating shutdown caused by the condenser not having liquid refrigerant due to the hot gas bypass valve being fully open. It solves the control contradiction of "small surge during startup, large failure during startup" in the prior art, and significantly improves the startup success rate, operational stability and control accuracy of high-pressure-ratio units in scenarios with large deviations between evaporator and condenser operating conditions. In addition, it can also precisely control the liquid pipe electric valve. Attached Figure Description

[0013] Figure 1 This is a flowchart of the high-pressure-ratio heat pump unit start-up IGV and hot gas bypass valve control method proposed in this invention. Detailed Implementation

[0014] The present invention will be further explained below with reference to specific embodiments. Example

[0015] Reference Figure 1 This embodiment proposes a method for regulating the IGV and hot gas bypass valve during the start-up of a high-pressure-ratio heat pump unit, including the following steps: S1: Parameter initialization configuration: Before the unit is started, all settings data are pre-configured to ensure that key parameters match the surge characteristics and operating standards of the current model; at the same time, the data acquisition system is started to collect parameters in real time. The data settings are shown in the table below: ; The collected data is shown in the table below: ; S2: Start initial state setting: After the unit start command is issued, two initial controls are executed simultaneously: (1) Control the opening degree of the inlet guide vane IGV to 0% to minimize the start current and ensure start safety; (2) Control the opening degree of the hot gas bypass valve to the preset initial opening degree SP-HvI to build the initial anti-surge condition. S3: Start-up delay and compressor start-up: Start a 120-second delay program, maintaining the initial state set in step S2 during the delay; after the delay ends, start the compressor and enter the dynamic adjustment stage of operating conditions; S4: Dynamic adjustment of IGV opening: Real-time monitoring of compressor current Icomp, and adjustment of IGV opening according to set logic, followed by continuous adjustment of IGV opening according to soft loading rules: Every 60 seconds, the IGV opening is incremented by 1 second until the IGV reaches the target operating opening to achieve stable loading; The logic behind its design is as follows: (1) If the compressor current Icomp > the compressor rated current SP-Ir×0.8, keep the IGV opening at 0% to avoid further increase in current, where 0.8 is the overload judgment threshold; (2) If the compressor current Icomp ≤ the compressor rated current SP-Ir×0.8, immediately increase the IGV opening to the preset minimum opening SP-Igvmin to get out of the extremely low flow risk zone; S5: Hot gas bypass valve condition judgment and adjustment: After the compressor starts, the condensing temperature Tcond and the condenser outlet water temperature Tcw are collected in real time, and the pressure ratio Pr is calculated according to the formula Pr = absolute pressure value of condenser / absolute pressure value of evaporator, and the hot gas bypass valve is adjusted based on the operating conditions. The logic for adjusting the hot gas bypass valve based on operating conditions is as follows: (1) Operating condition judgment a: If the condenser outlet water temperature Tcw > condensing temperature Tcond and the pressure ratio Pr < the normal control start pressure ratio SP-Prsp, control the hot gas bypass valve to close quickly to the fully closed state to avoid excessive loss of refrigerant in the condenser and ensure the normal operation of the cooling system. (2) Operating condition judgment b: If the condenser outlet water temperature Tcw ≤ condensing temperature Tcond or the pressure ratio Pr > the normal control start pressure ratio SP-Prsp, switch to the hot gas bypass valve inverse ratio control mode; The absolute pressure value of the condenser (Pcond) is collected in real time by the pressure sensor configured in the unit (corresponding to "condenser pressure Pcond" in the data acquisition table S1 of the instruction manual, in Bar, and described as "real-time acquisition of the absolute pressure value of the refrigerant in the condenser"); the absolute pressure value of the evaporator is acquired in real time by the pressure sensor preset in the evaporator cavity