JP5638502B2 - Pump control system - Google Patents

Description

  The present invention relates to a pump control system that minimizes energy consumption by operating a plurality of pumps at an optimum efficiency point, for example, in a control system that operates by arranging a plurality of pumps in parallel for water supply water distribution. The present invention also relates to a pump control system that can maintain operation at an optimum efficiency point even when pump characteristics deteriorate over time.

  In Patent Document 1, in order to appropriately determine the number of operating a plurality of variable speed pumps, a maximum efficiency curve in which the maximum efficiency point at each rotation speed of the pump is plotted on the discharge amount Q-discharge pressure H characteristic is obtained. In parallel with this, a unit change flow curve with an increase in the number of pumps and a unit change flow curve with a decrease in the number of pumps are set, and the discharge flow rate exceeding these change flow curves can be changed by increasing or decreasing the number of pumps operated. A method for realizing energy saving operation of a plurality of pumps is disclosed.

  In Patent Document 2, in a parallel pump disengagement control system controlled by constant discharge pressure control or estimated terminal pressure constant control, the total shaft power after disengagement operation is equal to the total shaft power before disengagement. Is called the energy saving parallel flow rate, and the energy saving parallel flow rate is calculated from the set multiplier, pump head-flow approximation formula, pressure control target curve, pump efficiency approximation formula, the number of parallel pumps, and the detection value of the pushing head. A parallel pump disconnection control method that saves energy compared to the conventional method by calculating, setting this value, and determining the number of pumps to be operated based on this value is disclosed.

Japanese Patent Laid-Open No. 2005-76452 JP 2010-216288 A

  Patent Document 1 described above describes a method of increasing / decreasing the number of pumps operating to realize energy-saving operation by considering the efficiency characteristic curve of the pump. However, when using a plurality of pumps having different characteristics, only the operating number is used. In addition, the distribution flow rate of each pump must be determined and operated at the same time. The prior art does not consider this point, and there is a problem that there is room for further energy saving operation. Moreover, since consideration is not given to deterioration with time of the pump characteristics, there is a problem that operation at an efficiency point cannot be performed with time and power is consumed more than necessary.

  Further, in Patent Document 2 described above, the optimal flow rate for switching the number of units is determined by considering the total shaft driving force of the pump. However, the application of the technique is constant discharge pressure control or estimated terminal pressure constant control. There is a problem that it cannot be applied to more advanced control. Further, since the number-of-units switching flow rate (disconnection flow rate) is determined based on the total shaft driving force that does not necessarily match the total energy consumption of the pump, there is a problem that strict energy consumption minimization cannot be realized. In addition, the operation state for switching the number of units depends on not only the flow rate but also the pressure, but the unit switching timing (disconnection timing) is determined only by the flow rate, and there is a problem that strict switching to achieve energy saving cannot be performed. . Moreover, since consideration is not given to deterioration with time of the pump characteristics, there is a problem that operation at an efficiency point cannot be performed with time and power is consumed more than necessary.

  The present invention has been made in consideration of such circumstances, and provides a pump control system that realizes the minimization of energy consumption by simultaneously obtaining not only the number of operating units that realize energy savings but also the optimal water distribution flow rate that each pump takes. There is to do. It is another object of the present invention to provide a pump control system capable of maintaining an optimum efficiency point operation of a pump regardless of time by estimating a characteristic curve of the pump online and using it for efficient operation of the pump.

  The pump control system of the present invention (first invention) is a pump control system that controls the operation of a plurality of pumps, and determines the number of operating pumps that determines the number of pumps to be operated according to the distribution flow rate and discharge pressure. Refer to the storage unit for storing a table, a flow rate distribution table that determines the distribution of the water flow rate to each pump according to the number of pumps, the water flow rate, and the discharge pressure, and the operation number determination table. Then, based on the water distribution flow rate and the discharge pressure, an operation number determination unit that determines the number of pumps to be operated, the number of pumps to be operated, and the water distribution flow rate determined by the flow rate distribution table, Based on the discharge pressure, a distribution flow rate calculation unit for calculating distribution of the distribution flow rate to each pump, the number of pumps to be operated stored in the operation number determination table, and the water distribution And a target rotation number calculation unit that sets a target rotation number of each pump based on the distribution of the distribution flow rate to each pump obtained by the flow rate calculation unit.

  The pump control system of the present invention (second invention) is the pump control system according to the first invention, wherein the number of pumps determined by the operating number determination table and the water distribution flow rate determined by the flow rate distribution table are the A characteristic curve indicating the characteristics, the number of pumps operated so that the overall energy consumption of each pump operated in accordance with a predetermined operation sequence, and the distribution flow rate distributed to each pump are the distribution flow rate. And obtained for each of the discharge pressures.

  The pump control system of the present invention (third invention) measures the water distribution flow rate of the pump, the discharge pressure, the rotational speed of each pump, and the power consumption of each pump, and based on these measured information. And a pump characteristic estimating unit for estimating the characteristic of each pump.

