Method for operating a heat and / or cold generator

Abstract

The invention relates to a method (100) for operating a heat and / or cold generator (10) of an HVAC system (1), in particular for a building, wherein the heat and / or cold generator (10) has at least one refrigerant circuit (20) with at least one compressor (22), and wherein the compressor (22) is operated as a function of a relative power value (P). rel ) is controlled, and the procedure (100) comprises the steps: • Determine (110) a maximum electrical power (P el_max ), • Determining (125) a maximum relative power value (P rel_max ), depending on the determined maximum electrical power (P el_max ), • Providing (130) the determined maximum relative power value (P) rel_max ).

Description

[0001] The invention relates to a method for operating a heat and / or cold generator of an HVAC system, a computer program, a machine-readable storage medium and a control unit. State of the art

[0002] For electrical heating and / or cooling devices in HVAC systems, such as heat pumps or air conditioners, an energy management system or the electricity grid operator may specify a limit on the electrical power consumption of the HVAC system. The HVAC system must or should adhere to this specification and limit its power consumption to the required value.

[0003] Common HVAC systems are typically controlled using the following procedure: The room setpoint temperature is converted into a supply setpoint temperature. The control unit uses the supply setpoint temperature to determine a relative power value. The electrical power is not used for control.

[0004] To adhere to a given electrical power limit, the electrical power must be converted into a relative power value. PI(D) controllers are often used for this purpose. The required PI(D) controller, which entails costs and tuning effort, is required. Disclosure of the invention

[0005] The invention relates to a method for operating a heat and / or cold generator of an HVAC system. In particular, the heat or cold generators are also referred to as heat pumps or air conditioning systems. The heat and / or cold generator of an HVAC system serves to heat or cool one or more rooms, or one or more buildings.

[0006] The heat and / or cold generator has at least one refrigerant circuit with at least one compressor. The heat and / or cold generator, in particular the compressor of the heat and / or cold generator, is controlled depending on a relative power value. The compressor of the heat and / or cold generator is controlled in particular by the relative power value. The relative power value is in particular a percentage value or a value between 0 and 1. In particular, the control takes place in a range between the minimum and maximum operating limits of the heat and / or cold generator using the relative power value.

[0007] The procedure includes the following steps.

[0008] In one method step, a maximum electrical output is determined. The maximum electrical output is the maximum available electrical output and / or the maximum electrical output that the heat and / or cold generator, in particular the compressor of the heat and / or cold generator, should and in particular may consume. The specification of the maximum electrical output comes in particular from the grid operator, an energy management system, a PV system (photovoltaic system), other electrical consumers or as a function of electricity prices. In particular, the maximum electrical output is provided by one of the aforementioned systems or a consumer. In particular, the determination here includes, among other things, reading out, retrieving or receiving the maximum electrical output.

[0009] In one process step, a maximum relative power value is determined. The maximum relative power value is determined depending on the determined maximum electrical power.

[0010] Determination includes in particular calculating the maximum relative power value.

[0011] In one method step, the determined maximum relative power value is provided. Providing comprises sending a control signal, in particular the determined maximum relative power value, or making the maximum relative power value available. Providing enables retrieval by systems and consumers, but also by components of the heat and / or cooling generator, in particular an inverter for controlling the compressor. Providing enables retrieval by, in particular, electrical consumers or an energy management system.

[0012] The measures listed in the subclaims result in advantageous developments and improvements of the features specified in the main claim.

[0013] According to an advantageous development, the method comprises limiting the heat and / or cooling generator to the provided maximum relative power value. The heat and / or cooling generator is only controlled up to this value. In particular, a simple limitation to a maximum electrical power can be achieved in this way. The limitation is carried out in particular by a control device of the heat or cooling generator, preferably by the control unit. According to a development, the cooling and / or heat generator can bypass the limitation, for example, to meet special specifications. Such a special specification can be, for example, the minimum temperature in a building.

[0014] According to an advantageous further development, the method comprises the following process steps.

[0015] In one process step, the electrical power consumed by the HVAC system, in particular the cooling or heating generator, preferably the compressor, is determined. This process involves reading, retrieving, receiving, and even measuring. During the process, the maximum electrical power is requested from or received from an energy management system, the grid operator, or a consumer.

