JPH0541840B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for adjusting the amount of water in water supply equipment.

In water supply equipment, the user at the end of the piping has a request to obtain the required pressure and flow rate, and although the flow rate used fluctuates, it is necessary to maintain the required pressure. Fluctuations in the amount of water used were responded to by changing the rotational speed of the turbo pump driven by a variable speed motor. In such cases, conventional control is performed such as keeping the discharge pressure constant or the estimated end pressure constant.

FIG. 1 shows an example of constant pressure control, with the horizontal axis showing the flow rate and the vertical axis showing the pressure. 1 is the pump performance curve. In this case, the pump discharge pressure P is the sum of the required pressure P _o at the end of the pipe and the pressure loss P _c in the pipe line at maximum flow rate, and the rotation speed is controlled so that the pump discharge pressure is a constant pressure. . However, according to this method, because the resistance of the pipe changes in proportion to the flow rate, the required pressure P _o at the end of the pipe fluctuates greatly, and the range shown by the diagonal lines in the figure is considered to be a loss of energy.

In the conventional control method shown in FIG. 2, which uses the same coordinates as in FIG. 1, the pump discharge pressure P is determined in consideration of the pressure loss in the pipeline so that the estimated end pressure is constant. The pump discharge pressure is changed according to a change in pressure loss P _c in the pipeline corresponding to the flow rate, that is, a resistance curve. Figure 2 shows the required pressure and flow rate at the end of the piping in a water supply system using a pump, which is equipped with a flowmeter, takes into account the pressure loss in the piping corresponding to the flow meter, and calculates the expected pressure loss to the required pressure at the end of the piping. The pump discharge pressure is calculated by adding .

Such methods are expensive because they require flow meters. In this case, since each piping is different and the pump characteristics are also different, it has to be applied to each individual pump device, and even if it is possible for large-scale pump equipment, it is not suitable for mass-produced and general-purpose pump devices. is not suitable.

When attempting to perform advanced control such as constant estimated end pressure control for the end control of the water supply equipment explained in relation to Figures 1 and 2 without using a flowmeter, other physical property values such as rotation speed and pressure may be used. One possible method is to calculate the flow rate from For example, a pump, a water supply pipe connected to the discharge side of the pump, a pressure detection means connected to the water supply pipe, a motor connected to the pump to drive it, a rotation speed control means for controlling the rotation speed of the pump, In a variable speed water supply device equipped with a speed detection means for detecting the rotational speed of a pump, the rotational speed control means uses an output signal from the speed detection means as an input signal to adjust the rotational speed of the pump to a predetermined rotational speed of the pump. A control target pressure output section that outputs a corresponding control target pressure based on the relationship with the control target pressure for each speed, and an output signal from the control target pressure output section and an output signal from the pressure detection means as input signals. A variable speed water supply device has been proposed, which is characterized by comprising a rotation speed control section that outputs a control signal for the rotation speed of a water pump. However, in order to perform this calculation, it is necessary to know detailed pump characteristics and the conditions at the site where the device is installed, which is difficult for mass-produced products.

The present invention aims to eliminate the above-mentioned drawbacks in variable speed water supply systems that control end pressure at a constant level based on pump rotational speed and pump discharge pressure, and to make the water supply end pressure constant regardless of differences in pump devices. Its purpose is to provide a means to obtain data.

The present invention includes a pump, a water supply pipe connected to the discharge side of the pump, a pressure detection means connected to the water supply pipe and outputting a pressure signal S1 representing the water pressure, and a motor connected to the pump and driving it. , a variable speed means for changing the speed of the motor, a speed detection means for detecting the rotational speed of the pump and outputting a rotational speed signal S3 representing the rotational speed, and a pressure setting means 1 for setting the required pressure PA at the maximum amount of water used. and a pressure setting means 2 for setting the required minimum pressure PB at the time of closing.
Using a data table that stores the relationship between pressure and pump rotational speed during pump shut-off operation and a coefficient obtained by searching the data table, a target pressure SV corresponding to the rotational speed represented by the rotational speed signal S3 is obtained. Calculated by the function derived from
a target pressure calculation means for outputting a target pressure signal SV representing the target pressure; and a target pressure calculating means for outputting a target pressure signal SV representing the target pressure; A speed signal S2 is sent to the variable speed means so as to match.
In a variable speed water supply system, the variable speed water supply device is equipped with a rotation speed control means for controlling the speed of the pump by outputting the pump speed, and a pressure detection means that automatically adjusts the pump speed to a plurality of predetermined rotation speeds and detects the water pressure at each rotation speed. This variable speed water supply device is characterized by having a set operation mode in which the data table can be automatically created by capturing data from the pump and storing it in association with the pump rotation speed.

