Control device, control method, and computer-readable recording medium

Abstract

The present application provides a kind of control device with the function of avoiding compressor (1) surge.The control device (40) has: variation instruction part (41), makes the instruction value of system (100) including compressor (1), i.e.the instruction value of the operating state of the compressor (1) is varied;Proportion coefficient calculation unit (44), calculate the proportion coefficient of the parameter variation of the parameter indicating the state of the compressor (1) or the motor (30) driving the compressor (1) when the system is operated based on the instruction value;And control unit, based on the value of the proportion coefficient, carry out the control of avoiding or inhibiting the compressor (1) surge.

Description

TECHNICAL FIELD

[0001] The present application relates to a control device, a control method, and a program. The present application claims priority from Japanese Patent Application No. 2020-196891 filed on November 27, 2020, and the content thereof is incorporated herein by reference. BACKGROUND

[0002] It is known that, in a centrifugal compressor used in a turbo-compressor or a turbo-refrigerator, if the flow rate is reduced in a state where the pressure difference before and after the compressor is high, the compressor will vibrate violently. This phenomenon is called surge. If surge occurs, not only the efficiency of the compressor will decrease, but also the compressor can be damaged. Therefore, the centrifugal compressor needs to be controlled by a control device that avoids surge. The control to avoid surge is composed of a function to detect surge and a function to change the operating conditions of the compressor. The function to change the operating conditions of the compressor is a function to change the operating conditions of the compressor from a high pressure difference and a small flow rate to a small pressure difference and a large flow rate. For example, a circulation flow pipe that connects a high-pressure pipe connected to the discharge side of the compressor and a low-pressure pipe connected to the suction side of the compressor is provided, thereby increasing the circulation flow rate of the fluid such as refrigerant from the high-pressure pipe through the circulation flow pipe to the low-pressure pipe. Thereby, the discharge side pressure of the compressor is reduced, and the flow rate of the fluid is increased by an amount equivalent to the circulation flow, thereby avoiding surge. Circulation is not necessarily required, for example, in the case where the fluid is air, the fluid is usually released to the air from the pipe on the discharge side of the compressor.

[0003] Among the work done by the compressor on the fluid, the work corresponding to the circulation flow rate is not used for the original purpose of refrigeration or the like, but only heats the fluid, and thus is a loss. Therefore, it is required that the circulation flow rate be the minimum required. In order to set the circulation flow rate to the minimum required, first, the detection accuracy of surge is important. The detection of surge of the compressor is usually performed based on the flow rate of the fluid compressed by the compressor and the discharge pressure of the compressor (or the pressure ratio of the suction side and the discharge side of the compressor) (Patent Literature 1). Instead of the flow rate of the fluid, the drive current of the motor can also be monitored (Patent Literature 2).

[0004] Here, the characteristic curve of the compressor exemplified in Figure 10 . Figure 10 Figure 10 ​The vertical axis of the graph is the discharge pressure (or compression ratio) of the compressor, and the horizontal axis is the flow rate of the fluid. The surge line Ll indicates the boundary line between the operating region in which surge occurs and the operating region in which surge does not occur in the relationship between the discharge pressure and the flow rate of the compressor. Surge is an abnormal operating state that occurs when the flow rate of the fluid in the compressor decreases. When the operating point of the compressor is in the region on the left side of the surge line Ll in the relationship between the discharge pressure and the flow rate, i.e., when it is high pressure (or high pressure difference) and small flow rate, the likelihood of surge occurrence increases. The region on the left side of the surge line Ll is referred to as the surge region. When the operating conditions of the compressor intrude into the surge region, the circulation flow rate adjusting valve provided on the circulation flow pipe is opened, the flow rate of the fluid is increased while the discharge pressure or pressure ratio is decreased, and the operating conditions are transitioned to the region on the lower right of the surge line Ll in which surge does not occur.

[0005] In this control, the accuracy of the surge line Ll is important. If the surge line Ll is not accurate, it can be necessary to circulate the fluid by an amount equivalent to the error. In this case, the loss of compressor work cannot be reduced. The cause of the error is described. Figure 10 The surge line L2 is a surge line that is changed from Ll after the passage of operating time due to dirt or the like in the compressor. This change largely depends on performance deterioration due to the operating time or operating history of the compressor or the like. Since the surge line L2 cannot be set without error in advance, the compressor is generally operated with a margin of loss, and the circulation flow rate adjusting valve or the like is opened just before surge occurs. As a measure against the error of the surge line L2, for example, in Patent Literature 3, a technique is disclosed in which surge occurrence is detected in consideration of the passage of operating time from the variation in the discharge pressure and the drive current of the compressor. However, the frequency or amplitude at the time of variation in the discharge pressure or flow rate (or drive current) is determined not only by the properties of the compressor alone but also depends on the size of the pipe connected to the compressor, the volume of the tank connected to the pipe, the temperature or composition of the fluid, the flow rate adjusting valve of the bypass pipe, or the like. Therefore, it is difficult to determine the threshold value for determining surge occurrence with respect to the variation in the discharge pressure or flow rate.

[0006] Generally, on the suction side of the compressor, the fluid does not receive the work of the compressor, and the fluid on the discharge side is the fluid that has received the work of the compressor. As a result, the temperature of the fluid on the suction side of the compressor is lower than that on the discharge side. However, if surge occurs, the flow of the fluid can be disturbed, and a phenomenon in which the fluid that has received the work of the compressor flows backward to the suction side can occur. Then, on the suction side of the compressor, an increase in the temperature of the fluid can occur. In Patent Literature 2, a technique is disclosed in which, using this property, a temperature sensor is installed on the suction side of the compressor, the increase in the temperature of the fluid on the suction side that is a result of backward flow due to surge is monitored, and false detection of surge is avoided. However, in the method of Patent Literature 2, surge occurrence can be detected only after the variation increases to the extent that backward flow occurs.

[0007] Prior Art Documents

[0008] Patent Documents

[0009] Patent Document 1: Japanese Patent Application Laid-Open No. 62-195492

[0010] Patent Document 2: Japanese Patent No. 4191560

[0011] Patent Document 3: International Publication No. 2013 / 051559 SUMMARY

[0012] Technical Problem to be Solved by the Invention

[0013] There is a need for a technique that reliably detects surge in a stage where surge is slight and takes measures.

[0014] The present invention provides a control device, a control method, and a program that can solve the above-described problem.

[0015] Means for Solving the Technical Problem

[0016] The control device of the present invention has a variation instruction unit that varies an instruction value for a system including a compressor, i.e., the instruction value that affects an operating state of the compressor, a proportional coefficient calculation unit that calculates a proportional coefficient of a variation in a parameter that represents a state of the compressor or a motor that drives the compressor when the system is operated based on the instruction value with respect to the instruction value, and a control unit that performs control to avoid or suppress surge of the compressor based on a value of the proportional coefficient. Alternatively, the control device of the present invention can have, instead of the control unit, a detection unit that detects surge of the compressor based on the value of the proportional coefficient.

[0017] The control method of the present invention varies an instruction value for a system including a compressor, i.e., the instruction value that affects an operating state of the compressor, calculates a proportional coefficient of a variation in a parameter that represents a state of the compressor or a motor that drives the compressor when the system is operated based on the instruction value with respect to the instruction value, and performs control to avoid or suppress surge of the compressor based on a value of the proportional coefficient.

[0018] The program of the present invention causes a computer to perform the following processing: varying an instruction value for a system including a compressor, i.e., the instruction value that affects an operating state of the compressor, calculating a proportional coefficient of a variation in a parameter that represents a state of the compressor or a motor that drives the compressor when the system is operated based on the instruction value with respect to the instruction value, and performing control to avoid or suppress surge of the compressor based on a value of the proportional coefficient.

[0019] Effects of the Invention

[0020] According to the above-described control device, control method, and program, it is possible to detect a surge early and reliably and take measures. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is a view showing an example of a refrigeration system according to the first embodiment.

[0022] Figure 2 is a view showing an example of a control device according to the first embodiment.

[0023] Figure 3 is a view showing an example of an operation of the control device according to the first embodiment.

[0024] Figure 4 is a view showing an example of a control device according to the second embodiment.

[0025] Figure 5 is a view showing an example of a refrigeration system according to the third embodiment.

