WO2021137121A1

WO2021137121A1 - Dc source in electrical installation

Info

Publication number: WO2021137121A1
Application number: PCT/IB2020/062447
Authority: WO
Inventors: Ismaël BEN-AL-LAL
Original assignee: Futech Bvba
Priority date: 2019-12-30
Filing date: 2020-12-24
Publication date: 2021-07-08
Also published as: EP4085503A1; BE1028004B1; BE1028004A1

Abstract

Electrical installation comprising: • - an AC input (2) and a rectifier (6) to supply the installation; • - a connection (3) for at least one electrical consumer supplied with DC voltage; • - a DC source (7) and a DC/DC converter (8) • - cabling (5) between the components

Description

DC source in electrical installation

The invention relates to an electrical installation with a DC source.

The invention relates more specifically to an electrical installation comprising:

- an AC input, configured to feed the electrical installation with an alternating voltage;

- a connection configured for connection of at least one electrical consumer;

- cabling running from the AC input to the connection; and

- a DC source.

Such an installation is a typical form of a residential or industrial installation for providing electricity in a home, business premises or industrial site. The AC input is typically formed here by a coupling to the electrical grid. The connection for connecting at least one electrical consumer is typically formed by a socket outlet. Cabling extends between the socket outlet and the coupling to the electrical grid. This cabling typically runs via an electrical box. In a home or industrial premises the cabling typically has a plurality of parallel segments, wherein each segment runs to one or more socket outlets. The cabling typically also has segments which run to lighting points. The different segments are primarily provided in order to be able to secure the cabling with safety modules. A type of cabling and a corresponding circuit breaker is here predetermined for each user or group of users. Specific segments can further be provided to run to a specific appliance, for instance a washing machine, a heating element, a cooker, and so on. Each cabling segment is typically connected to the electrical grid via a safety module, for instance a circuit breaker. The circuit breakers are typically placed in the electrical box.

Generating energy in an environmentally-friendly manner has become considerably more important in recent years. Many homes, business premises and sites are therefore provided with a solar panel installation. Combined heat and power (CHP) installations are also available, and are placed in different sizes and with different capacities, so that CHPs can also be placed in smaller electrical installations, for instance a household installation. Wind turbines can also be placed on industrial estates or in residential areas in order to generate energy in environmentally-friendly manner. A known problem in generating energy in environmentally-friendly manner is that the energy is not always generated at the exact moment that it is used. This causes an additional load on the electrical grid. This phenomenon makes transport of electricity more critical, and the transport costs of electricity will therefore become higher. In order to reduce this problem devices are placed for collecting and storing energy locally. An example hereof is a battery installation. When the electricity production is greater than the demand, electrical energy can be stored in a battery installation. The battery further generates electric power when the electricity demand is greater than the production. In this way the battery installation forms a buffer which can reduce transmission peaks in two directions, supply and removal. As an alternative to battery installations, heat-based energy buffers can also be provided.

The majority of the above described installations for producing energy in environmentally- friendly manner and for buffering energy are DC installations. This means that such installations run primarily on direct voltage. In practice such installations are therefore coupled via an inverter to the electrical grid, directly or indirectly via the electrical installation. The inverter has a power which depends on the power of the installation coupled thereto. A solar panel installation will thus be designed with a predetermined maximum power, and an inverter will be chosen with a power which is related thereto.

It is an object of the present invention to connect a DC source more optimally to an electrical installation.

For this purpose the electrical installation according to the invention is characterized in that the electrical installation further comprises a rectifier in the cabling for rectifying the alternating voltage, wherein the rectifier has an output voltage with a voltage variation which lies between a first direct voltage DC1 and a second direct voltage DC2, and wherein the difference between DC1 and DC2 is at least 5 volt, and wherein the DC source is connected via a DC voltage regulator to the cabling between the rectifier and the connection, and wherein the DC voltage regulator regulates a DC source voltage between DC1 and DC2 in order to supply a predetermined power of the DC source to the connection.

