SE535445C2 - Procedure for regulating power output in a district heating network. - Google Patents

Abstract

Method for controlling the power in a district heating network to which several properties (2) are connected, and is characterized in that the method comprises the steps a) to establish a certain group (6) of said properties (2), which properties comprise at least one sensor (38) for indoors temperature each and are associated with a respective lower temperature limit for the indoors temperature; b) for each of the properties in the certain group (6), to measure the indoors temperature in the property in question using said sensor (38) for indoors temperature and to establish a certain time value, constituting the expected time until the indoors temperature of the respective property reaches the respective lower temperature limit at a certain decreased heating power, which decreased power is lower than a certain respective normal power level; c) to calculate an expected total power in the district heating network during a future time period; and d) in case the said expected total power exceeds a predetermined value, during said time period only to distribute the respective decreased heating power to one or several of the properties in said group (6) for which the respective time value is larger than the length of the future time period, so that the total power no longer exceeds the predetermined value.

Description

It would thus be desirable to be able to provide a method of operating a district heating plant so that the highest power peaks are lower than in conventional operation, which would then have the consequence that the maximum capacity of the plant may be smaller.

Furthermore, such a procedure would be desirable which reduces the heat losses during operation of such a district heating plant.

The present invention solves the problems described above.

Thus, the invention relates to a method for regulating the power consumption in a district heating network, to which a plurality of properties are connected, characterized in that the method comprises the steps of a) determining a certain group of said properties, which properties comprise at least each sensor for indoor temperature and are associated with a respective lower temperature limit for the indoor temperature; b) for each of the properties in the certain group, measure the indoor temperature in the property in question with the aid of said indoor temperature sensors and determine a certain time value, which constitutes the expected time until the indoor temperature of the respective property has fallen from the current indoor temperature and down to the respective lower temperature limit at a certain throttled heating power, which throttling power is lower than a certain respective normal power level; c) calculate an expected total power output in the district heating network for a future time period; and d) if said expected total power consumption exceeds a predetermined value, during said time period only distributing the respective lower heating power to one or more of the properties in said group, for which the respective time value is greater than the length of the coming period, so that the total power consumption no longer exceeds the predetermined value, after which the indoor temperature is measured in the property or properties to which the respective calculated time values for the properties in the group are updated, the lower heating effect is currently distributed, and a or several of the properties, which currently have a respective estimated time value greater than the time remaining of the period, are heated with their respective lower power level, so that the total power consumption does not exceed the predetermined value, while other properties in the group are brought to heat with a respective normal power level.

The invention will now be described in detail, with reference to exemplary embodiments of the invention and the accompanying drawings, in which: Figure 1 is a schematic diagram of a property stock heated according to the present invention by means of a district heating system: and Figure 2 is a schematic diagram of a property heated according to the present invention.

Figure 1 shows a district heating plant comprising a central heat source 1, in the form of a combined heat and power plant, a plant for the recovery of residual heat, similar. a geothermal heating system or dy- Heat source 1 is arranged to distribute heat energy in cold weather to a number of properties 2. Connected to source 1. The distribution takes place by means of a main line 3 for suitable heating medium, such as hot water.

The properties 2 can be of different types, but it is preferred that they are at least for the most part, preferably exclusively, multi-family properties. A central control device 4 is arranged to regulate the heating effect distributed to each property 2. The control can for instance take place by means of a wireless transmitter 5 which communicates with receivers in each respective property (see below), which properties in this case are equipped with suitable conventional actuators for regulating the circulation of heating medium in the property in question, such as the circulation in a radiator circuit. Alternatively, the properties may themselves include conventional actuators for regulating a ventilation circuit. Instead of the wireless transmitter 5, for example, a wired or Internet-connected signal system can be used.

Figure 2 shows an exemplary property 20. Hot water from the heat source 1 arrives at a control unit 22 in the property 20 via an incoming line 21, and returns to the heat source 1 via an outgoing line 23. The control unit 22 is in turn connected to a radiator loop 24 , which is illustrated in principle and is arranged to distribute the incoming hot water to radiators arranged in the various rooms in the property. The control unit 22 is also connected to a control device 25 for domestic hot water, which is arranged to circulate domestic hot water in a HVAC circuit 26 in the property 20.

