AT513059A1 - Apparatus and method for improving energy use - Google Patents

Abstract

Device (1) for improving the use of energy, with a decentralized energy system (3) connected to the power supply (4), the decentralized energy system (3) having an input (6) for receiving control commands, characterized by an input (6) ) of the decentralized energy system (3) connected to the power grid (4), the local grid voltage (U1) of the power grid (4) determined locally in the control device (2) voltage thresholds (Us) based on Values of the local mains voltage (U1) is determined, and when exceeding the voltage thresholds (Us) on the output (5) of the control device (2) the input (6) of the decentralized power system (3) sends a command to control the decentralized power system (3) ,

Description

Ing. Roland Ochenbauer, Listgasse 12, A-2630 Temitz, roland.ochenbauer@ochenbauer.at

Apparatus and method for improving energy use

The present invention relates to a device for improving the use of energy, having a decentralized power system connected to the power supply, wherein the decentralized power system has an input for receiving control commands.

The invention further relates to a method for improving the use of energy by means of a decentralized energy system connected to the power grid.

Households and businesses are increasingly installing decentralized energy systems with a connection to a public low-voltage power grid. A known embodiment of a decentralized energy system is the decentralized generation system of electrical energy which is connected to the public low-voltage distribution network, for example, the decentralized cogeneration plant for the production of electrical energy and heat. The combined heat and power plant uses the principle of combined heat and power. A controlled according to the heat demand cogeneration feeds electrical energy, regardless of the load condition of the local low-voltage network in the public grid. Another known embodiment of a decentralized energy systems is the decentralized energy system with an energy storage. For example, the electrical energy is stored from the power grid in a decentralized energy system with an accumulator and fed back into the grid regardless of the load state of the local low-voltage network, controlled by the user. If, for example, many decentralized energy systems feed energy onto a network branch of a low-voltage power network at a point in time with little energy consumption on this network branch, this is very problematical because it very often leads to a load flow reversal on this network branch. The electrical energy flows φ · φ φ • Φ · · Μ Φ Φ • Φ • * «Φ Φ Φ Φ» Φ ΦΦ φ ΦΦ ΦΦΦφ via the low-voltage line back to the transformer station and via the transformer into the next grid levels. In the low-voltage line in which the load flow reversal occurs, the mains voltage in many cases rises problematically high because the low-voltage lines are very often not sufficiently dimensioned to be able to ausihehmen a variety of decentralized energy systems. As a further consequence, if this is simultaneously based on very many parts of the power grid, the grid frequency of the entire power grid increases. This energy surplus is dangerous because a grid only works when there is a balance in the grid between the energy fed in and the energy consumed. If the grid gets out of balance, the power grid breaks down in the worst case.

The invention is therefore based on the object of specifying an apparatus and a method for improving energy use, that the above-mentioned problems with decentralized energy systems do not come into play.

This is achieved in a first aspect of the invention by the characterizing part of the main claim Entchtungs in conjunction with the features of the preamble and the expediently designed features of the dependent claims.

This is achieved in a second aspect of the invention by the characterizing part of the method main claim in conjunction with the features of the preamble and the expediently designed features of the dependent claims.

The invention will now be explained with reference to exemplary embodiments, which are schematically illustrated in the drawing figures. -2- * ··· fr * fr · fr fr fr fr fr frfrfrfr fr fr

1 shows a schematic circuit diagram of the device 1 for improving the use of energy,

Fig. 2 shows schematically the course of the evaluated local mains voltage Ul shown in a diagram and

Fig. 3 shows schematically the evaluated network frequency Fl in connection with the course of the evaluated local mains voltage Ul in a diagram.

List of Reference Numerals Fig. 1: 1 ... device 2 ... control device 3 ... decentralized energy system 4 ... Power supply 5 ... output 6 ... input 7 ... fuel

LIST OF REFERENCES FIG. 2:

Ul ... local mains voltage Ud ... average local mains voltage Usl ... higher value of the voltage thresholds Us2 ... lower value of the voltage thresholds Un ... lowest value of the local mains voltage Uh ... highest value of the local mains voltage A .. local energy deficit B ... local energy surplus Diagram axis designation Fig 2: t / h ... time in hours UW ... voltage in volts -3- 1

LIST OF REFERENCES FIG. 3:

