JPH071039B2 - Variable speed water supply device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] [Field of the Invention] The present invention relates to a control device for performing large-scale adjustment of a water supply facility including a plurality of pumps.

“Prior Art” In water supply equipment, there is a demand from the user side at the end of piping to obtain the required pressure and flow rate, and it is necessary to maintain the required pressure although the used flow rate fluctuates. The fluctuation of the amount of water used is dealt with by changing the rotation speed of the turbo pump driven by the variable speed motor. In such a case, control such as constant discharge pressure or constant estimated end pressure is conventionally performed.

FIG. 4 shows an example of constant pressure control, in which the horizontal axis represents the flow rate and the vertical axis represents the pressure. 21 is the pump performance curve. In this case, the discharge pressure P of the pump is controlled by controlling the rotation speed so that the discharge pressure of the pump is a constant pressure at a pressure obtained by adding the pressure loss Pc of the pipeline at the maximum flow rate to the required pressure Pn at the end of the pipe. However, according to this method, due to the resistance of the conduit that changes in proportion to the square of the flow rate, the fluctuation of the required pressure Pn at the end of the pipe is large, and it is considered that energy loss occurs in the range indicated by the diagonal lines in the figure.

In the conventional control method shown in FIG. 5, which is shown in the same coordinates as in FIG. 4, the pump discharge pressure P is determined in consideration of the pressure loss in the conduit so that the estimated end pressure becomes constant. The flow rate of the pressure loss Pc in the pipeline changes correspondingly, that is, the pump discharge pressure is changed according to the resistance curve.

In Fig. 5, in the water supply system using a pump, the required pressure and flow rate at the end of the pipe are equipped with a flow meter, and the pressure loss in the pipe corresponding to the flow meter is taken into account The rotation speed is controlled so that the added amount is added to the pump to obtain the pressure.

Such a method is expensive because it requires a flow meter.
In this case, the piping is different and the pump characteristics are also different.Therefore, it has to be applied to each individual pump device. Not suitable.

In addition to the above, there is also a method of storing and controlling the performance of the pump, but it requires time and labor to collect data, and can be applied only to individual systems.

Japanese Patent Application No. Sho 58-24 as the latest technology for constant control of estimated end pressure
The variable speed water supply device of 8031 (Japanese Patent Publication No. 6-12116) is provided with a control device for keeping the estimated terminal pressure constant without a flow meter.

[Problems to be Solved by the Invention] The present invention, when the water supply device is to be configured using the latest technology of the above-mentioned constant estimated end pressure control, when operating multiple units,
This was done about the problem of how to easily calculate the target pressure SV. Normally, in the device of constant estimated end pressure control, the pump rotation speed HZX is input and the control target pressure SV at that rotation speed is calculated, while the speed control is applied toward that target pressure. .

If this control target pressure SV arithmetic expression is used with the sign in the embodiment, and there is one pump, SV = G (HZX) G (HZX) = ((PA−PB) / (HZMAX−HZB) × (HZX −HZB) + PB …… (A)

This formula is an arithmetic formula that satisfies the following conditions.

(Condition) The control target pressure SV is between two points (HZB, PB) and (HH) when the water amount is between zero and maximum, that is, when the pump speed HZX is between HZB and HZMAX.
ZMAX, PA) and the rotation speed is between HZB and HZMAX, PB <SV <P
It becomes A.

The variables in the above equation are only the control target pressure SV and the rotation speed HZX.

In such a control system, there is a problem of how to calculate the target pressure SV when operating a plurality of units.

Next, two ways of thinking about how to set the pump rotation speed when operating a plurality of units will be described.

1) Separate the target pressure calculation formula for parallel operation.

For example, it is conceivable to use the arithmetic expression SV = G2 (HZX) to obtain another control target pressure when operating two units in parallel.

However, according to this idea, the target pressure calculation formula for the number of vehicles must be provided, and the parameter must be considered for each target calculation formula. There may be some drawbacks such as incompatibility with the control device operating alone.

2) Next, it will be considered to perform constant estimated end pressure control by using the same target pressure calculation formula, singly or in plural. In order to realize this, we propose the concept of virtual rotation speed during parallel operation.

This is a concept to be introduced in order to perform the estimated end pressure control using one target pressure SV arithmetic expression both in the isolated operation and in the parallel operation. Up to now HZθ (load range of parallel operation) is added to the actual pressure of one pump to calculate the target pressure by substituting the actual rotational speed of one pump. The target pressure for parallel operation is obtained by substituting the virtual rotation speed (using equations (5), (6), (7) below) converted using the rotation speed (HZ2) of is there.

The virtual rotation speed is the value of the rotation speed that is substituted for the variable term of the rotation speed in the target pressure calculation formula during parallel operation.