[0026] Figure 6 is a view showing an example of a control device according to the third embodiment.

[0027] Figure 7 is a view showing an example of an operation of the control device according to the third embodiment.

[0028] Figure 8 is a view showing an example of a control device according to the fourth embodiment.

[0029] Figure 9 is a view showing an example of an operation of the control device according to the fourth embodiment.

[0030] Figure 10 is a view for explaining a surge line.

[0031] Figure 11 is a view showing an example of a hardware structure of the control device according to each embodiment. DETAILED DESCRIPTION

[0032] Hereinafter, with reference to Figures 1-11 , the control of a surge according to each embodiment will be described in detail.

[0033] <First Embodiment>

[0034] Structure of Refrigeration System

[0035] Figure 1 is a view showing an example of a refrigeration system according to the first embodiment.

[0036] like Figure 1 As shown, the refrigeration system 100 includes: a compressor 1, inlet guide vanes 2, a condenser 3, an evaporator 4, piping P1, piping P2, piping P3, a circulating flow piping P4, a circulating flow regulating valve V1, a pressure gauge G1, a compressor output control device 10, a variable speed drive device 20, an electric motor 30, and a surge control device 40. Piping P1 connects the discharge side of the compressor 1 to the condenser 3. Piping P2 connects the condenser 3 to the evaporator 4. Piping P3 connects the evaporator 4 to the suction side of the compressor 1. The circulating flow piping P4 connects piping P1 and piping P3. A circulating flow regulating valve V1 is provided on the circulating flow piping P4 to adjust the flow rate of the refrigerant flowing in the circulating flow piping P4. A tachometer for measuring the rotational speed can also be installed on the compressor 1 or the electric motor 30. A vibration meter can also be installed on the main body, rotating shaft, or bearings of the compressor 1 or the electric motor 30. A flow meter for measuring the flow rate of the refrigerant can also be installed on the discharge side piping P1 of the compressor 1. To monitor the pressure ratio, a pressure gauge for measuring the refrigerant pressure can be installed on the suction side piping P3 of the compressor 1. Furthermore, a noise meter N1 can be installed on the refrigeration system 100.

[0037] Compressor 1 compresses the refrigerant and discharges the high-temperature, high-pressure refrigerant. Compressor 1 is connected to and driven by motor 30. Compressor output control device 10 outputs a speed command value for compressor 1 to variable speed drive device (inverter) 20. As described later, in this embodiment, in order to detect the occurrence of surge, the speed command value is slightly varied, and its response is monitored. The variation of the speed command value is commanded by surge control device 40. Variable speed drive device 20 supplies current based on the speed command value to motor 30 to drive motor 30, which drives compressor 1 at a speed based on the speed command value. Inlet guide vane (IGV) 2 is provided on the suction side of compressor 1. Inlet guide vane 2 is controlled by compressor output control device 10. Compressor output control device 10 outputs an angle command value to inlet guide vane 2. Based on this angle command value, inlet guide vane 2 adjusts the angle of the guide vane and adjusts the flow rate of refrigerant drawn into compressor 1. A pressure gauge V1 is installed on the discharge pipe P1 of compressor 1. Pressure gauge G1 measures the refrigerant pressure on the discharge side of compressor 1. A noise meter N1 measures the vibration or abnormal noise emitted from compressor 1, inlet guide vanes 2, pipe P1, etc.

[0038] The refrigerant discharged from the compressor 1 is supplied to the condenser 3. The condenser 3 condenses the refrigerant at high temperature and high pressure. The condenser 3 is connected to a pipe 11, and cooling water is supplied to the pipe 11 from a not-shown cooling tower. In the condenser 3, the refrigerant exchanges heat with the cooling water flowing in the pipe 11. The refrigerant is condensed by radiating heat to the cooling water. The refrigerant condensed by the condenser 3 is depressurized by an expansion valve (not shown) provided to the pipe P2. The low-pressure refrigerant after the depressurization is supplied to the evaporator 4. The evaporator 4 evaporates the low-pressure refrigerant. The evaporator 4 is connected to a pipe 12, and cooling water is supplied to a not-shown load through the pipe 12. In the evaporator 4, the refrigerant exchanges heat with the cooling water flowing in the pipe 12. The refrigerant cools the cooling water supplied to the load side, and itself is vaporized by absorbing heat from the cooling water. The gaseous refrigerant after the vaporization is sucked into the compressor 1 after the flow rate is adjusted by the inlet guide vane 2, and is compressed again by the compressor 1. Thus, the refrigerant circulates in the refrigerant circuit.

[0039] The surge control device 40 acquires the current value supplied to the motor 30 from the variable speed drive device 20, the refrigerant pressure measured by the pressure gauge V1, or the rotation speed, vibration, vibration of the shaft and bearing of the compressor 1, and the rotation speed, consumed current, consumed power, vibration, vibration of the shaft and bearing of the motor, the flow rate of the refrigerant, the pressure ratio of the refrigerant before and after the compressor 1, the noise of the surroundings, and the like, and monitors the response corresponding to the variation of the rotation speed command value with respect to at least one of these parameters, thereby determining the occurrence condition of the surge. If the surge occurs, the surge control device 40 outputs the opening command to the circulation flow rate adjusting valve V1. For example, the circulation flow rate adjusting valve V1 is normally closed, and if the surge occurs, it is controlled to be opened according to the opening command from the surge control device 40. If the circulation flow rate adjusting valve V1 is opened, a part of the refrigerant discharged from the compressor 1 is sucked into the compressor 1 again through the pipe P1, the circulation flow pipe P4, and the pipe P3. Thus, the flow rate of the refrigerant flowing through the compressor 1 increases, and the discharge pressure of the compressor 1 decreases (or the pressure difference of the refrigerant on the suction side and the discharge side of the compressor 1 decreases), and the surge is avoided. Thus, the surge control device 40 monitors the occurrence condition of the surge in the compressor 1, and if the surge occurs, controls to avoid and suppress the surge by the opening control of the circulation flow rate adjusting valve V1.

[0040] (Configuration of the control device)

[0041] Next, the surge control of the first embodiment will be described in detail with reference to Figure 2

[0042] Figure 2 is a view showing an example of the control device (the compressor output control device 10 and the surge control device 40) according to the first embodiment.​

[0043] The compressor output control device 10 is provided with a rotational speed command section 101 and an adding section 102.

[0044] The rotational speed command section 101 calculates a rotational speed of the compressor 1 corresponding to a load of the refrigeration system 100 (referred to as a basic rotational speed), and outputs it to the adding section 102.

[0045] The adding section 102 acquires a rotational speed variation command value from the surge control device 40, and adds the rotational speed variation command value to the basic rotational speed. The adding section 102 outputs the added value as a rotational speed command value r n to the variable speed drive device 20. As will be described later, the rotational speed variation command value r n is a value that is periodically varied. For example, if the basic rotational speed is 10,000 (rpm), the magnitude of the variation is about 100 to 200 (rpm). The rotational speed command value r n output from the adding section 102 is, for example, a value that is periodically varied between 9,800 and 10,200 (rpm).

[0046] The surge control device 40 is provided with a rotational speed variation command section 41, a subtracting section 42, a variation calculation section 43, a proportional coefficient calculation section 44, an opening command value calculation section 45, and a hysteresis compensation section 46.

[0047] The rotational speed variation command section 41 calculates the above-mentioned rotational speed variation command value, for example, by the following equation (1), and outputs it to the compressor output control device 10.

[0048] [Equation 1]

[0049]

[0050] Here, a r and b r are arbitrary constants, t is time, and T is an arbitrary period. The length of T is, for example, about 10 seconds. The rotational speed variation command value can also include harmonics of integer multiples of the period T, as shown in the following equation (1A).

[0051] [Equation 2]

[0052]

[0053] The desired change in the speed command value is a short period. In refrigeration machines using compressor 1, due to the influence of the device's heat capacity, it takes about one minute for a difference in cooling capacity to be reflected after the speed command of compressor 1 is changed. However, if the change period of the speed command value is sufficiently short (less than one minute), the change in the variable command value will not be reflected in the cooling capacity. Based on this viewpoint, the period T of the speed command value is set to be shorter than the response period of the device using compressor 1 (for example, 10 seconds).