Fl ... network frequency

Fn ... standard frequency

Fsl ... higher network frequency limit

Fs2 ... lower grid frequency limit

Ul ... local mains voltage

Ud ... average local grid voltage

Usl ... higher value of voltage thresholds

Us2 ... lower Who the voltage thresholds A. .. local energy deficit B. .. local energy surplus Diagram axis designation Fig. 3: t / h ... time in hours frHz ... frequency in llcrtz U / V ... voltage in volts

In Fig. 1, a device 1 for improving energy use, with a connected to the power grid 4 decentralized energy system 3, wherein the decentralized power system 3 has an input 6 for receiving control commands. To the input 6 of the decentralized energy system 3, a control device 2 is connected. The control device 2 is connected to the power grid 4. The control device 2 measures the local mains voltage Ul, determines voltage threshold values Us locally in the control device 2 on the basis of the values of the local mains voltage Ul and transmits, on exceeding the voltage threshold values Us determined locally in the control device 2 on the output 5 of the control device 2 to the input 6 of the decentralized 3. The invention is based on the recognition that the measured change in the local grid voltage U1 can be used to generate a local excess energy B or -4-.

to locally determine a local energy deficit A in a network branch of the power network 4. Subsequently, a decentralized power system 3 is sent the command to inject electric power into the power grid 4 at a local power deficit A or the command to store electric power from the power grid 4 at a local power surplus B. Thus, an improvement in energy use in 3 reaches households and commercial enterprises with a decentralized energy system 3 and already in the individual network branches of the power network 4 the balance between fed-in energy and energy produced as best possible because the ratio of energy consumption, centrally fed energy and decentralized feed energy in each network branch on each transformer station is different , this requires the local measurement and evaluation of the local mains voltage Ul. An individually local autonomous measurement and evaluation of the local mains voltage Ul enables the efficient improvement of energy use in households and commercial enterprises with decentralized energy systems 3.

A preferred embodiment is that the decentralized energy system 3 is designed to feed electrical energy into the power grid 4. Electrical energy is generated with a decentralized energy system 3, for example, a small decentralized combined heat and power plants and fed into the power grid 4. Combined heat and power plants use a variety of fuels 7 to generate electrical energy and heat. As fuels 7 are mainly fossil fuels or renewable fuels 7 such as fuel oil, vegetable oil, biodiesel or natural gas or biogas used, in addition also woodchips and wood pellets as renewable resources. As a decentralized energy system 3 which is designed to feed electrical energy into the power grid 4, any other known in the art decentralized energy system 3 which is designed to feed electrical energy into the power grid 4 are used, for example, emergency diesel generators or decentralized energy systems 3 which are designed to store stored electrical energy in the power grid 4 such as accumulator systems, power generators of a compressed air storage system, power generators of a flywheel storage system, etc. -5- * A ·· * 4 * «

Decentralized energy is fed into a power grid 4 at the point in time in which a local power deficit B exists in a network branch of the power grid 4, which is a very effective way of using the fuels 7 supplied to the decentralized energy system 3 in an energy-efficient manner. Also, stored energy from decentralized energy systems 3, for example, from accumulators, is fed into the power network 4 at the times of a local energy deficit A, thereby using the stored energy in an energy-efficient manner.

A further preferred embodiment is that the decentralized energy system 3 is designed to store electrical energy from the power grid 4 and to feed electrical energy into the power grid 4. Electrical energy is stored with a decentralized energy system 3, for example in an accumulator, from the power grid 4.

The electrical energy from the power grid 4 is stored at the time in the decentralized energy system 3 in which there is a local energy surplus B in the respective network branch of the power network 4 and is in stored form the power grid 4 for times of local energy deficit A for feeding into the power grid 4 available. Decentralized energy systems 3 can store electrical energy using various technologies. Electrical energy can be stored, for example, electrochemically with accumulators or mechanically with flywheels or compressed air storage. As a decentralized energy system 3 which is designed to store electrical energy from the power grid 4, any other known in the art decentralized energy system 3 which is designed to store energy from the power grid 4 are used, for example, the batteries of electric vehicles when the batteries of the Electric vehicles also offer the opportunity to feed the stored electrical energy when needed in the power grid 4, etc.