  In the pump control system of the present invention (fourth invention), the pump characteristic estimation unit is based on the measured water distribution flow rate of the pump, the discharge pressure, the rotation speed of each pump, and the power consumption of each pump. The distribution curve and the discharge pressure when each of the pumps is operated by changing the parameters for determining the characteristic curves and performance curves of the pumps to be set to different set values from the original set values. The rotational speed and the power consumption are measured, and the characteristics of each pump are estimated based on the measured information.

  The pump control system according to the present invention (fifth invention) is characterized in that the pump characteristic estimated in the third invention is used as the pump characteristic curve in the second invention.

  The pump control system of the present invention (sixth invention) is characterized in that the characteristics of the pump estimated in the fourth invention are used as the pump characteristic curve in the second invention.

  In the present invention, the number of pumps to be operated and the flow rate distribution of the pump that minimize the total energy consumption of the pump are determined based on the two variables of the distribution flow rate and the discharge pressure that define the pump operation, thus realizing energy saving of the pump control system. it can. In addition, the pump characteristics are estimated from the measured data, and the number of pumps to be operated and the pump flow rate distribution are determined based on the latest estimated characteristics, so that the operation at the optimum efficiency point can be maintained regardless of changes in pump characteristics over time. In addition, by operating the pump with different parameters from the original parameters, operation in a wider operating range can be realized online. Therefore, since the pump characteristics can be estimated with high accuracy by using the measured data, the reliability of the optimum efficiency point operation can be improved and the increase in power consumption can be suppressed to the limit.

It is a block diagram of the pump control system of Example 1 of this invention. It is an operation number determination table of a pump. It is a flow distribution calculation table of a pump. It is a processing flow figure for creating table data. It is an example of the database which stores an optimal solution. It is explanatory drawing of the energy consumption calculation by a pump driving | operation. It is a process flow figure of the program which calculates a pump target number of rotations. It is an example of the performance curve and efficiency curve of a pump, and deterioration with time. Measurement data from actual operation. It is a block diagram of the pump control system of 2nd Example of this invention. It is an example of the measurement data stored in a database. It is a block diagram of the pump control system of 3rd Example of this invention. It is a block diagram of the pump control system of 4th Example of this invention. It is an example of a correction operation number determination table. It is a block diagram of the pump control system of 5th Example of this invention. It is an example of flow volume distribution correction calculation.

  Embodiments of the present invention will be described with reference to the drawings. A first embodiment will be described with reference to FIGS.

  FIG. 1 is a configuration diagram of a pump control system according to the first embodiment. The control system includes a distribution pipe 1, a distribution reservoir 11, a pressure sensor 2 that measures discharge pressure, a flow rate sensor 3 that measures distribution flow rate, variable speed pumps 4, 5, and 6, a rotation speed sensor 7 that measures pump rotation speed, 8, 9, the pump control system 100 that calculates the target rotation speed of each pump that realizes the target discharge pressure by inputting the target discharge pressure, the measured discharge pressure, and the measured distribution flow rate, and the measured rotation speed matches the target rotation speed PID control devices 12, 13, and 14 for adjusting the input signal to each pump are configured. Although FIG. 1 shows an example in which three pumps are arranged in parallel, a number other than this can be installed. The number of operating pumps increases with the increase of the distribution flow rate. Here, when the flow rate is small (small), only the pump 4 is operated, and as the flow rate increases, the pumps are added in the order of the pump 5 and the pump 6 to increase the number of operating units.

  The water distribution flow rate measured by the flow rate sensor 3 changes every moment according to the water demand. The pump control system 100 determines the target rotational speed of each pump (when the rotational speed is 0, the pump is regarded as stopped) so that the discharge pressure measurement value by the pressure sensor 2 matches the target discharge pressure with respect to the flow rate fluctuation. calculate. There are an infinite number of combinations of rotation speeds that achieve the target discharge pressure, but the pump control system calculates a rotation speed combination that gives the minimum energy consumption. In order to realize this, the pump control system includes an operating number determination unit 101, an operating number determination table 102, a flow rate distribution calculation unit 103, a flow rate distribution table 104, and a target rotation number calculation unit 105.

  Note that the above-described units included in the pump control system are actually executed by a software program for realizing these functions. These software programs have, for example, a module configuration including each of the above-described units. As actual hardware, a control unit such as a CPU downloads these software programs or the above-described tables from a recording device such as an HDD. By reading and executing, the above-described units are loaded onto the main storage device, and the units of the operating number determination unit 101, the flow rate distribution calculation unit 103, and the target rotation number calculation unit 105 are generated on the main storage device. ing.

  The operating number determination means 101 determines the number of pumps to be operated with reference to the operating number determination table 102 constructed in advance. An example of the operating number determination table 102 is shown in FIG. The horizontal axis and the vertical axis are the discharge pressure H and the water distribution flow rate Q, respectively. Low flow rate (when the flow rate is low) is a single pump operation range (only the pump 4 is operating), middle flow rate (when the flow rate is medium) is a dual operation range (two pumps 4 and 5 operation), high flow rate (When the flow rate is large) is the three-unit operating range.

