WO2015114847A1 - Method for controlling number of pumps, device for controlling number of pumps, pump system, heat source system, and program - Google Patents

Abstract

This method for controlling the number of pumps has a step of increasing/decreasing the number of operating pumps on the basis of the flow rate of a heating medium that is pumped to a load (40) by a plurality of pumps connected in parallel or the thermal load required by the load, and a frequency command value sent to the pumps of the plurality of pumps that are operating.

Description

Pump number control method, pump number control device, pump system, heat source system, and program

The present invention relates to a pump number control method, a pump number control device, a pump system, a heat source system, and a program.
This application claims priority based on Japanese Patent Application No. 2014-018187 filed in Japan on January 31, 2014, the contents of which are incorporated herein by reference.

In a heat source system that supplies a heat medium such as cold water or hot water (hereinafter referred to as cold / hot water) to a load device such as an air conditioner, in addition to the primary pump that pumps cold / warm water to the heat source machine, air conditioning separated from the heat source machine In many cases, a plurality of secondary pumps connected in parallel are provided between the heat source machine and the air conditioner for the purpose of re-pressure feeding the heat medium to the machine. In such a heat source system having a secondary pump, there is a method of determining the number of secondary pumps to be operated so as to satisfy the discharge flow rate to the load device. In such a method, generally, a threshold value is set as a reference for increasing / decreasing the pump, and the pump is added when the flow rate of the heat medium measured by a measuring instrument provided in the middle of the supply path exceeds the threshold value. In many cases, control is performed such that the system is started and stopped when it falls below a threshold value. However, if it is determined whether the number of pumps to be operated is increased or decreased based only on the measured flow rate in this way, the pump capacity is still sufficient, that is, the pump is started even though the pump frequency is more than the rated frequency. There is a possibility that.
For example, in Patent Document 1, a curve showing the relationship between the pump discharge pressure and the pump discharge flow rate determined for each number of operating secondary pumps, the flow rate of the heat medium supplied to the load device, and the pumps required for the curve. By changing the number of pumps operated with the flow rate determined at the intersection of the control lines indicating the correlation with the discharge pressure as a threshold value, a threshold value for the flow rate at which the discharge pressure can be maintained even after the number of units is changed is set.

Japanese Patent No. 5261153

In the case of the method of Patent Document 1, it is difficult to obtain a significant threshold value unless the pressure loss characteristic of the pipe is accurately grasped and a control line reflecting it is not obtained. Piping pressure loss is a loss of pump discharge pressure due to friction generated when a heat medium flows in the pipe, bending of the pipe, resistance by a valve, etc. Pressure loss characteristics are changes in pressure loss with respect to the flow rate of the heat medium. It is a characteristic. Especially when the load device is an air conditioner, the pressure loss of the system changes due to the control valve provided in the air conditioner. Therefore, unless the above control line is also changed, the threshold used for controlling the number of operating pumps is There is a possibility of shifting. If the number of pumps to be operated cannot be changed at an appropriate timing, the flow rate and pressure of the heat medium will fluctuate due to an extra change in the number of pumps, making it impossible to operate the heat source system stably.

The present invention provides a pump number control method, a pump number control device, a pump system, a heat source system, and a program.

According to the first aspect of the present invention, the method for controlling the number of pumps includes a flow rate of a heat medium pumped by a plurality of pumps connected in parallel to a load or a heat load required by the load, and a plurality of pumps. Of these, there is a step of increasing or decreasing the number of operating pumps based on the frequency command value commanded to each pump in operation.

According to the second aspect of the present invention, in the pump number control method according to the first aspect, the flow rate of the heat medium pumped to the load from the measured value of the discharge flow rate by the operating pump among the plurality of pumps. And a step of increasing or decreasing the number of operating pumps is a step in which the number determination flow rate value is greater than or equal to a predetermined threshold value Gα and the frequency command value commanded to each pump is previously determined. The number of pumps to be operated is increased when a predetermined threshold value Fα is exceeded, the number determination flow value is equal to or less than a predetermined threshold value Gβ, and a frequency command value commanded to each pump is determined in advance. The number of operating pumps is decreased when the threshold value Fβ or less is reached.

According to a third aspect of the present invention, in the pump number control method according to the first aspect, the method includes a step of calculating a thermal load required by the load, and the step of increasing or decreasing the number of operating pumps includes the step of When the thermal load is equal to or greater than a predetermined threshold value Lα and the frequency command value commanded to each pump is equal to or greater than a predetermined threshold value Fα, the number of operating pumps is increased. When the frequency command value commanded to each pump is equal to or less than a predetermined threshold value Lβ, the number of pumps to be operated is decreased.

According to the fourth aspect of the present invention, in the pump number control method according to the second or third aspect, the step of increasing or decreasing the number of operating pumps further includes a pump head of the pump and an additional number of pumps. Compared to the increase-permitted pump head that is the threshold to reduce or the decrease-permitted pump head that is the threshold to decrease the pump, the number of operating pumps is increased only when the additional-permitted pump head is smaller than the pump head. The number of pumps to be operated is reduced only when the reduction head permitting pump head is larger than the pump head.

According to a fifth aspect of the present invention, in the pump number control method according to the fourth aspect, the pump discharge flow rate after the increase in the number of pumps operated and a predetermined correlation of the pump head with respect to the pump discharge flow rate Based on the pump head calculated based on the above, the pump head when the frequency of the pump is operated at a predetermined threshold Fβ is calculated to obtain the additional pump permitting pump head, and the pump after the decrease in the number of pumps operated From the pump head calculated based on the discharge flow rate and the predetermined correlation, the pump head when the pump frequency is operated at a predetermined threshold value Fα is calculated, and the reduction permission pump head is A step of obtaining.

According to the sixth aspect of the present invention, in the method for controlling the number of pumps according to the second or third aspect, the operation is performed on the condition that the pump head after the increase / decrease in the number of operating pumps is equal to the current pump head. Obtaining a frequency command value after an increase in the number of operating pumps and a frequency command value after a decrease in the number of operating pumps based on a predetermined correlation between a pump head and a pump discharge flow rate at a predetermined frequency of the pump And the step of increasing / decreasing the number of operating pumps further increases the number of operating pumps only when the frequency command value after increasing the operating number is greater than the threshold Fβ, and the frequency command after decreasing the operating number Only when the value is smaller than the threshold value Fα, the number of operating pumps is decreased.

