EP1987402A1

EP1987402A1 - Model-based predictive regulation of a building energy system

Info

Publication number: EP1987402A1
Application number: EP07712263A
Authority: EP
Inventors: Markus Gwerder; Conrad GÄHLER; Nina Laubacher; Jürg Tödtli
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 2006-02-24
Filing date: 2007-02-21
Publication date: 2008-11-05
Also published as: WO2007096377A1

Abstract

In a method for the predictive control and/or regulation of a building energy system having at least one combined heat and power unit (1), control signals for a control and regulation unit (2) which is associated with the combined heat and power unit (1) are generated by a control and regulation device (20) which is superordinate to the control and regulation unit, wherein a model (21) of the thermal and energy behaviour of the building and the energy system as well as the users of the latter is used to generate the control signals and optimization is carried out using a sliding time horizon. One optimization criterion can be selected according to the current needs of the operator of the energy system. The optimization criterion is, for example, an indicator of the primary energy consumption of the energy system or else a measure of the carbon dioxide emission produced by the energy system.

Description

Model-based predictive control of a building energy system

Technical field of the invention

The invention relates to a method for controlling and regulating a power plant having at least one heat and power unit for a building, and to arrangements for carrying out the method, according to the preambles of claims 1, 14, 15 and 19.

PRIOR ART A predictive device for regulating or controlling supply quantities of a building is known, for example, from EP-A-1074900.

Technical task

The invention has for its object to provide a method by which at least one power-heat coupling device having energy system of a building can be controlled and / or regulated according to selectable optimization criteria. An arrangement should be specified with which the method can be carried out. Furthermore, an arrangement should be specified which can generally be used as a tool for dimensioning energy systems.

The object mentioned is achieved by the features of claims 1, 14, 15 or 19 according to the invention. Advantageous embodiments emerge from the dependent claims.

The claimed method can also be used advantageously in an arrangement for determining the so-called performance bond of an energy system, which allows a comparison with control and / or control devices operating according to other methods.

Embodiments of the invention will be explained in more detail with the aid of drawings. Details of the drawings

Show it:

1 is a block diagram of a first embodiment of the power plant,

2 is an energy flow diagram of a second embodiment of the energy system,

3 is an action plan with input and control variables of the second embodiment,

4 is a schematic diagram with an action plan for a third embodiment,

5 shows an action plan of a building energy system according to the third embodiment,

Fig. 6 is an action plan of a hot water tank in connection with the third embodiment, and

Fig. 7 is an action plan of a floor heating in connection with the third embodiment.

DETAILED DESCRIPTION OF THE INVENTION First Exemplary Embodiment In FIG. 1, 1 denotes a force-heat coupling device which can be controlled and / or regulated by means of a control and regulating device 2.

The combined heat and power unit 1 is part of an energy system for a building. The energy system has an additional boiler system 3, a service water system 4, a buffer memory 5 and a space heating system 6. A flow line 10 and a return line 11 form a connection for a heat transfer between the cogeneration unit 1, the auxiliary boiler system 3, the Service water system 4, the buffer memory 5 and the space heating system 6. The heat transfer medium is typically heating water.

The power-heat coupling device 1 here has a Stirling engine. The combined heat and power unit 1 is basically a device or an arrangement of devices by which - or by the - a return of electrical energy W from the power plant is made possible in an electrical energy network 12 and its - or their - waste heat in the energy system is usable. The electric power network 12 is, for example, a home network or a public network.

The power-heat coupling device 1 can basically be constructed on a different basis than on the Stirling engine; for example, based on a fuel cell or an explosion engine.

The system components 3, 4 and 6 are operated via other control and control devices: the auxiliary boiler system 3 is a control and control unit 13, the service water system 4 a control and control unit 14 and the space heating system 6 a control and 16 assigned.

By a control and regulating device 20 control signals for the control and regulating devices 2, 13, 14 and 16 of the power plant can be generated.

By the control signals generated by the control and regulating device 20 are the combined heat and power unit 1 and the auxiliary boiler system 3, the

Domestic hot water system 4 and the space heating system by means of associated control and regulating devices 2, 13, 14 and 16 optimally controlled and / or regulated. The control and regulating devices 20, which are the parent of the control and regulating devices 2, 13, 14 and 16 of the energy system, have a model 21 by means of which the thermal and energetic behavior of the building and the energy system and their users are described with advantage. Advantageously, the control and regulating device 20 has at least one correspondingly programmed Processor 22, through which an optimization of the operation of the power plant according to certain criteria and taking into account the model 21 is feasible.

