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NL2035048B1 - System and method of controlling a hot water energy storage system - Google Patents

System and method of controlling a hot water energy storage system Download PDF

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Publication number
NL2035048B1
NL2035048B1 NL2035048A NL2035048A NL2035048B1 NL 2035048 B1 NL2035048 B1 NL 2035048B1 NL 2035048 A NL2035048 A NL 2035048A NL 2035048 A NL2035048 A NL 2035048A NL 2035048 B1 NL2035048 B1 NL 2035048B1
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NL
Netherlands
Prior art keywords
electrical
current
output
power
electrical circuit
Prior art date
Application number
NL2035048A
Other languages
Dutch (nl)
Inventor
Mohana Martin
Bodis Pavol
Van Vliet Laurens
Original Assignee
Newton Energy Solutions Holding B V
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Publication date
Application filed by Newton Energy Solutions Holding B V filed Critical Newton Energy Solutions Holding B V
Priority to NL2035048A priority Critical patent/NL2035048B1/en
Priority to PCT/EP2024/065758 priority patent/WO2024251959A1/en
Application granted granted Critical
Publication of NL2035048B1 publication Critical patent/NL2035048B1/en

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
    • F24H9/00—Details
    • F24H9/20—Arrangement or mounting of control or safety devices
    • F24H9/2007—Arrangement or mounting of control or safety devices for water heaters
    • F24H9/2014—Arrangement or mounting of control or safety devices for water heaters using electrical energy supply
    • F24H9/2021—Storage heaters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
    • H02H3/08—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for AC mains or AC distribution networks
    • H02J3/12—Circuit arrangements for AC mains or AC distribution networks for adjusting voltage in AC networks by changing a characteristic of the network load
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B1/00—Details of electric heating devices
    • H05B1/02—Automatic switching arrangements specially adapted to apparatus ; Control of heating devices
    • H05B1/0227—Applications
    • H05B1/0252—Domestic applications
    • H05B1/0275—Heating of spaces, e.g. rooms, wardrobes
    • H05B1/0283—For heating of fluids, e.g. water heaters
    • H02J2105/52—
    • H02J2105/53—

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Heat-Pump Type And Storage Water Heaters (AREA)
  • Supply And Distribution Of Alternating Current (AREA)

Abstract

Method of controlling a hot water energy storage system comprising an electrical heater for heating a volume of water, wherein the method comprises the steps of: - providing an electrical system comprising an electrical circuit and at least one load device, the electrical circuit being connected to an external electrical network such as a mains and to the at least one load device, wherein the electrical circuit comprises a main power input/output for connection to the external electrical network and a first power output for powering the at least one load device, and wherein the electrical circuit is provided with an overcurrent protection device, such as a circuit breaker, arranged between the power input/output and the first power output, wherein the overcurrent protection device is arranged to interrupt the current flowing though it when said current exceeds a predefined maximum current threshold; - providing the electrical heater in parallel to the at least one load device on the first power output; - monitoring the current at the first power output of the electrical circuit; - determining, based on the monitored output current and the predefined maximum current threshold, an unused current amount representative for an amount of current still allowable at the first power output without exceeding the predefined maximum current threshold; and - controlling the electrical heater on the basis of the determined unused current amount. An associated control system and a method of installing a hot water energy storage system in an existing system are also described.

Description

System and method of controlling a hot water energy storage system
The present invention relates to a method of controlling a hot water energy storage system comprising an electrical heater for heating a volume of water. The present invention further relates toa system for controlling such a hot water energy storage system.
The energy sector is turning towards renewable energy sources to support the energy transition from fossil-fuel to carbon-free energy solutions. Renewable energy sources such as solar, wind and hydro-powered sources are typically fluctuating energy sources. The irregular energy production of renewable energy sources brings with it the issue of managing the balance between the supply and the demand at the local level and at the network level.
A well-known challenge in the field is thus, in times of overprodaction, the prolonged energy storage of the produced energy with a minimal energy loss. Among the storage options, electrical battery systems such as lithium-ion battery energy storage systems, and power conversion into chemicals (Power-to-X) or into heat (Power-to-Heat) are being investigated. Storage options based on conversion to heat use typically sensible heat storage, wherein heat is stored in a fluid contained in a reservoir. In sensible heat storage, heat is stored in a medium using the intrinsic heat capacity (Cp) of the medium. In contrast to latent heat storage and thermochemical storage, the medium in sensible heat storage typically does not undergo a chemical and/or phase change. Sensible heat storage has the advantage over thermochemical heat storage and latent heat storage that it allows for relatively simple systems as no multiphase physics, complex kinetics etc. are involved. One method for storing sensible heat is in the form of hot water tanks.
In such a hot water energy storage system, the water in the tank may be heated by an electrical heater and the energy can be stored for multiple days, typically up to five days in domestic hot water tanks. This enables the water to be heated whenever the real-time electricity prices are low due to, e.g.. a renewable power generation surplus, such that the stored hot water can be cheaply consumed irrespective of the electricity prices.
The power use of such an electrical heater is considerable in comparison with domestic appliances.
Therefore, when employed domestically, the electrical heater for heating the stored water is conventionally connected to a dedicated electrical circuit of a distribution board, i.e., an electrical group to which only the electrical heater is connected, wherein an electrical group is defined as the (domestic) electrical subsystem that is arranged after a circuit breaker protecting that electrical group. That is, an electrician would consider it self-evident to dedicate an electrical circuit entirely to the electrical heater to prevent that a simultaneous activation of both the electrical heater and another device would cause the respective circuit breaker to trip. Therefore, an additional electrical group is typically to be added when retrofitting such a hot water energy storage system in an existing system, but this may not always be possible in practice nor desirable in terms of costs.