According to the seventh aspect of the present invention, in the pump number control method according to any one of the second to sixth aspects, the discharge flow rate and the pump efficiency at a predetermined frequency of the pump in operation are preliminarily determined. Obtaining the pump efficiency after the increase in the number of operating pumps, the pump efficiency after the decrease in the operating number and the current pump efficiency based on the determined correlation, and the step of increasing or decreasing the number of operating pumps further includes The number of operating pumps is increased only when the pump efficiency after the increase in the operating number is equal to or higher than the current pump efficiency, and the operating number of pumps is increased only when the pump efficiency after the decrease in the operating number is higher than the current pump efficiency. Decrease.

According to the eighth aspect of the present invention, the number-of-pumps control device includes the number of operating pumps connected in parallel for pumping the heat medium to the load, the flow rate of the heat medium for pumping the load, or the load. And a pump number control unit that increases or decreases based on a thermal load required by the motor and a frequency command value commanded to each operating pump among the plurality of pumps.

According to a ninth aspect of the present invention, a pump system includes a plurality of pumps connected in parallel and a pump number control device according to the eighth aspect, and the pump head and flow rate per one pump. The number of operating pumps is changed so as not to change the measured value.

According to the tenth aspect of the present invention, the heat source system includes a load, a heat source unit that pumps a plurality of heat media connected in parallel, and a heat medium pumped from the plurality of heat source units connected in parallel. Is further provided with a secondary pump for pumping the pressure to the load, and a pump number control device according to the eighth aspect.

According to the eleventh aspect of the present invention, the program stores the computer of the pump number control device, the flow rate of the heat medium pumped to the load by a plurality of pumps connected in parallel, or the heat load required by the load. And a function of increasing or decreasing the number of operating pumps based on a frequency command value commanded to each operating pump among the plurality of pumps.

According to the pump number control method, the pump number control device, the pump system, the heat source system, and the program described above, it is possible to appropriately control the number of operating pumps at an appropriate timing without knowing the characteristics of the equipment such as pressure loss characteristics.

1 is a schematic view of a heat source system according to a first embodiment of the present invention. It is a functional block diagram of the pump number control apparatus by 1st embodiment of this invention. It is a figure which shows the processing flow of the pump number control apparatus by 1st embodiment of this invention. It is the schematic of the heat source system by the modification of 1st embodiment of this invention. It is a functional block diagram of the pump number control apparatus by the modification of 1st embodiment of this invention. It is a functional block diagram of the pump number control apparatus by 2nd embodiment of this invention. It is a figure which shows an example of the QH characteristic showing the characteristic of a pump. It is a figure which shows a change when the operation number of secondary pumps is increased from one to two. It is a figure which shows a change when the operation number of secondary pumps is increased from one to two. It is a figure which shows the processing flow of the pump number control apparatus by 2nd embodiment of this invention. It is a functional block diagram of the pump number control apparatus by 3rd embodiment of this invention. It is a figure which shows the processing flow of the pump number control apparatus by 3rd embodiment of this invention. It is a functional block diagram of the pump number control apparatus by 4th embodiment of this invention. It is a figure which shows an example of the correlation with the discharge flow rate of a pump, and pump efficiency. It is a figure which shows the processing flow of the pump number control apparatus by 4th embodiment of this invention.

<First embodiment>
Hereinafter, a heat source system according to a first embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a schematic view of a heat source system according to a first embodiment of the present invention.
As shown in FIG. 1, the heat source system of the present embodiment includes a heat source device 30, a primary pump 10, a secondary pump 20, a load 40, a flow meter 21, and a pump number control device 50. Yes.
The heat source unit 30 is a device that supplies a cooling or heating heat medium such as water to a load. The primary pump 10 pumps the heat medium to the heat source unit 30. The heat source unit 30 is a device that supplies a cooling or heating heat medium such as water to a load. In the heat source system according to the present embodiment, a plurality of combinations of the heat source device 30 and the primary pump 10 may be installed in parallel. The figure shows a state where a plurality of primary pumps 10 are installed in parallel.
The secondary pump 20 pumps the heat medium sent from the heat source device 30 to the load 40. The secondary pumps 20 are connected in parallel to each other, and control the flow rate of the heat medium supplied to the load 40 in response to a request from the load 40.

The flow meter 21 is a flow meter that measures the flow rate per unit time of the heat medium pumped from the pump.
The load 40 is, for example, an air conditioner. The load 40 radiates or absorbs heat from the heat medium, and then causes the heat medium to return to the heat source unit 30.
The pump number control device 50 is a device having a function of increasing / decreasing the number of operating secondary pumps 20 according to the required load required by the load 40.
In FIG. 1, two heat source units 30, a primary pump 10, and a secondary pump 20 are installed, but the number is not limited to these numbers. For example, six heat source devices 30 and six primary pumps 10 may be installed, and nine secondary pumps 20 may be installed.
In addition, the heat source system may be provided with a device (not shown) that controls the number of operating heat source units 30 in order to adjust the supply amount of the heat medium according to the required load of the load 40.

FIG. 2 is a functional block diagram of the pump number control device according to the first embodiment of the present invention.
The pump number control apparatus 50 in this embodiment is demonstrated using FIG.
As shown in FIG. 2, the pump number control device 50 includes a number determination flow value acquisition unit 101, a number determination frequency value acquisition unit 102, a pump frequency setting unit 103, a flow rate acquisition unit 104, a pump number control unit 105, and a storage unit 200. I have.

The number determination flow value acquisition unit 101 reads out and acquires the flow rate increase threshold value Gα and the flow rate decrease threshold value Gβ, which are threshold values used when increasing or decreasing the number of operating secondary pumps 20 according to the flow rate. Further, the number determination flow value acquisition unit 101 calculates the number determination flow value by the following equation (1), for example.

 

Here, Gload is a measured value of the flow rate of the heat medium such as water pumped from all the operating secondary pumps 20. G0i is the rated flow rate of the currently operating secondary pump. The number determination flow rate value is a ratio of the measured value of the discharge flow rate of all the operating pumps to the sum of the rated flow rates of the operating secondary pumps.
The number determination frequency value acquisition unit 102 reads out and acquires the frequency increase threshold value Fα and the frequency decrease threshold value Fβ, which are threshold values used when increasing or decreasing the number of operating secondary pumps 20 according to the frequency, from the storage unit 200. Further, the number determination frequency value acquisition unit 102 acquires the frequency command value output from the pump frequency setting unit 103 to each secondary pump 20 from the pump frequency setting unit 103 and sets it as the number determination frequency value.
The pump frequency setting unit 103 instructs the secondary pump 20 to operate the pump. The frequency is a frequency of electric power for rotating the motor that drives the secondary pump 20, and the pump frequency setting unit 103 controls the pump output by specifying the frequency and changing the number of rotations of the pump. To do. The pump frequency setting part 103 shall output the same frequency command value with respect to the some secondary pump 20 in a driving | running state.
The flow rate acquisition unit 104 acquires the flow rate of the heat medium measured by the flow meter 21.