By the higher-level control and regulating device 20 external signals a and b are advantageously detectable, which influence the optimization. A first external signal a is an example of information about the current rate of electrical energy and a second external signal b includes a current weather forecast.

The additional boiler installation 3 arranged in the exemplary energy installation, as well as the service water installation 4 and the space heating installation 6, could in principle be designed for operation with any energy source, for example for operation with oil, gas, wood, coal, electricity or a bio-energy source.

Second embodiment

In the energy flow diagram of an energy system of a building shown in FIG. 2, 25 denotes a cogeneration unit, 26 an auxiliary heat generator, 27 a storage of electrical energy Q _e (t) and 28 a heat storage with the energy Qth (t).

In the energy flow diagram of correlations between received by an energy supply network electrical power and _e ⁺ _l {t), which fed back to the electrical power grid energy and _e ^~ _l {t), which for example in the form of gas or oil are the power-heat coupling device 25 supplied energy u _wκκ (t), the example in the form of gas or oil the

Additional heat generator 26 supplied energy u _th {t) and the consumption of electrical energy q _e ι (t) and thermal energy q _th (t) shown.

In the action plan shown in FIG. 3, 30 means a first integrator and 31 a second integrator. The first integrator 30 models the Heat storage 28; the second integrator 31 models the memory 27 of electrical energy.

Symbols used in connection with the second embodiment mean: The cost of a unit of the fuel supplied to the cogeneration unit 25; Cost of a unit of the additional heat generator 26 supplied

fuel; Y _e ti) cost of a unit of electricity purchased from the grid;

Yield of a unit of electric power fed back to the grid

Energy; Efficiency of the auxiliary heat generator 26; electrical efficiency of the combined heat and power unit; thermal efficiency of the cogeneration unit; Duration of the sliding time horizon over which optimization takes place; : through the performance limits of corresponding parts of the system given maximum values of the corresponding control variables; maximum electrical energy storable in memory 27; and maximum in heat storage 28 storable thermal energy.

The following relationships apply:

Service costs c (t):

Energy costs C (T) in the time interval [θ, r]:

Control variables and their permissible values:

Limitation of memory contents:

Model equations and optimization problem, continuous

Known:

Searched:

so that

minimal {G25} and

Model equations and optimization problem, time-discrete derivation:

Solution of the differential equations according to the Euler method

Costs:

Optimization problem (Linear program (LP))

Known:

Determine

so that

under the following inequalities

and following equations

special cases

First special case: same tariffs for supply and return of electric power, that is:

It follows no longer individually, but only as a difference

We can therefore use the two control variables through the tax code

replace, but can accept positive and negative values. So there are only three control variables.

Second special case: No electrical storage, that is:

It follows:

It follows: U _{g [} (t) and u _{e [} (t) are no longer control variables. These quantities result from the consumption q _e ι (t) and the WKK production:

So there are only two control _quantities u _th and u _wκκ

Third special case: No thermal storage, that is:

It follows:

It follows is no longer taxable. This size results from the consumption and the WKK production:

Fourth special case: no electrical and no thermal storage. It stays as a tax quantity.

Third embodiment

An exemplary building energy system according to Figure 4 includes heat generator, heat consumers, electrical loads 43 and a higher-level controller 40 of the building energy system. The heat generator are a Stirling engine 41 and an auxiliary burner 42. The heat consumers here are a water heater 44 and a building with heat emitting devices 45th

The heat output of the heat generator becomes a first

Heizwasseraufbereiter 46 and a second Heizwasseraufbereiter 47 supplied. The Heizwasseraufbereiter 46 and 47 are coupled via a flow line 48 and a return line 49 with the hot water boiler 44 and the heat emitting devices 45.

In addition to covering the thermal power requirement of the heat consumer, the higher-level control system 40 of the building energy system also ensures that the electrical power requirements of the electrical loads in the building can be covered, namely by means of the produced by the Stirling engine 41 and / or the public network related electrical power. If the Stirling engine 41 generates more electrical power than the demand in the building, the electric power is exported to the public electric grid.

The Stirling engine 41, the auxiliary burner 42 and arranged in the flow line 49 Dreiweg- or distribution valve is by the parent

Controlled 40 according to requirements optimally controlled, the higher-level controller 40 advantageously the flow temperature Tv, the outside temperature T _A , the room temperature T _R , the storage tank temperature T _S p of the service water and tariff information to be supplied.