  There are two boundaries for each region: practice and dotted lines. The solid line is a unit switching line that is used when the distribution flow rate increases and the number of operating units increases, and the dotted line is a unit switching line that is used when the distribution unit flow rate decreases and the number of operating units decreases. The change of the switching line by increasing / decreasing the flow rate in this way is to prevent frequent on / off of the pump operation when the operation stays on the boundary. In the operating number determination means 101, when the latest measured values of the water distribution flow rate Q and the discharge pressure H are plotted on the operating number determination table, the operating number is determined depending on which number region the plot is in. If a plot exists in a narrow area between the solid line switching line and the dotted line switching line, the number of operating units one hour before is referred to and the number of operating units is set as the operating unit number at the latest time. This table gives the number of operating units that minimizes the total energy consumption of the pump, and the table creation method will be described later.

  The flow rate distribution calculation means 103 calculates the distribution flow rate of each pump when operating a plurality of pumps with reference to the flow rate distribution table 104. FIG. 3 shows an example of the flow rate distribution table 104. The upper stage (a) is a table 31 for determining the flow distribution D1 of one pump (pump 4) when operating two pumps, and the lower stage (b) is the table for two pumps (pumps 4, 5) when operating three pumps. Tables 32 and 33 for obtaining flow distributions D1 and D2. For the number of operating pumps, the information calculated by the operating number determination means 101 is utilized. In the case of operation of two pumps, the flow distribution D1 to the pump 4 is obtained by referring to the table 31 based on the measured distribution flow rate value and the measured discharge pressure value. When the distribution flow rate measurement value is Q, the flow rates Q1 and Q2 handled by the pump 4 and the pump 5 are given by the following equations.

Q1 ＝ Q ・ D1
Q2 = Q · (1-D1)
In the case of the operation of three pumps, the flow distributions D1 and D2 to the pumps 4 and 5 are obtained by referring to the tables 32 and 33 based on the measured distribution flow rate value and the discharge pressure measurement value. When the distribution flow rate measurement value is Q, the flow rates Q1, Q2, and Q3 that the pump 4, the pump 5, and the pump 6 handle are given by the following equations.

Q1 ＝ Q ・ D1
Q2 ＝ Q ・ D2
Q3 = Q ・ (1-D1-D2)
These tables 31, 32, and 33 provide a flow rate distribution that minimizes the total energy consumption of the pump. The table creation method will be described later.

The target rotational speed calculation means 105 determines the pump rotational speed that realizes the target discharge pressure by using the obtained number of operating units and flow rate distribution information, the discharge pressure measurement value, and the pump performance curve. Hereinafter, the target rotational speed in the case of operating three pumps is calculated.
Assume that the performance curves of the pumps 4, 5, 6 can be approximated as follows.
H ＝ a1 ・ N ² − b1 ・ Q ² (1)
H ＝ a2 ・ N ² − b2 ・ Q ² (2)
H ＝ a3 ・ N ² − b3 ・ Q ² (3)
Here, H is the pump head (discharge pressure), N is the pump speed, Q is the pump water flow rate, and ai, bi (i = 1, 2, 3) are positive constants.

The flow rate of the pumps 4, 5 and 6 determined by the flow rate distribution calculation means 103 is Q1, Q2, Q3, the rotation speeds of the pumps 4, 5, 6 are N1, N2, N3, and the discharge pressure measurement value is H0. Substituting into the curve gives:
H0 ＝ a1 ・ N1 ² − b1 ・ Q1 ²
H0 ＝ a2 ・ N2 ² − b2 ・ Q2 ²
H0 ＝ a3 ・ N3 ² − b3 ・ Q3 ²
These equations are solved for the rotational speeds N1, N2, and N3 to obtain the following equations.

N1 = ((H0 + b1, Q1 ² ) / a1) ^1/2 (4)
N2 = ((H0 + b1, Q2 ² ) / a2) ^1/2 (5)
N3 = ((H0 + b1, Q3 ² ) / a3) ^1/2 (6)
If there is no modeling error in the approximated performance curve, the target discharge pressure can be achieved by giving this calculated value as the target rotational speed of each pump. That is, the measured discharge pressure becomes equal to the target pressure. However, since there are not a few modeling errors, the target discharge pressure is not achieved, and a slight difference occurs between the measured discharge pressure and the target discharge pressure. Feedback compensation is used together to compensate for the deviation between the target value and the measured value due to modeling errors. This calculates the rotational speed correction amount ΔN based on the difference between the target discharge pressure and the measured discharge pressure, for example, using a PID control law.

  ΔN is added to N1, N2, and N3 calculated by the above equation, and the target rotational speeds N10, N20, and N30 of the pumps 4, 5, and 6 are calculated as follows.

N10 ＝ N1 ＋ ΔN (7)
N20 ＝ N2 +＋ N (8)
N30 ＝ N3 ＋ ΔN (9)
The calculated rotational speed is sent to a PID control device that controls the speed of the pump, and the rotational speed of the pump is controlled. Note that the target rotational speed can be calculated using Equations (7) and (8) for two-unit operation and Equation (7) for one-unit operation.