In parallel operation of two pumps, the rotation speed of each pump is from the actual rotation speed HZB (for example 31.6Hz) to the maximum rotation speed (for example 50Hz) of the pump required to generate the required pressure of the pump discharge part when the pump is shut off. Change. Therefore, the actual rotation speed signal from the rotation speed detecting means is about 30 to 50 Hz. One unit
Operating at 50Hz (maximum rotation speed of one unit) and the other 40Hz
In the case of driving with the above equation, how to calculate the virtual rotation speed in order to output an appropriate target pressure by the above formula (A) will be considered. For example, the actual operating speed of the second unit HZ2 = 40Hz is G
Substituting for (HZX) is inconvenient because the same target pressure as when the first pump was 40 Hz was calculated.

Maximum rotation speed HZMAX is 100Hz (50Hz + 50Hz) for 2 units
In this case, inconvenience occurs as shown in the diagram of FIG. 9 showing the target pressure D (case D), and inconvenience occurs even if two pump operating speeds are set and 90 Hz (50 Hz + 40 Hz) is substituted.
Assuming that the minimum rotation speed of the pump is about 30 Hz, in this way, 50 Hz or more suddenly becomes 80 Hz in parallel operation, and the target pressure SV becomes discontinuous in the range of 50 to 70 Hz. FIG. 9 shows the amount of water on the abscissa and the target pressure on the ordinate, and shows how the target pressure becomes large in each method. In the above method in which the maximum rotation speed of the pump is set to two, the curve marked with * in the figure results in a large discontinuity in the target pressure when paralleled. This is inappropriate for practical use.

In such a pump device that performs constant control of the estimated end pressure, when trying to operate in parallel with a device including a plurality of pumps, the target pressure calculation in the second pump becomes complicated. However, there is a drawback that it is difficult to properly determine the target pressure to be the second additional point.

INDUSTRIAL APPLICABILITY The present invention provides a control target pressure at the time of additional pump operation in a variable-speed water supply device that performs constant end pressure estimation control from the relationship between pump rotation speed and pump discharge pressure in a pump device including a plurality of pumps. A function to calculate the rotation speed of the additional pump for calculating, that is, a target pressure calculation from the actual rotation speed of the additional pump so that the control target pressure can be calculated by using the control target calculation formula during independent operation even when adding. It is an object of the present invention to provide a variable speed water supply device having a control device having a function of calculating a virtual rotation speed used for.

[Structure of Invention]

"Means for Solving Problems" The first invention of the present application has two pumps having the same pump characteristics, at least one of which is operated at a variable speed and the other pump is operated at a constant speed. Equipped with a rotation speed control means for detecting the discharge pressure and a pump rotation speed detecting means, and the pump discharge pressure and the rotation speed when the pump is shut off, and all that the user determines based on the equipment plan. When the pump is operating, the required pressure of the pump discharge part at the time of maximum water supply and the required rotation speed of the pump that obtains the required pressure are input, and the control target pressure for each rotation speed is calculated to obtain a constant estimated end pressure control. In the variable speed water supply device that operates, the virtual rotation speed HZi during parallel operation is HZi = HZθ + (HZ2-HZC) where HZi: Virtual rotation speed HZθ in calculation used for target pressure calculation HZθ: Actual maximum of the first pump Rotation speed HZ2: Added 2 Actual rotation speed of the second pump HZC: Because the second pump outputs the pressure of the pump discharge part that became the target pressure when the actual maximum rotation speed of the first pump was calculated in the target pressure calculation. The actual rotation speed required for the calculation is converted by the formula, and the virtual rotation speed HZi after the calculation conversion is used as the actual rotation speed HZX for control, and the required pressure PA at the required maximum water amount and the virtual pressure at the required maximum water amount are calculated. Rotation speed HZ
Select a function that approximates the pressure-rotation speed relationship that passes through the point MAX and the pump rotation speed HZB when the minimum pressure PB required when the pump is shut off, and substitute it into this function to obtain the control target pressure. It is a variable speed water supply device characterized in that a control device for calculating SV is provided.