[0054] Subtraction unit 42 acquires the speed command value r n Corresponding response parameters ( Figure 2 In the case of compressor 1, the speed n) and the speed command value r n The subtraction unit 42 calculates their difference and outputs the calculated difference to the variation calculation unit 43.

[0055] The variable calculation unit 43 calculates the compressor 1's rotational speed n and rotational speed command value r. n The deviation. If compressor 1 is in the set state, then the speed n of compressor 1 differs from the speed command value r of compressor 1. n Consistent. However, if surge occurs, the compressor speed will fluctuate, deviating from the commanded value by Δn=r. n -n. The magnitude of the deviation Δn can be calculated, for example, by means of variance. The variation calculation unit 43 calculates the variance by the following formula (2). E is the average. Variance is an example. As a variation, the deviation Δn can be used directly, or the amplitude of a specific frequency band contained in Δn can be used by means of Fourier transform, etc. Alternatively, the deviation from the average value of the rotational speed n can be used. This is also the case in other embodiments.

[0056] Var(Δn)=E((Δn-E(Δn)) 2 ) ···(2)

[0057] The proportional coefficient calculation unit 44 calculates the speed command value r based on the deviation (variance) calculated by the variation calculation unit 43. n The proportional coefficient of the response (speed n of compressor 1). First, the proportional coefficient calculation unit 44 calculates the proportional coefficient based on the speed command value r of Var (Δn). n The changes in the period T are evaluated by the following equations (3A) and (3B).

[0058] In Formula (3A), Formula (3B), a moving average value of the integrated function is calculated for the time interval T. In the moving average calculation, in Formula (3A), Formula (3B), the load coefficient is all 1 with respect to time. However, for example, a window function such as a Hanning window or a Hamming window can be used to attach a load coefficient to time to calculate the moving average value.

[0059] [Formula 3]

[0060]

[0061] [Formula 4]

[0062]

[0063] Then, the proportional coefficient calculation section 44 derives the following Formula (4) from Formula (3A), Formula (3B), and calculates the proportional coefficient K by Formula (4) n . If the period T is set to be sufficiently long with respect to the time scale of surge enhancement or disappearance, the following Formula (4) represents the proportional coefficient K of the variation in the rotational speed generated by the variation in the rotational speed command value with the period T n . In Formula (3A), Formula (3B), as a basic form, a variation component of the same period as the rotational speed variation period T is evaluated, but it is not limited thereto. For example, as a variation, a component of a period of T / 2, T / 3, T / 4,... can be evaluated. Also, in Formula (3A), Var(Δn) is a coefficient of sin((2π / T)t), and in Formula (3B), it is a coefficient of cos((2π / T)t), but essentially important is that the value of the coefficient repeats with the period T, and for example, it can be changed to sgn(sin((2π / T)t)) or sgn(cos((2π / T)t)). Here, sgn() is a function in which the value of sgn is 1 when the input value is positive, -1 when the input value is negative, and 0 when the input value is 0.

[0064] [Formula 5]

[0065]

[0066] The opening command value calculation section 45 determines the occurrence condition of surge based on the proportional coefficient K n , and calculates the opening command value u of the circulation flow regulating valve V1 corresponding to the occurrence condition of surge RCV1 . For example, the opening command value calculation section 45 has a function or the like that converts the proportional coefficient K n into the opening command value u of the circulation flow regulating valve V1 RCV1 . Based on the function or the like, the opening command value calculation section 45 determines the occurrence condition of surge and calculates the opening command value u of the circulation flow regulating valve V1 corresponding to the occurrence condition of surge n, the opening degree command value u of the circulation flow regulating valve V1 is calculated RCV1 . In Figure 2 , an example of a broken line function 451 possessed by the opening degree command value calculation section 45 is shown. With respect to the degree of surge, the lower the speed command, the more intense. Therefore, if the operating condition approaches the surge line, the proportional coefficient κ n becomes larger on the negative side. Therefore, in principle, it is sufficient to open the circulation flow regulating valve V1 using the proportional coefficient κn that becomes larger on the negative side. However, in actual use, even if the value is positive, if the proportional coefficient κ n becomes larger, the circulation flow regulating valve V1 should be opened. Therefore, as shown in the broken line function 451 of Figure 2 , the broken line becomes a shape in which the circulation flow regulating valve opening degree command value u n is changed if the value becomes larger, regardless of the positive or negative of the proportional coefficient κ RCV1 , and the circulation flow regulating valve V1 is opened.

[0067] The hysteresis compensation section 46 determines the opening degree of the circulation flow regulating valve V1 by hysteresis compensation when the magnitude of the proportional coefficient κ n exceeds the allowable limit of surge. The hysteresis compensation section 46 integrates the circulation flow regulating valve opening degree command value u RCV1 , and calculates the opening degree command value u RCV of the circulation flow regulating valve V1. The hysteresis compensation section 46 outputs the opening degree command value u RCV to the circulation flow regulating valve V1. Thereby, the low frequency component of the opening degree command value u RCV1 is amplified, and the opening degree command value u RCV is output to the circulation flow regulating valve V1.

[0068] (Action of Control Device)

[0069] Next, with reference to Figure 2 , Figure 3 , the detection of surge and the control to cope with surge will be described.

[0070] Figure 3 is a view showing an example of the action of the control device according to the first embodiment.

[0071] In the operation of the compressor 1, the compressor output control device 10 and the surge control device 40 repeatedly and continuously execute the following processing with a prescribed control period.

[0072] First, the compressor output control device 10 outputs a speed command value to the variable speed drive device 20 (step S11). The speed command unit 101 outputs a basic speed. The speed variation command unit 41 calculates the speed variation command value using formula (1). The adder unit 102 adds the basic speed to the speed variation command value and outputs the speed command value to the variable speed drive device 20.

[0073] Next, the surge control device 40 calculates the proportional coefficient of the response corresponding to the change in the speed command value (step S12). First, the change calculation unit 43 calculates the deviation between the speed command value and the response according to equation (2). Next, the proportional coefficient calculation unit 44 derives equation (4) according to equations (3A) and (3B), and calculates the proportional coefficient κ according to equation (4). n The proportionality coefficient calculation unit 44 calculates the proportionality coefficient κ. n Output to the opening command value calculation unit 45.

[0074] Next, the surge control device 40 is based on the proportional coefficient κ n Evaluate the occurrence of surge (step S13). For example, if the proportionality coefficient κ... n If the absolute value is less than the threshold, the opening command value calculation unit 45 determines that no surge has occurred; if it is above the threshold, it determines that a surge has occurred.

[0075] Next, the surge control device 40 calculates the opening command value u of the circulating flow regulating valve V1 corresponding to the surge occurrence condition. RCV (Step S14). For example, if surge does not occur, the opening command value calculation unit 45 calculates a value below 0 as the opening command value u. RCV1 If surge occurs, the opening command value calculation unit 45 calculates the opening command value u corresponding to the magnitude of the surge (the magnitude of the proportional coefficient). RCV1 For example, the greater the surge, the larger the opening command value calculation unit 45 calculates the opening command value u. RCV1 .

[0076] exist Figure 2 In the structural example, the opening instruction value calculation unit 45 performs steps S13 and S14 simultaneously based on the piecewise linear function 451.

[0077] Next, the surge control device 40 controls the opening degree of the circulating flow regulating valve V1 (step S15). For example, the hysteresis compensation unit 46 adjusts the opening command value u. RCV1 Opening command value u for lag compensation RCV The output is sent to the circulating flow regulating valve V1.

[0078] As described above, according to the present embodiment, the compressor output control device 10 outputs the compressor 1 with the periodically varying rotational speed command value. The surge control device 40 acquires the response corresponding to the variation of the rotational speed command value, and calculates the relationship (proportionality coefficient K n ) of both. The response of the compressor 1 such as the pressure or the rotational speed also varies due to factors other than the surge. Therefore, in order to accurately detect the response based on the surge, in the present embodiment, the rotational speed command value, which is particularly strongly affected by the surge, is varied, and the periodic component (Formula (3A), Formula (3B)) is extracted from the response of the compressor 1 corresponding thereto, the magnitude of the response is evaluated (Formula (4)), and the occurrence of the surge is determined based on the magnitude of the response. If this method is used, the size of the piping P1, P3, etc. connected to the compressor 1, the temperature or composition of the refrigerant, the circulation flow rate adjustment valve V1 of the circulation flow piping P4, etc. are excluded from the influence, and thus the occurrence of the surge can be accurately detected. By appropriately setting the threshold value for determining the occurrence of the surge, the occurrence of the surge can be quickly detected.