using the same principle. This acquisition process is synchronized with the condenser pressure acquisition and incorporated into the data acquisition system, which is a conventional parameter acquisition method in this field. S6: Hot gas bypass valve inverse proportional control mode execution: When entering the inverse proportional control mode, the real-time opening degree of IGV is further determined by the following logic: If the real-time opening degree of IGV Igvop ≥ the set opening value: the hot gas bypass valve is completely closed to avoid energy consumption increase due to ineffective bypass; if Igvop < the set opening value: the real-time opening degree of hot gas bypass valve Hvop is calculated, and the flow rate is kept stable through the inverse proportional relationship to prevent surge. The calculation formula is: Hvop=(SP-Hvst–Igvop) / SP-Hvst*SP-Hvmax; Its regulation logic makes the smaller the IGV opening, the larger the hot gas bypass valve opening, always maintaining the compressor inlet flow within the safe range; The hot gas bypass valve set action value (SP-Hvst) ranges from 30% to 50% (determined based on the rated power of the unit; the higher the power, the closer the value is to 50%). The IGV real-time opening degree (Igvop) ranges from 0% to 100%, with the "set opening degree value" being 20% ​​(i.e., when Igvop < 20%, the inverse proportional control calculation is triggered). This range is determined based on the commissioning data of multiple 100-500kW high-pressure-ratio units and conforms to industry-standard design practices. Furthermore, startup tests on three prototype units with different power ratings (150kW, 300kW, and 450kW) verified that: after using the formula Hvop=(SP-Hvst–Igvop) / SP-Hvst*SP-Hvmax for control, the surge rate during unit startup was 0, while the surge rate using the traditional control method was 12%; when Igvop=5% (minimum opening), Hvop calculated by the formula was 42%, at which point the compressor inlet flow rate was maintained at 0.8-1.2 m³ / min, which is within the safe flow range (surge is easily triggered below 0.5 m³ / min), proving that this technical solution can effectively prevent surge; S7: Continuous monitoring of operating status and steady-state transition: After the IGV gradually reaches the target opening degree according to the soft loading rule, it continuously monitors the pressure ratio Pr, compressor current Icomp and various temperature parameters. If the parameters of the unit are stable within the rated operating range, the current control state is maintained and the normal operation mode is entered. If the operating conditions fluctuate, the corresponding adjustment logic is re-executed in steps S4 and S5 to ensure that the unit is always away from the surge zone and to ensure operating stability. The "rated operating range" is specifically defined as follows: pressure ratio Pr is 1.8-3.5 (corresponding to 1.1-1.3 times the conventional control start-up pressure ratio SP-Prsp); compressor current Icomp is 0.8-1.0 times the rated current SP-Ir; condensing temperature Tcond is 40-55℃; condenser outlet water temperature Tcw is 35-45℃. This range is determined based on GB / T18430.1-2022 "Steam Compression Cycle Chillers (Heat Pumps) Part 1: Chillers (Heat Pumps) for Industrial or Commercial and Similar Uses" standard, combined with the design parameters of the model adapted to this invention. This embodiment achieves precise linkage control of the IGV and hot gas bypass valve during the startup of a high-pressure-ratio centrifugal heat pump unit. This not only meets the requirement of the IGV being fully or nearly fully closed during the startup of a fixed-frequency unit to reduce the starting current, but also precisely avoids the surge risk during the startup phase through the dynamic adaptation and adjustment of the hot gas bypass valve. This effectively prevents the cooling system failure and oil system or motor overheating shutdown caused by the condenser not having liquid refrigerant due to the hot gas bypass valve being fully open. It solves the control contradiction of "small surge during startup, large failure during startup" in the prior art, and significantly improves the startup success rate, operational stability and control accuracy of high-pressure-ratio units in scenarios with large deviations between evaporator and condenser operating conditions. In addition, it can also precisely control the liquid pipe electric valve.

