DE102011010791A1 - Grid-connected system for local production of renewable electric energy, has power management unit having local energy storage connected to local load and external power supply system - Google Patents

Abstract

The grid-connected system (1) has solar generator (2) connected to intelligent power management unit (9) having maximum power point tracker (MPP-T) charge controller (3), power inverter (4) and adjustable distributor (8). The power management unit has local energy storage (5) that is connected to local load (6) and external power supply system (7). A control unit measuring unit to measure a target output of a consumption alternating current to readjust direct current from the solar generator and/or the energy storage as required by the inverter. An independent claim is included for method for operating grid-connected system.

Description

The invention relates to a grid-connected system for the local generation of renewable electrical energy with a solar generator and a grid inverter. Furthermore, the invention relates to a method for operating a grid-connected system for the local generation of renewable electrical energy.

Grid-connected photovoltaic systems with mains-stirred inverters are known from the prior art, the solar generators are arranged, for example, on roofs of single or multi-family homes. In these systems, the solar power generated by the solar generator is fed directly to an inverter and fed without intermediate storage in the power grid of a consumer. Unconsumed solar power goes directly into the grid of a power company. The non-self-used solar power is paid by the energy supply company. In return, the electricity demand, which arises in times of no or only low power of the solar generator, from the power grid of the utility company related. This leads partly to high feed-in of photovoltaic systems in the power grid of the energy supply companies. Throughout the year, a full supply of solar power is often achieved, but by no means at all times. This sometimes leads to problems with the existing infrastructure of the existing electricity networks of the energy supply companies, as these are temporarily overloaded. Especially at high solar radiation and many grid-connected photovoltaic systems, high peak currents occur in the summer at noon. These peak currents are also the yardstick for the design of the infrastructure to be provided by the photovoltaic system operator, ie. H. These current peaks essentially define the power of the inverter to be provided. On the other hand, the weather and daytime dependent energy feeds lead to considerable problems in the regulation of conventional power plants. Finally, it is for the operator of a photovoltaic system on the one hand unsatisfactory and on the other expensive, with little or no sunlight to buy electricity from the power companies.

From the DE 196 30 432 A1 is a grid-connected photovoltaic system with power generator part and a network coupling part and an electrical energy storage part known. The energy storage part can be controlled from the power generator part in times of low power consumption and controlled deliver in times of high power demand electrical energy to the network coupling part with inverter. The aim is to cut peak loads in the case of large electricity grids connected to the public grid, but also to energy suppliers themselves.

The DE 42 15 550 A1 describes a method in which the direct current from a DC generator, if necessary, directly supplied to a DC storage and stored there and, if necessary, withdrawn from there and fed and transformed in the AC network is fed. In this case, the direct current generated by the DC generator is fed via Stormrichter and transformer in the AC grid. Alternatively, the power is supplied to the DC storage and only when needed from there, the stored electrical energy via converter and transformer fed into the grid. The purpose of this energy storage is a secondary reserve power available within seconds.

The DE 10 2008 059 293 A1 describes a steady, uninterruptible power supply of a consumer of a photovoltaic system with a battery buffer memory. The power supply should be independent of the power supply in daylight.

The invention is therefore based on the object to avoid the disadvantages of the known solutions of the prior art and to provide an improved grid-connected system for generating renewable electrical energy. In addition, a method for operating a grid-connected system for generating renewable electrical energy is to be presented.

This object is achieved by a grid-connected system for the local generation of renewable electrical energy with the features of claim 1. Advantageous embodiments and further developments of the invention are specified in the dependent claims.

According to the invention, a grid-connected system for the local generation of regenerative electrical energy with a solar generator and a grid inverter is provided, further comprising an intelligent power management unit with a control unit, a MPP-T (Maximum Power Point Tracker) charge controller and a local energy storage is provided.

An advantageous development of the invention provides that the solar generator is connected via the MPP-T charge controller with the energy storage and the grid inverter.

A further advantageous development of the invention provides that the control unit has means for measuring a nominal power of a local consumption alternating current to DC to track the solar generator and / or the energy storage to the inverter as needed. In addition, parameters such as the anticipated generation of solar power (daily gear) from external information sources, such as the Internet, can be used.

Yet another advantageous development of the invention provides that the control unit has a logic circuit which, in the event that the desired power P SOLL is less than a power of the solar generator, supplies the excess power to the energy store, and in the case that the SOLL power P SOLL is greater than the power of the solar generator, the difference DELTA P from energy storage and / or from the network of a power company relates.