The second invention of the present application has two pumps having the same pump characteristics, at least one of them is operated at a variable speed, another pump is operated at a constant speed, and a rotation speed control means of the pump is provided.
It is equipped with a pressure detector that detects the discharge pressure and pump rotation speed detection means, and the pump discharge pressure and rotation speed when the pump is shut off and the maximum water supply during operation of all pumps specified by the user based on the equipment plan. Required pressure of the pump discharge part at the time of
Input the required rotation speed of the pump that obtains the required pressure,
Virtual speed HZi during parallel operation is HZi = HZθ + (HZ2-HZA) where HZi is the target pressure calculation in a variable speed water supply system that performs constant estimated end pressure control by calculating the control target pressure for each rotation speed. Virtual rotation speed for calculation used for HZθ: Actual maximum rotation speed of the first pump HZ2: Actual rotation speed of the added second pump HZA: One pump at maximum water supply is the discharge part The actual rotational speed required to obtain the required pressure when the engine is shut off is calculated and converted, and the virtual rotational speed HZi after conversion is used as the actual rotational speed HZX for control, and the required pressure PA at the required maximum water amount And the virtual rotation speed HZ when the maximum amount of water is required
Select a function that approximates the pressure-rotation speed relationship that passes through the point MAX and the pump rotation speed HZB when the minimum pressure PB required when the pump is shut off, and substitute it into this function to obtain the control target pressure. It is a variable speed water supply device characterized in that a control device for calculating SV is provided.

The third invention of the present application has two pumps having the same pump characteristics, at least one of them is operated at a variable speed, another pump is operated at a constant speed, and a rotational speed control means for the pump is provided.
It is equipped with a pressure detector that detects the discharge pressure and pump rotation speed detection means, and the pump discharge pressure and rotation speed when the pump is shut off and the maximum water supply during operation of all pumps specified by the user based on the equipment plan. Required pressure of the pump discharge part at the time of
Input the required rotation speed of the pump that obtains the required pressure,
Virtual speed HZi during parallel operation is HZi = HZθ + (HZ2-HZB) where HZi is the target pressure calculation in a variable speed water supply system that performs constant estimated end pressure control by calculating the control target pressure for each rotation speed. Virtual rotation speed for calculation HZθ: Actual maximum rotation speed of the first pump HZ2: Actual rotation speed of the added second pump HZB: Discharge part of one pump when the pump is shut down Required pressure of
The actual rotation speed of the pump required to output PB is calculated by the formula, and the virtual rotation speed HZi after the calculation conversion is used as the actual rotation speed HZX for control, and the required pressure PA at the required maximum water volume and the required Virtual rotation speed HZ at maximum water volume
Select a function that approximates the pressure-rotation speed relationship that passes through the point MAX and the pump rotation speed HZB when the minimum pressure PB is required when the pump is shut off, and substitute it into this function to control the target pressure. It is a variable speed water supply device characterized in that a control device for calculating SV is provided.

[Operation] In the first invention of the present application, the rotation speed HZ2 of the second pump is detected by the rotation speed detection means, is input to the control device, and the constant HZC stored in the control device is used as data to obtain HZi. Calculate the rotational speed for calculating the control target pressure using the calculation command of the formula HZi = HZθ + (HZ2-HZC).

In the second invention of the present application, the rotational speed HZ2 of the second pump is detected by the rotational speed detection means, is input to the control device, and the constant HZA stored in the control device is used as data, and the above-mentioned formula HZi = Use the calculation command of HZθ + (HZ2-HZA) to obtain the control target pressure and obtain the calculated rotation speed.

According to the third invention of the present application, the rotational speed HZ2 of the second pump is detected by the rotational speed detection means, is input to the control device, and the constant HZB stored in the control device is used as data, and HZi is calculated by the above formula HZi = Use the calculation command of HZθ + (HZ2-HZB) to obtain the control target pressure and obtain the calculated rotational speed.

In each of the above inventions, the virtual rotation speed HZi is the actual rotation speed HZX in control, and the required pressure PA at the required maximum water amount and the virtual rotation speed HZMAX at the required maximum water amount and the minimum pressure required when the pump is shut off. Pump rotation speed when outputting PB
A function that approximates the pressure-rotation speed relationship passing through the point HZB is selected, and is substituted into this function to calculate the control target pressure SV.

“Practical example” According to the invention of Japanese Patent Application No. 58-248031 (Japanese Patent Publication No. 6-12116), when one pump is operated at a variable speed, each pump rotation speed is constant when the flow rate is constant. The data table that stores the pressure value of the pump and the pump rotation speed and pressure value when the required terminal pressure is output when all the multiple pumps are operating and the maximum flow rate is in use, that is, the pump discharge part at the time of maximum water supply is required. The control target pressure for each pump rotation speed can be determined by using the data on the relationship between the pressure and the required rotation speed of the pump that obtains the required pressure. Although it seems difficult to measure the pressure value for each rotation speed of the pump at a constant flow rate in the method of determining the control target pressure, it is necessary to input the measurement data at a constant flow rate = 0, that is, when the pump is in a closed state. It is simple and does not require a flow meter to measure a constant flow rate. Therefore, it is convenient to perform the operation at each rotational speed of the pump when the pump is shut off, since the operation can be performed without using the flowmeter.