Energy from a power grid 4 to store exactly at the time with a decentralized energy system 3, if in the respective network branch of the power network 4 is a local energy surplus B is an effective way to improve energy efficiency, since the stored energy for feeding into a power grid 4 to Times of a local energy deficit A is available. -6- »

Referring to Fig. 2, a method according to an embodiment of the invention will now be explained in more detail. A method for improving the use of energy by means of a connected to the power grid 4 decentralized energy system 3, characterized by the following steps in any order: - Determining the local mains voltage Ul of the power grid 4 - Determining the voltage thresholds Us - To effect predetermined operations in the decentralized energy system 3 when exceeded the voltage thresholds Us.

A preferred embodiment of the invention is characterized in that the voltage threshold values Us are determined on the basis of the values of the local mains voltage Ul and predetermined processes in the decentralized energy system 3 are effected when the voltage thresholds Us are exceeded, namely in the following manner: - meaningful Values of the local mains voltage Ul can be determined, shown in FIG. 2 in the diagram as a smoothed course of the local mains voltage Ul, in which 1.) the locally measured «! Momentanaufftähmeff the mains voltage of the power network 4 are stored for further processing in a first table; preferably the Momcntanaufhahmen the mains voltage with time stamp in a configurable interval 2 to 300 seconds, more preferably 20 seconds are stored in a first table, 2) the individual values of the instantaneous recordings of the mains voltage from the first table, which could include, for example, short voltage spikes, in Form of more meaningful, smoothed values of the local mains voltage Ul stored over a certain period of time in a second table for further processing; preferably for smoothing, the most recent one to three values of the instantaneous measurements of the mains voltage, more preferably three values of the instantaneous recordings of the mains voltage of the first table are added, the sum divided by the number of added values and the result in a second table with the time stamp of the respective first value of the first table is stored as a local mains voltage Ul, -7- • * * * *· * 3.) values of the first table no longer required to save memory space are deleted; preferred values in the first table older than 20 minutes are deleted 4.) obsolete values of the local mains voltage Ul of the second table are deleted; preferred values in the second table which are older than a configurable period 1 to 365 days, more preferably 14 days are deleted, - the average local grid voltage Ud is determined as average value from the meaningful values of the local grid voltage Ul of the second table; preferably the values of the local mains voltage Ul are added in the second table and the sum is divided by the number of added values in order to determine the average local grid voltage Ud; shown in Figure 2 in the diagram as an example of the average local grid voltage Ud, - the higher value of the voltage thresholds Usl is determined as the value between the average local grid voltage Ud and the highest value of the local grid voltage Uh from the meaningful second table; preferably the higher value of the savings threshold values Usl is determined as Werr between the highest value of the local grid voltage Uh in the second table and the average local grid voltage Ud in a configurable ratio, particularly preferably according to the formula that the highest value of the local grid voltage Uh in the second table is added to the average local grid voltage Ud and the sum is divided by two; shown in the diagram as an exemplary curve of the higher value of the Sparmungsschwellwerte Usl, - the lower value of the Sparmungsschwellwerte Us2 as a value between the average local grid voltage Ud and the lowest value of the local grid voltage Un, from the meaningful second table, is determined ; preferably, the lower value of the savings threshold Us2 is determined as the value between the lowest value of the local grid voltage Un in the second table and the average local grid voltage Ud in a configurable ratio, particularly preferably according to the formula that the lowest value of the local is determined - :: .. Η

Mains voltage Un is added in the second table with the average local mains voltage Ud and the sum is divided by two; shown in FIG. 2 in the diagram as an example of the lower value of the voltage threshold values

Us2 - for the period in which the local mains voltage Ul is lower than the lower value of the voltage thresholds Us2, which indicates a local energy deficit A in the power grid 4, the decentralized energy system 3 feeds electrical energy into the power grid 4, - for the period , in which the local mains voltage Ul is higher than the higher value of the voltage thresholds Usl, which can be inferred to a local energy surplus B in the power grid 4, the decentralized energy system 3 stores electrical energy from the power grid 4.

Referring to Fig. 3, a method according to an embodiment of the invention will now be explained in more detail.