[0079] In the above-described embodiment, the rotational speed n of the compressor 1 was described as an example of the response of the compressor 1, but other parameters can be used as the response corresponding to the variation of the rotational speed command value. For example, the current value variation, the pressure variation of the refrigerant discharged from the compressor 1, the pressure ratio variation of the refrigerant before and after the compressor 1, the flow rate variation of the refrigerant, the vibration of the compressor 1 main body, the vibration of the shaft and the bearing of the compressor 1, the rotational speed of the motor 30, the consumption current or power of the motor 30, the vibration of the motor 30 main body, the vibration of the shaft and the bearing, the noise of the surroundings can also be used for the surge control. In order to simplify the notation, the measured values used in the surge control are denoted as y i ···, (i = 1, 2, 3, ···). For example, y1 can be the rotational speed of the compressor 1, y2 can be the discharge pressure, y3 can be the pressure ratio, and y4 can be the flow rate. At this time, the variation calculating section 43 calculates the variation (variance) from the following Formula (5).

[0080] Var (y i ) = E ((Ay i - E (Ay i ))2 2 ), i = 1, 2, 3, ···

[0081] ··· (5)

[0082] The proportionality coefficient calculating section 44 extracts the periodic T component of the variation from the following Formula (6A), Formula (6B).

[0083] [Formula 6]

[0084]

[0085] [mathematical formula 7]

[0086]

[0087] The proportional coefficient can be calculated according to the above-described formula (6A), formula (6B), by the following formula (7). The proportional coefficient calculating section 44 calculates κ of formula (7) yi , and performs detection of surge and avoidance control based on κ yi .

[0088] [mathematical formula 8]

[0089]

[0090] According to the present embodiment, it is possible to operate the compressor in a state of slight surge while avoiding surge of the compressor. Thus, it is possible to improve the operation efficiency of the compressor and save power and the like.

[0091] <Second Embodiment>

[0092] (Configuration of Control Device)

[0093] Hereinafter, with reference to Figure 4 , the surge control based on the second embodiment of the present application will be described.

[0094] Figure 4 is a view showing an example of the control device according to the second embodiment.

[0095] In the configuration according to the second embodiment of the present application, the same symbols are attached to the functional sections that constitute the functional sections of the compressor output control device 10 and the surge control device 40 according to the first embodiment of the present application, and the description thereof is omitted. The surge control device 40A according to the second embodiment has a rotational speed fluctuation command section 41, a fluctuation calculating section 43A, a proportional coefficient calculating section 44A, an opening command value calculating section 45A, a hysteresis compensating section 46, and a weighted sum calculating section 47A.

[0096] The fluctuation calculating section 43A acquires a plurality of parameters y i (i = 1, 2, 3, ···), and calculates the fluctuation for each parameter by the above-described formula (5).

[0097] The proportional coefficient calculating section 44A calculates the proportional coefficient κ yi for each parameter by the above-described formula (7).

[0098] The opening command value calculating section 45A calculates the opening command value u yi for each parameter for which the proportional coefficient κ RCV1i calculated by the proportional coefficient calculating section 44A.

[0099] The weighted sum calculation section 47A calculates a weighted sum of the opening command values u RCV1i for the parameters calculated by the opening command value calculation section 45A with respect to the opening command value u

[0100] The hysteresis compensation section 46 calculates an opening command value u RCV1i that is hysteresis-compensated for the weighted sum of the opening command values u RCV calculated by the weighted sum calculation section 47A, and outputs the opening command value u RCV to the circulation flow regulating valve Vl.

[0101] As for the operation, the same as the first embodiment is used except that the weighted sum of the opening command values u RCVi of each parameter is used in addition to the plurality of parameters being set as the monitoring targets.

[0102] That is, first, the compressor output control device 10 outputs the variable speed drive device 20 with the variable speed command value including the variation (step Sll). Next, the surge control device 40 calculates the proportional coefficient K ni corresponding to the response of the variation of the speed command value for each parameter (step S12). Next, the surge control device 40 evaluates the occurrence of the surge (step S13) for each proportional coefficient K ni and calculates the opening command value u RCVi of the circulation flow regulating valve Vl corresponding to the occurrence of the surge (step S14). Next, the weighted sum calculation section 47A calculates the weighted sum of the opening command values u RCV1i (i = 1, 2, 3, ···). Next, the surge control device 40 performs the opening control of the circulation flow regulating valve Vl (step S15).

[0103] According to the second embodiment, the occurrence of the surge is determined based on the plurality of parameters, and thus effects of further improving the reliability in addition to the effects of the first embodiment are obtained.

[0104] <Third Embodiment>

[0105] (Configuration)

[0106] Hereinafter, with reference to Figures 5-6 , the surge control based on the third embodiment of the present application will be described.

[0107] Figure 5 is a view showing an example of the refrigeration system to which the third embodiment is applied.

[0108] As shown in the figure, the refrigeration system 100B is provided with a low-pressure side compressor (LP) la and a high-pressure side compressor (HP) lb connected in series. An inlet guide vane (LP) 2a is provided on the suction side of the compressor (LP) la, and an inlet guide vane (HP) 2b is provided on the suction side of the compressor (HP) lb. The compressor output control device 10B outputs separate angle command values to the inlet guide vane (LP) 2a and the inlet guide vane (HP) 2b. The compressor (LP) la and the compressor (HP) lb are provided coaxially and are driven by a common rotating shaft. That is, the compressor (LP) la and the compressor (HP) lb rotate at the same speed. The compressor output control device 10B outputs a rotational speed command value for the compressor (LP) la and the compressor (HP) lb to the variable speed drive device 20, and the motor 30 rotates the rotating shaft common to the compressor (LP) la and the compressor (HP) lb. For other structures of the refrigeration system 100B, the same structures as those described using the refrigeration system 100A are used. Figure 1

[0109] In the refrigeration system 100B, if one of the compressors surges, the discharge pressure or the flow rate of the refrigerant measured by the pressure gauge G1, etc. varies. For example, if the compressor (LP) la surges, the discharge pressure varies, and even if the compressor (HP) lb surges, the discharge pressure varies. Thus, in the case of a structure having a plurality of compressors, if one of the compressors surges, it does not matter how far the other operating condition is from the surge line. If it is possible to control so that the margin with respect to the surge line is equal among the compressors, it is effective for surge avoidance when there are a plurality of compressors. In the case of a structure having a plurality of compressors, the operating condition of one of the compressors can reach the surge region earlier than the other compressors. Figure 5

[0110] In the third embodiment, in order to avoid such a phenomenon, the angle command value of the inlet guide vane is varied, and based on the response, the angle control of the inlet guide vane is performed for each of the compressors, thereby making the margin of each of the compressors with respect to the surge line uniform, and avoiding that one of the compressors reaches the surge line much faster than the others, and that only for that compressor the circulation flow rate regulating valve V1 (common) is opened.

[0111] Structure of Control Device

[0112] Next, the control device (the compressor output control device 10B and the surge control device 40B) of the third embodiment will be described in detail with reference to Figure 6

[0113] Figure 6 is a figure showing an example of the control device according to the third embodiment.

[0114] ​​​The compressor output control device 10 is provided with an angle command section (LP) 103a, an angle command section (HP) 103b, an addition section 104a, a subtraction section 104b, a subtraction section 105a, and an addition section 105b.

[0115] The angle command section (LP) 103a calculates an angle command value r IGVL .

[0116] The angle command section (HP) 103b calculates an angle command value r IGVH .

[0117] The addition section 104a adds the angle command value for the inlet guide vane (LP) 2a to the angle variation command value output by the surge control device 40B, and calculates an angle command value r IGVL ( Equation (8A) ).

[0118] [Equation 9]

[0119]

[0120] The subtraction section 104b subtracts the angle variation command value output by the surge control device 40B from the angle command value for the inlet guide vane (HP) 2b, and calculates an angle command value r IGVH ( Equation (8B) ).

[0121] [Equation 10]

[0122]

[0123] The subtraction section 105a subtracts the compensation amount u IGVL output by the surge control device 40B from the angle command value r IGV , and calculates an angle command value u IGVL ( Equation (9A) ).