Next, a method for determining the control target pressure corresponding to each rotation speed when the invention of Japanese Patent Application No. 58-248031 (Japanese Patent Publication No. 6-12116) is applied to a plurality of variable speed water supply devices will be described.

HZX: The actual rotation speed of one unit in the load range of independent operation,
In the load range of two-unit operation, virtual rotation speed PX: Pressure calculated by equation (5), (6), or (7) described later PX: Pressure HZX = f (PX): Relationship between rotation speed and pressure when tightening PA: Required pressure at maximum required water volume HZMAX: Virtual rotation speed at maximum required water volume HZA: Required pressure at maximum required water volume Rotational speed required to output PA when tightening PB: Minimum pressure required when tightening HZB: Crimping The difference ΔHZ between the virtual rotation speed HZMAX at the required maximum water amount and the rotation speed HZA required to output the required pressure PA at the required maximum water amount when the rotation speed is set to the required minimum pressure PB ΔHZ = HZMAX−HZA Required pressure PA at the maximum required water amount and minimum pressure PB at the dead end
The difference ΔP is ΔP = PA-PB, and PM = ΔP + α + PB (0 ≤ α ≤ 1) and PM is the reference control target pressure PM when PM is the reference of the control target pressure SV at the intermediate point between the pressure loss PA and PB. HZM = ΔHZ x β + f (PM) (0 ≤ β ≤ 1) where HZM is the rotation speed that produces the corresponding flow rate, where K1 = (PM-PB) / (HZM-HZB) K2 = (PA-PM) / ( HZMAX-HZM) and K1, K2, and control target pressure SV for a certain pump speed HZX is HZX ≤ HZB SV = PB ...... (1) HZB <HZX ≤ HZM SV = K1 x (HZX-HZB) + PB ...... (2) HZM <HZX ≤ HZMAX SV = K2 x (HZX-HZM) + PM ... (3) HZMAX <HZX SV = PA ... (4) Above (1), (2), (3), (4) Determine according to the formula.

In the above, even if the values of α and β are fixed at 0.5, for example, the error between the curve showing the relationship between the control target pressure and the discharge amount and the resistance curve can be made practically no problem. These values are α,
The line determined by β is fixed to an empirically determined constant that relatively well matches the resistance curve.

In the above-mentioned process, the required pressure PA at the required maximum amount of water and the virtual rotation speed HZMAX at the required maximum amount of water and the pump rotation speed when the pump is tightened and the minimum required pressure (= required end pressure) PB is output. The HZB point is taken as the pressure-rotation speed coordinate, and these two points are approximated by connecting them with a polygonal line via the intermediate point (PM, HZM) coordinates. Such a method approximates the actual pump performance if the midpoint PM between PA and PB determined by α and β is appropriate, and a control target pressure suitable for practical use can be obtained.

FIG. 1 is a flow sheet showing a pump device. Pumps 2 and 12 driven by motors 1 and 11 whose rotational speeds are controlled by changing the frequency pump water from the water source 3 through suction pipes 4 and 14, pressurize the water and discharge it to discharge pipes 5 and 15. Then, it joins the water pipe 7 via the check valves 6 and 16. The pressure of the water in the water supply pipe 7 is detected by the pressure detector 8 and is sent to the demand side.

The signal of the discharge pressure detected by the pressure detector 8 is the control unit 9
To be sent to. A frequency signal is output from the control unit 9 and is input to, for example, inverters 13 and 23 that obtain a frequency power source of a thyristor conversion system. The inverters 13 and 23 output electric power of a required frequency and feed the motors 1 and 11 to the motors 1 and 1.
Drive 11 at the required speed. The frequency generated by the inverters 13, 23 and sent to the motors 1, 11 is sent to the control unit 9.

A microcomputer is used as the control unit 9, and a command for previously calculating the relationship between the pump rotation speed when the pump device is tightly closed and the pump discharge pressure, the pump rotation speed at the required maximum flow rate, and the control target pressure is calculated. Is provided with a storage device.

In such a pump device, for convenience of description, the pump 2 is first operated, and the pump 12 is additionally operated by increasing the flow rate in a state where the end estimated pressure constant control is performed at the maximum rotation speed of the pump 2. Actually, since the pumps actually operate alternately, the pumps 2 and 12 may naturally be operated in the reverse order.

In such a pump device, the control target pressure when the first pump 2 is operated independently is expressed by the equations (1) and (2).
It can be determined by (3) and (4).

Now, for example, the pump 2 has a maximum rotation speed HZθ (usually 50 Hz or 60
Hz) rotation, if the water supply load increases, the control target pressure cannot be followed and the pump 12 is additionally operated.
A method of obtaining the rotation speed in the additional operation of the pump 12 will be described below.