Next, a method for creating the table data of FIGS. 2 and 3 will be described with reference to FIGS. FIG. 4 shows a processing procedure for creating table data. For various combinations of water distribution flow rate Q and discharge pressure H, the following optimization problem is solved to determine the number of operating units and flow distribution that give the minimum energy for the combination. The following describes how to calculate the power consumption of a pump when operating one pump, operating two pumps simultaneously, and operating three pumps simultaneously. [1] When operating a single pump Determine the power consumption P during single-unit operation (during pump 4 operation).

P = k ・ Q ・ H / (ηp ・ ηm ・ ηi) (10)
ηp = −c1 · (Q / N) ² + d1 · (Q / N) (11)
H ＝ a1 ・ N ² − b1 ・ Q ² (12)
Where P is the power consumption of the pump 4 (kW), Q is the distribution flow rate (m ³ / min), H is the pump discharge pressure (m), ηp is the pump efficiency, ηm is the motor efficiency and constant, and ηi is the inverter efficiency Where N is the pump speed (rpm), and k, a1, b1, c1, and d1 are positive constants. Equation (11) approximates the efficiency curve of the pump 4, and equation (12) approximates the performance curve of the pump 4. When Q and H are given, the rotational speed N is obtained from the equation (12). By substituting it into the equations (11) and (10), the power consumption P of the pump is obtained.
[2] In the case of simultaneous operation of two units Based on the following equation, the power consumption P when two pumps are operating (when the pumps 4 and 5 are operating) can be calculated.
P = P1 + P2 (13)
P1 ＝ k ・ Q1 ・ H / (ηp1, ηm ・ ηi) (14)
ηp1 = −c1 ・ (Q1 / N1) ² + d1 ・ (Q1 / N1) (15)
H = a1, N1 ² − b1, Q1 ² (16)
P2 = k, Q2, H / (ηp2, ηm, ηi) (17)
ηp2 = −c2 ・ (Q2 / N2) ² + d2 ・ (Q2 / N2) (18)
H ＝ a2 ・ N2 ² − b2 ・ Q2 ² (19)
Q ＝ Q1 ＋ Q2 (20)
Where P is the total power consumption of the pump (kW), P1 is the power consumption of the pump 4 (kW), P2 is the power consumption of the pump 5 (kW), Q is the water distribution flow rate (m ³ / min), and Q1 is the pump 4 of distributed water flow (m ³ / min), Q2 is distributed water flow (m ³ / min), H is the pump discharge pressure (m), ηp1 the pump efficiency of the pump 4 of the pump 5, Itapi2 the pump efficiency of the pump 5, ηm is a constant based on motor efficiency, ηi is a constant based on inverter efficiency, N1 is the rotational speed of the pump 4 (rpm), N2 is the rotational speed of the pump 5 (rpm), k, ai, bi, ci, di (i = 1, 2) is a positive constant. There are innumerable combinations of Q1 and Q2 that satisfy the distribution flow rate Q, and the total power consumption P is determined accordingly. Here, Q1 and Q2 that minimize P are obtained by optimization calculation, and the corresponding power consumption P (minimum power consumption during two-unit operation) is set as the power consumption of the pump during two-unit operation.
[3] In the case of simultaneous operation of three units Based on the following equation, the power consumption P when three pumps are operated (when the pumps 4, 5, and 6 are operated) can be calculated.
P = P1 + P2 + P3 (21)
P1 ＝ k ・ Q1 ・ H / (ηp1, ηm ・ ηi) (22)
ηp1 = −c1 ・ (Q1 / N1) ² + d1 ・ (Q1 / N1) (23)
H = a1, N1 ² − b1, Q1 ² (24)
P2 = k, Q2, H / (ηp2, ηm, ηi) (25)
ηp2 = −c2 ・ (Q2 / N2) ² + d2 ・ (Q2 / N2) (26)
H ＝ a2 ・ N2 ² − b2 ・ Q2 ² (27)
P3 = k ・ Q3 ・ H / (ηp3 ・ ηm ・ ηi) (28)
ηp3 = −c3 ・ (Q3 / N3) ² + d2 ・ (Q3 / N3) (29)
H ＝ a3 ・ N3 ² − b3 ・ Q3 ² (30)
Q = Q1 + Q2 + Q3 (31)
Where P is the total power consumption of the pump (kW), P1 is the power consumption of the pump 4 (kW), P2 is the power consumption of the pump 5 (kW), P3 is the power consumption of the pump 6 (kW), and Q is the water distribution Flow rate (m ³ / min), Q1 is the flow rate of pump 4 (m ³ / min), Q2 is the flow rate of pump 5 (m ³ / min), Q3 is the flow rate of pump 6 (m ³ / min), H is pump discharge pressure (m), ηp1 is pump efficiency of pump 4, ηp2 is pump efficiency of pump 5, ηp3 is pump efficiency of pump 6, ηm is motor efficiency constant, ηi is inverter efficiency constant, N1 is pump 4, the rotation speed of the pump 5 (rpm), N3 is the rotation speed of the pump 6 (rpm), k, ai, bi, ci, di (i = 1, 2, 3) are positive Is a constant. There are innumerable combinations of Q1, Q2, and Q3 that satisfy the distribution flow rate Q, and the total power consumption P is determined accordingly. Here, Q1, Q2, and Q3 that minimize P are obtained by optimization calculation, and the corresponding power consumption P (minimum power consumption when three units are operating) is calculated as the pump power consumption when three units are operating. To do.