This raises the threshold for adopting hot water energy storage systems domestically in terms of costs and/or technical feasibility.
It is therefore an object of the present invention, amongst other objects, to at least alleviate the aforesaid drawbacks of conventional hot water energy storage systems, in particular to facilitate the installation and control of such a hot water energy storage system in existing systems.
To that end, a method of controlling a hot water energy storage system comprising an electrical heater for heating a volume of water, is provided, wherein the method comprises the steps of: - providing an electrical system comprising an electrical circuit and at least one load device, the electrical circuit being connected to an external electrical network such as a mains and to the at least one load device, wherein the electrical circuit comprises a main power input/output for connection to the external electrical network and a first power output for powering the at least one load device, and wherein the electrical circuit is provided with an overcurrent protection device, such as a circuit breaker, arranged between the power input/output and the first power output, wherein the overcurrent protection device is arranged to interrupt the current flowing though it when said current exceeds a predefined maximum current threshold; - providing the electrical heater in parallel to the at least one load device on the first power output; - monitoring the current at the first power output of the electrical circuit; - determining, based on the monitored output current and the predefined maximum current threshold. an unused current amount representative for an amount of current still allowable at the first power output without exceeding the predefined maximum current threshold; and - controlling the electrical heater on the basis of the determined unused current amount.
By controlling the electrical heater based on an amount of current available on an existing power output without triggering the circuit breaker, the electrical heater can be connected to a non- dedicated electrical group, i.e. to an already existing electrical group powering an existing load device, such that an additional electrical group does not have to be added necessarily when installing the hot water energy storage system. An electrical group is defined as a sub circuit with a dedicated circuit breaker for protecting any load of said sub circuit located downstream of said circuit breaker. Consequently, the installation of such a hot water energy storage system can be facilitated.
As mentioned above, the hot water energy storage system may comprise a water tank, wherein the electrical heater is arranged to heat a volume of water in the water tank. The electrical heater may typically comprise an electrical heating resistance. The at least one load (device) of the electrical system may be any electrical power consuming device, such as for example a washing machine, an oven, a dishwasher, etc.
The electrical system may receive AC power from the main power input/output. The main power input/output may be connected to the grid or to another AC source. The power consumption at the main power input/output may vary over time in dependence of the power use of the devices (whether load devices or source devices) connected to the electrical circuit. As mentioned above, the electrical system may typically be divided into a plurality of electrical subsystems, also called groups. Each group may be provided with a dedicated circuit breaker and may be associated with at least one device. The electrical system comprises at least one load device powered from one power output of the electrical circuit. As discussed previously, when retrofitting the hot water energy storage system into an existing electrical system, the water boiler may be connected to an existing group powering an existing load. In such a case, the electrical heater may be connected directly in parallel with the existing load at the power output associated with said load. Similarly, when designing a new (domestic) electrical system, at least one load and the electrical heater may be connected in parallel on the power output of a single group, both load and electrical heater being associated with a single circuit breaker. A skilled person may further envisage placing further loads in parallel on that group.
The real time electrical current within the electrical group holding the hot water energy storage system may then be monitored. More specifically, according to a preferred embodiment of the method, the real time current within the electrical group comprising the electrical heater may be sensed by a sensor, preferably a current clamp, installed around a cable of the electrical circuit in the vicinity of the circuit breaker of the group. In this manner, the current measurement can advantageously take place at the electrical cabinet, i.e, close to the distribution board where the circuit breaker is installed. When talking about the current at the power output powering the parallel loads, one will realize that said current is basically the current flowing through the circuit breaker associated with these loads, so monitoring the current at the power output amounts to monitoring the operational status of the overcurrent protection device.
It is noted that, instead of a direct sensing, the current at the power output may be calculated, estimated or extrapolated, for instance based on the current in the electrical heater and the current in the at least one load. A skilled person can envisage different solutions for monitoring the current flowing through the overcurrent protection devices without inventive step, by varying the type, number and locations of the sensors within the system.
Once monitored, the actual electrical current is compared to the maximum (or nominal) current that may flow through the circuit breaker, to determine an unused current amount of the group associated with that circuit breaker. The electrical heater can then be controlled to use no more than the unused current amount for heating the water. In this way, the operation of the electrical heater may be transparent for the other loads on the same power output, since the electrical heater under normal operation would not trigger the protection device.
The predefined maximum current threshold may be defined such that a nominal current of the circuit breaker can be briefly exceeded, i.e, for a period of up to 30 seconds. That is, the overcurrent protection device may be a time-delay circuit breaker which allows a certain period and amount of overcurrent before it interrupts the current therethrough. By adapting the sampling time of the monitoring and the dynamic of the determining and controlling steps, to the time/current behavior of the overcurrent protection device, it can be made sure that under normal operation, the protection device is not triggered by the operation of the electrical heater.
For example, the circuit breaker may be a thermal magnetic circuit breaker. Specifically, the circuit breaker has tripping characteristic B. Such circuit breakers are commonly used in socket outlets and lighting circuits. For example, the circuit breaker trips about instantaneously when the current is approximately 3 to 5 times the rated current. In addition, the circuit breaker trips once the current is about 1.5 times the rated current for an uninterrupted period of between 1 and 10 minutes.
Furthermore, the circuit breaker does not trip while the current is up to about 1.13 times the rated current.
Thermal energy storage can be used for balancing local energy supply and demand, in particular for peak shaving of typically intermittent renewable power generators such as photovoltaic panels.
