JPH10299664A - Operation controlling device for pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To succeed water supply at the time of failure by estimating at least two sets of pump torques corresponding to estimated no-discharge pump head of an operating pump, storing them, and adjusting the pump speed so as to coincide the pump torque with generated torque reference, with reference to the data. SOLUTION: When a control changeover switch 109 is set on the side indicated by a numeral 1, an output (h) of a pressure setter 101 is a pressure set value. A constant pressure control system of a variable speed control is thus formed. Abnormality of a pressure sensor is sensed based on the fact that the sensed pressure value is out of an allowable maximum value or always zero, or that the sensed pressure value is not interlocked with varying pump speed. At that time, an output of a PI controller 102 is forcibly set to be a value before sensing abnormality. The control changeover switch 109 is changed over to the torque controlling indicated by a numeral 2. A torque reference τs * is generated for performing constant pressure controlling with reference to at least too sets of data storing a torque value under the condition of a normally operated pressure sensor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a pump operation control device in an automatic water supply pump system.

[0002]

2. Description of the Related Art In automatic water supply facilities such as buildings and condominiums, in addition to the conventional constant pressure control for keeping the discharge pressure of a pump constant, recently, the estimated unfixed end pressure for keeping the pressure at the demand end almost constant has been recently increased. Control has come to be applied in terms of good water supply with low pressure fluctuations and energy savings.
In particular, as a means to vary the speed of the pump,
In addition, recent transistor inverters, which have been significantly improved in reliability, have been applied, and have greatly contributed to achieving this object. Here, the “estimated end pressure constant control” is a control in which the end pressure is estimated on the pump side and the estimated value is made almost constant, and a method of directly detecting and controlling the pressure at the remote water supply end. This is called as compared to By the way, an automatic water supply system is generally configured to obtain a control signal of the inverter from a microcomputer-type controller that executes closed circuit pressure control and necessary sequence control for controlling the inverter. I have. In closed-circuit pressure control, the actual pump discharge pressure is detected by a pressure detector, and this is compared with a set value of constant pressure control or a set value of estimated endless pressure constant control, and the deviation is input to a PI controller. The constant pressure control or the estimated terminal pressure constant control is performed by adjusting the frequency of the inverter by the proportional and integral operations of the controller. In other words, in terms of water supply reliability, this pressure detector
It will be required to improve the reliability equivalent to or higher than the current Inverness reliability. If this requirement is not satisfied, even if there is no problem in PI control and sequence control by software processing of the controller, the pressure detector may not operate due to ambient temperature, dust, poor mounting, aging, etc. If there is a malfunction, there is a high possibility of a water outage accident.

[0003] In order to improve the reliability of the water supply system, a pump of 100% capacity, a drive motor and an inverter are placed independently of each other, and as a parallel redundant system,
The automatic alternating operation system, which is designed to increase reliability and performs automatic alternating operation to extend the life by averaging wear and tear, is adopted as a general method. This is an important issue from the point of view.
Certainly, the pressure detector does not have a rotating part and a movable part unlike pumps and electric motors, and there is little concern about aging due to wear and reduction in reliability. However, in the unlikely event of a failure of the pressure detector, the high reliability due to the parallel redundancy with the automatic alternate operation system is lost. In the past, mean time between failures (MTBF = mean time between failur
When e) was low and there were many initial failures, a backup system was proposed in which an electromagnetic contactor was installed to bypass the inverter and connect the motor directly to the commercial power supply in case of an inverter failure.

However, this proposal does not utilize the high reliability of recent inverters as an effective resource, but also requires the addition of two sets of main circuit electromagnetic contactors for disconnecting the inverter and turning on commercial power. Cost is high. In addition, when the motor is turned on, a large starting flow flows, which disturbs the power supply system and generates a large amount of heat when starting the motor. Therefore, this backup system is not practical when a system for supplying emergency water by controlling the pump ON-OFF by a flow signal from a flow switch or the like is greatly restricted in terms of cost and performance. As a countermeasure, a backup operation control device that uses the soft-start and soft-stop functions of the inverter and controls the soft-start and soft-stop ON-OFF is conceivable. However, there is a problem that the speed control function that the user has cannot be fully utilized.