A further advantageous development of the invention provides that the grid inverter is designed for maximum consumption in a household or commercial enterprise. For example, in the case of a four-person household this can be a power per household of preferably 2-7 kW, particularly preferably of 3-5 kW.

Yet another advantageous development of the invention provides that the energy storage is designed as a daily storage with a storage capacity for a maximum night-time consumption in a household or commercial enterprise. This can for example be a storage capacity of preferably 5-20 kWh, particularly preferably 10-15 kWh for a four-person household per household, so that the power requirement for the night is stored. The energy storage device may preferably be a stationary battery with high cycle stability and high charge / discharge efficiency, for example Li-ion, NiMH or NaS batteries, but also lead-acid batteries, etc.

Finally, an advantageous development of the invention provides that at maximum power generation of the solar generator 1/3 of the power via the controllable grid inverter into the power grid (A) and 2/3 of the power are passed into the energy storage. The power inverter has 1/3 of the power of the solar generator as maximum power.

An intelligent power management unit that includes a Maximum Power Point Tracker (MPP-T) charge controller, a grid inverter, and a controllable distributor, with connections for the introduction of DC power from a regenerative generator and connections for the discharge of DC power are provided from an energy store to the MPP-T charge controller is characterized in that the MPP-T charge controller is connected to the power inverter and that the power inverter has a regulated distributor, the connections for the supply of alternating current to a consumer and connections for supplying or receiving AC power from an external power grid to control the delivery of the generated AC power to a load and / or an external power grid.

An advantageous further development of the intelligent power management unit provides that connections for measuring signals of a demand current are also provided in order to enable needs-based storage and / or conversion of direct current.

Yet another advantageous development of the intelligent power management unit provides that a local energy store is furthermore provided as an integral part of the intelligent power management unit. This provides a particularly compact power management unit that is easy to install and maintain.

• – Ermitteln eines Bedarfsstroms eines Verbrauchers;
• – Weiterleitung von Gleichstrom an einen Netzwechselrichter;
• – Abgabe des erzeugten Wechselstroms an den Verbraucher.

An inventive method for operating a grid-connected system for the local generation of regenerative electrical energy comprises the following steps

• - determining a demand flow of a consumer;
• - Forwarding of DC power to a network inverter;
• - Delivery of the generated alternating current to the consumer.

The invention will be described in more detail below together with the description of a preferred embodiment with reference to FIGS. Show it:

1 a schematic block diagram of a grid-connected system for generating renewable electrical energy with a smart power management unit according to the present invention;

2 a schematic block diagram of a grid-connected system for regenerative electrical energy of the prior art.

Embodiment 1: Increase of self-consumed solar power

The power of the consumption current B is measured and the controllable grid inverter generates exactly this power A. If more power is generated by the solar generator than power A is required, the remaining solar power goes into the power storage. If more is needed in consumption than the solar generator brings power, then comes the remaining electricity for A from the electricity storage. Result in normal operation: No electricity purchased from the grid of the energy supply company (RU). No electricity supplied to the grid of the utility company. The solar energy just generated or stored is provided primarily for self-consumption. This increases the proportion of self-consumed solar power. By means of forecasts from external sources, for example from Internet sites, about future solar power generation and a learning logic circuit for determining the load load profile, the system can be further regulated to optimize self-consumption. If the power storage is fully charged, the entire solar power of the solar generator is converted into AC A and fed. This means that part of the solar power goes into the grid of the energy supply company. If the power storage is empty, the controllable grid inverter switches off and the consumption current comes directly from the grid C of the power company. The power storage is designed in the present embodiment as daily storage, so that the power requirements for the night is stored. In private households, the power storage thus has about 5-20 kWh storage capacity.

Exemplary embodiment 2: Reduction of the connected load

In many places, the power lines of the power company network are at the power limit. Especially at high solar radiation and many grid-connected photovoltaic systems without electricity storage high current peaks occur in the summer at noon. The maximum power and thus the current peaks can be minimized by the grid-connected system according to the invention for the local generation of regenerative electrical energy and control 2. At full load of the solar generator 1/3 of the power flows through the controllable grid inverter into the power grid of the utility company A, 2/3 go into the power storage. If the solar generator supplies less than 1/3 of the maximum power, the controllable mains inverter will continue to be operated at full load. The additional power comes from the power storage. At night, the remaining (stored) solar power is fed into the grid. Result: On some days, the inverter power is fed into the utility grid for 24 hours. Since this only has 1/3 of the solar generator power, the new system technology reduces the peak current by 66%! The controllable power inverter requires an output power of only 1/3 of the solar generator power. The power storage must be so large that 2/3 of the solar power generation can be recorded on a beautiful summer's day.