[0124] u IGVL = r IGVL - u IGV ... (9A)

[0125] The addition section 105b adds the angle command value r IGVH to the compensation amount u IGV output by the surge control device 40B, and calculates an angle command value u IGVL ( Equation (9B) ).

[0126] u IGVH = r IGVH + u IGV ... (9B)

[0127] In the first and second embodiments, surge detection is performed by varying the speed of the compressor 1. In contrast, in the third embodiment, the angles of the inlet guide vanes 2a and 2b are varied. If the compressor speed is varied, the operating conditions are... Figure 10 The graph changes vertically. On the other hand, if the angle of the inlet guide vane is changed, the operating conditions change primarily horizontally. In the case of refrigeration system 100B, the rotation shafts of compressors (LP) and (HP) are shared, and their respective operating conditions cannot be independently changed by controlling their rotational speed. Therefore, in this embodiment, the operating conditions of compressors 1a and 1b are changed by altering the angles of the inlet guide vane (LP) and the inlet guide vane (HP), respectively. Here, the angle command value r... IGVL and angle command value r IGVH The larger the value is configured, the greater the compressor output (work or flow rate when the pressure ratio is equal).

[0128] The surge control device 40B includes an angle change command unit 41B, a change calculation unit 43B, a proportional coefficient calculation unit 44B, and a compensation amount calculation unit 48B.

[0129] The angle change command unit 41B calculates the angle change command value using the following formula (10) and outputs it to the compressor output control device 10B.

[0130] [Formula 11]

[0131]

[0132] Here, a IGV b IGV Let T be any constant, t be time, and T be time. IGV The period can be arbitrary. The angle change command value can also include, for example, the period T. IGV Harmonics that are integer multiples of each other.

[0133] Similar to the rotational speed command value, the desired angle change command value should have a short cycle. If the change cycle of the angle change command value is, for example, sufficiently short as 1 minute, then the change in the angle command value will not be reflected in the cooling capacity.

[0134] Variable calculation unit 43B calculates parameter y i The change in parameter y. iThis refers to the speed of compressor 1, current value, discharge pressure of compressor 1, pressure ratio before and after compressor 1, refrigerant flow rate, vibration of compressor 1 body, vibration of compressor 1 shaft and bearings, speed of motor 30, current or power consumption of motor 30, vibration of motor 30 body, vibration of shaft and bearings, etc. The variation calculation unit 43B calculates the variation (variance) using the above formula (5).

[0135] The proportionality calculation unit 44B calculates the proportionality coefficient corresponding to the change in the angle command value based on the variation (variance) calculated by the variation calculation unit 43B. First, the proportionality calculation unit 44B evaluates the components of the period T using the following formulas (11A) and (11B).

[0136] [Formula 12]

[0137]

[0138] [Formula 13]

[0139]

[0140] Then, the scaling factor calculation unit 44B derives the following equation (12) from equations (11A) and (11B), and calculates the scaling factor κ using equation (12). IGVyi .

[0141] [Formula 14]

[0142]

[0143] The compensation calculation unit 48B calculates the compensation amount u relative to the angle command values ​​of the inlet guide vanes (LP) 2a and (HP) 2b based on the degree of proximity of the compressor (LP) 1a and compressor (HP) 1b to the surge line under their operating conditions. IGV If the proportionality coefficient κ IGVyi If the value is positive, measures must be taken to address the surge of compressor (LP) 1a. If the proportionality coefficient κ... IGVyi If the value is negative, measures must be taken to address the surge of compressor (HP) 1b. Therefore, if the proportional coefficient κ... IGVyi If the value is positive, the compensation calculation unit 48B adjusts, for example, by a compensator with integral characteristics as shown in equation (13), to reduce the power of compressor (LP) 1a and increase the power of compressor (HP) 1b. IGV Let ε be the proportional gain, and let ε be a constant that determines the range of the incomplete integral.

[0144] [Formula 15]

[0145]

[0146] (Action of control device)

[0147] Next, with reference to Figure 6 , Figure 7 , a process of controlling the margin of the surge line equally between the compressors will be described.

[0148] Figure 7 is a view showing an example of the action of the control device according to the third embodiment.

[0149] In the operation of the compressor 1, the compressor output control device 10B and the surge control device 40B repeatedly and continuously execute the following processes with a prescribed control cycle.

[0150] The compressor output control device 10 adds or subtracts the variation amount to the angle command value with respect to the inlet guide vanes (LP) 2a and the inlet guide vanes (HP) 2b (step S21). First, the angle command section (LP) 103a calculates the angle command value u IGVL for the inlet guide vanes (LP) 2a. The angle command section (HP) 103b calculates the angle command value u IGVH for the inlet guide vanes (HP) 2b. Next, the addition section 104a adds the angle command value r IGVL calculated by the angle command section (LP) 103a to the variation component calculated by the angle variation command section 41B, and calculates the angle command value r IGVL . The subtraction section 104b calculates the angle command value r IGVH from the angle command value r IGVH calculated by the angle command section (HP) 103b, subtracting the variation amount calculated by the angle variation command section 41B.

[0151] Next, the surge control device 40 calculates the proportional coefficient of the response corresponding to the variation of the angle command value output to the inlet guide vanes (LP) 2a and the inlet guide vanes (HP) 2b (step S22). The variation calculation section 43B calculates the variation of the response parameter by formula (5). Next, the proportional coefficient calculation section 44B derives formula (12) from formula (11A), formula (11B), and calculates the proportional coefficient K IGVyi from formula (12). The proportional coefficient calculation section 44B outputs the proportional coefficient K IGVyi to the compensation amount calculation section 48B.

[0152] Next, the compensation amount calculation section 48B calculates the compensation amount of the angle command value corresponding to the degree of approach to the surge line (step S23). In the compensation amount calculation section 48B, if the proportional coefficient K IGVyiis positive, it indicates that the work of the compressor (LP) la is correspondingly more, and therefore if a burden above that is applied, the possibility of surge is high, and therefore the work of the compressor (LP) la is reduced (the angle of the inlet guide vane (LP) 2a is decreased), the compensation amount u that increases the work of the compressor (HP) lb (the angle of the inlet guide vane (HP) 2b is increased) is calculated IGV . In the proportional coefficient K IGVyi In the case where it is negative, the compensation amount calculation section 48B increases the work of the compressor (LP) la (increases the angle of the inlet guide vane (LP) 2a), and calculates the compensation amount u that reduces the work of the compressor (HP) lb (decreases the angle of the inlet guide vane (HP) 2b) IGV . The subtraction section 105a calculates the angle command value u IGVL from which the compensation amount u IGV is subtracted (Equation (9A)) to calculate the angle command value u IGVL . In contrast, the addition section 105b adds the angle command value u IGVH to the compensation amount u IGV to calculate the angle command value u IGVH . The compressor output control device 10B outputs the angle command value u IGVL to the inlet guide vane (LP) 2a. The compressor output control device 10B outputs the angle command value u IGVH to the inlet guide vane (HP) 2b. In this way, the angle command value of the inlet guide vane (LP) 2a is corrected in such a way as to vibrate in the opposite direction to the angle command value of the inlet guide vane (HP) 2b, and thus uniformization of the work and equalization of the margin to the surge line are achieved. In the present embodiment, a case where the work of the compressor that is approaching the surge line is reduced and the work of the compressor that is away from the surge line is increased at the same time is explained. This does not necessarily need to be done both, and for example, it is also possible to implement only the increase of the work of the compressor that is away from the surge line.

[0153] According to the present embodiment, the margin of the operating conditions of each compressor la, compressor lb with respect to the surge line is equalized between the compressors, and thus it is possible to avoid a situation where surge occurs only in one of the compressors. As a result, it is also possible to improve the possibility of avoiding surge as a whole of the refrigeration system 100B.

[0154] In the third embodiment, it is also possible to calculate the compensation amount u IGVyi for each of a plurality of parameters as in the second embodiment, and to calculate the weighted sum thereof to calculate the final compensation amount u IGV .

[0155] The third embodiment can be combined with the first or second embodiment. That is, it is possible to control the opening of the circulating flow regulating valve V1 while changing the speed command values ​​of compressor 1a and compressor 1b, and to control the angle of the inlet guide vane (LP) 2a and inlet guide vane (HP) 2b relative to the third embodiment.