The water in the tank may then be heated whenever an on-site renewable power generation system generates a surplus of electrical power, and optionally depending on the actual energy pricing.
Specifically, according to a further preferred embodiment, the method further comprises the steps of:
- providing an on-site electrical power generation system for generating electrical power, such as a photovoltaic system comprising at least one solar panel and a power converter (inverter for converting De power into Ac power), wherein the electrical circuit further comprises an additional power input for connection to the on-site electrical power generation system and 5 wherein the electrical circuit is further configured for supplying the generated electrical power from the additional power input to the main power input/output and/or to the first power output, preferably through an additional overcurrent protection device; - monitoring the electrical power at the main power input/output; - adapting the control of the electrical heater on the basis of the monitored electrical power at the main power input/output.
In other words, the local energy system (comprising the electrical system, the hot water energy storage system and the on-site electrical power generation system) may be connected to a public energy grid for taking electrical energy from, and supplying electrical energy to, said public energy grid. When electrical power can be supplied to the public grid due to a surplus of generated renewable power, the electrical heater is preferably controlled to use no more than the surplus amount of the electrical power for heating the water. This way, it can be ensured that the hot water energy storage system functions as a local preferred buffer for the on-site power generator by only using power when there is a surplus of power generated locally, instead of being a load for which poweris to be taken from the public grid.
The hot water energy storage system can be optionally used in combination with an electrical battery storage system connected to the electrical system. As such, according to a further embodiment, the method further comprises the steps of: - providing an electrical battery storage system for storing electrical energy, wherein the electrical battery storage system is connected to the electrical system in parallel to the electrical heater; - controlling the electrical battery storage system on the basis of the determined unused current amount, and optionally on the basis of any one or more of the monitored electrical power at the main power input/output, the state of charge of the hot water energy storage system, the state of charge of the electrical battery storage system.
When controlling the electrical battery storage system, its charge or discharge rate is controlled, preferably also on the basis of a state of charge of the electrical battery storage system. Optionally, the state of charge of the hot water energy storage system may also be taken into account for the control of the electrical battery storage system. The state of charge of the electrical battery storage system may for example be controlled according to weighted priorities between the available current, and the states of charge of both the hot water energy storage system and the electrical battery energy storage system, The electrical battery storage system may be connected to the same electrical circuit as the hot water energy storage system or to another electrical circuit of the electrical system. The electrical battery storage system may comprise, e.2., a lithium-ion battery home energy storage system.
It is then preferred if the controller is configured to control the electrical battery storage system and the electrical heater such that the electrical battery storage system is fully charged before powering the electrical heater or, alternatively, such that the power use of the electrical heater reaches its maximum before charging the electrical battery storage system. Alternatively, the same method of control may be applied to an electrical battery storage system used on its own and connected in the same way as the hot water energy storage system into an existing system, in which case when electrical power can be supplied to the public grid due to a surplus of generated renewable power, the electrical battery storage system is preferably controlled to use no more than the surplus amount of the electrical power for storing energy. More generally, the same method of power control of an auxiliary energy storage system connected in parallel to an existing load in an existing electrical system may be used as long as the same concept of an intelligent control to store energy into the auxiliary energy storage up to an amount allowed by the circuit breaker associated to that load, is concerned. Any type of energy storage system may benefit from that control method for retrofit purposes.
According to an embodiment, monitoring the electrical power at the main power input/output comprises: - sensing in real time the current lo flowing at the main power input/output with a current sensor, preferably with a clamp, and - determining a surplus amount of electrical current Is according to the following equations: when I; (t) > 0, L (t)= 0 and when I(t) <0, L(t) =~ Is(t), wherein I(t) denotes the current at the main power input/output and L(t) denotes the surplus amount of electrical current at an instant t.
Thatis, Ip is positive when the current at the main power input/output flows from the external electrical network to the electrical system, i.e. when the external electrical network operates as a source delivering power to the electrical system. In comparison, To is negative when the current at the main power input/output flows towards the external electrical network, i.e. when the electrical system operates as a source delivering power to the external electrical network.
In this way, the flow of power at the main power input/output can be easily monitored. Yet the flow of power could also be deduced, calculated, extrapolated from other sensed variables within the system, like for instance the current in each group of the electrical circuit.
According to another embodiments, adapting the control of the electrical heater on the basis of the monitored electrical power at the main power input/output comprises determining a target current for the electrical heater I; according to the following equations: when kk (0)=0 or L(t)» LO ht + D) = [,(t) + L(t) when OL (OK L(t), [,(¢ +1) =O) +10) wherein I (t) denotes the target current for the electrical heater at a control instant t in time, 1 (t+1) denotes the target current through the electrical heater at the next control instant (t+1) in time, I (t) denotes the surplus amount of current at a control instant t and 1, (1) denotes the unused current amount at an instant t.
In this way, the target current for the electrical heater can be easily set to fulfill the protection requirement of the group holding it and make the best use of the energy regenerated by the on-site electrical power generation system. In this way, the adoption of both domestic renewable energy sources and hot water energy storage can be facilitated while optimizing the benefits of both. It is further noted that extra and/or alternative control rules may influence the selection of a target current for the electrical heater. It may for instance be preferred when lo is positive (L(0)=0) to reduce the target current {,(¢ + 1) such as to reduce I9 down to zero, in order to minimize costs.
Further the target current may for instance be controlled to ensure that the current flowing through any wire of a portion of the electrical circuit associated with the circuit breaker (i.e. the group holding the hot water energy storage system and/or the electrical battery energy storage system) does not exceed the predefined maximum current threshold.