The number-of-pumps control unit 105 increases the number of operating pumps when the flow rate of the heat medium pumped by the pump and the pump frequency satisfy predetermined conditions. In the present embodiment, the number of operating pumps is increased when the following two conditions are satisfied.
<Additional condition 1: Judgment by flow rate>
Number of units judgment flow rate ≧ Gα (2)
<Additional condition 2: Judgment by frequency>
Unit judgment frequency value ≧ Fα (3)
Here, the number determination frequency value is the same value as the frequency command value Fset output to the secondary pump 20 by the pump frequency setting unit 103. Fα is a threshold acquired by the number determination frequency value acquisition unit 102.
That is, the ratio of the flow rate pumped by all of the currently operating secondary pumps 20 to the sum of the water feeding capacities of the operating secondary pumps 20 is equal to or greater than the threshold value Gα (formula (2)), and When the frequency command value output to each secondary pump 20 is equal to or greater than the threshold value Fα (formula (3)), the pump number control unit 105 increases the number of operating secondary pumps 20.

The pump number control unit 105 reduces the number of operating pumps when the flow rate of the heat medium pumped by the pump and the pump frequency satisfy a predetermined condition. In the present embodiment, the number of operating pumps is reduced when the following two conditions are satisfied.
<Decrease condition 1: Judgment by flow rate>
Number of units judgment flow rate ≦ Gβ (4)
Here, Gβ is a threshold acquired by the number determination flow value acquisition unit 101.
<Decrease condition 2: Judgment by frequency>
Unit judgment frequency value ≤ Fβ (5)
Here, Fβ is a threshold acquired by the number determination frequency value acquisition unit 102. The number determination frequency value is a frequency command value specified by the pump frequency setting unit 103 to the secondary pump 20, for example.
That is, the ratio of the flow rate pumped by all of the currently operating secondary pumps 20 to the sum of the water supply capacities of the currently operating secondary pumps 20 is less than or equal to the threshold Gβ (formula (4)). In addition, when the frequency command value output to each secondary pump 20 is equal to or less than the threshold value Fβ (formula (5)), the pump number control unit 105 decreases the number of operating secondary pumps 20.

The storage unit 200 holds threshold values such as Gα and Fα used for determining increase / decrease in the number of pumps, information representing the characteristics of the secondary pump 20, and the like. The characteristic information is, for example, a QH characteristic, a graph showing the correlation between the pump discharge flow rate and the pump efficiency.

FIG. 3 is a diagram showing a processing flow of the pump number control device according to the present embodiment.
A process of increasing or decreasing the number of operating secondary pumps 20 by the pump number control device 50 will be described using the processing flow of FIG.
As a premise, the heat source system shown in FIG. 1 is operating. For example, when the load 40 is an air conditioner and the user raises or lowers the temperature setting, the required load increases or decreases. The number of operating units shall be controlled. Further, it is assumed that the total flow rate of the secondary pump 20 immediately after the increase / decrease table of the pump does not change from that before the increase / decrease table, and the pump head (pump head) per one of the secondary pumps 20 does not change.
First, the flow rate acquisition unit 104 acquires the flow rate per unit time measured by the flow meter 21 (step S1). The flow rate measured by the flow meter 21 is the total flow rate of the heat medium pumped by one or a plurality of secondary pumps 20. Since this measured value is a value obtained by measuring the flow rate actually flowing through the pipe, it can be considered that the pressure loss characteristic of the pipe is reflected.
Next, the number determination flow value acquisition unit 101 reads out and acquires the threshold values Gα and Gβ stored in the storage unit 200. Further, the number determination flow value acquisition unit 101 calculates the number determination flow value by the equation (1) (step S2). The number determination flow value acquisition unit 101 outputs these values to the pump number control unit 105.
Next, the number determination frequency value acquisition unit 102 reads and acquires the threshold values Fα and Fβ stored in the storage unit 200. Further, the number determination frequency value acquisition unit 102 acquires the pump frequency command value commanded from the pump frequency setting unit 103 to the secondary pump 20 as the number determination frequency value (step S3). The number determination frequency value acquisition unit 102 outputs these values to the pump number control unit 105.

Next, the number-of-pumps control unit 105 evaluates the expressions (2) and (3) and determines “addition condition 1” and “addition condition 2” (step S4). Then, when the pump number control unit 105 satisfies both conditions (step S4 = Yes), one of the currently stopped secondary pumps 20 is started and the number of secondary pumps 20 is increased (step S5). ).
As a result of the comparison, if any one of “addition condition 1” and “addition condition 2” is not satisfied (step S4 = No), the process proceeds to step S6.

Next, the number-of-pumps control unit 105 evaluates the expressions (4) and (5) and determines “reduction table condition 1” and “reduction table condition 2” (step S6). When the pump number control unit 105 satisfies both conditions (step S6 = Yes), one of the currently activated secondary pumps 20 is stopped and the number of secondary pumps 20 is decreased (step S7). ).
As a result of the comparison, if any one of “reduction condition 1” and “reduction condition 2” is not satisfied (step S6 = No), the process proceeds to step S8.
Finally, the number-of-pumps control device 50 determines whether or not the heat source system has been stopped by an operation of a user or the like by a predetermined method. When the operation of the heat source system is stopped (step S8 = Yes), this processing flow ends. When the operation continues (step S8 = No), the processing from step S1 is repeated.