FIG. 2 is a diagram showing the relationship between the rotation speed of the pump and the control target pressure, in which the horizontal axis shows the control target pressure and the vertical axis shows the pump rotation speed. In the figure, S is a curve that determines the two-machine operation control target pressure.

The curve S shows a device operating in parallel in a large water amount range. Operating range of one pump (HZB, PB) ~ (HZ
θ, PC), the target pressure is calculated using the actual rotation speed of the pump, and in the range (HZθ, PC) to (HZMAX, PA) that exceeds HZθ, the pumps operate in parallel and the virtual rotation speed calculated by the formula of the present invention is calculated. Calculate the target pressure using

In the figure, Pi: Value of control target pressure when rotation speed is HZi HZMAX: Virtual maximum rotation speed at required maximum water volume This rotation speed is obtained from the following equation (5) or (6) or (7).

The above equations are equations for obtaining the virtual rotation speed. Since HZMAX is the maximum value of the virtual rotation speed, the actual maximum rotation speed of the second pump is added to the actual rotation speed HZ2 of the added second pump in the above formula (5), (6) or (7). It can be obtained by substituting.

HZθ: Maximum rotation speed of the first pump (usually 50Hz or 60H
z) PC: This is the control target pressure at the maximum rotation speed of the first pump. With reference to FIG. 2, at the calculated virtual rotation speed HZi, the point Pi at which the horizontal line from the ordinate HZi cuts the curve S and the vertical line hanging down the abscissa can be obtained as the control target pressure.

Here, the virtual rotation speed in the calculation used for control when calculating the control target pressure by calculating the conversion of the rotation speed during parallel operation.
Read about HZi.

The first method is to calculate the target pressure at the maximum rotation speed of the first pump 2 by the target pressure calculation
When the rotation speed required to take out when the clamp is cut off is HZC, the rotation speed of the second pump 12 is HZ2, and HZi = HZθ + (HZ2-HZC) (5).

The second method is to calculate the calculated virtual rotation speed HZi for calculating the control target pressure of the second pump 12 by HZi = HZθ + (HZ2-HZA) (6).

The third method is to calculate as HZi = HZθ + (HZθ−HZB) (7).

HZ on the vertical axis using the S curve in Fig. 2 using these relationships
The control target pressure SV on the horizontal axis can be obtained using i as a variable.

Next, a specific example of how to obtain the control target pressure will be described.

1) There is a diagram of discharge pressure P and rotation speed Hz when the pump is closed as shown in FIG.

This may be actually measured while closing the pump discharge port and increasing the rotation speed, or may be input in advance.

2) Now, the required pressure PA at the time of maximum water supply is 30 m, and the actual rotation speed at that time is 50 Hz (however, the rotation speed HZ2 of the second pump in parallel with two is 50 Hz). Also, the minimum pressure required for tightening PB
= 20m Maximum rotation speed of the first pump HZθ = 50H
z: HZA and HZB above are HZA = 38.7Hz HZB from Fig. 6 respectively.
= 31.6Hz.

3) Also, in order to simplify the explanation, consider the case where α = 0 and β = 0. The tense control target pressure SV is calculated by the following equation (8).

However, HZB ≤ HZX ≤ HZMAX 4) In the case of the first control method, equation (5) HZi = HZθ + (HZ2-HZC) is used. HZC to HZMA
In order to accurately determine the balance with X, first tentatively HZC = HZ
Calculate as A.

That is, using the formula (6) HZi = HZθ + (HZ2-HZA), and letting the actual maximum rotation speed of the second pump 12 be HZ2θ If HZX = 50Hz in the equation (9), the target pressure SV at the maximum pump rotation speed HZθ = 50Hz will be obtained during single unit operation.

The rotation speed when the pump is shut off to obtain the SV pump discharge pressure of 26.2 m is found to be 36.2 Hz from Fig. 6, and HZMAX is obtained again by setting this as provisional HZC = 36.2 Hz.

HZMAX = 50 + (50-36.2) = 63.8Hz Substituting this into (8) again, obtain SV50.

Temporary HZC at SV = 25.7m = 35.8Hz When repeated again, HZMAX = 64.2Hz SV50 = 25.6m Temporary HZC = 35.8Hz.

Therefore, HZMAX = 64.2Hz and HZC = 35.8Hz. According to the first control method, the curve S in FIG. 2 becomes as shown in FIG. Further, FIG. 10 is a Q-H diagram corresponding to FIG. 3 and the numerical values in the above calculation are described.

5) In the case of the second control method, equation (6) HZi = HZθ + (HZ2-HZA) is used.