Examples of the present invention will be described below. Third
The figure is a diagram showing, in three-dimensional coordinates, the characteristics of water supply equipment using non-compressible pumps such as turbo pumps. The vertical axis shows the rotation speed (rotation speed) ω of the pump as a percentage with the specified rotation diagram as 100, and the horizontal axis shows the pump discharge rate (flow rate) Q, passing through the intersection point M of the coordinates of speed and discharge rate. , coordinates representing the pump discharge pressure P are shown orthogonal to these coordinates.

The three groups of parallel ω-Q curves on the characteristic curve S shown in a mesh shape represent the relationship between the rotational speed of the pump and the discharge amount at the end of the piping of the water supply equipment, using the pump discharge pressure as a parameter, and ω A second group of P-ω curves that intersect with a third group of -Q curves shows the relationship between the rotational speed of the pump and the pump discharge pressure using the flow rate Q as a parameter.

The ω-Q curve 3 at each discharge pressure P is obtained by cutting the characteristic curved surface S with a plane parallel to the plane containing the ω-Q coordinate, passing the P coordinate axis indicating a predetermined discharge pressure.
-i (i: 1, 2, . . . ) is obtained as a cutting line of the characteristic curved surface S on a plane parallel to the plane containing the ω-Q coordinate.

By cutting the characteristic curved surface S with a plane that crosses the Q coordinate axis indicating a predetermined flow rate and is parallel to the plane containing the P-ω coordinate, the P- corresponding to the discharge amount Q is obtained on a plane parallel to the plane containing the P-ω coordinate. ω curve 2 is the characteristic surface S
obtained as the cutting line.

When the characteristic curved surface S is cut by a horizontal plane, a modified Q-H curve (modified pump performance curve) is obtained.

A water supply pipe is connected to the discharge side of the pump driven by the prime mover, and the water supply pipe is equipped with a pressure detection means and a means for detecting the rotational speed of the pump, so that the pressure can be brought close to the pressure at the end of the water supply pipe at each rotational speed of the pump. Determine the control target pressure that takes into account the
When equipped with a control device that changes the control target pressure as the pump rotational speed changes, assuming the flow rate is constant, a data table that stores pressure values at each rotational speed of the pump and the required end pressure at the maximum flow rate in use are stored. The control target pressure for each pump rotation speed can be determined using data on the pump rotation speed and the pressure value when the pump is pumping. This method of determining the control target pressure is advantageous because it can be performed at each pump rotational speed when the pump is closed, without using a flow meter.

Next, an example will be described in which the control target pressure corresponding to each rotational speed of the pump when the pump is closed is determined.

_{ω X} : Rotational speed P _{X :} Pressure ω _{X =} f( _P Required rotation speed for tightening at P _A P _B : Required minimum pressure for tightening ω _B : Required rotation speed for P _B △ω=ω _MAX −ω _A △P=P _A −P _B , _{P n =} △P x α + P _B (0≦α≦1), and the flow rate corresponding to _the reference control target pressure _{P n is} Letting the resulting rotational speed be ω _n , ω _n =△ω×β+f(P _n ) (0≦β≦1), where K ₁ = (P _n −P _B )/(ω _n −ω _B ) K ₂ = Find (P _A − P _n )/(ω _MAX −ω _n ), K ₁ and K ₂ , and calculate the control target pressure SV for a certain pump rotational speed ω _X as follows: ω _X ≦ω _B SV=P _S ……(1) _{ω B ＜ ω X ≦ ω n SV} = _{K 1 × ( ω
... (} 3) ω _MAX <ω

FIG. 4 is a flow sheet showing the pump device. Motor 1 that controls the rotation speed by changing the frequency
A pump 12 driven by the pump 1 pumps water from a water source 13 through a suction pipe 14, increases the pressure of the water, and discharges the water into a discharge pipe 15. The pressure in the discharge pipe 15 is detected by a pressure detector 16, and a check valve 17,
The water is sent to the demand side via the gate valve 18 and the water supply pipe 19.

A signal of the discharge pressure of the pump 12 detected by the pressure detector 16 is sent to the controller 21. A frequency signal is output from the controller 21,
For example, the signal is input to an inverter 22 that obtains a frequency power source using a thyristor conversion method, and the inverter 22 outputs a required frequency and sends it to the motor 11 to operate the motor 11 at a required speed. The frequency generated by the inverter 22 and sent to the motor 11 is sent to the controller 21.