  If the above method is used, the pump power consumption during one unit operation corresponding to the distribution flow rate Q and discharge pressure H, the total power consumption (minimum power consumption) of the pump during two unit operation, the pump during three unit operation Total power consumption (minimum power consumption) can be obtained. What gives the minimum value among these three power consumptions is the most efficient pump operation method (number of operating units and flow distribution). The optimum solution DB creation unit 42 in FIG. 4 obtains the most efficient operation method (number of operating units and flow rate distribution) offline for various Q and H by the above method, and stores it in the table shown in FIG. Remember. This table shows various values of water distribution flow rate Q and discharge pressure H (in the figure, Q is a value in increments of 0.1 from 5.0 to 30.0, H is in increments of 0.1 from 25.0 to 40.0 The number of operating pumps and the flow rate distribution that are optimal (minimum power consumption) are stored. By utilizing this table data, the operating number determination table of FIG. 2 and the flow rate distribution table of FIG. 3 can be created. The optimal switching line from N to N + 1 (or N + 1 to N) (N = 1, 2) is one, but two lines are set before and after that, and the line above is N The number determination table shown in FIG. 2 is created in such a way that the switching line from the base to the N + 1 unit and the lower line as the switching line from the N + 1 unit to the N unit are used.

The above-mentioned method is the optimum operation number and flow rate when the number of pumps changes from the simultaneous operation of pump 4 → pumps 4 and 5 to the simultaneous operation of 3 pumps 4, 5 and 6 as the flow rate increases. This is a distribution request. Depending on changes in pump characteristics described later, this operation sequence (pump 4 → pump 4, 5 → pumps 4, 5, 6) may not be the most efficient. That is, when the efficiency of the pump 6 becomes the highest as a single unit, the daily power consumption may be reduced by operating the pump 6 in a region where the flow rate is small. Assuming various operation sequences (6 operation sequences when using 3 pumps), the operation number judgment table and the flow distribution table are obtained, and the minimum consumption when operating for one day It is necessary to determine the operation sequence for supplying power and use it for pump control. The operation sequence is as follows: [1] Pump 4 → Pump 4, 5 → Pump 4, 5, 6
[2] Pump 4 → Pumps 4, 6 → Pumps 4, 5, 6
[3] Pump 5 → Pump 4, 5 → Pump 4, 5, 6
[4] Pump 5 → Pump 5, 6 → Pump 4, 5, 6
[5] Pump 6 → Pump 4, 6 → Pump 4, 5, 6
[6] Pump 6 → Pump 5, 6 → Pump 4, 5, 6
FIG. 6 is an explanatory diagram of a method for calculating the daily energy consumption for an operation sequence of a certain pump. First, for the operation sequence [1], an operation number determination table and a flow rate distribution calculation table are created and stored in the operation number and flow rate distribution calculation means 61. Calculates the optimal number of operating units X (t) and flow distribution D (t) at time t against the actual time series Q (t) and H (t) (t is time) of the daily water flow and discharge pressure. Then, using this, the energy consumption calculation means calculates the total power consumption P (t) of the pump, and further calculates the daily energy consumption by adding P (t) at all times. This is performed for the operation sequence [2] to [6], and the operation sequence giving the minimum energy consumption is adopted as the optimum operation sequence. If an order different from the original order [1] is obtained, the pump operation control shown in FIG. 1 is performed in that order. The calculation of the pump energy consumption can be performed using equations (10) to (31).

  FIG. 7 shows a flow of a control program for determining the target rotational speed in the pump control system of the first embodiment, which is executed in a predetermined cycle (for example, 1 minute cycle). In step 701, the number of pumps to be operated is determined by utilizing the measured water distribution flow rate, the measured discharge pressure, and the pump operation number determination table of FIG. In Step 702, only when the number of operating pumps is two or more, the pump flow distribution is determined using the measured water distribution flow, the measured discharge pressure, and the pump flow distribution calculation table in FIG. Calculate the distribution flow of water. Finally, in step 703, the target rotational speed of each pump is calculated using the above-described method, that is, the equations (7), (8), and (9), and the process is terminated. This calculated value is sent to a PID control device that controls the rotational speed of the pump, and the rotational speed of the pump is controlled. This is the end of the description of the first embodiment.

  Next, based on FIG. 8 to FIG. 11, a second embodiment will be described in which pump characteristics are estimated from various measurement data to create an operating number determination table and a flow rate distribution table. FIG. 8 shows the performance curve and efficiency curve of the pump. The solid line shows an example of characteristics when the pump is in a new state, and the dotted line shows an example of characteristics when the pump deteriorates with time. In the figure, N represents a standardized rotational speed (actual rotational speed divided by rated rotational speed). When the characteristic deterioration as shown in the figure occurs, the operation at the optimum efficiency point cannot be maintained, and there arises a problem that extra power is consumed. In order to maintain the operation at the optimum efficiency point, the deteriorated characteristics are estimated and reflected in the pump operation control, that is, the operation number judgment table and the flow distribution table are created based on the deterioration characteristics, and the pump operation control is performed. Need to do. The table creation method will be described below.