A preferred embodiment of the invention is characterized in that the local network frequency Fl of the power network 4 is determined and the voltage thresholds Us are changed by a predetermined factor when exceeding a predetermined net frequency limit Fs in the following manner that - the local network frequency Fl the power grid 4 is determined locally; shown in Figure 3 in the diagram as an exemplary course of the local grid frequency Fl of the power grid 4, - a higher grid frequency limit Fsl is given; preferably a higher net frequency limit value Fsl between 50.02 Hz and 50.2 Hz, particularly preferably 50.06 Hz is specified; shown in Figure 3 in the diagram as a higher grid frequency limit Fsl, - is given a lower grid frequency limit Fs2; preferably a lower net frequency limit Fs2 between 49.8 Hz and 49.98 Hz, particularly preferably -9-

• ♦ * *** «49.94 Hz is given; shown in the diagram as a lower grid frequency limit Fs2, - for the period in which the grid frequency Fl is higher than the higher grid frequency limit Fsl, the higher value of the voltage thresholds Usl and the lower value of the voltage swing values Us2 are reduced by a predetermined factor , Preferably, be reduced in the following manner: - the higher value of the voltage thresholds Usl is determined by multiplying the average local grid voltage Ud by a factor of 3, the highest value of the local grid voltage Uh multiplied by a factor of 2, the two products are added and the sum is divided by the factor 5, - the lower value of the voltage thresholds Us2 is determined by multiplying the average local grid voltage Ud by a factor of 2, the lowest value of the local grid voltage Un by a factor of 3, the two products be added and the sum by the F 3 in the diagram as a reduction of the voltage thresholds Us for the period in which the network frequency Fl is higher than the higher network frequency limit Fsl, - for the period in which the network frequency Fl is lower than the lower network frequency limit Fs2, the higher value of the voltage threshold values Usl and the lower value of the voltage threshold values Us2 are increased by a predetermined factor, preferably be increased in the following manner: the higher value of the voltage threshold values Usl is determined by multiplying the average local network voltage Ud by a factor of 2, the highest value of the local mains voltage Uh is multiplied by the factor 3, the two products are added and the sum is divided by the factor 5, - the lower value of the voltage thresholds Us2 is determined by multiplying the average local mains voltage Ud by a factor of 3 -10- becomes, the lowest Value of the local mains voltage Un is multiplied by the factor 2, the two products are added together and the sum is divided by the factor 5.

If, for example, the majority of network branches of a power network 4 have a local energy surplus B, then very often the entire power network 4 has an energy surplus. This means simplified explained that the generators of the central power generator are slowed down less due to the excess energy and therefore rotate faster and thus increases the Netzfiequenz FI. The grid frequency Fl always changes throughout the power grid 4 and therefore also has approximately the same values at each point of the grid 4. Therefore, it is useful to use the network frequency Fl as an indicator in the decentralized energy systems 3 for a nationwide energy surplus or a nationwide energy deficit and contribute as a factor to take into account the entire power system state in the local voltage-dependent control. In the power grids 4 of the future, more and more energy with decentralized energy systems 3 is fed and stored, with the result that the weakly dimensioned network branches of the power grids 4 must always be kept in the local balance between energy supply and energy consumption in order not to be overloaded. As described, this balance is optimally established by controlling the decentralized energy systems 3 via the local measurement and evaluation of the local mains voltage UI. However, if the entire power network 4 is not in optimum balance, this can be determined by evaluating the locally measured network frequency Fl in the decentralized energy systems 3 and have an influence on the voltage-dependent control of the decentralized energy systems 3. By a slight change in the voltage thresholds Us due to a mains frequency Fl exceeding a mains frequency limit value Fs, a factor for taking into account the entire power supply state is introduced into the local voltage-dependent control. For the period in which the network frequency Fl is lower than a predefined lower network frequency limit Fs2 and an energy deficit can be detected in the entire power network 4, the higher value of the voltage threshold values Usl and the lower value of the voltage threshold values Us2 is increased by a predetermined factor and thus the time the -11 - • · · • · ** «* *

· * · * I

Energy supply increased by the decentralized energy systems 3 and reduces the time of energy storage of the decentralized energy systems 3. For the period in which the grid frequency Fl is higher than a predetermined higher grid frequency limit Fs 1 and an excess of energy can be detected in the entire grid 4, the higher value of the voltage thresholds Usl and the lower value of the voltage thresholds Us2 is reduced by a predetermined factor and thus the Reducing the time of energy supply by the decentralized energy systems 3 and increasing the time of energy storage of the decentralized energy systems 3. A minimal change of the voltage thresholds Us in favor of the stability of the entire power network 4 is an additional contribution of the decentralized energy system 3 to the individual network branches of the low-voltage network for the best possible balance between total energy fed in and total energy consumed and thus an improvement in energy use throughout the electricity grid 4.