The effect by this embodiment is demonstrated. For example, in the “heat source system state 1” where the valve of the air conditioner is throttled due to a decrease in load and the pressure loss of the system is large, one secondary pump 20 is in operation, and the measured value of the discharge flow rate at that time is 100 m ³ / h. Conversely, in “heat source system state 2” in which the pressure loss is reduced due to the increase in load, one secondary pump 20 is in operation, and the measured value of the discharge flow rate is 100 m ³ / h. The threshold value for increasing the number of operating secondary pumps 20 from one to two is 100 m ³ / h.
At this time, since the pressure loss is large in “heat source system state 1”, if the measured value of the discharge flow rate is 100 m ³ / h even though the secondary pump 20 is operated at a frequency close to the maximum value, It is considered that it is appropriate control to set the number of secondary pumps 20 to operate in accordance with a preset threshold value. On the other hand, in the “heat source system state 2”, since the pressure loss is small, for example, the secondary pump 20 is operated at a frequency about half the maximum frequency, and a flow rate of 100 m ³ / h is obtained. In this case, it is not always appropriate to increase the number of operating secondary pumps 20, and if the frequency of the currently operating secondary pump 20 is increased, the flow rate required by the load device may be supplied. In such a case, in the conventional method in which only the flow rate is used to determine the increase / decrease table, the secondary pump is increased. The increase in the number of pumps causes a large change in the pressure and flow rate of the heat medium flowing through the system.
According to this embodiment, the secondary pump 20 can be increased or decreased without having to know the details of the equipment such as pressure loss by making a determination based on the frequency command value in addition to the actual flow rate measurement value including the system pressure loss information. become. Further, by determining the increase / decrease table using the pump frequency command value, it is possible to increase / decrease the secondary pump 20 in consideration of the remaining capacity of the pump. Therefore, it becomes difficult to increase or decrease the number of pumps, and the heat source system can be operated more stably than the conventional method. Similarly, when the pump is reduced, it is possible to prevent the pump from being reduced even though the pump capacity can be further reduced by reducing the frequency.

<Modification>
As a modification of the present embodiment, a heat load required by the load 40 can be used instead of the flow rate of the heat medium. Hereinafter, modified examples will be described with reference to FIGS.
FIG. 4 is a schematic view of a heat source system according to a modification of the present embodiment.
The heat source system of this modification includes a thermometer 22 and a thermometer 23. Other configurations are the same as those of the first embodiment.
The thermometer 22 is provided near the entrance of the load 40. The thermometer 22 measures the temperature of the heat medium supplied to the load 40.
The thermometer 23 is provided near the outlet of the load 40. The thermometer 23 measures the temperature of the heat medium returning from the load 40 to the heat source unit 30.

FIG. 5 is a functional block diagram of a pump number control device according to a modification of the present embodiment.
The pump number control device 50 of this modification is different from the first embodiment in that it includes a temperature acquisition unit 110 and a number determination thermal load acquisition unit 111 instead of the number determination flow value acquisition unit 101. Other configurations of the present embodiment are the same as those of the first embodiment.
The temperature acquisition unit 110 acquires the temperature of the heat medium measured by the thermometer 22 and the thermometer 23.

The number determination thermal load acquisition unit 111 reads a thermal load increase threshold value Lα and a thermal load decrease threshold value Lβ, which are predetermined threshold values, from the storage unit 200. The number determination thermal load acquisition unit 111 needs the load 40 by acquiring the flow rate of the heat medium from the flow rate acquisition unit 104 and the temperature of the heat medium measured by the thermometer 22 and the thermometer 23 from the temperature acquisition unit 110. The load (thermal load) is calculated. The heat load can be calculated using, for example, the following equation.
Heat load = Flow rate of heat medium x (| Temperature of recirculating heat medium-Temperature of heat medium to be supplied |) x Specific heat of heat medium x Specific gravity of heat medium (6)
Here, “the flow rate of the heat medium” is a value measured by the flow meter 21, and is a value acquired from the flow rate acquisition unit 104 by the number determination thermal load acquisition unit 111. The “temperature of the recirculating heat medium” is a temperature measured by the thermometer 23 and a value acquired from the temperature acquisition unit 110 by the number determination thermal load acquisition unit 111. “The temperature of the supplied heat medium” is the temperature measured by the thermometer 22, and is the value acquired by the number determination thermal load acquisition unit 111 from the temperature acquisition unit 110. The specific heat of the heat medium and the specific gravity of the heat medium are recorded in advance in the storage unit 200, and the number determination thermal load acquisition unit 111 reads these values from the storage unit 200.

In this embodiment, the pump number control unit 105 determines the number of pumps to be operated when the thermal load calculated by the number determination thermal load acquisition unit 111 or the pump frequency acquired by the number determination frequency value acquisition unit 102 satisfies a predetermined condition. increase. Specifically, the number of operating pumps is increased when the following two conditions are satisfied.
<Additional condition 1-1: Judgment by heat load>
Thermal load ≧ Lα (7)
<Additional condition 2: Judgment by frequency>
Unit judgment frequency value ≧ Fα (8)

In addition, the pump number control unit 105 reduces the number of operating pumps when the heat load or the pump frequency satisfies a predetermined condition. Specifically, the number of operating pumps is reduced when the following two conditions are satisfied.
<Decrease condition 1-1: Judgment by heat load>
Thermal load ≦ Lβ (9)
<Decrease condition 2: Judgment by frequency>
Number-of-units judgment frequency value ≤ Fβ (10)
In this modification, the increase condition 1-1 and the decrease condition 1-1 are different from the first embodiment. The increase base condition 2 and the decrease base condition 2 are the same as in the first embodiment.

A processing flow will be described. In this modification, in addition to the flow rate acquisition unit 104 acquiring the flow rate measured by the flow meter 21 in step S1 of FIG. 3, the temperature acquisition unit 110 measures the temperature of the heat medium measured by the thermometer 22 and the thermometer 23. To get. In step S <b> 2, the number determination thermal load acquisition unit 111 reads the threshold values Lα and Lβ stored in the storage unit 200. The number determination thermal load acquisition unit 111 acquires the flow rate of the heat medium from the flow rate acquisition unit 104, the temperature of the heat medium supplied from the temperature acquisition unit 110 to the load 40, and the heat recirculated from the load 40 to the heat source unit 30. Get the temperature of the medium. And the number determination thermal load acquisition part 111 calculates a thermal load by Formula (6). Further, in step S4, the pump number control unit 105 determines the above “addition condition 1-1” and “addition condition 2”. In step S6, the pump number control unit 105 performs the determination of the “reduction table condition 1-1” and the “reduction condition 2”. Other processing steps in this modification are the same as those in the first embodiment.
The threshold values of Gα, Gβ, Fα, Fβ, Lα, and Lβ used in the present embodiment and the modified examples are values determined in advance through experiments, simulations, and the like.