[0005]

SUMMARY OF THE INVENTION The present invention provides a means for solving such a problem. The present invention is directed to a single automatic alternating operation using a variable speed pump controlled by an inverter.
The present invention relates to backup operation control by software of an automatic water supply system that performs parallel automatic alternating operation and automatic rotation operation. In other words, the object of the present invention is to utilize the speed control function of the inverter, suppress the heat generation of the motor without disturbing the power supply, and control the torque of the motor to prevent the pressure detector even in the event of a failure. All software is built so that the water supply can be continued without stopping the pump, without adding hardware cost, low cost coordinating with the redundant basic drive system, It is to provide a highly reliable water supply system.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is to increase the speed of a pump configured to be able to supply water to a terminal hydrant by single operation or parallel operation of two or more units. At least one variable speed control device capable of variable speed control, a pressure detector disposed in a water supply pipe on the discharge side of the pump, and a pressure setting reference to be compared with a detection value of the pressure detector are set, and this deviation is set. In the operation control device of the pump in the automatic water supply pump system which performs the constant pressure control or the estimated terminal pressure constant control so as to be small, a means for estimating a cutoff head of the pump being operated, and a pump corresponding to the cutoff head The means for estimating the torque and at least the data of the cutoff head and the torque of two or more different pumps are stored. And means for generating a torque reference, to match the torque of the pump to the torque reference, is characterized in adjusting the speed of the pump.

[0007] In a pump operation control device of an automatic water supply pump system for performing constant pressure control or constant estimated end pressure without a pressure detector, a pump head in the case of constant pressure control or constant control of estimated terminal pressure. And at least two sets of pump torque data are stored, and a means capable of generating a torque reference corresponding to the shutoff head is provided based on the data to perform torque control.

[0008]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an overall configuration diagram in the case where the pump operation control device of the present invention is applied to a water supply system with two pumps, and FIG. 2 is a block diagram showing the principle configuration of the pump operation control device of the present invention. It is. In FIG. 1, reference numeral 1 denotes a pump operation control device of the present invention, and 2 ₁ ,
2 ₂ at a pressure detector for detecting the pump discharge pressure, pump suction side pressure respectively, detected pressure signal h, and outputs the h _su to the operation control device 1. The operation control device 1 outputs frequency commands f _1s and f _2s as output signals to the inverters 12 and 22.
The inverters 12 and 22 supply variable voltages and variable frequencies to the induction motors 11 and 21 that drive the pumps 13 and 23, respectively, so that the pump speeds can be independently adjusted. 3 a pressure of coercive pressure placed to stop the pump when the water supply amount is small evening link, the vacuum check valve for preventing backflow of water into the water retraction side 9 4, 5 _1, 5 ₂ is a check valve for preventing a backflow placed on the discharge side of the pumps 13 and 23, 6 ₁ and 6 ₂ are shut-off valves used for maintenance and inspection of the pumps 13 and 23, respectively.
Reference numerals 8 ₁ and 8 ₂ denote suction-side shut-off valves which are also used for maintenance and inspection of the pumps 13 and 23.

Reference numeral 7 denotes a flow switch which is installed between the discharge side collecting pipes of the pumps 13 and 23 and the water supply pipe extending to the water supply pipe discharge side 10, and detects a flow rate therebetween. FIG. 2 is a block diagram showing the internal configuration of the pump operation control device of the present invention shown in FIG. In the figure, 101 is a pressure setting device, 102 is a PI controller, 103 and 104.
Is a digital-to-analog converter, 105 is a linear commander having the same characteristics as the linear commander built in the inverter 12 or 22 in FIG. 1, 106 is a first-order lag element,
07 is a square arithmetic unit, 108 is a constant representing the pump characteristic a, and 109 is a pressure setting unit 10 when the pressure detector fails.
1 is a control changeover switch for changing over to the pump operation control device of the present invention instead of 1. 110 and 111 are operation changeover switches for the No. 1 pump and the No. 2 pump,
12 is a square computing unit; 113 is a square root computing unit for detecting the pump torque τ by performing a square root operation on the output of the square computing unit 112 to subtract the square value of the excitation current of the selected pump; 114 is a constant l08 representing the pump characteristic a.
3 shows a function generator for generating a reference torque (τ _s ^* ) set by the output h _po of FIG.