Therefore, HZMAX = HZθ- (HZ2θ-HZA) = 50 + 50-38.7 = 61.3Hz Pressure control is performed with this control target pressure SV as a target.
According to the equation (9), the curve S in FIG. 2 becomes as shown in FIG. If HZX = 50Hz in equation (9), the target pressure SV50 at the pump maximum rotation speed HZθ = 50Hz during one unit operation will be obtained.

As described above, the control target pressure obtained by the second control method outputs an approximate value, and has an error compared with the first method. In addition, there is a difference in the target pressure when switching from one-unit operation to two-unit operation. The table below shows a comparison of the pressure (HZX = HZθ) immediately before addition. (According to the table in FIG. 9) In this way, the target pressure differs by about 1 m depending on the method, but there is no practical problem.

FIG. 3 is a diagram showing the relationship between the flow rate and pressure of the pump device, with the horizontal axis representing the flow rate Q and the vertical axis representing the pressure. A curve R is a combined pump performance curve of the pumps 2 and 12 in parallel operation, and the rotation speed at that time is HZMAX. The curve I is the performance curve of the pump 2, and the maximum rotation speed at that time is HZθ. When F is a resistance curve, the maximum amount of water supply is at the intersection 18 of the combined pump performance curve R and the resistance curve F, and the required pressure at that point is PA. The ordinate of the intersection 19 of the performance curve I and the resistance curve F of the single pump is the control target pressure PC at the maximum rotation speed of the first pump 2, and the maximum pump 2 of the first pump 2 is calculated by calculating the pump control target pressure. At the rotational speed required for the second pump 12 to output the pressure that has become the control target pressure at the rotational speed when the second pump 12 is shut off, it starts from the intersection 19 between the performance curve of the first pump 2 and the resistance curve F. Shown as performance curve RC.

The rotational speed required to generate the required pressure PB when the pump is shut off is HZB. The performance curve is shown as IB. When the pumps 2 and 12 are operated in parallel, the required pressure PA at the maximum flow rate when the pump is shut off and the pump performance at the rotational speed HZA is shown by curve R.
Indicated by A.

Since PA>PC> PB as seen in this diagram, the rotation speed of the second pump 12 additional point is in the relationship of HZA>HZC> HZB, and the formula (6) is the second pump 12 The rotational speed HZi used in the calculation of the control target pressure is the smallest, the rotational speed HZi obtained by the equation (7) is the largest, and the rotational speed HZi obtained by the equation (5) is obtained by the equations (6) and (7). It is between the rotational speed HZi to calculate the control target pressure.

The control target pressure SV of the rotational speed obtained by these is calculated using the equations (1) to (4). The relationship between HZi and SV is stored in the storage device in the control unit 9 as a function of the diagram as shown in FIG.

Also in the variable speed water supply device in which three pumps can be operated in parallel, the rotational speed used for calculating the control target pressure of the third pump can be similarly obtained.

Next, a numerical calculation example of each embodiment of the present invention and numerical values obtained by the numerical calculation are plotted on the horizontal axis, and the vertical axis is the target pressure (lift).
The diagram of the above is shown in FIG.

Suppose that the control target pressure SV calculation formula is SV = G (HZX) G (HZX) = ((PA-PB) / (HZMAX-HZB)) x (HZX-HZB) + PB (1).

Case in the Example of the First Invention of the Present Application (FIG. 9 Target Pressure C, Diagram Plot Point ×) Virtual Rotational Speed Equation HZMAX = HZθ + (HZ2-HZC) In the present invention, HZC is calculated as described above. And HZC = 3
Calculated as 5.8Hz, the maximum rotation speed is HZMAX = HZθ + (HZθ-HZC) = 50 + (50-35.8) = 64.2
Calculate as Hz and set the calculation formula SV = G (HZi) as SV = KC (HZi-HZB) + PB (SV = 0.35 × ((1) coefficient KC = (PA-PB) / (HZMAX-HZB) = 0.31) HZi-31.6) + 2
0) and calculate the virtual rotation speed HZi during parallel operation as HZi = HZθ + (HZ2-HZC) {HZi = 50 + (HZ2-35.8)}.

When the virtual rotation speed at 40Hz is calculated with this, HZi = 50 + (40-35.8) = 54.2Hz, which is substituted into SV = G (HZX).

Calculate the target pressure with SV = G (54.2) = 26.93m.

When controlled in this way, the target pressure is controlled as shown by x in the figure depending on the amount of load water.

Since the HZC has a more accurate rotation speed at the additional point, the pressure at the additional point is smooth. This method can generate a target pressure that almost conforms to the resistance curve.