  9 shows the combination of the distribution flow rate measurement value Q and the discharge pressure gauge value H (Q, H) measured simultaneously at various times when the pump is operated with the pump control system of FIG. It is plotted on a plane. Using these measurement data, the pump performance curve and efficiency curve can be estimated. FIG. 10 is an overall configuration diagram of a second embodiment that estimates pump characteristic data and creates a flow rate distribution table and an operating number determination table. In the database DB 106, for example, every 10 minutes, the discharge pressure H measured by the pressure sensor, the water distribution flow rate Q measured by the flow sensor, the rotational speed N of each pump measured by the rotational speed sensor, the consumption of each pump The power measurement value is input and stored. An example of the stored data is shown in FIG. The number of revolutions and power consumption are stored for the number of pumps operated at the time of measurement. The DB stores data for the past week.

  The pump characteristic estimation means 107 estimates the performance curve and efficiency curve of each pump from the data stored in the DB by the following method. Here, it is assumed that the operation sequence is pump 4 → pump 4, 5 → pump 4, 5, 6. Data of one pump operation (during pump 4 operation) is extracted from the DB, and is set as a water distribution flow rate Qi, a discharge pressure Hi, a rotation speed Ni, and power consumption Pi (i = 1, 2,... N). It is assumed that the performance curve and characteristic curve of the pump 4 can be approximated by the following equations.

H ＝ a1 ・ N ² − b1 ・ Q ² (32)
ηp = −c1 · (Q / N) ² + d1 · (Q / N) (33)
Further, the following formula is established with respect to power consumption.

P = k ・ Q ・ H / (ηp ・ ηm ・ ηi) (34)
Where P is the pump power consumption (kW), Q is the water distribution flow rate (m ³ / min), H is the pump discharge pressure (m), ηp is the pump efficiency, ηm is the motor efficiency constant, and ηi is the inverter efficiency constant , N is the pump speed (rpm), and k, a1, b1, c1, and d1 are positive constants.

  By eliminating ηp from the equations (33) and (34), the following equation is obtained.

k ・ Q ・ H / (ηm ・ ηi ・ P) = − c1 ・ (Q / N) ² + d1 ・ (Q / N) (35)
Estimating the pump characteristics is to estimate the parameters a1, b1, c1, and d1 in the equations (32) and (33). Parameters a1, b1, c1, and d1 use n pieces of measurement data (Qi, Hi, Ni, Pi) (i = 1, 2,... N), and these data are the most fitted to equations (32) and (35). This can be done by utilizing the least squares method. The obtained parameters and the equations (32) and (33) are used as the latest characteristics of the pump 4.

  Next, data at the time of simultaneous operation of two pumps is extracted from the DB, and is extracted from the distribution flow rate Qi, discharge pressure Hi, pump 4 rotation speed N1i, pump 5 rotation speed N2i, and pump 5 power consumption P2i (i = 1, 2, ... m). Utilizing these data, the characteristics of the pump 5 are estimated. Assume that the performance curve and efficiency curve of the pump 5 can be approximated by the following equations.

H ＝ a2 ・ N2 ² − b2 ・ Q2 ² (36)
ηp2 = −c2 ・ (Q2 / N2) ² + d2 ・ (Q2 / N2) (37)
Further, the following formula is established with respect to power consumption.

P2 = k ・ Q2 ・ H / (ηp2 ・ ηm ・ ηi) (38)
Where P2 is the power consumption of pump 5 (kW), Q2 is the water flow rate of pump 5 (m ³ / min), H is the pump discharge pressure (m), ηp2 is the efficiency of pump 5, and ηm is the motor efficiency. , Ηi is a constant in terms of inverter efficiency, N2 is the rotational speed (rpm) of the pump 5, and k, a2, b2, c2, and d2 are positive constants.

  By deleting ηp2 from the equations (37) and (38), the following equation is obtained.

k ・ Q2 ・ H / (ηm ・ ηi ・ P2) = − c2 ・ (Q2 / N2) ² + d2 ・ (Q2 / N2) (39)
The following equation is obtained by substituting the discharge pressure Hi, which is the measurement data, and the rotational speed N1i of the pump 4 into the equation (32).

Hi = a1 ・ N1i ² − b1 ・ Q ²
Since a1 and b1 have been estimated from this equation, the flow rate Q of the pump 4 is obtained by the following equation.

Q = ((a1 ・ N1i ² −Hi) / b1) ^1/2 (40)
From this Q and the measured total water distribution flow rate Qi, the water distribution flow rate Q2i of the pump 5 can be calculated by the following equation.

Q2i = Qi-Q (41)
Data of m sets of this Q2i and the discharge pressure Hi, which is the measurement data, the rotational speed N1i of the pump 4, the rotational speed N2i of the pump 5, and the power consumption P2i (i = 1, 2,... M) of the pump 5 are expressed by the equation (36 ) The parameters a2, b2, c2, and d2 are estimated by utilizing the least square method so as to best fit (39). The obtained parameters and the equations (36) and (37) are used as the latest characteristics of the pump 5.