According to another aspect, the present invention also relates to a system configured for executing the method described above. Hereto, a control system for controlling a hot water energy storage system comprising an electrical heater for heating a volume of water, is provided for use in an electrical system comprising an electrical circuit and at least one load device, the electrical circuit being connected to an external electrical network such as a mains and to the at least one load device, wherein the electrical circuit comprises a main power input/output for connection to the external electrical network and a first power output for powering the at least one load device, and wherein the electrical circuit is provided with an overcurrent protection device, such as a circuit breaker, arranged between the power-input/output and the first power output, wherein the overcurrent protection device is arranged to interrupt the current flowing though it when said current exceeds a predefined maximum current threshold, wherein the electrical heater is connected in parallel to the at least one load device on the first power output; wherein the control system comprises: - a first monitoring device for monitoring the current at the first power output of the electrical circuit; - a processor configured for receiving the monitored output current and the predefined maximum current threshold, and for determining based thereon an unused current amount representative for an amount of current still allowable at the first power output without exceeding the predefined maximum current threshold; - a controller in communication with the processor and configured for controlling the electrical heater on the basis of the determined unused current amount.
This allows to integrate the hot water energy storage system into an existing local electricity distribution system having a plurality of occupied electrical groups, wherein each group is defined by its own circuit breaker, without the need to add an additional group, and thus an additional circuit breaker, as the system ensures that the current passing through the respective circuit breaker, to which the hot water storage system is connected, does not exceed the maximum allowable current.
According to a preferred embodiment of the system, the first monitoring device is a current sensor, preferably a clamp, for sensing the current at the first power output flowing through the overcurrent protection device. In this way, the current may be easily monitored. Alternatively, the current may be obtained indirectly from other measured, estimated, extrapolated data from the system.
According to a preferred embodiment, the processor comprises a comparator for comparing the current sensed at the first power output with the predefined maximum current threshold. Via a comparator, the unused current amount may easily be determined.
According to a preferred embodiment, the controller is configured for regulating the current to the electrical heater to remain under the determined unused current amount, preferably the controller is configured for setting a target current of the electrical heater based on the determined unused current amount. In this way, the addition of the electrical heater may remain transparent to the rest of the system.
According to a preferred embodiment, the electrical system further comprises an on-site electrical power generation system for generating electrical power, such as a photovoltaic system comprising solar panels,
- wherein the electrical circuit further comprises an additional power input for connection to the on-site electrical power generation system and wherein the electrical circuit is further configured for supplying the generated electrical power from the additional power input to the main power input/output and/or to the first power output: - wherein the control system further comprises a second monitoring device for monitoring the electrical power supplied at the main power input/output; - wherein the processor is further configured for adapting the control of the electrical heater on the basis of the monitored electrical power at the main power input/output.
This allows to optimize the energy management within the local energy system. The electrical heater may be indeed preferably controlled to use no more than the surplus amount of the electrical power for heating the water. This way, it can be ensured that the hot water energy storage system functions as a local preferred buffer for the on-site power generator by only using power when there is a surplus of power generated locally, instead of being a load for which power is to be taken from the public grid. The power consumption from the external network and thus the associated costs can thus be mitigated.
According to another aspect of the invention, a method of installing a hot water energy storage system comprising an electrical heater (10) for heating a volume of water in an existing electrical system is provided. The existing electrical system comprises an existing electrical circuit and at least one existing load device, the existing electrical circuit being connected to an external electrical network such as a mains and to the at least one existing load device, wherein the existing electrical circuit comprises a main power input/output for connection to the external electrical network and a first power output for powering the at least one existing load device, and wherein the existing electrical circuit is provided with an existing overcurrent protection device, such as a circuit breaker, arranged between the power-input/output and the first power output, wherein the existing overcurrent protection device 1s arranged to interrupt the current flowing though it when said current exceeds a predefined maximum current threshold. The method of installing comprises the steps of: - connecting the electrical heater in parallel to the at least one existing load device on the first power output of the existing electrical circuit; - installing a control system according to any of the above control system claims.
In this way. no modification of the existing system is required and the hot water energy storage can be electrically retrofitted at low costs.
According to an embodiment, the electrical heater may be physically installed in the vicinity of the at least one load device, while the control system may be physically installed in the vicinity of the overcurrent protection device. The electrical heater is associated with a tank of water and requires typically a rather consequent amount of installation space, like an attic, a garage, a utility room, and may typically be physical arranged close to a washing machine having similar space requirements. In the installation space, the power output cables may not be easily accessible (cabling in the walls) but an easy connection to the power output may well be available (plug in the wall). The overcurrent protection device is typically located in an electrical cabinet at the entrance of the premises with cables leaving said electrical cabinet which are typically easily accessible and identifiable for each group. By installing the electrical heater in the vicinity of the load device and the control system in the electrical cabinet, a simple, practical and unintrusive installation method is offered. Wireless communication in between the electrical heater and the control system may further avoid any large cable laying on the premises.
The present invention is herein further elucidated with reference to the attached drawing. Figure 1 schematically represents an electrical system 100 comprising a first electrical circuit 101, a second electrical circuit 102 and a third electrical circuit 103. Each electrical circuit 101, 102, 103 is provided with a double pole circuit breaker 111, 112, 113 and comprises a current carrying conductor Ly, La, La that carries current from the respective circuit breaker 111, 112, 113 to electric loads connected to that circuit, and a current returning conductor Ny, Na, Nj that returns current to the circuit breaker 111, 112, 113. The circuit breakers 111, 112, 113 are connected to an AC source, for instance the public grid, via main conductors Ly and No (defining a main input/output) and a kilowatt-hour meter 104, for instance a smart meter. Each circuit breaker 111, 112, 113 interrupts the current therethrough when the current exceeds a respective predefined maximum current threshold.