5 shows an action plan of the modeled building energy system with the subsystems heat generator WE and heat consumer WV and associated input and output signals.

The modeled building energy system includes the heat generator WE and the heat consumer WV. The modeled heat generators are the Stirling engine SM and the auxiliary burner ZB. The modeled Heat consumers WV include a hot water storage WWSp and a heating circuit with a floor heating BH and the building Geb.

Disturbances are the hot water demand Q _{ww Bed} , the ambient temperature TU ₁ MG ', which prevails around the hot water tank, the outside temperature T _A , the power demand P _{el Bed} and the internal and external external heat ß _FL with the airing can be detected.

Heat generator: • Stirling machine with control signal u _SM

• Additional burner with the control signal u _ZB

Heat consumer:

• DHW cylinder with the tank temperature T _Sp , which must be within a permissible temperature tolerance range.

• Floor heating and building: The room temperature T _R must be in one

Temperature tolerance band lie and the flow temperature T _v may not exceed a certain temperature value.

The control signal u _HK is an auxiliary signal, which divides the generated thermal power Q _th on the two heat consumers, namely on the

DHW tank WWSp and the heating circuit with the floor heating BH and the building Geb. So that the hot water tank WWSp no negative

Power can be supplied, the heat flow Q _th wws _p must always be positive. This also prevents energy from being drawn from the hot water storage and supplied to the heating circuit.

The disturbance Qψψ _Bed refers to the thermal power, which is obtained from the hot water tank for the everyday use of Hot water in the household. This power must always be available and the memory must therefore have enough energy stored.

In addition to the thermal requirements, the need for electric power P _{el Bed} must also be met: either by the electric power P _{el SM} produced by the Stirling engine or by electricity from the public grid.

Modeling Stirling Machine:

Burner:

Total heat production:

The hot water tank is modeled as a linear system of differential equations. The input, output and disturbance variables are shown in FIG. 6.

The floor heating as well as the building are modeled as linear

Systems of differential equations. The input, output and disturbance variables are shown in FIG. 7. The thermal power QHK 'which is generated for the space heating, must first be converted into the flow temperature T _v . Im the

Floor heating block BH is modeled as this heat passes through the water pipes and through the soil layers in the room and this supplies the necessary heat output QBH G _eh . The modeled building consists of exterior walls and a number of partitions. The heat loss of the building is composed of the loss through the exterior walls and the windows as well as the natural air exchange and ventilation losses. optimization problem

restrictions

The following comfort conditions must be observed:

The following performance conditions must be observed:

In order to be able to minimize the costs for the electricity supply from the public network or to maximize any profits from the sale of electrical energy into the public network, an auxiliary variable z is introduced. The following conditions for the auxiliary variable z must be observed:

If the first of the two inequalities for the auxiliary variable z becomes active - i. to the equality condition -, then z is equal to the cost of the electrical energy obtained in the time step At from the public grid.

If the second of the two inequalities for the auxiliary variable z becomes active - i. for the equality condition -, z is equal to the gain for the electrical energy delivered to the public network in time step At.

Quality criterion The optimum operating mode of the building energy system specified here is the cost-optimal operation. For cost-optimized operation, the quality criterion J should be minimized over the optimization horizon (N steps with time increment At):

The quality criterion sums up the energy costs of the Stirling engine, the auxiliary burner and the costs of drawing electrical energy beyond the optimization horizon. These costs for the purchase of electrical energy can also be negative, namely, when electrical energy is exported. In this case, electrical energy is sold. The conditions for the auxiliary variable z allow different costs k _imp for purchases or gains g _exp for

Sales of electrical energy to integrate in the optimization.

Both the quality criterion as well as those by a linear

System of differential equations and constraints are linear. Therefore, the optimization can be done by means of linear programming LP.

In order to determine the performance bond or in use as a control or regulating function - ie with so-called model predictive control - only the manipulated variables u of the first step in the optimization horizon are used by the optimization in order to carry out an optimization again after the sampling time has expired, which is a so-called Moving Horizon matches.