[0016] Consumers can in particular be a wallbox, a household appliance, a storage battery, etc.

[0017] In one process step, the ambient temperature and / or the flow target temperature are determined. This determination includes reading, receiving, measuring, and / or calculating.

[0018] In a further process step, the maximum relative power value is determined based on the determined ambient temperature and the determined flow target temperature. In particular, the maximum relative power value can be determined even more precisely.

[0019] According to a further development of the invention, the method also comprises steps for determining the proportionality factor, as shown in the method steps listed below.

[0020] In one method step, the electrical power, in particular the electrical power, is determined. In particular, the required, in particular the consumed, electrical power is determined. The required electrical power can be measured, in particular, using a power meter. However, it is also conceivable to determine it using a table. The electrical power is the power at which the heat and / or cooling generator is operating at a defined point in time, in particular the point in time of the determination.

[0021] In one method step, the relative power value, in particular the set relative power value, is determined. The determination particularly includes reading or receiving the set relative power value of the compressor or the inverter controlling the compressor. In particular, the value with which the compressor is controlled is retrieved. The set relative power value is the power value with which the heat and / or cold generator is operated at a defined point in time, in particular the point in time of the determination.

[0022] In one process step, the ambient temperature and / or the flow temperature are determined. Preferably, the ambient temperature and / or the flow temperature are measured.

[0023] In one method step, the proportionality factor is determined depending on the determined electrical power, the determined relative power value, the ambient temperature, and the flow temperature. The determined proportionality factor is provided. In particular, the determined proportionality factor is stored, preferably saved, in a memory location.

[0024] In particular, the values ​​are determined at a defined time and / or within a defined period of time. Preferably, the electrical power, the relative power value, the ambient temperature, and the flow temperature are determined at the same time, in particular within a defined period of time. In particular, the period is less than 10 s, preferably less than 1 s. In particular, the electrical power, the relative power value, the ambient temperature, and the flow temperature are determined simultaneously.

[0025] According to a further development of the invention, the method also comprises steps for determining the simplified proportionality factor, as shown by the method steps listed below.

[0026] In one method step, the electrical power, in particular the current electrical power, is determined. In particular, the currently required, and in particular consumed, electrical power is determined. The required electrical power can be measured, in particular, using a power meter. However, it is also conceivable to determine it using a table. The current electrical power is the power at which the heat and / or cooling generator is operating at a defined point in time, in particular the point in time of the determination.

[0027] In one method step, the relative power value, in particular the set relative power value, is determined. The determination particularly includes reading or receiving the set relative power value of the compressor or the inverter controlling the compressor. In particular, the value with which the compressor is controlled is retrieved. The set relative power value is the power value with which the heat and / or cold generator is operated at a defined point in time, in particular the point in time of the determination.

[0028] In one method step, the proportionality factor is determined as a function of the determined electrical power and the determined relative power value. The determined proportionality factor is provided. In particular, the determined proportionality factor is stored, preferably saved, in a memory location.

[0029] In particular, the values ​​are determined at a defined point in time and / or within a defined period of time. Preferably, the electrical power and the relative power value are determined at the same point in time, in particular within a defined period of time. In particular, the period of time is less than 10 s, preferably less than 1 s. In particular, the electrical power and the relative power value are determined simultaneously.

[0030] Optionally, one or more of the process steps are repeated. The repetition can be time-controlled or event-driven.

[0031] In particular, this makes it possible to react to changes in the cooling and / or heating generator.

[0032] An advantageous refinement is characterized by the use of a low-pass filter to determine the proportionality factor. In particular, the low-pass filter makes the determination of the proportionality factor more robust.

[0033] According to a further development of the invention, the method comprises the method steps listed below.

[0034] In a process step, the relative performance value is also determined depending on the determined proportionality factor.

[0035] According to a further development of the invention, the maximum relative power value is determined using the following formula: Prel_max=Pel_max(X∗(TSink−TQuel))

[0036] Preferably, in heating mode, the ambient temperature T Quel and the flow setpoint temperature T Senke . In cooling mode, the ambient temperature T Senkeand the flow setpoint temperature T Quel .

[0037] According to a further development of the invention, the maximum relative power value is determined using the following formula: Prel_max=Pel_maxY

[0038] Furthermore, the invention relates to a computer program which is configured to carry out all steps of the method.