The control unit 22 comprises a wireless receiver 27 which is arranged to communicate with the transmitter 5. A control device 28 for a ventilation system further comprises a receiver 29 arranged to communicate with the transmitter 5. Indoor air is ventilated away from the ventilation system through a chimney 30.

Alternatively, all communication between the control device 4 and the property 20 can pass through the control unit 22, which in turn controls, for example, the control devices 25 and 28. Other actuators present in the property 20 can in a corresponding manner be controlled either directly from the control device 4 or from the control unit 22.

Wastewater drains from the property 20 through a sewer line 31.

The energy balance in the property is thus essentially determined by the following energy flows: 0 The difference in heat energy between incoming hot water 32 and outgoing, cooled water 33. 0 Outgoing heat energy via hot wastewater 35. 0 Ventilated indoor air 34, possibly after exhaust air heat recovery. 0 Heat losses 36 via the property walls, roof. basis and o Supplied heat energy originating from the property's use, from various internal sources, in the property 20 exemplified by people and a computer 37. Cooling inside the property 20 of consumed domestic hot water also constitutes such an internal energy source.

The property 20 further comprises at least one sensor 38 for indoor temperature, which is arranged to measure the indoor temperature in the property 20 and communicate the measured value to the central control device. 4 in a manner conventional per se, for example wireless as described above for the communication between the control device 4 and the control unit 22, the transmitter 5 also being a receiver for wireless signals from the sensor 38. The communication can also take place via the control unit 22. It is preferred that the property 20 comprises a plurality of such sensors for indoor temperature, preferably arranged in several different rooms in the property 20. According to the invention, a certain group 6 (see figure 1) is first selected of the properties 2 which are connected to the heat source 1. Which of the properties 2 that are selected depend on the current operational applications, but all properties 7 in the group 6 include at least one sensor 38 for indoor temperature devices. control device 4 connected sensors for indoor temperature; which does not have the possibility to be controlled from the central control device 4; or who for some other reason do not have the conditions to participate in the procedure described herein.

Other properties 9 that are not selected may, for example, have special operating conditions, such as that they must maintain a certain, constant indoor temperature, which may, for example, be the case with hospitals, certain archives and so on.

Furthermore, each property 7 in the group 6 is associated with a respective lower temperature limit for the indoor temperature, below which the indoor temperature of the property must not fall.

The method according to the present invention aims at the power control of the properties 2 in the district heating network for a certain future period of time. The future time period used depends on the specific application, but can be a period that begins immediately or later, and can for example consist of a certain part of a day, such as between 18 and 24 the next evening.

For each of the properties 7 in the group 6, the indoor temperature is measured, and communicated to the control device 4. A certain time value is then determined for all properties 7, which constitutes an estimate of the expected time until the indoor temperature of the respective property has fallen from the current indoor temperature and down to the respective lower temperature limit if only a certain restricted heating effect is distributed to the property, starting immediately, which restricted effect is lower than a certain or normal power level. Thus, the time value is the length of a certain time period.

The normal power level is chosen to represent a heating effect that is distributed to the property in question during normal operation under the current operating conditions. The normal power level can, for example, be the heating power distributed to the property in question at the current operating mode or the heating power that. is expected to be distributed to the property in question during the coming time period, given information regarding expected weather and control parameters for the heat distribution to the property.

The certain lower power level consists of a suitable power level which is lower than the normal power level and preferably lower than an expected lowest possible power level in order to be able to maintain the prevailing indoor temperature during the above specified time period and given the then expected operating conditions in terms of outdoor temperature and such. According to a preferred embodiment, the lower power level corresponds to that the distribution of heat energy to the property in question is completely interrupted, alternatively that the distribution of heat energy to the stability radiator loop is interrupted but that the distribution of heat energy to the hot water in the property is maintained at a normal level.