The invention is based on the insight that many electrical consumers can run when a rectified voltage or direct voltage is applied instead of an alternating voltage. Most electronic devices will thus themselves comprise a rectifier, which rectifies the input voltage first. These devices further have a smoothing device and voltage reducing mechanism for smoothing the rectified voltage and reducing it to a desired voltage, for instance 24V or 12V. When a rectified voltage is applied to such a device, this will have a negligible effect on the primary functionality of this device. Even when this rectification has an output voltage with a voltage variation, this has been found in practice not to be a drawback. This is because two rectifiers, one in the cabling and one in the device, can be connected in series. Other electrical devices, for instance heaters, typically comprise an electrical resistance. For an electrical resistance it makes no difference whether an alternating voltage is applied, a rectified voltage is applied or a direct voltage is applied. By providing the DC source with a direct voltage regulator the DC source voltage can be regulated. The power supplied by the source can be determined in simple manner by multiplying the output voltage by the output current. This can be averaged over the time, for instance every second, in order to determine the supplied power. By providing an output voltage with a voltage variation a direct connection between the cabling with the rectified output voltage on the one hand and the DC source on the other can be made in extremely simple manner via a direct voltage regulator. The voltage set by the direct voltage regulator directly determines whether the supplied power originates from the DC source or from the AC input.

When a DC source is connected to a rectified voltage, the following effect occurs. If the rectified voltage is greater than the source voltage, the current and thus the power will be supplied by the AC input. If the source voltage is greater than the rectified voltage, the current and thus the power will be supplied by the DC source. Because a rectified voltage typically comprises a ripple, and is thus not constant direct voltage, the DC voltage regulator can regulate the DC source voltage so as to be higher than the rectified voltage part of the time and to be lower than the rectified voltage another part of the time. By selecting a higher DC source voltage the percentage of time during which the DC source voltage is higher than the rectified voltage will become greater and the power supplied by the DC source to the electrical consumer will increase. By selecting a lower DC source voltage the percentage of time during which the DC source voltage is higher than the rectified voltage will decrease, so that the power supplied by the DC source also decreases. This shows that the output power of a DC source can be regulated with extremely simple electronics. This further allows the electric power of the DC source to be used directly in an electrical installation in simple manner. When the DC source is connected via an inverter to the AC input, the inverter can take a smaller form, i.e. with less power, because at least part of the power is consumed directly in the electrical installation via the direct voltage.

The cabling preferably comprises an electrical box where the cabling runs to the AC input on one side and where on the other side the cabling in each case runs in a plurality of parallel segments to one or more connections for electrical consumers. The rectifier is preferably placed in the cabling in order to rectify voltage in at least one of the plurality of segments of the cabling. By selecting parallel segments and placing the rectifier therein a predetermined part of the electrical installation can be used with direct voltage, while the other part of the electrical installation remains running on alternating voltage.

The rectifier is preferably placed in the electrical box. The rectifier is preferably connected to the cabling at a distance from the connection. The distance is preferably greater than 20 cm, preferably greater than 50 cm, more preferably greater than 1 metre, and most preferably greater than 2 metres. The invention is aimed at electrical installations for running a part of the installation on direct voltage. Connecting the rectifier to the cabling at a distance from the connection makes it possible to connect a plurality of electrical consumers to the connection, simultaneously in parallel or successively in time, and to consume power from the DC source.

The rectifier is preferably a double-sided rectifier which converts the alternating voltage to a pulsating direct voltage. The rectifier preferably has an output voltage with a voltage variation lying between a first direct voltage DC1 and a second direct voltage DC2, and wherein the difference between DC1 and DC2 is at least 5 volt. The DC voltage regulator is preferably provided to regulate the DC source voltage to be between DC1 and DC2. More preferably, the DC voltage regulator is further provided to regulate the DC source voltage to be higher than the highest of DC1 and DC2 in order to supply the whole of the power to the connection via the DC source and/or is provided to go below the lowest of DC1 and DC2 in order to supply the whole of the power to the connection via the AC input. The effects and advantages of these features are elucidated below with reference to the figures.

The voltage variation preferably has a frequency which is related to the alternating voltage frequency. The voltage in the cabling between the rectifier and the connection is preferably at least equal to the output voltage with the voltage variation. The voltage in the cabling between the rectifier and the connection is preferably at least equal to the DC source voltage. The voltage in the cabling between the rectifier and the connection is preferably equal to the highest voltage of the output voltage with the voltage variation and the DC source voltage.