[0039] Furthermore, the invention relates to a machine-readable storage medium on which the computer program is stored.

[0040] Furthermore, the invention relates to a control unit which is configured to carry out all steps of the method.

[0041] Exemplary embodiments are illustrated in the figures and explained in more detail in the following description. They show: Fig. 1 the schematic structure of an HVAC system and Fig. 2 the procedure of the procedure.

[0042] In Fig. 1 shows an HVAC system 1 with a heat and / or cold generator 10. The HVAC system 1 or the heat and / or cold generator 10 is colloquially referred to as an air conditioning system or heat pump.

[0043] The HVAC system 1 has a heat and / or cold generator 10. The heat and / or cold generator 10 has a refrigerant circuit 20. The refrigerant circuit 20 comprises at least one compressor 22, an expansion valve 34, and two heat exchangers 26a, 26b, in particular a first heat exchanger 26a and a second heat exchanger 26b. The compressor 22, the expansion valve 24, and the two heat exchangers 26a, 26b are connected via refrigerant lines such that a refrigerant can circulate in the refrigerant circuit 20. Furthermore, a switching valve 28 is provided. The switching valve 28 is designed, for example, as a four-way valve.

[0044] The refrigerant is in particular propane (R290), CO2 (R744) or a blend.

[0045] Preferably, the compressor 22 operates as a compressor. The compressor 22 compresses the refrigerant, in particular using electrical energy. The compressor 22 is advantageously controlled by an inverter 80. The inverter 80 is designed and configured to control the compressor 22.

[0046] The inverter 80 is in particular part of a control unit 90. The control unit 90 is in particular part of the heat and / or cold generator 10.

[0047] In particular, the compressor 22 comprises an electric motor, which is preferably designed as a brushless, electrically commutated electric motor. The inverter 80 has at least one, preferably six, electrical switching elements, which are connected in particular to form a 6H-bridge. The switching elements energize the phases, in particular three phases, of the compressor 22 in such a way that the compressor executes a rotary movement. The rotary movement results in the compression of the refrigerant by means of a compressor unit, in particular a scroll compressor.

[0048] The switching valve 28 allows the refrigerant compressed by the compressor 22 to be fed either first to the first heat exchanger 26a or to the second heat exchanger 26b. The flow directions are indicated by the curved arrows.

[0049] In a first switching position of the switching valve 28, indicated by the dashed arrows, the refrigerant is supplied from the first heat exchanger 26a to the compressor 22. The refrigerant compressed by the compressor 22 is supplied to the second heat exchanger 26b. In the first switching position, heat is absorbed at the first heat exchanger 26a, resulting in cooling. In contrast, heat is released at the second heat exchanger 26b. In particular, this can also be referred to as heating operation.

[0050] In a second switching position of the switching valve 28, indicated by the solid arrows, the refrigerant is supplied from the second heat exchanger 26b to the compressor 22. The refrigerant compressed by the compressor 22 is supplied to the first heat exchanger 26a. In the first switching position, heat is absorbed at the second heat exchanger 26b, resulting in cooling. In contrast, heat is released at the first heat exchanger 26a. This can also be referred to as cooling mode.

[0051] Depending on the direction of refrigerant flow, the heat exchanger downstream of compressor 22 acts as a condenser / condenser. The refrigerant is liquefied in the condenser. The condensation of the refrigerant leads to heat release by the refrigerant. This heat release, in turn, leads to heating of the heat exchanger.

[0052] Furthermore, the expansion valve 24 is located downstream of the heat exchanger, which acts as a condenser. The expansion valve 24 expands the refrigerant. Expansion here means the decompression of the refrigerant.

[0053] The expanded refrigerant is then fed to the second heat exchanger. The second heat exchanger acts as an evaporator. In the evaporator, the refrigerant evaporates, absorbing heat energy. The evaporated refrigerant is then fed to the compressor 22 for compression. This leads, in particular, to a cooling of the heat exchanger.

[0054] Preferably, depending on the switching position, heat or cold is provided at the second heat exchanger 26b. The heat exchanger 26b transfers the heat / cold to another medium. The other medium can be a gas, in particular air, or a liquid.

[0055] In particular, in air-to-air air conditioning systems, the additional medium is air. In heat pumps (air-to-water or water-to-water), the additional medium is usually a liquid, especially water.