The controller 21 uses a microcomputer, which calculates in advance the relationship between the pump rotational speed and pump discharge pressure at the time of shutoff of the pump device, the pump rotational speed at the required maximum flow rate, and the control target pressure mentioned above. It is equipped with a storage means in which instructions to be executed are stored. This storage means is a pressure-frequency storage 23 in which the pressure signal detected by the pressure detector 16 is inputted via the controller 21, and the frequency signal sent from the inverter 22 to the controller 21 at that time is inputted to the controller 21. It is input from 21. This input relationship is the rotational speed of the pump 12 and the pump discharge pressure during the shutoff operation, with the rotational speed of the pump 12 during the pump shutoff operation as a frequency.

The relationship between the rotational speed of the pump 12 and the pump discharge pressure when the pump is shut off is input to the pressure-frequency memory 23 as shown in FIG.

First, the gate valve 18 is fully closed. When the system starts, the controller 21 starts the motor 11 in step 1.
An initial value Hz ₀ of the frequency corresponding to a suitably low rotational speed of the motor determined from the characteristics of is sent as a signal to the inverter 22, and the inverter 22 starts the motor 11 using electric power of this frequency. The signal of the output frequency Hz ₀ as the electric power is fed back to the controller 21, inputted into the pressure-frequency memory 23, and stored.

In step 2, the controller 21 sets the initial value of the frequency to Hz.
The inverter 22 is instructed to generate a frequency equal to ₀ plus 1, and the inverter 22 rotates the motor 11 at an increased speed and increases the rotational speed of the pump 12.

In step 3, after step 2, the frequency sent from the inverter 22 to the controller 21 and the signal from the pressure detector 16 that drives the motor 11 at that frequency and indicates the cut-off pressure of the pump 12 are sent to the controller 21.
is received from the controller 21 and the pressure-frequency memory 23
The relationship between the frequency and the pressure, that is, the relationship between the rotational speed of the pump 12 and the pressure indicated by the pressure detector 16 when the pump is shut off, is stored in the pressure-frequency memory 23.

In step 4, it is determined whether or not the frequency calculated in step 2 is 50Hz.
If not, return to step 2.

After repeating the above steps, when step 4 reaches 50 Hz, the controller 21 stops transmitting the signal to the pressure-frequency memory 23. Thus the pressure-frequency memory 23
The rotational speed of the pump 12 every 1 Hz during the shut-off operation and the relationship between the rotational speed and the discharge pressure are stored in the memory. The storage device 23 is not special and can also store data necessary for other controls as described above.

FIG. 6 is a flowchart showing the operation of FIG. 4.

The pressure detector 16 changes as the flow rate used changes. That is, as the flow rate used increases or decreases, the value of the pressure signal S1 indicated by the pressure detector 16 decreases or increases. A pressure signal S1 indicated by the pressure detector 16 is sent to the controller 21.

In the controller 21, the signal S2 sent from the inverter 22 is sent to the routine 100, and as described above, in the routine 100, the pump pressure-frequency characteristic at the time of shut-off and the frequency at the maximum flow rate are extracted from the pressure-frequency memory 23. Pressure (voltage at maximum flow rate),
The control target pressure SV is calculated using the required closing pressure P _B at the time of setting, the required pressure P _A at the maximum flow rate, etc. The obtained control target pressure SV is determined in routine 101 from the difference between the pressure signal S1 and the control target pressure SV, the rate of change of the difference, etc., so that the pump discharge pressure P is the control target pressure.
A frequency output signal is calculated so as to approach SV (PI calculation), and is output to the inverter 22. The controller 21 changes the speed of the motor 11 via the inverter 22 to change the pressure value in a direction opposite to that indicated by the pressure detector 16 . Such control is performed so that the pressure indicated by the pressure detector 16 becomes the control target pressure SV determined above, and the rotational speed of the motor 11 and thus the pump 12 and the detected pressure of the pressure detector 16 correspond to each other. Change.

FIG. 7 is a block diagram showing the controller. The signal S1 of the pressure detector 16 and the frequency signal S2 of the inverter 22 are input to the microcomputer via the interface 24, and these values and the pressure signal at pump cut-off stored in the pressure frequency memory 23 are Using data such as speed and formulas, the central processing unit 25 calculates the frequency so that the control target pressure SV is achieved, and outputs the frequency to the inverter 22 via the interface 24.
controls the rotational speed of the motor 11 to operate the pump 12 so that the control target pressure SV is achieved.

Although FIG. 7 uses a memory device of a microcomputer, it goes without saying that a memory device may be added to the wire logic circuit.