The DC voltage regulator preferably further comprises an ammeter for regulating the predetermined power on the basis of the ammeter and the DC source voltage. By regulating a predetermined power a safety can be obtained and overload can be prevented. The power supplied by the DC source can be regulated to be higher by increasing the DC source voltage. By increasing the DC source voltage the time during which the DC source voltage is higher than the rectified voltage with voltage variation will be longer, whereby the current is supplied by the DC source for longer. Similarly, the power supplied by the DC source can be reduced by reducing the DC source voltage because the time during which the DC source voltage is higher than the rectified voltage with voltage variation decreases. It will be apparent here that the current, and thus also the power, is always supplied to the connection by the one with the highest voltage.

The DC source is preferably selected from at least one of a battery, a solar panel installation, a wind turbine and a combined heat and power installation. This means that the DC source can be formed by a battery and/or a solar panel installation and/or a wind turbine and/or a combined heat and power installation. The DC source is preferably connected via an inverter to the cabling between the rectifier and the AC input. By connecting the DC source via an inverter to the AC input power which does not flow via the DC voltage regulator can flow via the inverter to the grid or to the alternating voltage part of the electrical installation.

The AC input is preferably a polyphase system and the rectifier a polyphase rectifier. Three-phase electrical grids are often provided in Europe. The three phases are separated by 120 degrees relative to each other. When a lot of electric power is desired, all phases of the grid are connected to a residential or industrial electrical installation. In many cases only one phase of the grid is connected to a residential or industrial electrical installation. As elucidated at length hereinbelow with reference to figure 5, this preferred embodiment of the invention has a stabilizing effect on the three-phase system. More specifically, energy will be drawn to the maximum extent from the least loaded phase and be drawn to the least extent from the most heavily loaded phase. This restores the balance in the three-phase system. Although the elucidation relates to three-phase systems, it will be apparent to the skilled person that these principles can be applied in a wider sense, in polyphase systems. This preferred embodiment of the invention is therefore preferably not limited to three-phase systems.

The invention will be further described with reference to an exemplary embodiment shown in the drawing.

In the drawing: figure 1 shows a diagram of an electrical installation according to a first embodiment of the invention; figure 2 shows a diagram of an electrical installation in a building according to a second embodiment of the invention; figure 3 shows a schematic representation of an electrical box in which the invention according to a preferred embodiment is applied; figure 4 shows a schematic representation of a safety module in which the invention according to a further preferred embodiment is applied; and figure 5 shows a graph of application of the invention in a three-phase system.

The same or similar elements are designated in the drawing with the same reference numerals.

In this description voltage variation is defined as the variation in the voltage as a result of the rectification of the alternating voltage. The voltage variation typically displays a non-linear repetitive pattern, which pattern is preferably typically a set pattern.

Figure 1 shows a schematic representation of an electrical installation 1 according to a first embodiment of the invention. Electrical installation 1 can be applied or integrated in an existing residential or industrial electrical installation in simple manner. The figure shows an AC input 2 on the left-hand side. AC input 2 is typically formed by a connection to the electrical grid. Alternatively, AC input 2 comprises a diesel generator or similar generator where an alternating voltage is supplied. AC input 2 is connected via cabling 5 to a connection 3 for connection of an electrical consumer 4. Connection 3 is shown in figure 1 as a socket outlet. In most situations this will be correct in a residential environment or in a small industrial environment. The shape, contacts and specifications of socket outlets are typically regionally regulated. A socket outlet can have different properties in Europe than in the US. The skilled person will appreciate what a socket outlet is, and this is therefore not elucidated further in this description. Some electrical consumers 4 are not connected to cabling 5 via a socket outlet but via a small junction box or switch box. The connection is therefore initially not limited to a socket outlet. A rectifier 6 is placed in cabling 5, between AC input 2 and connection 3. Rectifier 6 will rectify the alternating voltage of AC input 2. This is shown at the bottom in figure 1, wherein an alternating voltage 9 is shown on the left and rectified voltage 10 is shown on the right. The rectifier is preferably a double rectifier, typically formed by a bridge with four diodes. A rectifier is known and is therefore not elucidated further in this description. It will be apparent that rectifiers other than those with a bridge with diodes can also be used in the context of the invention for rectifying alternating voltage 9 into a rectified voltage 10. Rectified voltage 10 is preferably not smoothed, or smoothed to negligible extent or at least not optimally. This means that the rectified voltage 10 has a ripple. A ripple is defined as a periodic fluctuation between a minimum voltage V_M and a maximum voltage V_T. The difference between the minimum voltage V_M and the maximum voltage V_T is preferably at least 5V, more preferably at least 10V, more preferably at least 20V. The way in which the ripple is used to control the power which is supplied by the DC source is described below.