[0056] Preferably, the first heat exchanger 26a is arranged such that it can absorb heat from an ambient medium (air, liquid) outside the building or release heat to the ambient medium.

[0057] In particular, in an air-conditioning system or an air-to-water heat pump, heat is transferred to or absorbed by the air, particularly the ambient air of the building, in the first heat exchanger 26a. If the ambient temperature is determined, this is the temperature of the ambient air before it is processed by the heat pump.

[0058] In particular, in a water-to-water heat pump or a water-to-air heat pump, heat is transferred to or absorbed by a liquid, in particular water, in the first heat exchanger 26a. If the ambient medium is water, the heat is extracted from the ground, in particular by means of the medium, and supplied to the heat exchanger. Heat can also be supplied to the ground. The liquid can also be in the form of brine. These are brine-to-air or brine-to-water heat pumps. Water-to-air or water-to-water heat pumps are colloquial terms. It is clear to the person skilled in the art that this also includes systems with liquids other than water, in particular brine.

[0059] In Fig. 1, a fluid circuit 30 is formed, for example, on the second heat exchanger 26b. The second heat exchanger 26b serves to transfer heat between the heat and / or cold generator 10 and the fluid circuit 30.

[0060] A liquid, in particular water, circulates in the fluid circuit 30. The liquid is preferably heated or cooled by the second heat exchanger 26b. At least one pump 32 is formed in the fluid circuit 30. Furthermore, two thermal consumers 34a, 34b are formed, for example. The thermal consumers 34a, 34b are each formed on a line 35a, 35b, which runs parallel to the second heat exchanger 26b.

[0061] The flow through each strand 35a, 35b is regulated by means of at least one valve 36a, 36b.

[0062] The thermal consumers 34a, 34b can, in particular, be a hot water tank, a radiator, an underfloor heating system, or the like. The thermal consumers 34a, 34b act like a heat exchanger. The thermal consumers 34a, 34b extract heat from the fluid or heat the fluid of the fluid circuit 30.

[0063] Preferably, the refrigerant circuit 20 or parts of the refrigerant circuit 20 are installed outside the building. In particular, the first heat exchanger 26a, the compressor 22 in an air conditioning system, but also in heat pumps, is installed outside the building in an outdoor unit (ODU). Heat pump systems also have an outdoor unit. In this case, the outdoor units usually contain the refrigerant circuit.

[0064] In Fig. 2, the method 100 according to the invention is shown. To control the cooling and / or heating generator 10 of an HVAC system 1 with a refrigerant circuit 20, the relative power value P rel used. The relative power value P rel is given in particular as a percentage value, or as a value relative to a maximum possible performance.

[0065] In a method step 110, the maximum electrical power P el_maxThis is the maximum power that can be made available to the cooling and / or heating generator 10 and / or the HVAC system 1, in particular to the compressor 22. In particular, the largest consumer in a cooling and / or heating generator 10 with a refrigerant circuit 20 is the compressor 22, as long as the cooling and / or heating generator 10 does not have any additional resistance-based heat generators, in particular PTC.

[0066] Determining 110 the maximum electrical power P el_max is carried out by receiving, retrieving, reading and / or measuring. In particular, the determination comprises the evaluation of a control signal, preferably the extraction of P el_max from the control signal. The maximum electrical power P el_maxcorresponds in particular to the maximum available electrical power. The maximum electrical power is provided in particular by an energy management system, a PV system, the grid operator or an electrical consumer, preferably a wallbox and / or a smart household appliance and / or a smart home component. The maximum available electrical power can in particular be provided by an energy management system or dependent on an electricity price. The maximum available electrical power can in particular depend on the electrical energy currently generated by a PV system or on the electricity price.

[0067] The maximum available electrical power can be provided by a grid operator, depending on the condition of the power grid.

[0068] The control unit 90 has a communication interface that enables receiving, retrieving, or reading. The communication interface enables, in particular, communication with a PV system (photovoltaic system), preferably an inverter, a PV system, or an energy management system, or the power grid operator, or with a consumer, or with a system and / or device and / or server and / or interface that can provide electricity prices. Communication is particularly wired, in particular via a bus system, EEBus, Modbus, Powerline, M-Bus, Ethernet, EIB, CAN, KNX, EMS, OpenTherm, or wirelessly, preferably Bluetooth, NFC, RFID, ANT+, Dash7, GPRS, EDGE, UMTS, 5G, LTE, WIMAX, Zigbee, Thread, Matter, Z-Wave, 868 MHz, or WIFI.