<Second Embodiment>
Hereinafter, a heat source system according to a second embodiment of the present invention will be described with reference to FIGS.
In addition to the first embodiment, the second embodiment relates to an embodiment for preventing the repetition of pump increase / decrease units and performing more stable pump operation.
FIG. 6 is a functional block diagram of the pump number control device according to the present embodiment.
The pump number control device 50 according to the present embodiment is different from the first embodiment in that a pump head acquisition unit 107 is provided. Other configurations of the present embodiment are the same as those of the first embodiment.
The pump head acquisition unit 107 acquires the pump head of the secondary pump 20 that is currently in operation of the secondary pump 20 and the pump head after the increase / decrease of the secondary pump based on the QH characteristics possessed by the storage unit 200. Here, the pump head is the head of the pump. The QH characteristic is a pump performance curve showing the relationship between the discharge flow rate and the pump head when the pump is operated at the maximum frequency. An example of the QH characteristic is shown in FIG. In general, the pump discharge flow rate (Q) and the pump head (H) have a relationship in which the pump head decreases as the discharge flow rate is increased. The QH characteristics have different trajectories depending on the type of pump. The storage unit 200 stores a QH characteristic indicating the QH correlation of the secondary pump 20 used in the heat source system, and the pump head acquisition unit 107 increases or decreases using the QH characteristic. A pump head corresponding to the discharge flow rate of the secondary pump 20 per unit before and after the unit is acquired.

Next, how to obtain the pump head will be described more specifically. First, each symbol used to obtain a pump head will be described using an example of an additional pump.
8A and 8B are diagrams showing changes when the number of operating secondary pumps 20 is increased from one to two. Hereinafter, the secondary pump 20 that has been in operation from the beginning is referred to as a pump 20-1, and the second secondary pump 20 to be added is referred to as a pump 20-2.
FIG. 8A is a diagram of a single-unit operating state. The flow rate per unit time pumped by one pump 20-1 is GA, and the total flow rate per unit time pumped by all pumps 20-1 is GinA. In this figure, since the number of operating units is one, GinA = GA. The frequency of the pump 1 is fA, and the head of the pump 20-1 is HA.
FIG. 8B is a diagram of a two-unit operating state. The flow rate per unit time by the pump per unit pumped by each of the pump 20-1 and the pump 20-2 is GB, and the total flow rate per unit time pumped by the two pumps 20-1 and 20-2. Is GinB.
In this figure, since the number of operating units is 2, GinB = GB × 2. The frequency of the pump 20-1 and the pump 20-2 is fB, and the heads of the pump 20-1 and the pump 20-2 are HB. That is, in FIG. 8B, the pump number control device 50 controls the secondary pumps 20 in the operating state so that they have the same frequency regardless of the operating number. In addition, when the number of secondary pumps 20 is increased or decreased, the pump number control device 50 performs control so that the total flow rate (GinA) and the pump head (HA) do not change before and after that. These conditions are preconditions common to the first to fourth embodiments.

In summary, each value after increasing from n to n + m can be expressed as follows.
Total flow rate: GinB = GinA Discharge flow rate per unit: GB = (n / (n + m)) GA
Pump head per unit: HB = HA
Pump frequency: fB (same for all operating pumps)

Next, a method for obtaining the pump head will be described. It is assumed that the secondary pump 20 is operated at a frequency 1 and a discharge flow rate 1 is obtained. First, the discharge flow rate when the pump is operated at the maximum frequency can be obtained by multiplying the discharge flow rate 1 by the value obtained by dividing the maximum frequency by the frequency 1. Next, the QH characteristic is read using the discharge flow rate at the maximum frequency obtained, and a pump head corresponding to the discharge flow rate when the pump is operated at the maximum frequency is obtained. Next, the determined pump head is multiplied by the square of the ratio of the current frequency 1 to the pump maximum frequency. The value obtained in this way is the pump head.
First, the additional head permission pump head (HB ′) is obtained by the following equation (11).

 

Here, the first term F (x) on the right side represents a function for obtaining the pump head from the discharge flow rate indicated by the QH characteristic. Fβ is the frequency reduction threshold described in the first embodiment. Further, fmax is the maximum frequency (pump maximum frequency) of each secondary pump 20. This pump head obtained using the frequency reduction threshold Fβ means a pump head (addition permission pump head) when one secondary pump 20 is reduced from a state where one secondary pump 20 is increased.

Also, the pump head acquisition unit 107 similarly obtains the pump head (HB) in the state after increasing the pump by the following equation (12). Here, using the frequency and flow rate before the increase increases the secondary pump 20 so as not to change the pump head as described above, so that the pump head after the increase is equal to the current (before the increase) pump head. Because.

 

The number-of-pumps control unit 105 uses these values to determine the next condition in addition to the two additional conditions in the first embodiment.
<Additional condition 3: Judgment by pump head>
Additional head permitting pump head <Pump head after additional base (13)
That is, in addition to “addition condition 1” and “addition condition 2”, the number-of-pumps control unit 105 increases the number of secondary pumps 20 to be operated if the number of pumps is greater than the permitted number of pumps. The additional head permission pump head is a value obtained using the frequency lowering threshold, and is a reference value for lowering the pump after the number of operating pumps is increased. In order to eliminate such waste in consideration of the possibility that the pump head after the increase seems to fall below this value even if the number of operating units is increased, the pump may be reduced again. Let's add such a condition.

Next, a description will be given of a method in which the pump head acquisition unit 107 obtains the reduction permission pump head. The reduction-permitted pump head is a reference value for increasing the number of pumps after the number of operating pumps has decreased.
Each amount after the secondary pump 20 is reduced from n units to nm units in the same manner as when the number of units is increased can be expressed as follows.
Water flow rate: GinB = GinA Water flow rate per vehicle: GB = (n / (nm)) GA
Pump head per unit: HB = HA
Pump frequency: fB (same for all operating pumps)
The reduction base permission pump head can be obtained by the following equation (14).

 

Fα is the frequency increase threshold described in the first embodiment. Moreover, the pump head acquisition part 107 calculates | requires the pump head (HB) in the state after a pump reduction | decrease stand by Formula (12). Since the pump head after the reduction is not different from the pump head before the reduction, it can be obtained by Expression (12).
The pump number control unit 105 uses these values to determine the following conditions in addition to the two reduction conditions in the first embodiment.
<Decrease condition 3: Judgment by pump head>
Reduction head permission pump head> Pump head after reduction ... (15)
That is, the number-of-pumps control unit 105 reduces the number of operating secondary pumps 20 if the number of pumps is equal to or less than the reduction-permitted pump head in addition to “reduction conditions 1” and “reduction conditions 2”. This condition takes into consideration that the number of pumps may be increased again after a decrease in the number of operating pumps as in the case of increasing the number of pumps.