A hot water energy storage system 10 that includes a water tank and an electrical (variable-power) heater for heating a volume of water in the tank is connected to the first electrical circuit 101. In addition, washing machine 11 is connected to the first electrical circuit 101. The conductors Ly and
Ny define the power output of the first electrical circuit 101, to which the hot water energy storage system 10 and the washing machine 11 are connected in parallel.
A photovoltaic system, comprising a photovoltaic module 20 and an inverter 21, is connected to the second electrical circuit 102 via the inverter 21 for supplying generated electrical power to the grid by means of the main conductors Lo and Nz. One or more other loads, schematically represented as a single load 30, are similarly connected to the third electrical circuit 103. The various loads 10, 11, 30 and the photovoltaic system 20, 21 are provided with a protective earthing
PE.
A first current sensor, typically a clamp, 1 is installed around the current carrying conductor L; of the first electrical circuit 101 and is configured to measure the current I; through the first current carrying conductor L;. A second current sensor 2, typically a clamp. is installed around the main current carrying conductor Ly and is configured to measure the current I through the main current carrying conductor Lo, 1.e., from the grid to the electrical circuits 101, 102, 103. The sensors 1, 2 are connected to a processing and control module 3 in communication with the hot water storage system 10 via a (optionally wireless) connection 4.
In case the meter 104 is a smart meter, the smart meter 104 may be connected to the processing and control module 3 and configured to measure the current I through the main current carrying conductor Ly such that the second clamp 2 can be omitted. The smart meter 104 then functions as the second current sensor.
Furthermore, instead of wireless communication, the connection 4 may use power-line communication (PLC). In this way, data may be communicated via the conductors of the electrical system 100, ie the communication may be performed over the existing electrical wires within the building in which the electrical system 100 is arranged.
The processing and control modale 3 is configured to calculate, based on the predefined maximum current of the first circuit breaker 111 and the measured current through the first current carrying conductor Li, an unused current amount representing an amount of current that still can be potentially consumed (consumable) at the first power output without exceeding the predefined maximum current threshold of the first circuit breaker 111. The unused current amount may be calculated using the following equation wherein 1, (t) denotes the unused current amount at an instant t, Ena denotes the predefined maximum current, and I; (t) denotes the current through the first current carrying conductor L; at an instant t : u(t) = Lpax — 11(8)
The processing and control module 3 is further configured to calculate, based on the measured current Io through the main current carrying conductor Lo a surplus amount of electrical current.
That is, when the photovoltaic system 20, 21 generates and supplies more current to the electrical system 100 than used by the loads 10, 11, 30, the current through the main current carrying conductor Lo would be negative. In other words, a surplus amount of electrical current may be monitored by detecting when the current Io through the main conductor flows from the electrical circuit 100 towards the external network connected to the main input/output Lo and No, i.e. in the example of a domestic installation connected to a grid, towards the grid upstream of the kilowatt- hour meter 104. When monitoring the current I(t) through the current sensor 2, the direction of the power flow between the external network and the local network may be established and be described according to the following equations: - when Iy(t) 20, L(t) = 0 and - when I(t) <0, LD) =- Int)
The current through the electrical heater may be controlled (open loop or closed loop regulation) to follow a target. The processing and control module 3 is configured to then control the target current Lof the water heater of the hot water storage energy system 10 on the basis of the surplus amount of electrical current I, and the unused current amount I, using for example the following equations, wherein 1 (©) denotes the target current for the electrical heater at a control instant t in time, | (t+1) denotes the target current through the electrical heater at the next control instant (t+1) in time, Is (t) denotes the surplus amount of current at a control instant t and kL (t) denotes the unused current amount at an instant t : - when I (= 0 or when L(t)> L(t), I,(t + 1) = [,(t) +10) - when O<I{(0O< It). I, (t + 1) = [,(t) + I(t)
The surplus amount of current I and the unused current amount I, may thus be used as thresholds for determining the maximum heating power (current) of the boiler. It is noted that the processor and the controller may be incorporated in a single element or in separate elements, which need not be collocated. The processor and/or controller may each be housed either in the vicinity of the electrical heater or in the vicinity of the protection device, depending on circumstances.
According to the previous equations, all the surplus current may be transferred to the water heater rather than the external network. Yet, based on the electricity pricing, a different strategy may be selected to rather prioritize redistribution to the external network if financially more interesting. As a further alternative, a weighted system between redistribution to the external network, and local use by the water heater may be envisaged taking into account real time electricity pricing information.
Although schematically shown separated in Figure 1, the sensors 1, 2, the processing and control module 3, the meter 104 and the circuit breakers 111, 112, 113 may be conveniently arranged in a single electrical cabinet.
Instead or in addition of a hot water energy storage system 10, an electrical battery storage system may be connected to the first electrical circuit 101 in the same way as the hot water energy storage system 10 in which case the electrical battery storage system may be as well controlled on the basis of the determined unused current amount. For instance, when electrical power can be supplied to the public grid due to a surplus of generated renewable power, the electrical battery storage system 10 may be controlled on the basis of the determined unused current amount to charge the electrical battery storage up to an amount of current still allowable at the first power output without exceeding the predefined maximum current threshold.
More generally, when more than one storage system would be available, the amount of current consumed or generated by each storage system should further be taken into account when deciding how to control each storage systems. For instance when an electrical battery system may be delivering power (to the hot water storage system), the amount of current delivered by the electrical battery system may be taken into account in the control equations of the hot water storage system, since this added current would be transparent to the first circuit breaker 111. For that purpose an additional sensor sensing the current flowing to/from the electrical battery storage system may be used. An electrical battery storage system may indeed (contrary to a hot water storage system) operate electrically in the electrical circuit 101 both as a source or as a load.