In addition, an expected total power consumption in the district heating network is calculated during the coming time period. that this total It is preferred power output represents an expected maximum, instantaneous power output during the coming time period, and that it is calculated based on available data be 15 20 25 30 535 4-45 regarding the properties' construction and use, weather forecasts and so on further. See below for a more detailed description of this.

According to the invention, a predetermined, maximum power output for the heat source 1 is established. According to a preferred embodiment, this maximum power output is the actual maximum power for the plant, more preferably the actual maximum power minus a certain predetermined safety margin.

In the event that the above-mentioned expected total power output exceeds this predetermined maximum power output, the control device 4 according to the invention will during the said time period regulate the distribution of heat energy so that a certain or some of the properties 7 in group 6 only receive the respective above described, lower heating effects. By restricting the heating power to at least one of the properties 7 sufficiently in this way, it can be achieved that the total power consumption during the coming period does not exceed the predetermined value. Thus, the power peak that, during conventional operation of the plant, would have been the result of the decreasing outdoor temperature or the other circumstances that were the basis for the forecast high total power can be eliminated, by temporarily reducing the heating power that is distributed. during the period to one or more properties.

According to the invention, the calculated respective time value described above for each property 7 in the group 6 is used to determine to which property or properties the respective lower power is to be distributed. More specifically, one or more of the properties 7 in the group 6 are selected to form an additional group 10, where all properties in the group 10 have a respective time value which is greater than the coming period. The said selection is also made so that the expected total power output from source 1, when the group 10 is operated with the respective lower power outputs, no longer exceeds As the respective time of the properties in the group 10 the predetermined value during the coming period. period is longer than the coming period, their respective indoor temperature will not fall below the respective lower temperature limit during operation at the respective lower power during the coming period.

According to a preferred embodiment, the property or properties in group 6 that have the greatest respective time value are selected to be included in group 10.

It is further preferred that the individual property having the greatest time value is selected in a first step, after which the property having the second greatest time value is selected, and so on, until the total expected total effect does not exceed the predetermined value, wherein the properties thus selected constitute the group 10.

By the control device 4 in this way being arranged to distribute a respective lower heating power to a limited proportion 10 of the connected property stock 2, it is thus achieved that the impending power peak can be reduced, which means that the system can be dimensioned with lower maxi grind capacity and still be able to supply heat energy with an expected operational reliability.

It has further been shown that in most district heating-connected property stocks there are generally at a given time properties for which the supplied district heating energy can be temporarily restricted without their respective indoor temperature risking falling below a contractually regulated 10 20 25 30 535 445 l0 lowest temperature. In fact, in operation according to the invention, that is, the properties' respective "thermal inertia", i.e. their volumetric heat capacity, is used to even out the power peaks which load the heat source 1.

In addition, heat losses in the district heating network as a whole decrease, as these are proportional to the distributed power and therefore decrease with decreasing variance.

It is also possible that the operating conditions will change during the coming period. In addition, properties other than those in group 10 some time into the coming period may prove to be more suitable for a restricted energy supply. Therefore, it is preferable to, during the coming period, regularly update which properties are currently to be included in group 10 for lower power distribution. Such an update follows, according to a preferred embodiment, the same rules as the original selection, and preferably takes place periodically, such as at least once an hour, or continuously.

In other words, the indoor temperature in the property or properties to which the respective lower heating effect is currently distributed is measured, and the estimated time values for the properties in the certain group are updated. Then one or more of the properties, which currently have a respective estimated time value that is greater than the time remaining of the period, are heated with their respective lower power level.

The selection is coordinated so that the total power consumption for all connected properties 2 does not exceed the predetermined value, while other properties in group 6 except those included in group 10, including possibly properties that were heated during the period with their respective lower power level, heated with a respective normal power level. 15 20 25 30 535 445 ll In this way, the advantages described above can be achieved, at the same time as the variations in indoor temperature in individual properties are reduced.

It is preferred that the control device 4 calculates the above-described estimate of the total power output from the source 1 during the coming period based on available information about the plant, the individual connected properties 2 and additional available information regarding the expected operating conditions during the coming period. - oden.