[0156] <Fourth Implementation>

[0157] The following is for reference. Figures 8-9 The surge control based on the fourth embodiment of the present invention will be described.

[0158] The first to third embodiments relate to early detection of surge and control to prevent surge. The fourth embodiment is used to set the opening of the circulating flow control valve V1 to the required minimum when the compressor's operating conditions have exceeded the surge threshold and the valve is opened. For this purpose, in the fourth embodiment, the opening of the circulating flow control valve, which is the dominant factor in surge prevention and control, is varied using a proportional coefficient corresponding to the response of the compressor 1.

[0159] Even if the control of the first to third embodiments is implemented, for example, a situation may arise where the compressor 1 must operate under surge conditions depending on the request of the refrigeration system 100 or the load condition. The control of the fourth embodiment described below is effective in this case.

[0160] (Structure of the control device)

[0161] Figure 8 This is a diagram illustrating an example of the control device (surge control device 40C) according to the fourth embodiment.

[0162] The compressor output control device 10 has the same structure as the first embodiment or the second embodiment. In addition to the structure of the first embodiment or the second embodiment, the surge control device 40C also includes an opening degree change command unit 41C, a change calculation unit 43C, a proportional coefficient calculation unit 44C, an opening degree command value calculation unit 45C, a hysteresis compensation unit 46C, an adder 106, and an adder 107.

[0163] The opening change command unit 41C calculates the opening change command value of the circulating flow regulating valve V1, for example, by the following formula (14).

[0164] [Formula 16]

[0165]

[0166] Here, a RCV b RCVis an arbitrary constant, t is time, T RCV is an arbitrary period. The opening variation command value can include a harmonic of an integer multiple of the period T RCV

[0167] The addition section 106 adds the opening command value u RCV of the circulation flow regulating valve V1 calculated through the processing of the first embodiment or the second embodiment to the opening variation command value calculated by the opening variation command section 41C.

[0168] The variation calculation section 43C calculates the variation of the parameter y i . The variation calculation section 43C calculates the variation (variance) through the above-described equation (5).

[0169] The proportional coefficient calculation section 44C calculates the proportional coefficient of the response corresponding to the variation of the opening command value based on the variation (variance) calculated by the variation calculation section 43C. First, the proportional coefficient calculation section 44C evaluates the component of the period T RCV through the following equations (15A), (15B).

[0170] [Equation 17]

[0171]

[0172] [Equation 18]

[0173]

[0174] Then, the proportional coefficient calculation section 44B derives the following equation (16) from the equations (15A), (15B), and calculates the proportional coefficient K RCVyi through the equation (16).

[0175] [Equation 19]

[0176]

[0177] The opening command value calculation section 45C calculates the opening command value u RCVyi of the circulation flow regulating valve V1 based on the proportional coefficient K RCV1 . For example, the opening command value calculation section 45 has a function or the like that converts the proportional coefficient K RCVyi into the opening command value u RCV1 of the circulation flow regulating valve V1, and calculates the opening command value u n of the circulation flow regulating valve V1 based on the function or the like and the proportional coefficient K RCV1 Figure 8 ​​The diagram shows an example of the piecewise linear function 452 of the opening command value calculation unit 45. Regarding the degree of surge, the smaller the opening command value of the circulating flow control valve V1, the more severe the surge. As shown in the piecewise linear function 452, the proportional coefficient κ... RCVyi The value is below 0 before exceeding the threshold; if it exceeds the threshold, the proportionality coefficient κ... RCVyi The larger the value of u, the larger the calculated opening command value of the circulating flow control valve. RCV1 Therefore, the opening degree of the circulating flow regulating valve V1 is compensated to the minimum required limit.

[0178] When the proportionality coefficient κ RCVyi When the magnitude exceeds the allowable limit of surge, the hysteresis compensation unit 46 calculates the compensation amount u of the circulating flow regulating valve V1 through hysteresis compensation, for example, by the following formula (17). RCV3 and will compensate amount u RCV3 Output to the addition section 107. RCV Let ε be the proportional gain, ε be a constant that determines the range of the incomplete integral, and s be the Laplace operator.

[0179] [Formula 20]

[0180]

[0181] Adding unit 107 combines the opening command value of the circulating flow regulating valve V1 calculated by adding unit 106 with the compensation amount u. RCV3 Add them together to calculate the final opening command value u of the circulating flow control valve V1. RCV2 The surge control device 40 will control the opening command value u. RCV2 The output is sent to the circulating flow regulating valve V1.

[0182] (The operation of the control device)

[0183] Next, refer to Figure 8 , Figure 9 The control of the circulating flow regulating valve V1 during surge detection is explained.

[0184] Figure 9 This diagram illustrates an example of the operation of the control device according to the fourth embodiment.

[0185] As a premise, assuming a surge occurs, the circulating flow regulating valve V1 is opened to a predetermined degree. Alternatively, assuming the relationship between the discharge pressure of compressor 1 or the pressure ratio before and after compressor 1 and the refrigerant flow rate falls within the surge region. Furthermore, assuming the control of either the first or second embodiment is performed. During the period when the circulating flow regulating valve V1 is open, the surge control device 40C repeatedly and continuously performs the following process at a predetermined control cycle.

[0186] First, the surge control device 40C varies the opening degree command value of the circulation flow regulating valve V1 (step S31). The opening degree variation command section 41C calculates the opening degree variation command value by Expression (14). The addition section 106 adds the opening degree command value u RCV calculated by the control of the first embodiment or the second embodiment to the opening degree variation command value.

[0187] Next, the surge control device 40C calculates the proportional coefficient of the response corresponding to the variation of the opening degree command value (step S32). First, the variation calculation section 43C calculates the variation (variance) of the parameter according to Expression (5). Next, the proportional coefficient calculation section 44C derives Expression (16) according to Expressions (15A), (15B), and calculates the proportional coefficient K RCVyi according to Expression (16). The proportional coefficient calculation section 44C outputs the proportional coefficient K RCVyi to the opening degree command value calculation section 45C.

[0188] Next, the surge control device 40C calculates the compensation amount of the opening degree command value (step S33). First, the opening degree command value calculation section 45C calculates the opening degree command value u RCVyi based on the proportional coefficient K RCV1 and the function 452. Next, the hysteresis compensation section 46 calculates the compensation amount u RCV3 according to Expression (17).

[0189] Next, the surge control device 40C performs the opening degree control of the circulation flow regulating valve V1 (step S34). The addition section 107 adds the opening degree command value including the variation component calculated in step S31 to the compensation amount u RCV3 , and calculates the opening degree command value u RCV2 . The surge control device 40C outputs the opening degree command value u RCV2 to the circulation flow regulating valve V1.

[0190] According to the present embodiment, it is possible to control the opening degree of the circulation flow regulating valve V1 to the minimum opening degree required to suppress the surge when the surge occurs, and thus it is possible to suppress the loss of the work of the compressor 1.

[0191] The fourth embodiment can be combined with the first to third embodiments. For example, by combining the first or second embodiment, the third embodiment, and the fourth embodiment, it is possible to appropriately adjust the angles of the inlet guide vanes (LP) 2a, the inlet guide vanes (HP) 2b, the circulation flow regulating valve V1, and the refrigerant flow through the circulation flow pipe P4 to avoid the surge, or to suppress the degree of the surge. In the case where the rotation speed of the compressor 1, the angles of the inlet guide vanes (LP) 2a, and the opening degree of the circulation flow regulating valve V1 are adjusted at the same time, the period T of changing the rotation speed of the compressor, the period T of changing the angle of the inlet guide vanes, and the period T of changing the opening degree of the circulation flow regulating valve V1 IGVWith changing the period T of the circulating flow RCV The values ​​must be distinct. For example, if T is set to 3 seconds, T... IGV Set to 15 seconds, T RCV Set to 75 seconds, etc., and ideally set the shortest period in order of fastest response, with other periods set to integer multiples of the shortest period.

[0192] Figure 11 This is a diagram illustrating an example of the hardware structure of the control device involved in each embodiment.

[0193] The computer 900 has a CPU 901, a main storage device 902, an auxiliary storage device 903, an input / output interface 904, and a communication interface 905.