FIG. 9 is a diagram showing a processing flow of the pump number control apparatus according to the present embodiment.
A process of increasing or decreasing the number of operating secondary pumps 20 by the pump number control device 50 will be described using the processing flow of FIG. The same processes as those in FIG. 3 will be described with the same reference numerals.
First, Step S1 to Step S3 are the same as in the first embodiment. That is, the flow rate acquisition unit 104 measures the flow rate measured by the flow meter 21, the unit determination flow value acquisition unit 101 uses the threshold values Gα and Gβ, the unit determination flow rate value, and the unit determination frequency value acquisition unit 102 uses the threshold values Fα and Fβ Get the frequency value.
Next, the pump head acquisition unit 107 obtains the pump head after the pump increase / decrease table by Expression (12), the increase permission pump head by Expression (11), and the decrease permission pump head by Expression (14) (Step S10).
Next, the number-of-pumps control unit 105 determines “addition condition 1”, “addition condition 2”, and “addition condition 3” (step S11). Then, when all three conditions are satisfied (step S11 = Yes), the pump number control unit 105 increases the number of operating secondary pumps 20 by one (step S5).
As a result of the comparison, if any one of “addition condition 1”, “addition condition 2”, and “addition condition 3” is not satisfied (step S11 = No), the process proceeds to step S12.

Next, the number-of-pumps controller 105 determines “reduction condition 1”, “reduction condition 2”, and “reduction condition 3” (step S12). When all three conditions are satisfied (step S12 = Yes), the number-of-pumps control unit 105 decreases the number of operating secondary pumps by one (step S7).
As a result of the comparison, if any one of “reduction condition 1”, “reduction condition 2”, and “reduction condition 3” is not satisfied (step S12 = No), the process proceeds to step S8. The process in step S8 is the same as that in FIG. That is, the processing from step S1 is repeated until the heat source system stops.

In the first embodiment, the criteria for determining whether to increase or decrease the secondary pump 20 using the measured flow rate and pump frequency are shown. However, the method according to the first embodiment alone does not take into account the state after the pump is added or reduced, so the determination of the addition or reduction is performed again, and the addition and reduction may be repeated. There is sex.
According to the present embodiment, when determining whether to increase or decrease the number of stations, in addition to the flow rate measurement value and pump frequency after the increase / decrease, the pump operation state after the increase (decrease) is estimated from the QH characteristics. Increasing the number of units can be prevented by increasing or decreasing the number of units after comparing with the threshold pump head.
This embodiment can be combined with a modification of the first embodiment.

<Third embodiment>
Hereinafter, a heat source system according to a third embodiment of the present invention will be described with reference to FIGS.
As in the second embodiment, the third embodiment relates to an embodiment for preventing the repetition of pump increase / decrease units and performing more stable pump operation in addition to the first embodiment.
FIG. 10 is a functional block diagram of the pump number control device 50 according to the present embodiment.
The pump number control device 50 according to the present embodiment is different from the first embodiment in that a pump frequency estimated value acquisition unit 108 is provided. Other configurations of the present embodiment are the same as those of the first embodiment.
The pump frequency estimated value acquisition unit 108 acquires the post-increase pump frequency estimated value and the post-decrease pump frequency estimated value, which are estimated values of the frequency after the secondary pump 20 is increased or decreased.
Specifically, the pump head after the number of units can be obtained by Expression (16).

 

In other words, assuming that the required discharge flow rate ((n / n + m) × GA) per pump after the increase is obtained at the pump frequency (fB) after the increase, based on the discharge flow rate at the maximum pump frequency in that case. Then, the pump head (HB) after the addition is obtained by multiplying the pump head obtained from the QH characteristic by the square of the ratio of the pump frequency (fB) after the addition to the pump maximum frequency (fmax).
On the other hand, HB obtained by equation (16) is the same as HA (increase / decrease so that HB = HA), and HA should be obtained using the current pump frequency, measured flow rate, and QH characteristics. (Formula (12)). Using this relationship, the pump frequency estimated value acquisition unit 108 derives a frequency fB such that HB = HA from a map showing the correlation between the frequency prepared in advance and the pump head or an inverse function. , FB is the estimated pump frequency after the increase.

Then, the number-of-pumps control unit 105 determines whether or not to allow the number of pumps to be increased after the number of stations is increased by frequency in addition to the “number of conditions 1” and “number of conditions 2” (“number of conditions 4”). )I do.
<Additional condition 4: Judgment by frequency>
fB> Fβ (17)
Here, fB is the post-increase pump frequency estimated value obtained by the pump frequency estimated value acquisition unit 108, and Fβ is the frequency decrease threshold described in the first embodiment. In this embodiment, in addition to “addition condition 1” and “addition condition 2”, if the frequency after the addition does not exceed the frequency reduction threshold, the pump may be reduced. In order to prevent this, this condition is added to the pump addition determination.

In the same way, perform the judgment after the number of units is reduced. The pump frequency estimated value acquisition unit 108 substitutes the flow rate per pump and the pump maximum frequency after reduction in the formula (18), and uses the fact that the value of the formula (18) is equal to the above HA, The post-reduction pump frequency estimated value fB is obtained from a map or inverse function.

 

In addition to the “reduction condition 1” and “reduction condition 2”, the number-of-pumps control unit 105 determines that the number of pumps is not allowed to enter again after the reduction according to the frequency (“reduction condition 4”). )I do.
<Decrease condition 4: Judgment by frequency>
fB <Fα (19) Here, fB is the post-reduction pump frequency estimated value obtained by the pump frequency estimated value acquisition unit 108, and Fα is the frequency increase threshold described in the first embodiment. That is, in this embodiment, in addition to the “reduction condition 1” and “reduction condition 2”, if the frequency after the decrease is not less than the frequency increase threshold value, the number of pumps may be increased. In order to prevent this, this condition is added to the pump reduction judgment.