[0016] Furthermore, in S3 of this embodiment, the control process of the liquid line electric valve after the compressor starts is as follows: S301: Control the liquid line electric valve to the initial opening degree 1, the initial opening degree 1 is SP-Epvl-1; S302: The condition for determining that the liquid pipe electric valve has reached the initial opening degree 2 is: lgvop>SP-lgvmin or Pevap≤SP-EvPlow; S303: Determines that the initial opening time of the liquid line electric valve has reached the set value, which is SP-TepvITm; S304: When the initial opening time of the liquid pipe electric valve in S303 reaches the set value, it switches to the normal control mode of the liquid pipe electric valve. The normal control mode of the liquid pipe electric valve is as follows: after the initial opening time of the liquid pipe electric valve is reached, the liquid pipe electric valve is controlled by PID to keep the evaporator Ltd stable at within 0.2℃ above or below the target Ltd of the evaporator. PID stands for Proportional-Integral-Derivative, which is one of the most widely used industrial control algorithms and controllers.

[0017] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for regulating the IGV and hot gas bypass valve during startup of a high-pressure-ratio heat pump unit, characterized in that, Includes the following steps: S1: Parameter initialization configuration: Before the unit is started, all settings data are pre-configured to ensure that key parameters match the surge characteristics and operating standards of the current model; at the same time, the data acquisition system is started to collect parameters in real time. S2: Start initial state setting: After the unit start command is issued, two initial controls are executed simultaneously: (1) Control the opening degree of the inlet guide vane IGV to 0% to minimize the start current and ensure start safety; (2) Control the opening degree of the hot gas bypass valve to the preset initial opening degree SP-HvI to build the initial anti-surge condition. S3: Start-up delay and compressor start-up: Start a 120-second delay program, maintaining the initial state set in step S2 during the delay period; After the delay period ends, the compressor is started, and the dynamic adjustment phase of the operating conditions begins. S4: Dynamic adjustment of IGV opening: Real-time monitoring of compressor current Icomp, and adjustment of IGV opening according to set logic, followed by continuous adjustment of IGV opening according to soft loading rules: Every 60 seconds, the IGV opening is incremented by 1 second until the IGV reaches the target operating opening to achieve stable loading; S5: Hot gas bypass valve condition judgment and adjustment: After the compressor starts, the condensing temperature Tcond and the condenser outlet water temperature Tcw are collected in real time, and the pressure ratio Pr is calculated according to the formula Pr = absolute pressure value of condenser / absolute pressure value of evaporator, and the hot gas bypass valve is adjusted based on the operating conditions. S6: Hot gas bypass valve inverse proportional control mode execution: When entering the inverse proportional control mode, the real-time opening degree of IGV is further determined by the following logic: If the real-time opening degree of IGV Igvop ≥ the set opening value: the hot gas bypass valve is completely closed to avoid energy consumption increase due to ineffective bypass; if Igvop < the set opening value: the real-time opening degree of hot gas bypass valve Hvop is calculated, and the flow rate is kept stable through the inverse proportional relationship to prevent surge. The calculation formula is: Hvop=(SP-Hvst–Igvop) / SP-Hvst*SP-Hvmax; S7: Continuous monitoring of operating status and steady-state transition: After the IGV gradually reaches the target opening degree according to the soft loading rule, it continuously monitors the pressure ratio Pr, compressor current Icomp and various temperature parameters. If the unit's parameters are stable within the rated operating range, it maintains the current control state and enters the normal operating mode. If the operating conditions fluctuate, it returns to steps S4 and S5 to re-execute the corresponding adjustment logic to ensure that the unit is always away from the surge zone and to ensure operational stability.

2. The method for regulating the IGV and hot gas bypass valve during startup of a high-pressure-ratio heat pump unit according to claim 1, characterized in that, The logic set in S4 is as follows: (1) If the compressor current Icomp > the compressor rated current SP-Ir×0.8, keep the IGV opening at 0% to avoid further increase in current, where 0.8 is the overload judgment threshold; (2) If the compressor current Icomp ≤ the compressor rated current SP-Ir×0.8, immediately increase the IGV opening to the preset minimum opening SP-Igvmin to get out of the extremely low flow risk zone.

3. The method for regulating the IGV and hot gas bypass valve during startup of a high-pressure-ratio heat pump unit according to claim 1, characterized in that, In S5, the logic for adjusting the hot gas bypass valve based on operating conditions is as follows: (1) Operating condition judgment a: If the condenser outlet water temperature Tcw > condensing temperature Tcond and the pressure ratio Pr < the normal control start pressure ratio SP-Prsp, control the hot gas bypass valve to close quickly to the fully closed state to avoid excessive loss of refrigerant in the condenser and ensure the normal operation of the cooling system. (2) Operating condition judgment b: If the condenser outlet water temperature Tcw ≤ condensing temperature Tcond or the pressure ratio Pr > the normal control start pressure ratio SP-Prsp, switch to the hot gas bypass valve inverse ratio control mode.

4. The method for regulating the IGV and hot gas bypass valve during startup of a high-pressure-ratio heat pump unit according to claim 1, characterized in that, In S6, the adjustment logic makes the opening of the hot gas bypass valve larger as the opening of the IGV is smaller, so as to always maintain the compressor inlet flow rate within the safe range.

5. The method for regulating the start-up IGV and hot gas bypass valve of a high-pressure-ratio heat pump unit according to claim 1, in step S3, the control process of the liquid line electric valve after the compressor starts is as follows: S301: Control the liquid line electric valve to the initial opening degree 1, the initial opening degree 1 is SP-Epvl-1; S302: The condition for determining that the liquid pipe electric valve has reached the initial opening degree 2 is: lgvop>SP-lgvmin or Pevap≤SP-EvPlow; S303: Determines that the initial opening time of the liquid line electric valve has reached the set value, which is SP-TepvITm; S304: When the initial opening time of the S303 hydraulic valve reaches the set value, it switches to the normal control mode of the hydraulic valve.

6. According to the high-pressure-ratio heat pump unit start-up IGV and hot gas bypass valve regulation method described in claim 5, the conventional control of the liquid pipe electric valve in the conventional control mode is as follows: after the initial opening degree of the liquid pipe electric valve has been reached, the liquid pipe electric valve is controlled by PID to keep the evaporator Ltd always stable within 0.2℃ above or below the target Ltd of the evaporator. PID stands for Proportional-Integral-Derivative, which is a widely used industrial control algorithm and controller.

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