[0069] In a further method step 125, the maximum relative power value P is determined rel_maxThe compressor is controlled by a relative power value P rel controlled. In particular, the value is between 0 and 1 or 0% and 100%. However, the compressor can also be operated at partial load, particularly at 20%, 50%, or 75%, etc.

[0070] In a further method step 130, the determined maximum relative power value P rel_max In particular, providing comprises transmitting or making available, in particular making available, a control signal, in particular the determined maximum relative power value. In particular, the value is provided in such a way that the heat and / or cold generator can be and / or is controlled thereby.

[0071] The compressor 22 is controlled in such a way that it reaches the maximum relative power value P rel_max If the maximum relative power value P rel_maxFor example, at 50%, the compressor is only controlled at a maximum of 50%. The compressor 22 thus operates at 50% of its maximum possible power. Accordingly, the maximum relative power value P provided in process step 130 rel_max to a limitation 140 of the cooling and / or heating generator 10.

[0072] In a further optional method step 115, the ambient temperature is determined. The ambient temperature is detected, in particular measured, by a temperature sensor or retrieved from a system, in particular from a database. If the ambient temperature is determined, this is the temperature of the ambient air before it is processed by the heat pump.

[0073] In a further optional method step 120, the flow temperature in fluid circuit 30 is determined. The determination includes reading, receiving, but also measuring and / or calculating. Preferably, the flow target temperature is provided. During the determination, the provided flow target temperature is retrieved.

[0074] The flow temperature is measured by a temperature sensor 38. The temperature sensor 38 is arranged downstream of the first heat exchanger 26a in the fluid direction.

[0075] Preferably, the maximum relative power value P is determined rel_max depending on the measured ambient temperature and / or the flow setpoint temperature.

[0076] In heating mode, the ambient temperature corresponds to the source temperature T Quel and the flow setpoint temperature of the sink temperature T Senke and in cooling mode the ambient temperature corresponds to the sink temperature T Senkeand the flow setpoint temperature of the source temperature T Quel . In particular, the determination is carried out using the following formula. Prel_max=Pel_max(X∗(TSink=TQuel))

[0077] X is the proportionality factor, which will be explained in more detail below.

[0078] The previous formula is based on the formula below, which describes the electrical power consumption in the compressor 22. Pel=dmdtref∗cpref∗(Thp−Tlp) P el corresponds to the electrical power consumption. dmdtref corresponds to the mass flow in the refrigeration circuit. cp ref corresponds to the specific heat capacity of the refrigerant. T hp corresponds to the high pressure temperature, which corresponds to the sink temperature T Senke corresponds. T Ip corresponds to the low pressure temperature, which corresponds to the source temperature T Quelcorresponds.

[0079] In heating mode, the ambient temperature T Quel and the flow setpoint temperature T Senke and in cooling mode the ambient temperature T Senke and the flow setpoint temperature T Quel .

[0080] The following simplifications can be made. dmdtref*cpref can be replaced by P rel This is possible because dmdtref proportional to the speed n rel is. n rel is proportional to P rel . cp ref is constant. This results in the following simplification. Pel≈Pref∗(TSink−TSource)

[0081] Added to this by a proportionality factor X, we get Pel=X∗Pref∗(TSink−TQuel)

[0082] This gives the formula for determining the relative electrical power value P rel : Prel=Pel(X∗(TSink−TQuel))

[0083] And according to the maximum relative electrical power value P rel_max : Prel_max=Pel_max(X∗(TSink−TQuel))

[0084] The proportionality factor X is determined as follows: X=Pel(PRel∗(TSink−TQuel))

[0085] To determine the proportionality factor X, P el and P rel The value is determined by reading, querying, or measuring it. Preferably, the ambient temperature and / or the flow temperature are measured.

[0086] The proportionality factor X is determined at regular intervals or at defined events. Once the proportionality factor X is determined, it is stored in a machine-readable memory. From there, it can be retrieved and used to determine the maximum relative power P rel_max be used.