Figure 1 further shows the DC source 7. DC source 7 can be formed by a solar panel installation, a battery, a CHP, a wind turbine, analogous or similar direct current installation or combinations thereof. DC source 7 is connected via a direct voltage regulator 8, also referred to as DC voltage regulator, to the cabling 5 downstream of rectifier 6. The current direction will be defined here as the direction in which the electric power runs. In an electrical installation 1 the electric power will always run from the AC input 2 to the consumer 3.

The DC voltage regulator can be integrated in the DC source 7. Alternatively, the DC source has a direct voltage regulating mechanism which supplies a constant or variable output voltage which is optimal for the DC source, and a further DC voltage regulator 8 is placed between cabling 5 and DC source 7. In all situations the output voltage of DC voltage regulator 8 is deemed the DC source voltage. The DC source voltage is shown at the bottom in figure 1 as V_DC. In contrast to the rectified alternating voltage 10, the voltage of which has a ripple, the DC source voltage is almost flat.

A rectifier 6 has the property that current can flow through the rectifier in only one direction. This has the direct consequence that current from DC source 7 is prevented from supplying power or passing current to AC input 2. The rectifier prevents upstream flow of current and power. DC voltage regulator 8 also has the property that current can flow in only one direction, such that power from AC input 2 cannot run to DC source 7. In other words, rectifier 6 only allows a power flow to connection 3 and DC voltage regulator 8 also only allows a power flow to connection 3.

By connecting the DC source voltage to the cabling downstream of rectifier 6, the situation as shown at bottom right in figure 1 can be created. In this situation the DC source voltage V_DC is chosen such that it lies between the minimum voltage V_M and the maximum voltage V_T of the rectified voltage 10. As a result, the highest voltage will be alternately determined, downstream of rectifier 6, by the rectified voltage 10 and the DC source voltage 11. The power to connection 3 will hereby also be alternately supplied by AC input 2 via rectifier 6, and by DC source 7 via DC voltage regulator 8. The amount of power supplied by DC source 7 can here be regulated by setting the height of the DC source voltage 11. By making DC source voltage 11 the same as or smaller than the minimum voltage V_M no power will be supplied by DC source 7 to connection 3. By making DC source voltage 11 the same as or higher than the maximum rectified voltage V_T 100% of the power consumed by the electrical consumer 4 will be supplied by DC source 7. The skilled person will appreciate that by selecting a DC source voltage 11 between the maximum rectified voltage V_T and the minimum voltage V_M a percentage of the power is supplied by the DC source.

Preferably provided in the DC voltage regulator 8 is an ammeter which directly or indirectly measures the current flowing to the cabling. The DC voltage regulator can determine the power on the basis of the current measurement and taking into account the set voltage. When the power is higher than desired, voltage regulator 8 can reduce the DC source voltage. When the supplied power is lower than desired, the DC voltage controller can increase the DC source voltage 11. It will be apparent that when no electrical consumer 4 is coupled to connection 3, the electrical power which can be supplied by the DC source is always 0, irrespective of the set DC source voltage 11.

Figure 2 shows a preferred application of electrical insulation 1. Figure 2 shows a house where a DC source 7 is provided. A solar panel installation can for instance be provided as DC source 7 on the roof of a house. A battery installation can alternatively or additionally be provided as DC source 7. The DC source 7 is preferably connected via an inverter 18 to AC input 2. Inverter 18 converts the direct voltage of DC source 7 to an alternating voltage which corresponds to the alternating voltage of AC input 2 such that DC source 7 can supply power via inverter 18 to AC input 2. It will be apparent here that the supplied power can either be returned to AC input 2, for instance to the electrical grid, the supplied power alternatively and preferably being consumed locally at the house.