Depending on the status of the battery storage system (load or source), the control of the current through the electrical heater may thus be adapted according to other equations/control schemes as long as the concept of keeping the current flowing through the first circuit breaker 111 under its predefined maximum current nx is kept.
The electrical battery storage system and/or the hot water energy storage system 10 can be similarly installed as described above in a three-phase electrical system.
The present invention is not limited to the shown embodiment but extends also to other embodiments falling within the scope of the appended claims.

Claims (13)

CONCLUSIESCONCLUSIONS 1. Werkwijze voor het regelen van een warmwater-energieopslagsysteem dat een elektrische verwarmer voor het verwarmen van een volume water omvat, waarbij de werkwijze de stappen omvat van: - het verschaffen van een elektrisch systeem dat een elektrisch circuit en ten minste één lastinrichting omvat, waarbij het elektrische circuit is verbonden met een extern elektrisch netwerk, zoals een net, en met de ten minste ene lastinrichting, waarbij het elektrische circuit een hoofdvermogensingang/-uitgang voor verbinding met het externe elektrische netwerk en een eerste vermogensuitgang voor het voeden van de ten minste ene lastinrichting omvat, en waarbij het elektrische circuit is voorzien van een overstroombeveiligingsinrichting, zoals een stroomonderbreker, die is ingericht tussen de vermogensingang/-uitgang en de eerste vermogensuitgang, waarbij de overstroombeveiligingsinrichting is ingericht om een erdoorheen stromende stroom te onderbreken wanneer de stroom een vooraf gedefinieerde maximale stroomdrempel overschrijdt; - het op de eerste vermogensuitgang voorzien van de elektrische verwarmer parallel aan de ten minste ene lastinrichting; - het monitoren van een stroom bij de eerste vermogensuitgang van het elektrische circuit; - het op basis van de gemonitorde uitgangsstroom en de vooraf gedefinieerde maximale stroomdrempel bepalen van een hoeveelheid ongebruikte stroom die representatief is voor een hoeveelheid stroom die nog toelaatbaar is bij de eerste vermogensuitgang zonder de vooraf gedefinieerde maximale stroomdrempel te overschrijden; en - het regelen van de elektrische verwarmer op basis van de bepaalde hoeveelheid ongebruikte stroom.1. A method for controlling a hot water energy storage system comprising an electric heater for heating a volume of water, the method comprising the steps of: - providing an electrical system comprising an electrical circuit and at least one load device, the electrical circuit being connected to an external electrical network, such as a mains, and to the at least one load device, the electrical circuit comprising a main power input/output for connection to the external electrical network and a first power output for supplying the at least one load device, and the electrical circuit being provided with an overcurrent protection device, such as a circuit breaker, arranged between the power input/output and the first power output, the overcurrent protection device being arranged to interrupt a current flowing therethrough when the current exceeds a predefined maximum current threshold; - providing the electric heater in parallel with the at least one load device on the first power output; - monitoring a current at the first power output of the electrical circuit; - determining, based on the monitored output current and the predefined maximum current threshold, an amount of unused current that is representative of an amount of current that is still permissible at the first power output without exceeding the predefined maximum current threshold; and - controlling the electric heater based on the determined amount of unused current. 2. Werkwijze volgens conclusie 1, waarbij het monitoren van de stroom bij de eerste vermogensuitgang van het elektrische circuit het in real time meten van de door de overstroombeveiligingsinrichting stromende stroom met een stroomsensor, bij voorkeur met een stroomtang, omvat.2. A method according to claim 1, wherein monitoring the current at the first power output of the electrical circuit comprises measuring the current flowing through the overcurrent protection device in real time with a current sensor, preferably with a current clamp. 3. Werkwijze volgens de voorgaande conclusie, waarbij het bepalen van de hoeveelheid ongebruikte stroom het met de vooraf gedefinieerde maximale stroomdrempel vergelijken van de bij de eerste vermogensuitgang gemeten stroom omvat.3. A method according to the preceding claim, wherein determining the amount of unused current comprises comparing the current measured at the first power output with the predefined maximum current threshold. 4. Werkwijze volgens een van de bovenstaande conclusies, waarbij het op basis van de hoeveelheid ongebruikte stroom regelen van de elektrische verwarmer het regelen van de stroom naar de elektrische verwarmer om onder de bepaalde hoeveelheid ongebruikte stroom te blijven omvat, bij voorkeur door een doelstroom van de elektrische verwarmer in te stellen op basis van de bepaalde hoeveelheid ongebruikte stroom.4. A method according to any preceding claim, wherein controlling the electric heater based on the amount of unused power comprises controlling the power to the electric heater to remain below the specified amount of unused power, preferably by setting a target current of the electric heater based on the specified amount of unused power. 5. Werkwijze volgens een van de bovenstaande conclusies, verder omvattende de stappen van: - het verschaffen van een lokaal elektriciteitsopwekkingssysteem voor het opwekken van elektrisch vermogen, zoals een fotovoltaisch systeem dat ten minste één zonnepaneel en een vermogensomzetter omvat, - waarbij het elektrische circuit verder een extra vermogensingang voor verbinding met het lokale elektriciteitsopwekkingssysteem omvat en waarbij het elektrische circuit verder is ingericht voor het van de extra vermogensingang leveren van het opgewekte elektrische vermogen aan de hoofdvermogensingang/-uitgang en/of aan de eerste vermogensuitgang, bij voorkeur via een extra overstroombeveiligingsinrichting (102); - het monitoren van een elektrische stroom bij de hoofdvermogensingang/-uitgang; - het aanpassen van de regeling van de elektrische verwarmer op basis van de gemonitorde elektrische stroom bij de hoofdvermogensingang/-uitgang.5. A method according to any one of the preceding claims, further comprising the steps of: - providing a local electricity generation system for generating electrical power, such as a photovoltaic system comprising at least one solar panel and a power converter, - wherein the electrical circuit further comprises an additional power input for connection to the local electricity generation system and wherein the electrical circuit is further arranged to supply the generated electrical power from the additional power input to the main power input/output and/or to the first power output, preferably via an additional overcurrent protection device (102); - monitoring an electrical current at the main power input/output; - adjusting the control of the electric heater based on the monitored electrical current at the main power input/output. 