[0087] To improve the accuracy of the proportionality factor X, it can optionally be made more robust against errors using a low-pass filter.

[0088] The following formula results Xnew=Pel(Pel∗(TSink−TQuel))−XoldFilterconst∗Xold

[0089] X alt represents the last determined proportionality factor. X neu is the proportionality factor that is used until a new proportionality factor is determined. In the next calculation, X neu to X alt .

[0090] A further development of the invention is based on the simplification described above: Pel≈Pref∗(TSink−TSource)

[0091] It is assumed that the T Senke - T Quel are also constant. This results in the addition of a proportionality factor Y: Pel=Y∗Pref

[0092] This gives the formula for determining the relative electrical power value P rel : Pref=PelY

[0093] And according to the maximum relative electrical power value P rel_max : Prel_max=Pel_maxY

[0094] The proportionality factor Y is determined as follows: Y=PelPRel

[0095] To determine the proportionality factor Y, P el and P rel The determination is carried out by reading, querying, or measuring the values.

[0096] The proportionality factor Y is determined at regular intervals or at defined events. Once the proportionality factor Y is determined, it is stored in a machine-readable memory. From there, it can be retrieved and used to determine the maximum relative power P rel_max be used.

[0097] To improve the accuracy of the proportionality factor Y, it can optionally be made more robust against errors using a low-pass filter.

[0098] The following formula results Ynew=PelPRel−YaltFilterconst∗Yalt

[0099] Y alt represents the last determined proportionality factor. Y neu is the proportionality factor that is used until a new proportionality factor is determined. In the next calculation, Y neu to Y alt .

[0100] A thermal consumer consumes heat or cold.

Claims

[1] Method (100) for operating a heat and / or cold generator (10) of an HVAC system (1), in particular for a building, wherein the heat and / or cold generator (10) has at least one refrigerant circuit (20) with at least one compressor (22), and wherein the compressor (22) is controlled as a function of a relative power value (P rel ), and wherein the method (100) comprises the steps: • Determine (110) a maximum electrical power (P el_max ), • Determining (125) a maximum relative power value (P rel_max ), depending on the determined maximum electrical power (P el_max ), • Providing (130) the determined maximum relative power value (P rel_max ). [2] Method (100) according to the preceding claim, characterized by the steps: • Limiting (140) the control of the heat and / or cold generator (10) to the maximum relative power value provided (P rel_max ). [3] Method (100) according to one of the preceding claims, characterized by the steps: • Determine (115) the ambient temperature, • Determine (120) the flow target temperature, • Determine (125) the maximum relative power value (P rel_max ) additionally depending on the determined ambient temperature and the determined flow target temperature. [4] Method (100) according to one of the preceding claims, characterized by the steps: • Determine (210) the electrical power (P el ), • Determine (220) the relative power value (P rel ), • Determine (230) the ambient temperature and the flow temperature, • Determining (240) the proportionality factor (X) depending on the determined electrical power (P el ), the determined relative performance value (P rel ), and the ambient temperature, and / or the flow temperature. [5] Method (100) according to one of the preceding claims, characterized by the steps: • Determine (210) the electrical power (P el ), • Determine (220) the relative power value (P rel ), • Determination (240) of the proportionality factor (Y) depending on the determined electrical power (P el ), the determined relative performance value (P rel ). [6] Method (100) according to the preceding claim, characterized by that a low-pass filter is used to determine the proportionality factor (X, Y). [7] Method (100) according to one of the preceding claims, characterized by the steps: • Determining (15) the maximum relative power value additionally depending on the determined proportionality factor (X, Y). [8] Method according to one of the preceding claims, characterized by that determining the maximum relative power value (P rel_max ) is done using the formula • Prel_max=Pel_max(X∗(TSink−TQuel)), where in heating mode the ambient temperature T Quel and the flow setpoint temperature T Senke and where in cooling mode the ambient temperature T Senke and the flow setpoint temperature T Quel corresponds; or • Prel_max=Pel_maxY. [9] Computer program which is arranged to carry out all steps of the method (100) according to one of the preceding claims. [10] A machine-readable storage medium on which the computer program according to the preceding claim is stored. [11] Control unit configured to carry out all steps of the method (100) according to any one of claims 1 to 8.

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