[0194] The aforementioned compressor output control device 10, compressor output control device 10B, surge control device 40, surge control device 40A, surge control device 40B, and surge control device 40C are actually installed in the computer 900. Furthermore, each of these functions is recorded as a program in the auxiliary storage device 903. The CPU 901 reads the program from the auxiliary storage device 903, expands it in the main storage device 902, and executes the aforementioned processing according to the program. The CPU 901 secures a storage area in the main storage device 902 according to the program. Furthermore, the CPU 901 secures a storage area in the auxiliary storage device 903 for the data being processed according to the program.

[0195] Programs for implementing all or part of the functions of compressor output control device 10, compressor output control device 10B, surge control device 40, surge control device 40A, surge control device 40B, and surge control device 40C can be recorded on a computer-readable recording medium. The computer system reads the program recorded on the recording medium and executes it to perform processing based on each functional unit. The term "computer system" here includes hardware such as an operating system or peripheral devices. In the case of using a WWW system, "computer system" also includes a homepage providing environment (or display environment). "Computer-readable recording medium" refers to portable media such as CDs, DVDs, and USB drives, and storage devices such as hard drives built into the computer system. Furthermore, when the program is distributed to computer 900 via a communication line, the receiving computer 900 can also open the program in main storage device 902 and execute the aforementioned processing. The program can be a program for implementing a part of the aforementioned functions, or it can be a program that can implement the aforementioned functions by combining with programs already recorded in the computer system.

[0196] As described above, the embodiments relating to the present application have been described, but all of these embodiments are merely suggested as examples and are not intended to limit the scope of the application. These embodiments can be implemented in other various forms, and various omissions, substitutions, and changes can be made thereto without departing from the scope of the application. These embodiments and modifications thereof, and the embodiments included in the scope or the spirit of the application, are also included in the application recited in the scope of the claims and the scope equivalent thereto.

[0197] <Notes>

[0198] As for the control device, the control method, and the program described in each of the embodiments, for example, the following is grasped.

[0199] (1) The control device (the compressor output control device 10, the compressor output control device 10B, the surge control device 40 to 40C) relating to the first aspect includes: a variation instruction unit (the rotation speed variation instruction unit 41, the angle variation instruction unit 41B, the opening degree variation instruction unit 41C) that causes a variation in an instruction value to a system (the refrigeration system 100) including a compressor 1, a compressor la, and a compressor lb, that is, the instruction value (the rotation speed, the IGV opening degree, the circulation flow rate regulating valve opening degree) that affects an operation state of the compressor 1, the compressor la, and the compressor lb; a proportional coefficient calculation unit 44, a proportional coefficient calculation unit 44A, a proportional coefficient calculation unit 44B, and a proportional coefficient calculation unit 44C that calculate a proportional coefficient that represents a variation in a parameter indicating a state of the compressor or a motor 30 that drives the compressor when the system is operated based on the instruction value with respect to the instruction value; and a control unit (the hysteresis compensation unit 46, the hysteresis compensation unit 46B, the subtraction unit 105a, the addition unit 105b, and the addition unit 107) that performs control for avoiding or suppressing a surge of the compressor based on a value of the proportional coefficient.

[0200] The instruction value that affects the operation state of the compressor is caused to vary, and a response thereof is measured, and a proportional coefficient of a variation in the measured parameter with respect to the variation in the instruction value is calculated. Then, control for causing the operation state of the compressor to transition to an operation point at which a surge is avoided is performed in accordance with the magnitude of the proportional coefficient. Thus, even if a surge can occur, the surge can be rapidly avoided, and even if a surge has occurred, the surge can be quickly suppressed.

[0201] (2) The control device (the compressor output control device 10, the surge control device 40A) relating to the second aspect is the control device of (1), in which the proportional coefficient calculation unit 44A calculates the proportional coefficient for each of a plurality of the parameters, and the control unit performs control for avoiding or suppressing a surge of the compressor based on values of a plurality of the proportional coefficients.

[0202] The reliability of the control can be improved by performing surge avoidance control based on a plurality of parameters.

[0203] (3) The control device (compressor output control device 10, surge control device 40 to 40A) according to the third aspect is the control device according to (1) to (2), wherein the command value is a rotational speed command value of the compressor, the variation command section periodically varies the rotational speed command value, the proportional coefficient calculation section calculates the proportional coefficient when the rotational speed command value is periodically varied, and the control section performs control to increase the flow rate of the fluid sucked and discharged by the compressor in accordance with the magnitude of the proportional coefficient.

[0204] The surge can be detected with high accuracy by varying the rotational speed of the compressor that most affects the surge and monitoring the response thereof.

[0205] (4) The control device (compressor output control device 10, compressor output control device 10B, surge control device 40 to 40B) according to the fourth aspect is the control device according to (1) to (3), wherein the system has a plurality of the compressors, and an inlet guide vane that controls the flow rate of the fluid sucked by the compressor is provided for each of the compressors, the command value is an angle command value of the inlet guide vane, the variation command section periodically varies the angle command value, the proportional coefficient calculation section calculates the proportional coefficient when the angle command value is periodically varied, and the control section performs control to adjust the angle command value of each of the inlet guide vanes in accordance with the magnitude of the proportional coefficient so as to equalize the work borne by the plurality of the compressors.

[0206] Thus, in the system having a plurality of compressors, even when the rotational speed of each of the compressors cannot be individually controlled, the surge can be avoided by individually controlling the inlet guide vanes.

[0207] (5) The control device (compressor output control device 10, compressor output control device 10B, surge control device 40 to 40B) according to the fifth aspect is the control device according to (4), wherein the control section (subtraction section 105a, addition section 105b) changes the inlet guide vane provided to the compressor in which the possibility of occurrence of the surge is low among the plurality of the compressors so as to increase the work borne by the compressor.

[0208] If the risk of the surge in one of the compressors becomes high, the IGV opening degree of the compressor in which the possibility of occurrence of the surge is low is increased. Thus, the burden among the plurality of the compressors can be equalized, and the margin from the surge line can be equalized.

[0209] (6) The control device involved in the sixth method (compressor output control device 10, compressor output control device 10B, surge control device 40-40C) is the control device of (1) to (5), wherein the command value is the opening command value of the flow regulating valve installed on the piping connecting the suction side and the discharge side of the compressor, the change command unit causes the opening command value to change periodically, the proportional coefficient calculation unit calculates the proportional coefficient when the opening command value of the flow regulating valve changes periodically, and the control unit adjusts the opening command value according to the magnitude of the proportional coefficient.

[0210] If surge occurs, the flow control valve located on the piping connecting the compressor's suction and discharge sides will be opened to suppress surge. However, this control can also vary the opening of the flow control valve and adjust its opening based on the response, thereby making the flow control valve opening appropriate. For example, the opening of the flow control valve can be set to the minimum limit.

[0211] (7) The control device involved in the seventh method is the control device of (6), wherein when the discharge pressure of the compressor or the ratio of the pressure before and after the compressor is in a relationship with the flow rate of the fluid drawn in and discharged by the compressor, the probability of a predetermined surge is high ( Figure 10 When considering the relationship between the region to the left of the surge line L1, the processing described in (6) is performed.

[0212] By performing the treatment described in (6) under operating conditions that cause surge, the opening of the flow control valve can be quickly appropriated.

[0213] (8) The control device involved in the eighth method (compressor output control device 10, compressor output control device 10B, surge control device 40-40C) is the control device of (1) to (7), wherein the parameter is at least one of the following: the speed of the compressor, the vibration of the compressor, the current flowing through the compressor, the flow rate of the fluid sucked in and discharged by the compressor, the pressure of the fluid, the pressure ratio of the fluid before and after the compressor, the speed of the motor, the vibration of the motor, the current flowing through the motor, the power consumed by the motor, and the ambient noise.

[0214] The control methods described in (1) to (7) can be implemented using the various parameters mentioned above, and therefore can utilize the parameters that are easy to measure.

[0215] (9) The control device according to the ninth aspect includes: a variation instruction section that varies an instruction value for a system including a compressor, that is, the instruction value that affects an operating state of the compressor; a proportional coefficient calculation section that calculates a proportional coefficient that represents a variation of a parameter indicating a state of the compressor or a motor that drives the compressor when the system is operated based on the instruction value, with respect to the instruction value; and a detection section (opening degree instruction value calculation section 45 to 45C) that detects a surge of the compressor based on a value of the proportional coefficient.