  Using the same concept, the performance curve and efficiency characteristics of the pump 6 can be estimated by utilizing the measurement data obtained when three units are operating simultaneously. Here, assuming that the performance characteristic curves of the pumps 4 and 5 are known, the water distribution flow rates of the pumps 4 and 5 are calculated using those measurement data. The distribution flow rate of the pump 6 can be calculated by subtracting the distribution flow rates of the pumps 4 and 5 from the measured total distribution flow rate. Using this, the characteristics of the pump 6 can be estimated by the same method as described above.

  The table creation means 108 of FIG. 12 creates the operating number determination table and the flow rate distribution table by the method of FIG. 4 by utilizing the latest pump characteristics obtained. The created table is set in the pump control system 100 and pump control is performed. As described above, by performing pump control utilizing the latest pump characteristic data, it is possible to maintain the operation at the optimum efficiency point of the pump and to suppress the increase in power consumption due to characteristic deterioration to some extent. The above processing can be performed online or offline.

  Next, a third embodiment will be described with reference to FIG. FIG. 12 is an overall configuration diagram of a pump control system that enables data measurement in a wider operation region. As shown in FIG. 9, in the optimum operation of the pump, since the operation region in which the measurement is performed is limited, it may be difficult to correctly estimate the performance curve and efficiency curve of the pump even if the data is used. Conceivable. In response to this problem, the processing content of the target rotational speed calculation means is changed in order to enable data measurement in a wider operating region. In the target rotational speed measuring means 1051 in FIG. 12, the target rotational speed is calculated by the following equation instead of the equations (7) to (9).

N10 = N1 x correction factor (42)
N20 = N2 x number of corrected stations (43)
N30 = N3 x correction factor (44)
The correction coefficient is a constant larger than 1, and is set to a value of about 1.1 to 1.3, for example. The pump is operated at a higher rotational speed. Since N becomes large, operation in a region where Q / N is smaller in FIG. 9B and operation in a region where H is larger in FIG. Can be spread. For example, such correction processing is performed for one day, and data measurement is performed. The estimation accuracy of the pump characteristics can be improved by estimating the pump characteristics using data of a wider area obtained by adding the conventional measurement data to this data. In addition, since the discharge pressure slightly higher than the target is realized by this correction, the energy consumption temporarily increases.

  Next, a fourth embodiment will be described with reference to FIGS. FIG. 13 is an overall configuration diagram of a pump control system that enables data measurement in a wider operating region, and provides an embodiment different from the third example. Specifically, a modified operation number determination table 1021 different from the conventional one is used. FIG. 14 shows an example of this table. The operation range of the single-unit pump is expanded by using a modified switching line that shifts the single-unit operation to the two-unit operation upward from the original one. The characteristic estimation accuracy can be improved by expanding the operation region.

  Next, a fifth embodiment will be described with reference to FIGS. FIG. 15 is an overall configuration diagram of a pump control system that enables data measurement in a wider operation region, and provides an embodiment different from the third and fourth examples. In FIG. 15, the flow rate distribution calculation is performed using a method different from the conventional method. As shown in FIG. 16, the flow distribution correction calculation means 1031 multiplies the search value in the flow distribution table given in FIG. 3 by a correction coefficient to obtain the final flow distribution.

  For example, if the correction coefficients k and k1 in FIG. 16 are made smaller than 1, the flow distribution D1 of the pump 4 can be made smaller than the original flow distribution, and if the correction coefficient is made larger than 1, the water distribution distribution D1 of the pump 4 is originally set. Can be larger than the flow distribution. If the correction coefficient k2 is smaller than 1, the flow distribution D2 of the pump 5 can be made smaller than the original flow distribution, and if the correction coefficient is larger than 1, the water distribution D2 of the pump 5 can be made larger than the original flow distribution. Of course, the flow distribution of the pump 6 can be controlled by these factors. By operating the correction coefficient in this way, the range of the water distribution flow rate of the pumps 4, 5, 6 can be expanded. When pump estimation is performed using the obtained measurement data, the estimation accuracy can be improved.

  In each of the above-described embodiments, the number of pumps to be used and the flow rate distribution of the pump that determines the minimum total energy consumption of the pump are determined based on the two variables of the distribution flow rate and the discharge pressure, and the pump characteristics are determined from the measurement data. Estimated and determined the number of pumps to be operated and the pump flow rate distribution based on the latest estimated characteristics, or operated the pump with different parameters from the original parameters, and operated in a wider operating range online. However, the deterioration level of the pump is estimated by verifying the transition of the power consumption data obtained by the energy consumption calculation means, and the fact that the maintenance time of the pump has arrived is output to an output medium such as a display device (not shown). It is good also as making a business announce. For example, if the increase in energy consumption over a certain period exceeds a predetermined threshold, or if the increase in power rate calculated based on energy consumption exceeds a predetermined threshold, the maintenance time has come. It may be announced. In this case, the operator can easily know that the pump should be replaced at an appropriate timing.