According to a preferred embodiment, the calculation is based at least in part on historical data regarding the total power consumption for the connected properties 2 under different types of operating conditions. For example, different historically measured total power outputs during periods with different outdoor temperatures can be tabulated, whereby the calculation can be done by interpolation or in another suitable, conventional way.

According to another preferred embodiment, the calculation is based at least in part on a measured value for the outdoor temperature in the vicinity of at least one of the connected properties 2 in the certain group.

The colder it is outdoors, the higher the heating effect required to maintain a desired indoor temperature.

According to a further preferred embodiment, the calculation is based at least in part on a weather forecast covering said future time period and at least one of the properties 2. Although the current outdoor temperature gives a good indication of the power requirement for a future period, especially 12 if the coming period soon begins, a weather forecast provides better precision in the calculation.

In the event that an outdoor temperature measurement or a weather forecast is only relevant for some of the connected properties 2, for example due to local meteorological differences, an in itself conventionally performed estimate of the operating conditions for other properties can be used.

It is preferred that the control device 4 is arranged to control the distribution of heating power to non-power-restricted, connected properties by means of a pre-known control algorithm, which may be conventional in itself. In this case, it is preferred that the expected total power output be calculated based at least in part on the known properties of this control algorithm. For example, a weather forecast covering a particular property can form the basis for a simulation of how the control algorithm will control the heating effect of the property in question, given an initial indoor temperature and the lower temperature limit for the property, and based on such a simulation the total heating effect over time for that property. Based on this, the total heating effect for all connected properties 2 can then be calculated.

In addition, it is preferred that the total power output be calculated at least in part on historical data regarding periodic patterns in the use 37 of the connected properties 2, and the additional heating effect that such use is expected to give rise inside the properties in the coming time period. . Various types of uses, such as visiting people and animals inside the properties; the use of technical equipment, lighting and domestic hot water; ventilation and so on constitute either heat sources or heat sinks which affect the operation of the heating system. Since such activities are largely periodic and to some extent predictable in nature, they can be measured and then used in the calculation to give a more expected value of the total effect during the coming period.

It is also preferable to use a priori knowledge concerning at least one, preferably all the thermal properties of the properties, in particular their heat capacity, soul base for the calculation of the total power consumption in the coming period. In other words, information is collected in an initial step regarding the heat leakage through the property shell 36 and ventilation 34, which information can be obtained, for example, from available type descriptions of different properties, and supplemented with information regarding heat recovery systems for ventilation, additional insulation, and so on, alternatively actual measurements on site. Then this information, together with the corresponding data describing additional energy depressions such as the wastewater 31, can be used to make a model of the property as a body with a certain heat capacity. Finally, the model can be used to calculate the expected power requirement during the coming period, especially in combination with historical data regarding utilization and / or the control algorithm used.

It is possible to combine in different ways and depending on available information the different ways described above to calculate the expected total energy requirement for the coming period, with the overall aim of achieving as reliable an estimate as possible.

In a manner similar to that described above with respect to the calculation of the expected total effect on the property portfolio, it is preferred that the time value of at least 15, 25 all of the properties 7 in the group 6 be calculated. based on the volumetric heat capacity of the property in question as it is modeled using available information regarding the energy flows 34, 35, 36 and so on as above. With the aid of such a thermal model, for example, suitable conventional differential equations can be set up which describe the indoor temperature of the property 20 as a function of time, supplied energy and operating conditions in general. Such equations can then be solved to calculate the expected time until the indoor temperature has dropped to the lower limit.

It is further preferred that the time value of at least one, preferably all, properties 7 in the group 6 is calculated based on a measured value for the outdoor temperature in the vicinity of the property and / or in the case of a weather forecast covering said future time period and the property in question, analogous to the described above for the expected total effect.

Furthermore, and also analogous to that described above for the expected total power, it is preferred that said time value for at least one, preferably all, of the properties 7 in the group 6 is calculated based on a control algorithm known per se which controls the heating power distributed to the property in question for the purpose of maintaining an indoor temperature therein above the minimum permitted level and / or historical data regarding periodic patterns in use and the additional heating effect that this use is expected to give rise to in the property in the coming time period.