An actual example is shown in FIG. 8th
In the figure, the horizontal axis shows the flow rate Q, and the vertical axis shows the pressure P, assuming that the pressure at the maximum flow rate used = 4 kg/cm ² and the minimum pressure P _A required when the pump is closed is 2 kg/cm ² . α=0.5, β=0.6
The control target pressure calculated by is shown in curve 23,
The terminal pressure P _o =P _B remains almost constant.

In the embodiment, the pressure-frequency memory 23 automatically stores the data at the pump cut-off time, but it does not necessarily have to be the pump cut-off time. The relationship may be stored.

In the above embodiment, data corresponding to the pump discharge pressure corresponding to frequency changes of 1 Hz is inputted into the pressure-frequency memory 23 and stored.

However, if the rotational speed of the pump is set in advance at a plurality of locations (minimum two locations), it is possible to control the terminal pressure to be constant based on the pressure-frequency characteristic of the pump. Such control is suitable for obtaining one pressure frequency under a plurality of conditions where the pump discharge amount is equal.

FIG. 8 is a flowchart showing control in such a case.

When the system is started, the initial value Hz ₀ of the frequency in step 10 is set in the controller 21.

In step 11, a speed increase command is issued and the frequency Hz ₀ +
1 is sent from the controller 21 to the inverter 22.
Thus, the motor 11 is operated at an increased speed due to the increased frequency of the inverter 22.

In step 12, the predetermined frequency Hz ₁
It is determined whether the frequency has reached Hz 1 or not, and if the frequency has not reached Hz ₁ , the process returns to step 11. Thus the frequency is Hz1
Then, in step 13, the frequency Hz ₁ and the signal from the pressure detector 16 at that time are sent to the pressure-frequency memory 23 via the controller 21 and stored therein.

Next, in step 14, Hz+1 is generated from the controller 21 and the pump speed is further increased. Then, in step 15, it is determined whether Hz+ ₁ has reached a predetermined frequency _Hz2 , which is moderately larger than the frequency Hz1, and if it has not, the process returns to step 14. Hz
When +1 becomes Hz ₂ , proceed to step 16 and change the frequency to Hz _2.
The pressure signal indicated by the pressure detector 16 at that time is sent to the pressure-frequency memory 23 via the controller 21 and stored therein.

Such movements can be automatically memorized while the pump 12 is in motion. Therefore, the terminal pressure can be controlled to be constant based on the stored pressure-frequency relationship.
The relationship between pressure and frequency that can be stored in this way may be stored at multiple locations, and in the first embodiment, the relationship is stored every 1 Hz.

The embodiments of a variable speed water supply device with constant terminal pressure water supply pressure control to which the variable speed water supply device of the present invention can be applied are as follows.

In the present invention, the relationship between the rotational speed predetermined in the control target pressure output section and the control target pressure for each rotational speed is such that the pump discharge pressure is the required pressure when the pump is fully operated. In the set operating mode in the state of a function or data table based on the rotational speed and its discharge pressure value, and the rotational speed of the pump and its discharge pressure value with a predetermined flow rate flowing through the system at the required pressure. It can be applied to variable speed water supply equipment. Here, the required pressure corresponds to the discharge pressure because the pump is running at full capacity, but in this case, the required pressure means the desired pressure at the end of the piping, taking into account the pressure loss due to the piping in the system. The pressure is smaller than the discharge pressure at that time. Note that in the latter case, it is also possible to employ data at two or more flow rate values. The above description relates to the embodiments.

A second aspect applicable to the present invention is to use the present invention so that the relationship between the rotational speed predetermined in the control target pressure output section and the control target pressure for each rotational speed is determined when the pump is in full operation. When the maximum flow required by the system is flowing into the system at the required pressure, and when any flow rate other than the maximum flow rate (generally a flow rate smaller than the maximum flow rate is selected) is flowing at the required pressure. The present invention is applicable to a variable speed water supply system in which the operating mode is set according to a function or a data table based on the rotational speed and discharge pressure value of the pump in each state.

A third aspect applicable to the present invention is that the relationship between the predetermined rotational speed of the control target pressure output unit and the control target pressure for each rotational speed is such that a predetermined flow rate is supplied to the system at the required pressure. The operating mode can be set in a function or data table state based on the rotational speed and corresponding discharge pressure value in each state when the pump is running at various rotational speeds when the pump is closed and when the pump is closed. It is a variable speed water supply device.

A fourth aspect to which the present invention can be applied is that the relationship between the rotational speed predetermined in the control target pressure output section and the control target pressure for each rotational speed is such that a predetermined flow rate is allowed to flow through the system at the required pressure. The rotational speed of the pump and the corresponding discharge pressure value when the pump is operated at various rotational speeds while maintaining an arbitrary constant flow rate other than the predetermined flow rate (generally a flow rate value smaller than the maximum flow rate is selected) It is a variable speed water supply device that is set in a set operating mode based on the state of a function or data table.