6. Werkwijze volgens de voorgaande conclusie, verder omvattende de stappen van: - het verschaffen van een elektrisch batterijopslagsysteem voor het opslaan van elektrische energie, waarbij het elektrische batterijopslagsysteem parallel aan de elektrische verwarmer is verbonden met het elektrische systeem; - het regelen van het elektrische batterijopslagsysteem op basis van de bepaalde hoeveelheid ongebruikte stroom, en optioneel op basis van een of meer van: de gemonitorde elektrische stroom bij de hoofdvermogensingang/-uitgang, een laadtoestand van het warmwater- energieopslagsysteem, een laadtoestand van het elektrische batterijopslagsysteem, een elektrische stroom die van/naar het elektrische batterijopslagsysteem stroomt.6. A method according to the preceding claim, further comprising the steps of: - providing an electrical battery storage system for storing electrical energy, the electrical battery storage system being connected to the electrical system in parallel with the electrical heater; - controlling the electrical battery storage system based on the determined amount of unused power, and optionally based on one or more of: the monitored electrical current at the main power input/output, a state of charge of the hot water energy storage system, a state of charge of the electrical battery storage system, an electrical current flowing from/to the electrical battery storage system. 7. Regelsysteem voor het regelen van een warmwater-energieopslagsysteem dat een elektrische verwarmer voor het verwarmen van een volume water omvat, voor gebruik in een elektrisch systeem dat een elektrisch circuit en ten minste één lastinrichting omvat, waarbij het elektrische circuit is verbonden met een extern elektrisch netwerk, zoals een net, en met de ten minste ene lastinrichting, waarbij het elektrische circuit een hoofdvermogensingang/-uitgang voor verbinding met het externe elektrische netwerk en een eerste vermogensuitgang voor het voeden van de ten minste ene lastinrichting omvat, en waarbij het elektrische circuit is voorzien van een overstroombeveiligingsinrichting, zoals een stroomonderbreker, die is ingericht tussen de vermogensingang/-uitgang en de eerste vermogensuitgang, waarbij de overstroombeveiligingsinrichting is ingericht om de erdoorheen stromende stroom te onderbreken wanneer de stroom een vooraf gedefinieerde maximale stroomdrempel overschrijdt, waarbij de elektrische verwarmer parallel aan de ten minste ene lastinrichting is verbonden met de eerste vermogensuitgang; waarbij het regelsysteem omvat: ~ een eerste monitorinrichting voor het monitoren van de stroom bij de eerste vermogensuitgang van het elektrisch circuit; - een processor die is ingericht voor het ontvangen van de gemonitorde uitgangsstroom en de vooraf gedefinieerde maximale stroomdrempel, en voor het op basis daarvan bepalen van een hoeveelheid ongebruikte stroom die representatief is voor een hoeveelheid stroom die nog toelaatbaar is bij de eerste vermogensuitgang zonder de vooraf gedefinieerde maximale stroomdrempel te overschrijden; en - een regelaar die in verbinding staat met de processor en is ingericht voor het regelen van de elektrische verwarmer op basis van de bepaalde hoeveelheid ongebruikte stroom.7. A control system for controlling a hot water energy storage system comprising an electric heater for heating a volume of water, for use in an electrical system comprising an electrical circuit and at least one load device, the electrical circuit being connected to an external electrical network, such as a mains, and to the at least one load device, the electrical circuit comprising a main power input/output for connection to the external electrical network and a first power output for supplying the at least one load device, and the electrical circuit being provided with an overcurrent protection device, such as a circuit breaker, arranged between the power input/output and the first power output, the overcurrent protection device being arranged to interrupt the current flowing through it when the current exceeds a predefined maximum current threshold, the electric heater being connected to the first power output in parallel with the at least one load device; the control system comprising: ~ a first monitoring device for monitoring the current at the first power output of the electrical circuit; - a processor configured to receive the monitored output current and the predefined maximum current threshold, and to determine on the basis thereof an amount of unused current representative of an amount of current still permissible at the first power output without exceeding the predefined maximum current threshold; and - a controller connected to the processor and configured to control the electric heater on the basis of the determined amount of unused current. 8. Regelsysteem volgens de voorgaande conclusie, waarbij de eerste monitorinrichting een stroomsensor is, bij voorkeur een stroomtang, voor het meten van de stroom bij de eerste vermogensuitgang die door de overstroombeveiligingsinrichting stroomt.8. Control system according to the preceding claim, wherein the first monitoring device is a current sensor, preferably a current clamp, for measuring the current at the first power output flowing through the overcurrent protection device. 9. Regelsysteem volgens de voorgaande conclusie, waarbij de processor een comparator voor het met de vooraf gedefinieerde maximale stroomdrempel vergelijken van de bij de eerste vermogensuitgang gemeten stroom omvat.9. Control system according to the preceding claim, wherein the processor comprises a comparator for comparing the current measured at the first power output with the predefined maximum current threshold. 