DESCRIPTION OF SYMBOLS 100 Pump control apparatus 101 Operating number determination means 102 Operating number determination table 1021 Corrected operation number determination table 103 Flow rate distribution calculation means 1031 Flow rate distribution correction calculation means 104 Flow rate distribution table 105 Target rotation speed calculation means 1051 Target rotation speed calculation means (rotation speed (With correction)
106 Database 107 Pump characteristic estimation means 108 Table creation means.

Claims (10)

A pump control system for controlling the operation of a plurality of pumps,
Determines the number of operating pumps and the flow distribution that give the minimum power consumption for the combination of the distribution flow rate of the plurality of pumps measured by the flow sensor and the discharge pressure of the plurality of pumps measured by the pressure sensor. , on the basis of the characteristic curve and the performance curve of each pump, the distributed water flow and said discharge pressure and the number of operating units determination table defining a pump volume to be operated in accordance with, the number of the pump the distributed water flow and the A storage unit that stores a flow rate distribution table that determines the distribution of the water flow rate to each pump according to the discharge pressure; and
With reference to the operation number determination table, based on the water distribution flow rate and the discharge pressure, an operation number determination unit that determines the number of pumps to be operated,
A distribution flow rate calculation unit that calculates distribution of the distribution flow rate to each pump based on the number of pumps to be operated and the distribution flow rate and the discharge pressure determined by the flow distribution table;
The target rotational speed of each pump is set based on the number of pumps to be operated stored in the operation number determination table and the distribution flow rate distribution to each pump obtained by the distribution flow rate calculation unit. A target speed calculator,
A pump control system comprising: The pump control system according to claim 1,
The number of the pump defined by the number of operating units judgment table, and the distributed water flow defined by the flow distribution table, on the basis of the characteristic curve showing the characteristics of the pumps, each driven by driving a predetermined order The number of the pumps operating so that the overall energy consumption of the pump is minimized, and the distribution flow rate distributed to each pump is determined for each distribution flow rate and discharge pressure.
A pump control system characterized by that. The pump control system according to claim 1 or 2,
A pump characteristic estimation unit that measures the water distribution flow rate of the pump, the discharge pressure, the rotation speed of each pump, and the power consumption of each pump, and estimates the characteristics of each pump based on the measured information Comprising
A pump control system characterized by that. The pump control system according to claim 3,
The pump characteristic estimator is a characteristic curve and a performance curve showing the characteristics of each pump determined based on the measured water distribution flow rate, the discharge pressure, the rotation speed of each pump, and the power consumption of each pump. Measure the water distribution flow rate, discharge pressure, rotation speed of each pump, and power consumption when each pump is operated by changing the parameter for determining the value to a setting value different from the original setting value. Based on the information, estimate the characteristics of each pump,
A pump control system characterized by that.   3. The pump control system according to claim 2, wherein the characteristic of the pump estimated by the estimation method according to claim 3 is used as the characteristic curve of the pump.   The pump control system according to claim 2, wherein the pump characteristic estimated by the estimation method according to claim 4 is used as the pump characteristic curve. The pump control system according to any one of claims 4 to 6,
The characteristics of each pump estimated by the pump characteristic estimation unit indicate the deterioration characteristics of the pump.
A pump control system characterized by that. A pump control system for controlling the operation of a plurality of pumps,
A flow sensor for measuring the distribution flow rate of the plurality of pumps;
A pressure sensor for measuring discharge pressures of the plurality of pumps;
For the combination of the water distribution flow rate and the discharge pressure, the number of operating pumps and the flow distribution that give the minimum power consumption were determined, and the flow rate sensor measured based on the characteristic curve and performance curve of each pump. An operation number determination table that determines the number of pumps to be operated according to the distribution flow rate and the discharge pressure measured by the pressure sensor, and the number of pumps, the distribution flow rate, and the discharge pressure to each pump according to the discharge pressure An optimization unit for creating a flow rate distribution table that defines the distribution of the water flow rate;
With reference to the operation number determination table, based on the water distribution flow rate and the discharge pressure, an operation number determination unit that determines the number of pumps to be operated,
A distribution flow rate calculation unit that calculates distribution of the distribution flow rate to each pump based on the number of pumps to be operated and the distribution flow rate and the discharge pressure determined by the flow distribution table;
Based on the number of pumps to be operated and the distribution flow rate distribution to each pump obtained by the distribution flow rate calculation unit, a target rotation number calculation unit that sets the target rotation number of each pump;
A pump control system comprising: The pump control system of claim 8,
For each of the operation sequence patterns determined for each of the pumps, the optimal number of pumps to be operated and the flow distribution at an arbitrary time with respect to the actual time series values of the water distribution flow rate and the discharge pressure in one day, To calculate the power consumption of the pump, add the calculated power consumption for all times to calculate the daily power consumption of the pump control system, and the calculated daily power consumption is Energy consumption calculation unit that adopts the minimum operation sequence as the optimal pump operation sequence,
A pump control system comprising: The pump control system of claim 9,
A rotational speed sensor for measuring the rotational speed of each pump;
The performance curve of each pump is estimated based on the water distribution flow rate measured by the flow sensor and the rotation speed measured by the rotation speed sensor, and the efficiency curve of each pump is calculated based on the water distribution flow rate per rotation speed. An estimated pump characteristic estimator;
A pump control system comprising:

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