The different types of information described above can be combined in many different ways to maximize the reliability in estimating the time value. The district heating network can be designed so that, for at least one of the properties 7 in the group 6, heat energy can be selectively distributed for heating either indoor air and / or domestic hot water. This can take place, for example, as shown in Figure 2, where a control unit 22 is arranged to control hot water to either a radiator circuit 24 and / or a HVAC circuit 26.

In this case, it is preferred that access to hot domestic hot water be given priority. As long as there is a need for additional domestic hot water in a certain of the properties that can be controlled selectively with regard to air and hot water, it is then preferred that a down-regulation of the heating effect distributed to the property in question only refers to the heating of indoor air and not the heating. of domestic hot water in the property. In other words, in this case, the energy supply to such a property is not restricted completely, only all or part of the energy supply to the radiator circuit 24.

This means that the thermal inertia in the housing body can be used for the purposes of the invention without affecting the supply of domestic hot water.

In order to determine when there is a need for additional domestic hot water, it is preferred that the temperature in the hot water circulation circuit is measured, in a conventional manner, communicated to the control unit 22, and the control device 4 or another control device arranged to regulate the heating power to VVC- the circuit in question. In this case, a need for additional domestic hot water is considered to exist when the measured temperature falls below a predetermined value, such as 55 ° C.

A method according to the present invention thus achieves that a smoother operation can be achieved without the need for additional heat sources in the form of, for example, fossil fuel firing to cope with power peaks. The inventors' calculations show that a plant can be designed with only 70-85% of the maximum capacity that would be required in conventional operation. In many cases, this can also be achieved by means of software installations in an existing system, without additional additional equipment than communication links between various sensors which are often present in themselves and the control device 4.

Alternatively, with the aid of the invention, more properties can be connected to a central heat source 1, since the heat energy can be taken out at a more even and higher level than before, when the maximum capacity was not utilized other than during power peaks.

Preferred embodiments have been described above. However, it will be apparent to those skilled in the art that many changes may be made to the described embodiments without departing from the spirit of the invention.

In the event of an approaching expected power peak, for example, the heat energy depots in one or more of the connected properties 2 can be increased before the period in question begins. Thus, a property's indoor air can be heated one or a few ° C above the normal temperature before the start of the period, which increases the property's time value and thus the possibilities to regulate the energy supply to the property during the coming time period without falling below the lower temperature limit. - sen. Correspondingly, the domestic hot water in the property can be overheated before the period begins, so that less heating of the domestic hot water is required during the period.

It may also be known that the need for domestic hot water is great in a coming period when the outdoor temperature is also expected to fall, such as the period in the evening between 18 and 24 o'clock. In this case, the indoor temperature can be raised in the property in question during the day. , to a higher temperature than would have been the case during conventional operation, and thereafter the heating effect to the radiator circuit in the property can be regulated down during the period 18-24 while the heating of the domestic hot water is maintained during these hours.

In addition to, or instead of, the historical data regarding the operation of the properties that can form the basis for the calculation of the expected total heating effect and the time values of the individual properties, an adaptive procedure can also be used, according to which operating data is compiled by a central device, such as the control device 4, and where the parameters in a per se conventional energy model over the entire plant or individual properties are continuously adjusted based on actual outcomes of different operating situations. It is especially preferred that the energy impact from the use of the properties is quantified in this way, by measuring the actual outcome of the indoor temperature given the added heating effect, outdoor temperature and the volumetric heat capacity of the house body. Such a method will be able to calculate increasingly expected value values for both the expected total effect and the time values described above.

Thus, the invention should not be limited by the described embodiments, but may be varied within the scope of the appended claims.