All features and combinations of features mentioned in the description of the figures and / or shown alone in the figures can be used not only in the respectively specified combination of features but also in other combinations or alone.

The invention is not limited to the illustrated embodiments, but includes all variants and modifications that fall within the scope of the appended claims. -12-

Claims (15)

1. Device (1) for improving the use of energy, with a to the power grid (4) connected decentralized energy system (3), wherein the decentralized energy system (3) has an input (6) for receiving control commands, characterized by an the input (6) of the decentralized energy system (3) connected control device (2), which is connected to the mains (4), the local mains voltage (Ul) of the power network (4) determined locally in the control device (2) voltage thresholds (Us ) is determined on the basis of the values of the local mains voltage (Ul), and when the voltage thresholds (Us) on the output (5) of the control device (2) exceed the input (6) of the decentralized power system (3), a command for controlling the decentralized energy system (3) sends. 2. Device according to claim 1, characterized in that the control device (2) locally determines the mains frequency (Fl) of the power network (4) and changes the voltage threshold values (Us) by a predetermined factor when a predetermined mains frequency limit value (Fs) is exceeded. 3. Apparatus according to claim 1 or 2, characterized in that the decentralized energy system (3) is adapted to feed electrical energy into the power grid (4). 4. Device according to one of claims 1 to 3, characterized in that the decentralized energy system (3) is adapted to store electrical energy from the power grid (4). -13- • «4 •« * · r · 4 • · ♦ * * · ♦ * * 4 • ♦ · 5. A method for improving the use of energy by means of a to the power grid (4) connected decentralized energy system (3), characterized by the following steps in any order: - Determining the local grid voltage (Ul) of the power grid (4) - Determining the voltage thresholds (Us ) - effecting predetermined processes in the decentralized energy system (3) when the voltage threshold values (Us) are exceeded. 6. The method according to claim 5, characterized in that the voltage threshold values (Us) are determined on the basis of the values of the local mains voltage (U1). 7. The method according to claims 5 or 6, characterized in that the mains frequency (Fl) of the power network (4) is determined locally and when exceeding a predetermined frequency limit value (Fs) the voltage threshold values (Us) are changed by a predetermined factor. 8. The method according to any one of claims 5 to 7, characterized in that the decentralized energy system (3), taking into account the local grid voltage (Ul) and the voltage thresholds (Us) feeds electrical energy into the power grid (4). 9. The method according to any one of claims 5 to 8, characterized in that the decentralized energy system (3), taking into account the local mains voltage (Ul) and the voltage thresholds (Us) electrical energy from the power grid (4) stores. 10. The method according to any one of claims 5 to 9, characterized in that the lower value of the voltage thresholds (Us2) as a value between the average local grid voltage (Ud) over a defined period of time and the lowest value of the local grid voltage (Un) in a defined Period is determined. -14- 11. The method according to any one of claims 5 to 10, characterized in that the higher value of the voltage threshold values (Usl) as a value between the average local grid voltage (Ud) over a defined period of time and the highest value of the local grid voltage (Uh) in one determined period. 12. The method according to any one of claims 5 to 11, characterized in that for the period in which the network frequency (Fl) is lower than a predetermined lower network frequency limit (Fs2), the higher value of the voltage thresholds (Usl) and the lower value of the voltage thresholds (Us2) can be increased by a predetermined factor. 13. The method according to any one of claims 5 to 12, characterized in that for the period in which the grid frequency (Fl) is higher than a predetermined higher grid frequency limit (Fsl), the higher value of the voltage thresholds (Usl) and the lower value of Spannungsscbwressenwerte (Us2) can be reduced by a predetermined factor. 14. The method according to any one of claims 10,12 or 13, characterized in that for the period in which the local mains voltage (Ul) is lower than the lower value of the voltage thresholds (Us2), the decentralized energy system (3) electrical energy in the Power supply (4) feeds. 15. The method according to any one of claims 11,12 or 13, characterized in that for the period in which the local mains voltage (Ul) higher than the higher value of the voltage thresholds (Usl) is the decentralized energy system (3) electrical energy from the Power grid (4) stores. -15-