In FIG. 2, the control changeover switch 109
Is on the “1” side, the output h _{s of the} pressure setter 101 is
Is set as a pressure set value, and a known constant pressure control system based on variable speed control of a pump is configured. Now, the pressure detection value overflows the allowable maximum value, is always zero, or the pressure detection signal value does not decrease even if the pump speed decreases, or the pressure detection signal value does not increase even if the pump speed increases. When the abnormality of the detector is detected, the output of the PI controller 102 is forcibly set to the value before the abnormality is detected and holds the value. At the same time, the control changeover switch 109 switches from "1" to "2", and switches to the torque control of the present invention. Function generator 1l4, under the final set pressure during commissioning, i.e., when the sound pressure detector, the fully closed discharge-side shut-off valve ₆₁ (the time NO.1 pump operation) from the fully open position At least two sets of data in which the pump constant output h _po and the value of the torque τ are stored while changing the pump constant to the position, and a pump torque reference for performing constant pressure control based on the current value of the pump constant h _po τ _s ^*
Is to occur.

Here, in the present invention, the torque reference τ _s ^*
The reason for using is described. The control changeover switch 10 in which the pump is operated under a constant pressure control system
When 9 is on the “1” side, there is no proportional relationship between the pump speed and the flow rate. Therefore, when the pressure detector is out of order, it is difficult to estimate the flow rate from the inverter frequency and determine the compensation value of the frequency at which the pressure becomes almost constant even if the water supply load fluctuates, so that the constant pressure control cannot be performed. If the efficiency of the pump is constant under constant pressure, the shaft power of the pump is proportional to the flow rate.Therefore, if the pressure detector fails, the flow rate is estimated from the motor current to compensate for the pressure fluctuation. However, as an alternative, this is considered first. However, in this case, there are the following problems.

First, since the motor current contains an exciting current component, it is difficult to detect the flow rate by the motor current when the flow rate is small. Second, by setting the pressure,
In particular, in a direct feed water supply system, the relationship between the current and the torque differs depending on the magnitude of the pressure on the suction side,
Third, at low flow rates, the pump efficiency is greatly reduced, and the efficiency varies considerably depending on speed and model. Therefore, in the present invention, for the first problem, the relationship between the motor torque and the flow rate excluding the exciting current component was obtained, and for the second and third problems, the pressure set value was used as a parameter. Focusing on the fact that the relationship between the cutoff head and the motor torque is almost linear, the controller measures and stores the actual value immediately before the pressure setting is completed and operation starts. This problem is solved by generating a torque reference τs * that becomes a constant pressure with reference to FIG.

FIG. 3 is a characteristic graph showing characteristics of a function generator for generating a torque reference according to the present invention. In this characteristic graph, as an example, it is assumed that effective indentation head = (indentation head) − (fixed loss head of check valve 4) ≒ 0, and pressure setting hs = 1.0 p.u. And 0.75p.
u. Is calculated by calculating the relationship between the motor torque and the pump's cutoff head, where? Is a parameter.
Here, the pressure setting hs, the cutoff head _hpo , and the motor torque τ are all ratios to the rated values, that is, the unit method p.
u. (Per unit). As can be seen in FIG. 3, the characteristics of the two with the pressure setting as a parameter are:
It can be seen that there is a substantially linear relationship. That is, if the speed of the pump is adjusted by the inverter so that the actual motor torquer matches the torque reference of the motor corresponding to the cutoff head, a water supply operation at a substantially constant pressure can be performed as a result.