FIG. 11 is a diagram showing a processing flow of the pump number control device according to the present embodiment.
A process of increasing or decreasing the number of operating secondary pumps 20 by the pump number control device 50 will be described using the processing flow of FIG. The same processes as those in FIG. 3 will be described with the same reference numerals.
Steps S1 to S3 are the same as in the first embodiment.
Next, the pump frequency estimated value acquisition unit 108 obtains an estimated value fB of the pump frequency after the pump increase / decrease table using a map or an inverse function (step S13).
Next, the number-of-pumps control unit 105 determines “addition condition 1”, “addition condition 2”, and “addition condition 4” (step S14). Then, when all three conditions are satisfied (step S14 = Yes), the pump number control unit 105 increases the number of operating secondary pumps 20 by one (step S5).
As a result of the comparison, if any one of “addition condition 1”, “addition condition 2”, and “addition condition 4” is not satisfied (step S14 = No), the process proceeds to step S15.

Next, the number-of-pumps controller 105 determines “reduction conditions 1”, “reduction conditions 2”, and “reduction conditions 4” (step S15). Then, when all three conditions are satisfied (step S15 = Yes), the number-of-pumps control unit 105 reduces the number of operating secondary pumps by one (step S7).
As a result of the comparison, if any one of “reduction condition 1”, “reduction condition 2”, and “reduction condition 3” is not satisfied (step S12 = No), the process proceeds to step S8. The process in step S8 is the same as that in FIG. That is, the processing from step S1 is repeated until the heat source system stops.

According to the present embodiment, the pump frequency after the increase (decrease) is estimated, and the value is compared with the frequency decrease (addition) threshold. In addition to the two conditions of the first embodiment, the secondary pump 20 is increased if the estimated pump frequency after the increase exceeds the frequency decrease threshold. Similarly, in addition to the two conditions of the first embodiment, the secondary pump 20 is reduced if the estimated pump frequency after reduction is below the frequency increase threshold. By considering the frequency after the increase / decrease of the secondary pump 20, it is possible to prevent repeated increase and decrease.
This embodiment can be combined with a modification of the first embodiment.

<Fourth embodiment>
Hereinafter, a heat source system according to a fourth embodiment of the present invention will be described with reference to FIGS.
The fourth embodiment relates to an embodiment in which the number of operating pumps is changed in consideration of pump efficiency in addition to the first to third embodiments.
FIG. 12 is a functional block diagram of the pump number control apparatus according to the present embodiment.
The pump number control device 50 of this embodiment is different from that of the first embodiment in that a pump frequency estimated value acquisition unit 108 and a pump efficiency acquisition unit 109 are provided. Other configurations of the present embodiment are the same as those of the first embodiment.
As described in the third embodiment, the pump frequency estimated value acquisition unit 108 acquires the post-increased pump frequency estimated value and the post-decreasing pump frequency estimated value using a map or an inverse function.
The pump efficiency acquisition unit 109 obtains an estimated value of the pump efficiency after the increase / decrease of the secondary pump 20 using a graph or the like indicating the correlation between the pump discharge flow rate and the pump efficiency held by the storage unit 200. FIG. 13 shows an example of the correlation between the discharge flow rate and the pump efficiency when the pump is operated at the maximum frequency. FIG. 13 shows that the pump efficiency changes according to the pump discharge flow rate. It can be understood that when the number of operating secondary pumps 20 is increased or decreased, the discharge flow rate per unit changes, and the pump efficiency changes accordingly.

The current pump efficiency η _A per unit in the state before the increase is obtained by the following equation (20).

 

Here, η (x) is a function indicating the relationship between the pump discharge flow rate and the pump efficiency.
Similarly, the post-increase pump efficiency η _B per unit is obtained by the following equation (21).

 

Here, f _B is the pump frequency estimated value after the increase calculated by the pump frequency estimated value acquiring unit 108.

Then, in addition to “addition condition 1” and “addition condition 2”, the number-of-pumps control unit 105 performs an addition permission determination based on pump efficiency (“addition condition 5”).
<Additional condition 5: Judgment by pump efficiency>
η _B ≧ η _A (22)
That is, the number-of-pumps control unit 105 does not increase unless the pump efficiency after the increase is equal to or higher than the pump efficiency before the increase in addition to “addition condition 1” and “addition condition 2”.

Similarly, the pump efficiency acquisition unit 109 obtains the pump efficiency after the reduction per unit by the following equation (23).

 

The number-of-pumps control unit 105 performs a reduction permission determination based on pump efficiency (“reduction condition 5”) in addition to “reduction condition 1” and “reduction condition 2”.
<Decrease condition 5: Judgment by pump efficiency>
η _B ≧ η _A (24)
That is, the number-of-pumps control unit 105 does not decrease unless the pump efficiency after the reduction is equal to or higher than the pump efficiency before the reduction, in addition to the “reduction condition 1” and “reduction condition 2”.

Since the pump efficiency is not considered in the first to third embodiments, there is a possibility that the number of pumps may be increased or decreased to operate at an inefficient operating point.
According to this embodiment, it is possible to increase or decrease the number of pumps while suppressing power consumption by considering pump efficiency.

FIG. 14 is a diagram showing a processing flow of the pump number control device according to the present embodiment.
A process of increasing or decreasing the number of operating secondary pumps 20 by the pump number control device 50 will be described using the processing flow of FIG. The same processes as those in FIG. 11 will be described with the same reference numerals.
Steps S1 to S3 are the same as those in the first to third embodiments. The next step S13 is the same as in the third embodiment (FIG. 11).
Next, the pump efficiency acquisition part 109 calculates | requires the pump efficiency before and behind a pump increase / decrease stand (step S17).
Next, the number-of-pumps control unit 105 determines “addition condition 1”, “addition condition 2”, and “addition condition 5” (step S18). Then, when all three conditions are satisfied (step S18 = Yes), the pump number control unit 105 increases the number of operating secondary pumps by one (step S5).
As a result of the comparison, if any one of “addition condition 1”, “addition condition 2”, and “addition condition 5” is not satisfied (step S18 = No), the process proceeds to step S18.

Next, the number-of-pumps controller 105 determines “reduction condition 1”, “reduction condition 2”, and “reduction condition 5” (step S18). Then, when all three conditions are satisfied (step S18 = Yes), the number-of-pumps control unit 105 reduces the number of operating secondary pumps by one (step S7).
As a result of the comparison, if any one of “reduction conditions 1”, “reduction conditions 2”, and “reduction conditions 5” is not satisfied (step S18 = No), the process proceeds to step S8. The process in step S8 is the same as that in FIG. That is, the processing from step S1 is repeated until the heat source system stops.