Case in Example of Second Invention of the Present Application (FIG. 9 Target Pressure A, Diagram Plot Point Δ) Virtual Rotation Speed Formula HZMAX = HZθ + (HZ2-HZA) In the present invention, the maximum rotation speed is HZMAX = HZθ + (HZθ -HZA) = 50 + (50-38.7) = 61.3
Calculated as Hz and the coefficient of equation (1) KA = (PA-PB) / (HZMAX-HZB) = 0.34
Is calculated as SV = G (HZi) SV = KA (HZi−HZB) + PB (SV = 0.34 × (HZi−31.6) +2
0) and calculate the virtual rotation speed HZi during parallel operation as HZi = HZθ + (HZ2-HZA) (HZi = 50 + (HZ2-38.7)).

When the virtual rotation speed at 40Hz is calculated, HZi = 50 + (40-38.7) = 51.3Hz, which is substituted into SV = G (HZX).

Calculate the target pressure with SV = G (51.3) = 26.63m.

When controlled in this way, the target pressure is controlled as indicated by Δ in the figure, depending on the amount of load water.

Since the HZA does not have an accurate rotation speed at the additional point, the pressure at the additional point will drop slightly and become discontinuous at the time of addition, but it is possible to generate the target pressure that is almost along the resistance curve within the range where there is no practical problem.

Case in Example of Third Invention of the Present Application (FIG. 9 Target Pressure B, Diagram Plot Point ◯) Virtual Rotation Speed Formula HZMAX = HZθ + (HZ2-HZB) In the present invention, the maximum rotation speed is HZMAX = HZθ + (HZ2θ -HZB) = 50 + (50-31.6) = 68.
Calculated as 4 Hz, and the coefficient KB = (PA−PB) / (HZMAX−HXB) = 0.27 in equation (1) is used to calculate SV = G (HZi) as SV = KB (HZi−HZB) + PB (SV = 0.27 × ( HZi-31.6) + 2
0) and calculate the virtual rotation speed HZi during parallel operation as HZi = HZθ + (HZ2-HZB) (HZi = 50 + (HZ2-31.6)).

When the virtual rotation speed at 40Hz is calculated with this, HZi = 50 + (40-31.6) = 58.4Hz, and this is substituted into SV = G (HZX).

Calculate the target pressure with SV = G (58.4) = 27.28m.

When controlled in this way, it is controlled at a target pressure such as ◯ in the figure depending on the amount of load water.

Since the HZB does not have an accurate rotation speed at the additional point, the pressure at the additional point rises slightly at the time of addition and becomes discontinuous, but it is possible to generate a target pressure that is almost along the resistance curve within the range where there is no practical problem.

In the present invention, since the control system is shared, the problem is solved by using a virtual pump rotation speed of 50 Hz or more when operating two units in parallel. That is, in the formula (1), the target value in the range of one unit operation is output up to 30 to 50 Hz, and the target pressure during parallel operation is output above 50 Hz.

According to the present invention, the estimated water amount in the table attached to the diagram of FIG. 9 is 75.60 to 1
The range of 00.00% is the part during parallel operation.

Although there are some differences in the target pressures of the three methods, the adjustment of each method enables the control to keep the terminal pressure almost constant within a range where there is no practical problem.

As described above, the present invention introduces the concept of virtual rotation speed calculation as described above regardless of the target pressure SV calculation formula, and uses one target pressure SV calculation formula without distinction between independent operation and parallel operation. There is a remarkable effect in that it is possible to control the estimated end pressure.

〔The invention's effect〕

The first, second and third inventions of the present application are
The relationship between the pressure when the pump is shut off and the pump rotation speed is easily obtained, and the control target pressure can be determined without requiring special technical calculation. Further, since one target pressure calculation formula can be applied to a pump system in which a plurality of pumps are operated in parallel, not only can the calculation formula be reduced, but the control target pressure at the pump addition point can be appropriately determined. It was

In the embodiment, all the two pumps having the same pump characteristic have variable speeds. However, when the first pump has the maximum rotation speed, the additional operation of the pumps is performed, so that the two pumps having the same pump characteristic are used. This also applies when at least one of the pumps is a variable speed pump and the rest are constant speed pumps.

[Brief description of drawings]

FIG. 1 is a flow sheet of the pump device of the embodiment, FIG. 2 is a diagram showing the relationship between the rotational speed of the pump and the control target pressure, and FIG. 3 is a diagram showing pump performance curves, FIG. 4, FIG. The figure is a diagram for explaining control of the water supply pressure in the conventional example, FIG. 6,
7 and 8 are diagrams for explaining an example for obtaining the rotational speed and control target pressure of the second pump, FIG. 9 is a diagram showing an example of numerical calculation, and FIG. 10 is according to the present invention. It is the diagram which showed the result of the numerical calculation example on the pump performance curve.