The house has an electrical box, shown at bottom right in the house, from which a plurality of parallel segments depart to different consumers or consumer units. The shown bottom two of the parallel segments are here separated from the other consumer, and these two parallel segments form the predetermined segments which are set to direct voltage. Provided in the electrical box is a rectifier 6 which rectifies the alternating voltage of AC input 2. The lower two segments of the cabling are therefore fed with a rectified voltage. One of the segments has a plurality of connections 3. The other segment runs to a specific consumer, for instance a heating system 12.

The heating system is for instance connected to the cabling via a switch box 3’. Figure 2 shows that the DC source is connected to two DC voltage regulators 8a and 8b.

By providing two DC voltage regulators it is possible to set the amount of power supplied by the DC source for each of the voltage regulators individually. Each DC voltage regulator hereby forms a safety for each of the segments. When it is for instance known that heating system 12 is a 15 kW heating system, the DC power can be regulated to 15 kW via voltage regulator 8a, such that precisely that power is supplied directly by the DC source. Voltage regulator 8a can further ensure that the supplied power does not rise considerably above 15 kW. The DC source can still supply more than 15 kW to the electrical installation via the additional voltage regulator 8b. The amount of power that runs from DC source 7 to consumers 3 can then be further regulated via voltage regulator 8b. Alternatively, only one voltage regulator is provided and connected to all rectified segments.

Figure 3 shows an electrical box 14 in which the invention according to an embodiment is applied in a preferred manner. The figure shows that the AC input is connected to an AC connection bar 15 in electrical box 14. Connection bars are applied in electrical boxes in order to connect different cabling segments in simple manner. A plurality of parallel segments are illustrated schematically in figure 3 and designated with reference numeral 13. Each parallel segment runs to one or more consumers. The consumers can be connections such as socket outlets, or can be lighting, or can run to a specific consumer such as a washing machine, heater, charging point for an electric car, or other.

Figure 3 does not show how the plurality of parallel segments are connected to connection bar 15. Multiple solutions for this are known in the market, wherein safety modules such as circuit breakers are snapped onto a connection bar and are thereby electrically connected to the connection bar. Figure 3 shows that not only an AC connection bar 15 is provided in electrical box 14, but a DC connection bar 16 is also provided in the same electrical box 14. AC connection bar 15 is connected via rectifier 6 to DC connection bar 16. When setting up the electrical installation it is then possible to make a choice for each of the parallel segments 13 to couple them to the AC connection bar 15 or to couple them to the DC connection bar 16. This makes it possible to set up an electrical box and distinguish between direct current cabling segments and alternating current cabling segments in extremely simple manner. DC source 7 is connected via DC voltage regulator 8 to DC connection bar 16. Similarly to the description above, this allows a predetermined power to be supplied via DC source 7 to DC connection bar 16 by regulating the voltage via DC voltage regulator 8. DC source 7 is preferably connected via an inverter 18 to AC input 2. This connection allows the power which is not put out via DC connection bar 16 to be sent back to the grid via AC input 2 or to be consumed locally via AC connection bar 15. Figure 3 shows the connection between AC input 2 and AC connection bar 15. The skilled person will appreciate that inverter 18 can also be connected directly to AC connection bar 15. Figure 3 further shows schematically a distance 17 between the connection and electrical box 14.

Figure 4 shows an alternative manner of applying the invention as according to a preferred embodiment. Figure 4 shows schematically that an AC input 2 is connected via a safety module 19, such as a circuit breaker, to the electrical connection 3. This is a traditional setup as applied in many homes and industries. According to the invention, safety module 19 can be provided internally or externally with the rectifier 6. Safety module 19 can further be provided internally or externally with the DC voltage regulator 8 which is coupled to the DC source 7. This embodiment does not require two connection bars 15 and 16 in the electrical box. In this embodiment safety module 19 is used to couple the DC source.

Figure 5 shows that the invention can be applied in a three-phase system. Shown at the top in figure 5 is the alternating voltage 9 of a three-phase system. When this alternating voltage is sent through the known three-phase rectifier, rectified voltage 10 is obtained, which is shown at the bottom in figure 5. This rectified voltage also has a minimum voltage V_M and a maximum voltage V_T. Compared to a one-phase rectified voltage, the difference between the minimum voltage V_M and the maximum voltage V_T of a three-phase rectified voltage is considerably smaller. The operating principle, particularly for setting of the DC source voltage V_DC, is fully analogous to the above described.