[0216] The instruction value that affects the operating state of the compressor is varied, and a response thereof is measured, and a proportional coefficient of a variation of a measured parameter with respect to a variation of the instruction value is calculated. Then, the occurrence of the surge is detected based on a magnitude of the proportional coefficient. Thus, the occurrence of the surge can be detected early and reliably.

[0217] (10) The control method according to the tenth aspect includes: varying an instruction value for a system including a compressor, that is, the instruction value that affects an operating state of the compressor; calculating a proportional coefficient that represents a variation of a parameter indicating a state of the compressor or a motor that drives the compressor when the system is operated based on the instruction value, with respect to the instruction value; and performing control for avoiding or suppressing a surge of the compressor based on a value of the proportional coefficient.

[0218] (11) The program according to the eleventh aspect causes a computer 900 to execute the following processing: varying an instruction value for a system including a compressor, that is, the instruction value that affects an operating state of the compressor; calculating a proportional coefficient that represents a variation of a parameter indicating a state of the compressor or a motor that drives the compressor when the system is operated based on the instruction value, with respect to the instruction value; and performing control for avoiding or suppressing a surge of the compressor based on a value of the proportional coefficient.

[0219] Industrial Applicability

[0220] According to the above-described control device, control method, and program, the occurrence of the surge can be detected early and reliably, and measures can be taken.

[0221] Explanation of Symbols

[0222] 100, 100B - refrigeration system, 1 - compressor, 1a - compressor (LP), 1b - compressor (HP), 2 - inlet guide vanes, 2a - inlet guide vanes (LP), 2b - inlet guide vanes (HP), 3 - condenser, 4 - evaporator, P1, P2, P3, 11, 12 - piping, P4 - circulation flow piping, V1 - circulation flow adjusting valve, G1 - pressure gauge, N1 - noise meter, 10 - compressor output control device, 20 - variable speed drive device, 30 - electric motor, 40, 40A, 40B, 40C - surge control device, 41 - rotational speed variation command section, 41B - angle variation command section, 41C - opening degree variation command section, 42 - subtraction section, 43, 43A, 43B, 43C - variation calculation section, 44, 44A, 44B, 44C - proportional coefficient calculation section, 45, 45A, 45C - opening degree command value calculation section, 46, 46C - hysteresis compensation section, 47A - weighted sum calculation section, 48B - compensation amount calculation section, 101 - rotational speed command section, 102 - addition section, 103a - angle command section (LP), 103b - angle command section (HP), 104a - addition section, 104b - subtraction section, 105a - subtraction section, 105b - addition section, 106, 107 - addition section, 900 - computer, 901 - CPU, 902 - main storage device, 903 - auxiliary storage device, 904 - input / output interface, 905 - communication interface.

Claims

1. A control device comprising: The change command unit changes the command value for the system including the compressor, that is, the command value that affects the operating state of the compressor. The proportionality coefficient calculation unit calculates a proportionality coefficient relative to the command value for the change of a parameter representing the state of the compressor or the motor driving the compressor when the system is operated based on the command value. and The control unit, based on the value of the proportional coefficient, performs control to avoid or suppress compressor surge. The system comprises multiple compressors connected in series, and for each compressor, there are inlet guide vanes for controlling the flow rate of the fluid drawn into the compressor. The command value is the angle command value of the inlet guide vane, and the change command unit causes the angle command value to change periodically. The scaling factor calculation unit calculates the scaling factor that causes the angle command value to change periodically. The angle command value is configured such that the larger the value, the greater the power output of the compressor. The control unit adjusts the angle command value of each inlet guide vane to vibrate in the opposite direction according to the magnitude of the proportional coefficient, so as to equalize the work undertaken by the multiple compressors.

2. The control device according to claim 1, wherein, The scaling factor calculation unit calculates the scaling factor for each of the plurality of parameters. The control unit performs control to avoid or suppress compressor surge based on the values ​​of multiple proportional coefficients.

3. The control device according to claim 1 or 2, wherein, The command value is the compressor speed command value, and the change command unit causes the speed command value to change periodically. The proportional coefficient calculation unit calculates the proportional coefficient that causes the speed command value to change periodically. The control unit controls the flow rate of the fluid drawn into and discharged by the compressor to increase based on the magnitude of the proportional coefficient.

4. The control device according to claim 1, wherein, For multiple compressors, the control unit alters the inlet guide vanes on compressors less likely to experience surge, thereby increasing the work performed by those compressors.

5. The control device according to claim 1 or 2, wherein, The command value is the opening command value of the flow regulating valve installed on the piping connecting the suction and discharge sides of the compressor, and the variable command unit causes the opening command value to change periodically. The proportional coefficient calculation unit calculates the proportional coefficient that causes the opening command value of the flow control valve to change periodically. The control unit adjusts the opening command value according to the magnitude of the proportional coefficient.

6. The control device according to claim 5, wherein, When the discharge pressure of the compressor or the pressure ratio of the compressor to the front and rear pressures is in a relationship with the flow rate of the fluid drawn in and discharged by the compressor that is in a relationship where the likelihood of a predetermined surge is high, the processing described in claim 5 shall be performed.

7. The control device according to claim 1 or 2, wherein, The parameters are at least one of the following: compressor speed, compressor vibration, current flowing through the compressor, flow rate of fluid drawn in and discharged by the compressor, fluid pressure, pressure ratio of the fluid before and after the compressor, motor speed, motor vibration, current flowing through the motor, power consumed by the motor, and ambient noise.

8. A control device comprising: The change command unit changes the command value for the system including the compressor, that is, the command value that affects the operating state of the compressor. The proportionality coefficient calculation unit calculates a proportionality coefficient relative to the command value for the change of a parameter representing the state of the compressor or the motor driving the compressor when the system is operated based on the command value. and The detection unit detects the surge of the compressor based on the value of the proportional coefficient. The system comprises multiple compressors connected in series, and for each compressor, there are inlet guide vanes for controlling the flow rate of the fluid drawn into the compressor. The command value is the angle command value of the inlet guide vane, and the change command unit causes the angle command value to change periodically. The scaling factor calculation unit calculates the scaling factor that causes the angle command value to change periodically. The angle command value is configured such that the larger the value, the greater the power output of the compressor. The detection unit controls the angle command value of each inlet guide vane to vibrate in opposite directions according to the magnitude of the proportional coefficient, so as to equalize the work undertaken by the multiple compressors.

9. A control method that causes a change in a command value for a system including a compressor, i.e., a command value that affects the operating state of the compressor. Calculate the proportionality coefficient relative to the command value for the change in a parameter representing the state of the compressor or the motor driving the compressor when the system is operating based on the command value. Based on the value of the proportional coefficient, control is performed to avoid or suppress compressor surge. The system comprises multiple compressors connected in series, and for each compressor, there are inlet guide vanes for controlling the flow rate of the fluid drawn into the compressor. The command value is the angle command value of the inlet guide vane, causing the angle command value to change periodically. Calculate the scaling factor that causes the angle command value to change periodically. The angle command value is configured such that the larger the value, the greater the power output of the compressor. Based on the magnitude of the proportional coefficient, control is performed to adjust the angle command value of each of the inlet guide vanes to vibrate in opposite directions, so as to equalize the work undertaken by the multiple compressors.

10. A computer-readable recording medium having a program recorded thereon, the program causing a computer to perform the following processes: This causes a change in the command value for the system, including the compressor, that is, the command value that affects the operating state of the compressor. Calculate the proportionality coefficient relative to the command value for the change in a parameter representing the state of the compressor or the motor driving the compressor when the system is operating based on the command value. Based on the value of the proportional coefficient, control is performed to avoid or suppress compressor surge. The system comprises multiple compressors connected in series, and for each compressor, there are inlet guide vanes for controlling the flow rate of the fluid drawn into the compressor. The command value is the angle command value of the inlet guide vane, causing the angle command value to change periodically. Calculate the scaling factor that causes the angle command value to change periodically. The angle command value is configured such that the larger the value, the greater the power output of the compressor. Based on the magnitude of the proportional coefficient, control is performed to adjust the angle command value of each of the inlet guide vanes to vibrate in opposite directions, so as to equalize the work undertaken by the multiple compressors.

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