Front page continued (72) Inventor Hironao Hiraiwa 11-11 Haneda-Asahi-cho, Ota-ku, Tokyo Ebara Densan Co., Ltd. (72) Inventor Takuo Akahori 1-3-1 Ginza, Chuo-ku, Tokyo Stock market Incorporated Ebara Densan (72) Inventor Shinji Aoto 1-3-1 Ginza, Chuo-ku, Tokyo Stocks Association Ebara Densan (56) References Japanese Patent Publication No. 45-24511

Claims (3)

[Claims] 1. A pump having two pumps having the same pump characteristics,
At least one of them is operated at a variable speed, the other pumps are operated at a constant speed, a rotation speed control means for the pump is provided, and a pressure detector for detecting discharge pressure and a pump rotation speed detection means are provided, Input the pump discharge pressure and rotation speed when the pump is shut off, the required pressure of the pump discharge part at the time of maximum water supply during all pump operations, and the required rotation speed of the pump that can obtain the required pressure. Virtual speed HZi during parallel operation is HZi = HZθ + (HZ2-HZC) in a variable speed water supply system that performs constant estimated end pressure control by calculating the control target pressure for each HZi: calculation used for target pressure calculation Above virtual rotation speed HZθ: Actual maximum rotation speed of the first pump HZ2: Actual rotation speed of the added second pump HZC: Actual maximum rotation speed of the first pump in the target pressure calculation Pump discharge at the target pressure when It is necessary to convert the pressure of the part by the formula of the actual rotation speed required for the second pump to close it and to use the virtual rotation speed HZi after the conversion as the actual rotation speed HZX for control. Required pressure PA at maximum water volume and virtual rotation speed HZ at required maximum water volume
Select a function that approximates the pressure-rotation speed relationship that passes through the point MAX and the pump rotation speed HZB when the minimum pressure PB required when the pump is shut off, and substitute it into this function to obtain the control target pressure. A variable speed water supply device, which is provided with a control device for calculating SV. 2. Having two pumps having the same pump characteristics,
At least one of them is operated at a variable speed, another pump is operated at a constant speed, a rotation speed control means for the pump is provided, and a pressure detector for detecting the discharge pressure and a pump rotation speed detection means are provided, Input the pump discharge pressure and rotation speed when the pump is shut off, the required pressure of the pump discharge part at the time of maximum water supply during all pump operations, and the required rotation speed of the pump that can obtain the required pressure. In the variable-speed water supply system that performs constant control of the estimated end pressure by calculating the control target pressure of HZi = HZθ + (HZ2-HZA), the virtual rotation speed HZi during parallel operation is HZi: Virtual rotation speed of HZθ: Actual maximum rotation speed of the first pump HZ2: Actual rotation speed of the added second pump HZA: One pump at maximum water supply shows the required pressure of the discharge part Pump required to take out when turning off The actual rotation speed is calculated and converted, and the virtual rotation speed HZi after the conversion is used as the actual rotation speed HZX for control.The required pressure PA at the required maximum water volume and the virtual rotation speed at the required maximum water volume HZ
Select a function that approximates the pressure-rotation speed relationship that passes through the point MAX and the pump rotation speed HZB when the minimum pressure PB required when the pump is shut off, and substitute it into this function to obtain the control target pressure. A variable speed water supply device, which is provided with a control device for calculating SV. 3. Having two pumps having the same pump characteristics,
At least one of them is operated at a variable speed, another pump is operated at a constant speed, a rotation speed control means for the pump is provided, and a pressure detector for detecting the discharge pressure and a pump rotation speed detection means are provided, Input the pump discharge pressure and rotation speed when the pump is shut off, the required pressure of the pump discharge part at the time of maximum water supply during all pump operations, and the required rotation speed of the pump that can obtain the required pressure. Virtual speed HZi during parallel operation is HZi = HZθ + (HZ2-HZB) in a variable speed water supply system that performs constant estimated end pressure control by calculating the control target pressure for each HZi: calculation used for target pressure calculation Above virtual rotation speed HZθ: Actual maximum rotation speed of the first pump HZ2: Actual rotation speed of the added second pump HZB: Required pressure of the discharge part of one pump when the pump is tightened
The actual rotation speed of the pump required to output PB is calculated by the formula, and the virtual rotation speed HZi after the calculation conversion is used as the actual rotation speed HZX for control, and the required pressure PA at the required maximum water volume and the required Virtual rotation speed HZ at maximum water volume
Select a function that approximates the pressure-rotation speed relationship that passes through the point MAX and the pump rotation speed HZB when the minimum pressure PB required when the pump is shut off, and substitute it into this function to obtain the control target pressure. A variable speed water supply device, which is provided with a control device for calculating SV.