Application of the invention in a three-phase system has a further advantage. The three phases are not loaded equally in practice. This may result in a situation where a first phase is loaded considerably more heavily than other phases, which has the further consequence that the voltage of this one phase is lower than the voltage of the other phases. The lower voltage is shown schematically in figure 5 with reference numeral 20. Setting the direct voltage V_DC may result in the situation where the heavily loaded phase 20 is lower in voltage than the set DC source voltage V_DC, such that this phase 20 is not loaded further, and the power of the DC source is supplied. The other phases, which are loaded less and have a higher voltage, can however supply power to the consumer because their voltage exceeds the DC source voltage. The invention thus has a balancing effect on a three-phase system. In other words, in a three-phase situation the most power will always be supplied by the phase with the highest voltage. In practice this is always the phase that is loaded least, and is thus best suited to supply more power.

The skilled person will appreciate on the basis of the above description that the invention can be embodied in different ways and on the basis of different principles. The invention is not limited to the above described embodiments. The above described embodiments and the figures are purely illustrative and serve only to increase understanding of the invention. The invention will not therefore be limited to the embodiments described herein, but is defined in the claims.

Claims

1. Electrical installation comprising:

- an AC input configured to feed the electrical installation with an alternating voltage;

- a connection configured for connection of at least one electrical consumer;

- cabling running from the AC input to the connection;

- a DC source; characterized in that the electrical installation further comprises a rectifier in the cabling for rectifying the alternating voltage, wherein the rectifier has an output voltage with a voltage variation which lies between a first direct voltage DC1 and a second direct voltage DC2, and wherein the difference between DC1 and DC2 is at least 5 volt, and wherein the DC source is connected via a DC voltage regulator to the cabling between the rectifier and the connection, and wherein the DC voltage regulator regulates a DC source voltage between DC1 and DC2 in order to supply a predetermined power of the DC source to the connection.

2. Electrical installation according to claim 1, wherein the cabling comprises an electrical box where the cabling runs to the AC input on one side and where on the other side the cabling in each case runs in a plurality of parallel segments to one or more connections for electrical consumers.

3. Electrical installation according to the foregoing claim, wherein the rectifier is placed in the cabling in order to rectify voltage in at least one of the plurality of segments of the cabling.

4. Electrical installation according to the foregoing claim, wherein the rectifier is placed in the electrical box.

5. Electrical installation according to any one of the foregoing claims, wherein the rectifier is connected to the cabling at a distance from the connection.

6. Electrical installation according to the foregoing claim, wherein the distance is greater than 20 cm, preferably greater than 50 cm, more preferably greater than 1 metre, and most preferably greater than 2 metres.

7. Electrical installation according to any one of the foregoing claims, wherein the rectifier is a double-sided rectifier which converts the alternating voltage to a pulsating direct voltage.

8. Electrical installation according to any one of the foregoing claims, wherein the voltage variation has a frequency which is related to the alternating voltage frequency.

9. Electrical installation according to any one of the foregoing claims, wherein the voltage in the cabling between the rectifier and the connection is at least equal to the output voltage with the voltage variation.

10. Electrical installation according to any one of the foregoing claims, wherein the voltage in the cabling between the rectifier and the connection is at least equal to the DC source voltage.

11. Electrical installation according to any one of the foregoing claims, wherein the voltage in the cabling between the rectifier and the connection is equal to the highest voltage of the output voltage with the voltage variation and the DC source voltage.

12. Electrical installation according to any one of the foregoing claims, wherein the DC voltage regulator is further provided to regulate the DC source voltage to be higher than the highest of DC1 and DC2 in order to supply the whole of the power to the connection via the DC source and/or is provided to go below the lowest of DC1 and DC2 in order to supply the whole of the power to the connection via the AC input.

13. Electrical installation according to any one of the foregoing claims, wherein the DC voltage regulator further comprises an ammeter for regulating the predetermined power on the basis of the ammeter and the DC source voltage.

14. Electrical installation according to any one of the foregoing claims, wherein the DC source is additionally connected via an inverter to the cabling between the rectifier and the AC input.

15. Electrical installation according to any one of the foregoing claims, wherein the AC input is a polyphase system and wherein the rectifier is a polyphase rectifier.