Exemplary Embodiment 3 Optimization in Smart Metering

In the future, consumer electricity prices will be time- and supply-dependent, and may also introduce time and supply-based compensation for solar power. The grid-connected system according to the invention for the local generation of regenerative electrical energy preferably supplies the consumers with directly generated and / or stored solar power in times with a high power purchase price and feeds into the power grid with a high remuneration price. For this purpose, the grid inverter receives via an interface, eg. To the Internet, to an intelligent electricity meter or other intelligent intermediate devices, data on the current feed and consumption electricity price and the daily cycle of these values. The controllable mains inverter is regulated by the consumption current B, so that the photovoltaic system brings the optimal yield.

The invention is not limited in its execution to the above-mentioned preferred embodiment. Rather, a number of variants is conceivable, which makes use of the claimed in the claims solution even in other types.

LIST OF REFERENCE NUMBERS

1

System for electric power generation

2

solar generator

3

MPP trackers Charge Controller

4

Netwechselrichter

5

energy storage

6

consumer

7

Electricity supply company

8th

Adjustable distributor

9

intelligent power management unit

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 19630432 A1 [0003]
• DE 4215550 A1 [0004]
• DE 102008059293 A1 [0005]

Claims (11)

Networked system ( 1 ) for the local generation of renewable electrical energy with a solar generator ( 2 ), characterized in that the solar generator with an intelligent power management unit ( 9 ), which is an MPP-T (Maximum Power Point Tracker) charge controller ( 3 ), a network inverter ( 4 ) and a controllable distributor ( 8th ), wherein the power management unit ( 9 ) with a local energy store ( 5 ), a local consumer ( 6 ) and an external power grid ( 7 ) connected is. Grid-connected system for local generation of renewable electrical energy according to claim 1, wherein the solar generator is connected via the MPP-T charge controller with the energy storage and the grid inverter. Grid-connected system for the local generation of renewable electrical energy according to claim 1 or 2, wherein the control unit comprises means for measuring a nominal power of a local consumption AC power to track DC from the solar generator and / or the energy storage to the inverter as needed. A grid coupled regenerative electrical energy generation system according to any one of claims 1-3, wherein the control unit comprises a logic circuit which, in the event that the desired power P SOLL is less than a power of the solar generator, supplies the excess power to the energy storage; Case that the SOLL power P SOLL is greater than the power of the solar generator, the difference DELTA P from the energy storage and / or from the network of a power company relates. Grid-connected system for the local generation of regenerative electrical energy according to one of the preceding claims, wherein the grid inverter is designed for maximum consumption in a household or commercial enterprise. Grid-connected system for the local generation of renewable electrical energy according to one of the preceding claims, wherein the energy storage is designed as a daily storage with a storage capacity for a maximum night-time consumption in a household or commercial enterprise. Grid-connected system for the local generation of renewable electrical energy according to claim 1, wherein at maximum power generation of the solar generator 1/3 of the power via the controllable grid inverter into the power grid (A) and 2/3 of the power are passed into the energy storage. Intelligent power management unit ( 9 ), which contains a MPP-T (Maximum Power Point Tracker) charge controller ( 3 ), a network inverter ( 4 ) and a controllable distributor ( 8th ), wherein connections for the introduction of direct current from a regenerative generator and connections for the introduction or withdrawal of direct current from an energy store at the MPP-T charge controller ( 3 ), the MPP-T charge controller ( 3 ) with the network inverter ( 4 ) and wherein the network inverter ( 4 ) a regulated distributor ( 8th ) having connections for the supply of alternating current to a consumer and terminals for the supply or recording of alternating current from an external power network to control the delivery of the generated alternating current to a consumer and / or an external power grid. Intelligent power management unit ( 9 ) according to claim 8, further comprising terminals for measuring signals of a demand current, in order to enable needs-based storage and / or conversion of direct current. Intelligent power management unit ( 9 ) according to claim 8 or 9, further comprising a local energy store ( 5 ) as an integral part of the intelligent power management unit ( 9 ) is provided. Method for operating a grid-connected system for the local generation of regenerative electrical energy, comprising the following steps: - determining a demand flow of a consumer; - Forwarding of DC power to a network inverter; - Delivery of the generated alternating current to the consumer.

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