FIG. 5 is a control flow showing a procedure for obtaining reference data for generating a signal of a function generator for generating a relationship between the cutoff head and the motor torque as shown in FIG. According to the procedure shown in FIG. 5, the _cutoff head and the motor torque for the maximum flow rate are set to h _po1 by steps 1 to 5,
It can be stored as τ _1. In steps 6 to 10, the _cutoff head and the motor torque for the minimum flow rate can be stored as h _po2 and τ ₂ . Then, based on these stored data, the torque reference τ _s ^* can be calculated for an arbitrary cutoff head h _po by the following equation (1). τ _s ^* = [(τ _{1 −τ 2} / (h _po1 −h _po2 )] × (h _po −h _po2 ) + τ ₂ (pu) (l) On the other hand, the input signal h of the function generator 114 _{For obtaining po} , first, an estimated value f ^* of the motor frequency is created by the linear commander 105 having the same characteristics as the linear commander built in the inverter, and from this estimated value f ^* , the delay time to the motor speed is calculated. An estimated value n ^* of the pump speed is obtained by a temporary delay element 106 for setting the time until the relationship between the pressure and the flow rate of the pump system becomes a steady state, and this is calculated by a square calculator 107 to obtain a pump constant a. _Multiplied and calculated as an ^{* 2} = h _po .

Further, in the constant pressure control system, since the speed control range of the motor is relatively narrow at 60% to 100%, the motor torque τ can be expressed as follows in the case of operating the No. 1 pump. (2) can be approximately calculated. ^{_{τ ≒ (I 1 2 -Im 1}} 2) 1/2 (p.u.) (2) where, I ₁ = (NO.1 pump load current) / (rated current of the NO.l pump) (p. u.) Im ₁ = (excitation current of NO.1 pump) / (rated pump flow of NO.1 pump) (pu) τ = (torque of NO.1 pump) / (rated of NO.1 pump) (Torque) (pu) Normally, in the inverter control of the pump, the (voltage / frequency) ratio of the inverter is set to be constant, and the exciting current component is
Can be set as a constant value.

[0016] That is, (2) as shown in FIG. 2 on the basis of the equation, the primary current of the motor from the operation switching switch 111 I ₁
(Pu) is taken in, the square value of the excitation current Im ₁ is subtracted from the square operation value obtained by the square operation unit 112, and the result is calculated by the square root operation unit 113 to obtain the motor torque τ It is clear that this is an approximate value of (pu). Thus, after the control changeover switch 109 is switched to the “2” side, a torque control circuit is formed in which the output τ _s ^* of the function generator 114 is used as a torque setting value and τ is used as a torque detection value. The discharge pressure is controlled to be substantially constant.
In the case of the No. 2 pump operation, the operation changeover switches 110 and 111 shown in FIG.
Control is performed in the same manner as in the case of the pump.

[0017] The detection signal h _su from the suction side pressure detector 2 ₂ input to the operation controller 1, although not shown, when the suction side pressure has dropped below the reference value, stopping the pump It is used for an interlock such as to do. In the description so far, τ ₁ , τ ₂ ,
h _po1 and h _po2 are measured by actually measuring the actual operating conditions of the pump, stored in the storage device of the controller, and described as generating a torque reference τ _s ^* corresponding to h _po. Design values and test values τ1, τ2,
It is also possible to input and set h _po1 and h _po2 in the storage device, and similarly generate the torque reference τ _s ^* . In this case, the pressure detector is not necessary from the beginning, and a so-called water supply system without a pressure detector can be constructed.

[0018] In addition, it is selected to set a torque reference.
Parameters and h_po= A * n *^TwoThe pump cutoff
If it is a parameter indicating the head, the estimated value of the pump speed n
* But it is fine. Of course, even at the actual speed n, its squared value
n^Two But also a * n calculated from actual speed^TwoBut can be used
Noh. In the present invention, the cutoff head h expressed in the unit method_po
Is convenient for displaying and checking data.
Because. Approximate expression of pump head-flow rate characteristics
For the pump constant a in the equation, the pump's rated head H
_N, Rated speed N_N, Rated flow Q_N Is expressed in units of
It can be obtained from the equation. In the present invention, the constant pressure system
Describes a variable speed pump system that runs under your control
However, in principle, the pump is
It is also applicable when driving under the original conditions. Toes
Τ under constant control of estimated terminal pressure₁, Τ_Two,
h _po1, H_po2Can be measured and stored, or entered and recorded
If you can remember, h_poEstimated end pressure becomes constant corresponding to
Torque reference τ_s ^*Can be produced.