10. Regelsysteem volgens een van de bovenstaande regelsysteemconclusies, waarbij de regelaar is ingericht voor het regelen van de stroom naar de elektrische verwarmer om onder de bepaalde hoeveelheid ongebruikte stroom te blijven, waarbij de regelaar bij voorkeur is ingericht voor het op basis van op de bepaalde hoeveelheid ongebruikte stroom instellen van een doelstroom van de elektrische verwarmer.10. A control system according to any of the above control system claims, wherein the controller is adapted to control the current to the electric heater to remain below the specified amount of unused current, wherein the controller is preferably adapted to set a target current of the electric heater based on the specified amount of unused current. 11. Regelsysteem volgens een van de bovenstaande regelsysteemconclusies, - waarbij het elektrische systeem verder een lokaal elektriciteitsopwekkingssysteem voor het opwekken van elektrisch vermogen omvat, zoals een fotovoltaisch systeem dat zonnepanelen omvat,11. Control system according to any of the above control system claims, - wherein the electrical system further comprises a local electricity generation system for generating electrical power, such as a photovoltaic system comprising solar panels, ~ waarbij het elektrische circuit verder een extra vermogensingang voor verbinding met het lokale elektriciteitsopwekkingssysteem omvat en waarbij het elektrische circuit verder is ingericht voor het van de extra vermogensingang leveren van het opgewekte elektrische vermogen aan de hoofdvermogensingang/-uitgang en/of aan de eerste vermogensuitgang; - waarbij het besturingssysteem verder een tweede monitorinrichting omvat voor het monitoren van het elektrisch vermogen dat wordt toegevoerd aan de hoofdvermogensingang/- uitgang; - waarbij de processor verder is ingericht voor het aanpassen van de regeling van de elektrische verwarmer op basis van het gemonitorde elektrische vermogen bij de hoofdvermogensingang/-uitgang.~ wherein the electrical circuit further comprises an auxiliary power input for connection to the local electricity generation system and wherein the electrical circuit is further configured to supply the generated electrical power from the auxiliary power input to the main power input/output and/or to the first power output; - wherein the control system further comprises a second monitoring device for monitoring the electrical power supplied to the main power input/output; - wherein the processor is further configured to adjust the control of the electric heater based on the monitored electrical power at the main power input/output. 12. Werkwijze voor het in een bestaand elektrisch systeem installeren van een warmwater- energieopslagsysteem dat een elektrische verwarmer (10) voor het verwarmen van een volume water omvat, waarbij het bestaande elektrische systeem een bestaand elektrisch circuit en ten minste één bestaande lastinrichting omvat, waarbij het bestaande elektrische circuit is verbonden met een extern elektrisch netwerk, zoals een net, en met de ten minste ene bestaande lastinrichting, waarbij het bestaande elektrische circuit een hoofdvermogensingang/-uitgang voor verbinding met het externe elektrische netwerk en een eerste vermogensuitgang voor het voeden van de ten minste ene bestaande lastinrichting omvat, en waarbij het bestaande elektrische circuit is voorzien van een bestaande overstroombeveiligingsinrichting, zoals een stroomonderbreker, die is ingericht tussen de vermogensingang/-uitgang en de eerste vermogensuitgang, waarbij de overstroombeveiligingsinrichting is ingericht om de erdoorheen stromende stroom te onderbreken wanneer de stroom een vooraf gedefinieerde maximale stroomdrempel overschrijdt, waarbij de werkwijze de stappen omvat van: - het met de eerste vermogensuitgang van het bestaande elektrische circuit verbinden van de elektrische verwarmer parallel aan de ten minste ene bestaande lastinrichting; en - het installeren van een regelsysteem volgens een van de bovenstaande regelsysteemconclusies. 12. Method for installing a hot water energy storage system comprising an electric heater (10) for heating a volume of water in an existing electrical system, the existing electrical system comprising an existing electrical circuit and at least one existing load device, the existing electrical circuit being connected to an external electrical network, such as a grid, and to the at least one existing load device, the existing electrical circuit comprising a main power input/output for connection to the external electrical network and a first power output for supplying the at least one existing load device, and the existing electrical circuit being provided with an existing overcurrent protection device, such as a circuit breaker, arranged between the power input/output and the first power output, the overcurrent protection device being arranged to interrupt the current flowing through it when the current exceeds a predefined maximum current threshold, the method comprising the steps of: - connecting the electric heater to the first power output of the existing electrical circuit in parallel with the at least one existing load device; and - installing a control system according to one of the above control system claims. 13 Werkwijze volgens de voorgaande conclusie, waarbij de elektrische verwarmer fysiek in de buurt van de ten minste ene lastinrichting geïnstaleerd wordt, terwijl het regelsysteem fysiek in de buurt van de overstroombeveiligingsinrichting geïnstalleerd wordt.13. Method according to the preceding claim, wherein the electric heater is physically installed in the vicinity of the at least one load device, while the control system is physically installed in the vicinity of the overcurrent protection device.
NL2035048A 2023-06-08 2023-06-08 System and method of controlling a hot water energy storage system NL2035048B1 (en)

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DE102013109608A1 (en) * 2013-09-03 2015-03-05 Sma Solar Technology Ag Method and feed-in control for feeding electrical power into a line branch
WO2015172183A1 (en) * 2014-05-15 2015-11-19 Gng Electrical Pty Ltd Generation load control
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