Claims (14)

W N 25 30 P B »T 535 445 18 E N T K R .A 'V Method for regulating the power consumption in a district heating network, gen B) b) C) d) to which a plurality of properties characterized (2) that the method comprises ste- are connected, EV determine a certain group of (2 ), sensors (6) which properties comprise (38) said properties at least each for indoor temperature and are associated with a respective lower temperature limit for the indoor temperature; for each of the properties in the certain group (6), with the aid of said sensor measure the indoor temperature in (38) and determine a certain time value, the property in question for indoor temperature which constitutes the expected time until the indoor temperature of the respective property has dropped from the current indoor temperature and down to the respective lower temperature limit at a certain throttled heating power, which throttled power is lower than a certain respective normal power level; calculate an expected total power consumption in the district heating network over a future time period; and if said expected total power consumption exceeds a predetermined value, during said time period distributing only the respective lower heating power to one or more of the properties in said group (6), the time value is greater than the length of the coming period, for which or which respectively, so that the total power consumption no longer exceeds the predetermined value, after which the indoor temperature is measured in the property or properties to which the respective lower heating power is currently distributed, the calculated time values for the properties in the properties the group (6) is updated, and one or more of the properties, which currently have a respective estimated time value that is greater than the time remaining of the period, are brought to heat with their respective lower power level, so that it total withdrawal does not exceed the predetermined value, while other properties ~ in the group (6) are heated by a respective norm l power level, and that the regulation in step d) of how much power is distributed to the said one or more of the properties in the group (6) takes place by bringing a control device locally arranged in each such respective property to be regulated equally locally and / or ventilation circuit. circulation in an arranged heating system Method according to claim 1, characterized in that in step d) the respective lower heating effect is distributed only to the one or the of the properties in said group (6), is greatest. for which or which the respective time value 3. A method according to claim 1 or 2, characterized in that the expected total power output in step c) is calculated based on historical data regarding the total power output under different types of operating conditions. Method according to one of the preceding claims, characterized in that the expected total power consumption in step c) is calculated based on a measured value for the outdoor temperature in the vicinity of at least one of the connected properties (2). Method according to any one of the preceding claims, characterized in that the expected total power consumption in step c) is calculated based on a weather forecast, which covers said future time period and at least one of the connected properties (2). ). Method according to one of the preceding claims, characterized in that the expected total power output in step c) is calculated based on a control algorithm known per se, which controls the heating power distributed to the connected properties (2). with the aim of maintaining an indoor temperature in each of the mentioned properties (2) above a certain minimum permitted level. Method according to one of the preceding claims, characterized in that the expected total power output in step c) is calculated based on historical data regarding periodic patterns in the utilization (37) of the connected property and the additional heating power, (37) which this use is expected to give rise to inside the properties (2) during the coming time period. 8. Procedure according to any. of the preceding claim, the characteristic (20) is calculated based on the property t e c k n a t a v that the time value of at least a certain of the connected properties (2) the heat capacity of the unit (2). 9. Procedure according to. somewhat, of the preceding claims, know a measured value for the outdoor temperature in the vicinity of the property (20). a v that the time value of at least a certain property in the certain group (6) is calculated based on Method according to one of the preceding claims, characterized in that the time value of at least a certain property (20) in the certain group (6) is calculated based on a weather forecast, (20) . covering the said future time period and the property 11. ll. Method according to one of the preceding claims, characterized in that the time value of at least a certain property (20) in the certain group (6) is calculated based on a control algorithm known per se, which controls the heating effect, which is distributed to the property (20). for the purpose of maintaining an indoor temperature therein above a certain minimum permissible level. Method according to one of the preceding claims, characterized in that the time value of at least a certain property in the certain group (6) is calculated based on historical data concerning periodic patterns in the use (20) as this use (37). ) of the property, and the additional heating effect (37) is expected to give rise to it in the coming time period. Method according to one of the preceding claims, characterized in that the district heating network can distribute heat energy for heating both indoor air and domestic hot water to at least one of the properties (7) (6), hot water is present in the property, in the certain group and that, as long as there is a need for further draining, a down-regulation of the heating effect distributed to the property in question only refers to the heating of indoor air and not the heating of hot water in the property. 14. A method according to claim 13, characterized in that there is a need for additional domestic hot water that the temperature in the hot water circulation circuit is measured, gives, when the measured temperature falls below a predetermined value.