The symbols used in the third embodiment mean: g profit

/ Quality criterion k costs

N number of steps in the optimization horizon

P performance

Q heat flow, W

T temperature t time, s or h U control signal

Z auxiliary variable

Δ difference η efficiency,

The indices used in connection with the symbols mean:

A outside bed needed

BH floor heating el electric exp export (electric power) i running variable

P performance

F, L foreign (heat), airing

Go building

HK heating circuit imp import (electrical power)

L max air max min minimum nom nominal

R space

SM Stirling machine

Sp storage th thermally

UMG environment

V flow

WW hot water

WWSp hot water storage

Eg additional burner In the proposed method for predictive control and / or regulation of an energy plant having at least one cogeneration unit, a criterion for the optimization according to current needs of the operator of the energy system can be selected. The criterion of optimization can be an example of a measure of the operating costs of the energy system or a measure of the energy costs of the energy system. The criterion of optimization can also be an indicator for the primary energy consumption of the energy system or a measure of the carbon dioxide emissions produced by the energy system. In another case, the criterion of optimization may be a measure of the particulate matter output produced by the energy system. If necessary, but also after

Combinations of different masses are optimized: the criterion of optimization in another exemplary case is a combination of at least two masses or indicators for operating costs, energy costs, primary energy consumption, carbon dioxide or particulate matter emissions. In principle, the criterion of optimization can also be time-dependent.

A control and regulating device 20, which operates according to a method according to one of claims 1 to 13 allows the construction of an arrangement for dimensioning a power-heat coupling device 1 having energy system for a building. By way of example, the maximum energy store Q _dmax storable in the memory 27, and / or the maximum thermal energy Q _thmRX storable in the heat store 28, and / or the capacity of the energy _{storage device}

Cogeneration device 1 are dimensioned. In addition, the said arrangement for dimensioning the energy system also allows optimal

Dimensioning of a building envelope or heat dissipation device 45.

A variant of the arrangement for dimensioning a power-heat coupling device 1 having energy system for a building has a model used for the optimization of the power plant a control and

Control device which operates according to a method according to one of claims 1 to 13.

Claims

claims

1. A method for predictive control and / or regulation of at least one power-heat coupling device (1) having energy system of a building with the method step:

- Generating of control signals for a force-heat coupling device (1) associated control and regulating device (2) by a control and regulating unit superordinate control and regulating device (20), wherein for generating the control signals a model (21) of the thermal and energetic behavior of the building and the power plant and their users is used, and an optimization over a sliding time horizon is performed.

2. Method according to claim 1, characterized in that at least one signal influencing the optimization is detected and the optimization is carried out by linear or quadratic programming.

3. The method according to any preceding claim, characterized in that the control signals are recalculated several times per hour and output to the control and regulating device.

4. The method according to any preceding claim, characterized in that a tolerance band of several Kelvin is specified for room temperature setpoints.

5. The method according to any preceding claim, characterized in that a tolerance band of several Kelvin is specified for setpoint values of the temperature of a hot water tank present in the energy system.

6. The method according to any preceding claim, characterized in that a time-dependent tolerance band is specified for setpoint values of process variables.

7. Method according to any preceding claim, characterized that the criterion of optimization is a measure of the operating costs of the energy system.

8. A method according to any preceding claim, characterized in that the criterion of optimization is a measure of the energy costs of the

Energy system is.

9. The method according to any preceding claim, characterized in that the criterion of optimization is an indicator of the primary energy consumption of the energy system.

10. The method according to any preceding claim, characterized in that the criterion of the optimization is a measure of the carbon dioxide emissions produced by the energy system.

11. The method according to any preceding claim, characterized in that the criterion of optimization is a measure of the produced by the energy plant particulate matter emissions.

12. The method according to any preceding claim, characterized in that the criterion of the optimization is a combination of at least two masses or indicators for operating costs, energy costs, primary energy consumption, carbon dioxide or particulate matter emissions.

13. The method according to any preceding claim, characterized in that the criterion of the optimization is time-dependent.

14. Arrangement with a combined heat and power device (1), one connected to the cogeneration unit (1) control and regulating device (2) and with a control and regulating device (2) parent control and

Control device (20) for carrying out the method according to one of claims 1 to 13.

15. Arrangement for dimensioning a power-heat coupling device (1) having energy system for a building, characterized by a control and regulating device (20) which operates according to a method according to one of claims 1 to 13.

16. The arrangement according to claim 15, characterized in that the maximum in memory 27 storable electrical energy ß _{e / max can be} optimized.

17. Arrangement according to claim 15, characterized in that the maximum in the heat accumulator 28 storable thermal energy ß _{fÄmax is} optimized.

18. Arrangement according to claim 15, characterized in that the performance of the cogeneration unit 1 can be optimized.

19. Arrangement for determining the so-called performance bond of an energy system with a device (20) for carrying out the method according to one of claims 1 to 13.