Although the present invention has been described with reference to the water supply system of the single-alternating operation type, the sum of the torques (τ ₁ + τ ₂ ) of the pumps is used as the detection value of the torque in the parallel operation system as well. If the total torque reference Δτ _s ^* can be generated from the function generator, a pump operation control device having the same function can be constructed. FIG.
However, in principle, the present invention is not limited to this method as described above. For example, the present invention can be applied to a conventional water receiving tank type. In this case, the suction-side check valve and the suction-side pressure detector are omitted. FIG. 4 is an explanatory diagram for explaining an application different from the above of the present invention, and shows a relationship between a motor torque and a flow rate under the same conditions as in FIG.
That is, if the maximum flow rate and the minimum flow rate can be measured under the constant pressure control, the flow rate measurement values for the two sets of motor torques can be obtained in the same manner as shown in FIG. The flow rate of the running pump can be estimated from the motor torque. This is used as a display value of the flow rate when the pressure detector is sound, and even in the case of a pressure detector failure, the torque control shown in FIG. The numerical value can be estimated.

[0020]

As described above, according to the present invention,
Utilizing the speed control function of the inverter, without disturbing the power supply, suppressing the heat generation of the motor, and controlling the torque of the motor, even in the event of a failure of the pressure detector, without stopping the pump, All of the software is constructed so that the water supply can be continued, so low cost and highly reliable water supply can be coordinated with the redundant basic drive system without adding hardware cost. There is an effect that the system can be provided.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram when a pump operation control device of the present invention is applied to a water supply system with two pumps.

FIG. 2 is a block diagram showing a configuration of a pump operation control device of the present invention.

FIG. 3 is an explanatory diagram for explaining characteristics of the function generator according to the present invention;

FIG. 4 is an explanatory diagram when the present invention is applied to flow rate detection.

FIG. 5 is a control flow showing a procedure for acquiring data for a function generator.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Operation control device 2 _{1, 2} Pressure detector 3 Pressure tank 4 Pressure reducing check valve 5 _{1, 2} Check valve for backflow prevention 6 _{1, 2} Shutoff valve 7 Flow switch 8 _{1, 2} Suction side shutoff valve 9 Water draw-in Side 10 Water supply pipe discharge side 11, 21 Induction motor 12, 22 Inverter 13, 23 NO. 1, 2 pump 101 Pressure setting device 102 PI controller 103, 104 Digital-analog converter 105 Linear commander 106 Primary delay element 107 Square operator 109 Control changeover switch 110, 111 Operation changeover switch 112 Square calculator 113 Square root operation Instrument 114 Function Generator

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI // H02P 7/74 H02P 7/74 G (72) Inventor Tomoyama Tanji 3-24-6 Ayase, Adachi-ku, Tokyo SA Inside the Yama Works

Claims (2)

[Claims] At least one variable speed control device capable of variable speed control of the speed of a pump configured to supply water to a terminal hydrant by independent operation or parallel operation of two or more units, and discharge of the pump A pressure detector disposed in the water supply pipe on the side of the drain and a pressure setting reference to be compared with the detected value of the pressure detector are set, and constant pressure control or constant estimated end pressure control is performed so as to reduce this deviation. A pump operation control device for the automatic water supply pump system, wherein a means for estimating a cutoff head of the pump during operation; and a means for estimating a torque of the pump corresponding to the cutoff head.
At least two different sets of pump heads,
Means for storing torque data and generating a torque reference corresponding to the cutoff head of the pump based on the data, and adjusting the speed of the pump so that the torque of the pump matches the torque reference. An operation control device for a pump, comprising: 2. An operation control device for a pump in an automatic water supply pump system which performs constant pressure control or constant estimated endless pressure control without a pressure detector. 2. The pump according to claim 1, further comprising means for storing at least two sets of data of the cutoff head and the pump torque, and providing means for generating a torque reference corresponding to the cutoff head based on the data, and performing torque control. Operation control device.