This embodiment can be combined with the second and third embodiments as well as the first embodiment and its modifications. When combined with the second or third embodiment, it is possible to prevent the repetition of the increase / decrease units of the secondary pump 20 and to increase the number of pumps operated so as to satisfy the flow rate measurement value to the load while searching for an operating point with good pump efficiency. Since it can be determined, an energy saving effect can be expected.

The above-mentioned pump number control device has a computer inside. Each process of the above-described number-of-pumps control apparatus is stored in a computer-readable recording medium in the form of a program, and the above process is performed by the computer reading and executing this program. Here, the computer-readable recording medium means a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like. Alternatively, the computer program may be distributed to the computer via a communication line, and the computer that has received the distribution may execute the program.

The program may be for realizing a part of the functions described above.
Furthermore, what can implement | achieve the function mentioned above in combination with the program already recorded on the computer system, what is called a difference file (difference program) may be sufficient.

In addition, it is possible to appropriately replace the constituent elements in the above-described embodiments with known constituent elements without departing from the spirit of the present invention. The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

According to the pump number control method, the pump number control device, the pump system, the heat source system, and the program described above, it is possible to appropriately control the number of operating pumps at an appropriate timing without knowing the characteristics of the equipment such as the pressure loss characteristics.

DESCRIPTION OF SYMBOLS 10 Primary pump 20 Secondary pump 21 Flow meter 22 Thermometer 23 Thermometer 30 Heat source machine 40 Load 50 Pump number control device 101 Number determination flow value acquisition part 102 Number determination frequency value acquisition part 103 Pump frequency setting part 104 Flow rate acquisition part 105 Pump Number Control Unit 107 Pump Head Acquisition Unit 108 Pump Frequency Estimated Value Acquisition Unit 109 Pump Efficiency Acquisition Unit 110 Temperature Acquisition Unit 111 Number Determination Thermal Load Acquisition Unit 200 Storage Unit

Claims (11)

1. Based on the flow rate of the heat medium pumped by a plurality of pumps connected in parallel or the heat load required by the load, and the frequency command value commanded to each operating pump among the plurality of pumps A pump number control method comprising a step of increasing or decreasing the number of operating pumps.
2. Obtaining a number determination flow value indicating a flow rate of the heat medium pumped to the load from a measurement value of a discharge flow rate by an operating pump among the plurality of pumps;
   The step of increasing / decreasing the number of operating pumps is performed when the number-of-units determination flow value is not less than a predetermined threshold value Gα and the frequency command value commanded to each pump is not less than a predetermined threshold value Fα. The number of operating units is increased, and the pump operation is performed when the number determination flow rate value is equal to or less than a predetermined threshold Gβ and the frequency command value commanded to each pump is equal to or less than a predetermined threshold Fβ. Reduce the number of units,
   The method for controlling the number of pumps according to claim 1.
3. Calculating a thermal load required by the load,
   The step of increasing or decreasing the number of operating pumps is the operation of the pump when the thermal load is equal to or greater than a predetermined threshold value Lα and the frequency command value commanded to each pump is equal to or greater than a predetermined threshold value Fα. The number of pumps is increased, and the number of operating pumps is decreased when the thermal load is not more than a predetermined threshold value Lβ and the frequency command value commanded to each pump is not more than a predetermined threshold value Fβ. ,
   The method for controlling the number of pumps according to claim 1.
4. The step of increasing / decreasing the number of operating pumps further includes a pump head of the pump, an increase permission pump head that is a threshold for increasing the pump, or a decrease permission pump head that is a threshold for decreasing the pump, The number of operating pumps is increased only when the increase-permission permission pump head is smaller than the pump head, and the number of pump operation is decreased only when the decrease permission pump head is larger than the pump head. Or the pump number control method of Claim 3.
5. From the pump head calculated based on the pump discharge flow rate after the increase in the number of pumps operated and the pump head predetermined correlation with the pump discharge flow rate, the frequency of the pump was operated at a predetermined threshold value Fβ. The pump head is calculated by calculating the pump head when the pump is allowed, and the pump head calculated from the pump discharge flow rate after the decrease in the number of pumps operated and the predetermined correlation is used. The pump number control method according to claim 4, further comprising a step of calculating a pump head when the frequency is operated at a predetermined threshold value Fα to obtain the reduction base permission pump head.
6. Pumps based on a predetermined correlation between the pump head and the pump discharge flow rate at a predetermined frequency of the pump being operated on condition that the pump head after the increase / decrease in the number of pumps operated is equal to the current pump head Having a step of acquiring a frequency command value after an increase in the number of operating units and a frequency command value after a decrease in the number of operating units,
   The step of increasing / decreasing the number of operating pumps further increases the number of operating pumps only when the frequency command value after increasing the operating number is greater than the threshold value Fβ, and the frequency command value after decreasing the operating number is The pump number control method according to claim 2 or 3, wherein the number of operating pumps is decreased only when the value is smaller than the threshold value Fα.
7. Based on a predetermined correlation between the discharge flow rate at a predetermined frequency of the pump in operation and the pump efficiency, the pump efficiency after increasing the number of operating pumps, the pump efficiency after decreasing the operating number, and the current pump efficiency are acquired. And having a process of
   The step of increasing / decreasing the number of operating pumps further increases the number of operating pumps only when the pump efficiency after the increase in operating number is greater than or equal to the current pump efficiency, and the pump efficiency after decreasing the operating number is The method for controlling the number of pumps according to any one of claims 2 to 6, wherein the number of operating pumps is reduced only when the pump efficiency is equal to or higher than a current pump efficiency.
8. The operation number of a plurality of pumps connected in parallel for pressure-feeding the heat medium to the load, the flow rate of the heat medium pressure-fed to the load or the heat load required by the load, and each pump being operated among the plurality of pumps A pump number control device comprising a pump number control unit that increases or decreases based on the frequency command value commanded to
9. A plurality of pumps connected in parallel;
   The apparatus for controlling the number of pumps according to claim 8,
   A pump system that changes the number of pumps operated so as not to change a pump head and a flow rate measurement value per pump.
10. Load,
    A heat source unit that pumps a plurality of heat media connected in parallel;
    A secondary pump for further pumping a heat medium pumped from a plurality of heat source devices connected in parallel to a load;
    A pump number control device according to claim 8;
    A heat source system comprising:
11. The computer of the pump number control device,
    Based on the flow rate of the heat medium pumped by a plurality of pumps connected in parallel or the heat load required by the load, and the frequency command value commanded to each operating pump among the plurality of pumps A program for functioning as a means for increasing or decreasing the number of operating pumps.

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