Further, the fifth and sixth embodiments to which the present invention can be applied are embodiments in which a thyristor conversion type frequency power source is used for the above-described present invention, and in the inverter control type, the rotational speed of the pump is detected. The rotational speed of the pump can be determined from the frequency without the need for a special tachometer.

A seventh application of the present invention is to control the rotational speed of the pump set in the control target pressure output section and the control target pressure for each rotational speed of the pump to the rotational speed control means in the first invention. A reset unit with a function to correct the relationship is added, and the maximum flow rate when determining the relationship between the preset pump rotation speed and the control target pressure for each pump rotation speed during normal use. If a flow rate higher than that flows into the system, the flow rate value will be used as the new maximum flow rate and the relationship between the pump rotation speed set in the control target pressure output section and the control target pressure for each pump rotation speed will be corrected again. Then, a storage command is issued again, and the pressure-frequency storage device 23 stores the data in a suitable area.

As described above, the present invention provides a pump, a water supply pipe connected to the discharge side of the pump, a pressure detection means connected to the water supply pipe, a motor connected to the pump to drive it, a means for changing the pump rotation speed, and a pump rotation speed. In a variable speed water supply system equipped with speed detection means, we have installed a memory device that stores the pressure inside the water supply pipe and the pump rotation speed at any pump rotation speed, so the unique characteristics of the variable speed water supply system can be automatically stored in the memory device. By sampling and storing data in
It is possible to inexpensively produce equipment that can perform advanced and appropriate control, regardless of variations in mass-produced products, differences in models, or differences in site.

[Brief explanation of the drawing]

Figures 1 and 2 are diagrams showing conventional control methods;
Figure 3 is a diagram showing the characteristics of water supply equipment in three-dimensional coordinates.
Fig. 4 is a flowchart of the water supply equipment used in the present invention, Fig. 5 is a flowchart of an embodiment of the invention, Fig. 6 is a flowchart showing the entirety of the invention, and Fig. 7 is a block diagram of the controller, etc. 8 is a diagram showing an experimental example of the present invention, and FIG. 9 is a flowchart of another embodiment of the present invention. 1... Pump performance curve, 2... P-V curve, 3
...V-Q curve, 11 ... motor, 12 ... pump, 13 ... water source, 14 ... suction device, 15 ... discharge pipe, 16 ... pressure detector, 17 ... check valve, 1
8...Gate valve, 19...Water pipe, 21...Control unit, 22...Inverter, 23...Pressure-frequency memory, 24...Interface, 25...Central processing unit, M...Coordinates The intersection of P, _P
Discharge pressure, P _A ... Required pressure at maximum flow rate, P _B ... Required tightening pressure at setting, P _c ... Pressure loss, P _o ... Required pressure at the end of piping, △P _X ... Pressure loss in piping, Q
...Discharge amount (flow rate), Q _X ...Flow rate, S...Characteristic surface, S1...Pressure signal, S2...Signal, SV...
Control target pressure, V, V _X ... rotation speed, ω _X ... rotation speed.

Claims (1)

[Claims] 1. A pump, a water supply pipe connected to the discharge side of the pump, a pressure detection means connected to the water supply pipe and outputting a pressure signal S1 representing the water pressure, and a pressure detection means connected to the pump and configured to output a pressure signal S1 representing the water pressure. A driving motor, a variable speed means for changing the speed of the motor, a speed detection means for detecting the rotational speed of the pump and outputting a rotational speed signal S3 representing the rotational speed, and a required pressure at the maximum amount of water used.
A pressure setting means 1 for setting PA, a pressure setting means 2 for setting the required minimum pressure PB at shut-off, a data table storing the relationship between pressure and pump rotation speed during pump shut-off operation, and the rotation speed signal S3. A target pressure SV corresponding to the rotation speed represented is calculated by a function derived using the coefficient obtained by searching the data table, and a target pressure signal representing the target pressure is calculated.
target pressure calculation means for outputting SV; and in response to the target pressure signal SV and the pressure signal S1, the variable speed is adjusted so that the pressure represented by the pressure signal S1 matches the target pressure SV. In a variable speed water supply device comprising a rotation speed control means for controlling the speed of the pump by outputting a speed signal S2 to the means, the pump speed is automatically adjusted to a plurality of predetermined rotation speeds, and the pump speed is adjusted at each rotation speed. A variable speed water supply device characterized by having a setting operation mode in which the data table can be automatically created by capturing water pressure from a pressure detection means and storing it in relation to the pump rotation speed.