An embodiment of invention generally relates to a power plant installation having an infeed connection, for feeding energy into an external energy supply grid, and at least one energy-generating unit, for generating electrical energy.
The prior connection practice of what in the specialist language are called renewable energies (RE) is inadequate, and results in ever greater problems in the electrical energy supply grid. These problems are characterized by two significant aspects: infeed that fluctuates with time, and connection points that, for the grid, are randomly distributed. Owing to this connection practice, renewable energies at present do not constitute a replacement for conventional power plants. Moreover, reliability of supply is jeopardized, e.g. because of overloading of operating equipment and voltage range deviations, and high fluctuations occur in the price of electricity, sometimes even negative electricity prices.
Hitherto, there has been no known holistic approach to solving the above-mentioned problem. Mostly, only partial aspects are solved, or the symptoms, rather than the causes, are remedied. Thus, for example, the use of intelligent operating equipment, such as controllable distribution transformers, solves only the symptom “voltage range deviation”, but not the cause thereof.
Although further so-called “smart grid” approaches, such as adjusting the load to the generation (called “demand side management” in the specialist language) do contribute somewhat toward the evening-out of fluctuating infeed, they likewise do not solve the fundamental problem since, to maintain most commercial and social processes, it is still necessary for generation to follow demand, and not vice versa. Also, the increased use of information technology, smart meters etc. does not remedy the main problem of regenerative infeed, namely, the fluctuating character and its local distribution.
A further known solution approach resides in grid expansion (in particular in the distribution grid), if regenerative infeeds can overload operating equipment or jeopardize the (n−1) reliability. Although local bottlenecks are remedied as a result, these measures are nevertheless very expensive and often over-dimensioned, since they are not designed for the nominal power of the regenerative infeeds, even if the latter occur only at a few points in the year. Also not to be disregarded is the problem of acceptance of new electricity lines in the population.
The inventors recognize that So-called “virtual” power plants address the problem of fluctuating infeed in that, by corresponding coordination of spatially distributed infeeds and storages, they cause an infeed behavior to be generated that can be regulated in aggregate. This, however, necessitates a large amount of communication resource. However, the randomly distributed connection of the operating equipment in the grid and the problems associated therewith—such as jeopardized reliability of supply, voltage range deviations, high grid expansion costs, etc.—are not remedied.
Overall, therefore, the inventors recognize at present there is not yet any concept that fully addresses and remedies the problems of regenerative infeed.
At least one embodiment of the invention accordingly includes specifying a power plant installation in which at least one of the above-mentioned problems in the infeed of regenerative energy are reduced in comparison with conventional power plant installations.
At least one embodiment of the invention is directed to a power plant installation. Advantageous developments of the power plant installation according to the invention are specified in dependent claims.
It is accordingly provided, according to at least one embodiment of the invention, that the power plant installation has at least one energy-generating unit, at least one energy storage unit, and at least one decoupled sub-grid, which is connected to the infeed connection via a converter of the power plant installation and is electrically decoupled from the infeed connection and the external energy supply grid by the converter, the at least one energy-generating unit and/or the at least one energy storage unit are connected to the decoupled sub-grid, and the power plant installation has a controller that, by controlling the converter, the energy generating unit and/or the energy storage unit, adjusts the infeed behavior of the power plant installation acting outwardly on the infeed connection.
At least one embodiment of the invention additionally relates to a method for operating a power plant installation that is connected to an external energy supply grid via an infeed connection and that has at least one energy-generating unit.
With regard to such a method, it is provided according to at least one embodiment of the invention that the energy of the at least one energy-generating unit and/or energy of at least one energy storage unit of the power plant installation is fed into an own sub-grid of the power plant, wherein the energy of the at least one energy-generating unit is fed into the external energy supply grid either directly, via the infeed connection, or via a converter and the infeed connection, or -entirely or at least in part—stored intermediately in the at least one energy storage unit.
The invention is explained more fully in the following on the basis of example embodiments, wherein there are shown, by way of example:
For reasons of clarity, in the figures the same references are used in each case for components that are identical or comparable.
It is accordingly provided, according to at least one embodiment of the invention, that the power plant installation has at least one energy-generating unit, at least one energy storage unit, and at least one decoupled sub-grid, which is connected to the infeed connection via a converter of the power plant installation and is electrically decoupled from the infeed connection and the external energy supply grid by the converter, the at least one energy-generating unit and/or the at least one energy storage unit are connected to the decoupled sub-grid, and the power plant installation has a controller that, by controlling the converter, the energy generating unit and/or the energy storage unit, adjusts the infeed behavior of the power plant installation acting outwardly on the infeed connection.
A substantial advantage of the power plant installation according to at least one embodiment of the invention resides in that, owing to the dimensioning of the power plant installation, owing to the provided controlling of the converter, the energy generating unit and/or the energy storage unit, and owing to the provided decoupling of the sub-grid from the external energy supply grid, with regard to the infeed behavior at the common infeed connection, an optimum infeed can be achieved, even with use of regenerative energies. Thus, inside the power plant installation, the problems of energy infeed fluctuating with time can be reduced, and the effect on the external energy supply grid is less than in the case of present installations.
As already mentioned, the power plant installation is particularly suited to the use of regenerative energy-generating units. Accordingly, it is considered to be advantageous if the power plant installation has at least one regenerative energy-generating unit.
Preferably, the power plant installation has at least two regenerative energy-generating units, which differ from each other in respect of their energy-generating characteristic and/or their energy-generating technology. A differing energy-generating characteristic and/or energy-generating technology within the power plant installation helps to minimize fluctuations at the infeed connection. Wind power installations or photovoltaic installations, for example, may be used as regenerative energy-generating units.
Preferably, a reduction of fluctuations is at least also effected by energy storage. In this regard, it is considered to be particularly advantageous if the power plant installation has at least two energy storage units, which differ from each other in respect of their storage characteristic and/or their storage technology. Power-to-gas storages, or batteries, preferably in the form of redox flow batteries or lithium-ion batteries, for example, may be used as energy storage units. For example, lithium-ion and redox flow batteries are suitable as minute-storages and hour-storages; power-to-gas storages are suitable as long-duration storages, and are characterized by a large storage capacity.
Controlling of the energy-generating units and of the energy storage units is preferably effected by way of droop controllers, using electrical state variables, in the decoupled sub-grid, thereby making it possible to avoid the use of additional communication resources between the energy-generating units and/or energy storage units.
It is also considered to be advantageous if at least one sub-grid is directly coupled to the infeed connection of the power plant installation, and at least one energy storage unit and/or at least one energy-generating unit is connected to the directly coupled sub-grid.
Owing to the directly coupled sub-grid, properties of a conventional power plant installation (short-circuit power or mass inertia), can advantageously be integrated into the operating behavior of the power plant installation.
Preferably, the energy storage units connected to the directly coupled sub-grid and the energy-generating units connected to the directly coupled sub-grid each have a communication module that enables communication with the controller.
The controller, the energy storage units and the energy-generating units are preferably realized in such a manner that the power plant installation can run predefined infeed schedules, render predefined grid services and/or provide electrical energy having predefined electrical parameters.
It is also advantageous if the controller, the energy storage units and the energy-generating units are realized in such a manner that the infeed behavior of the power plant installation emulates the infeed behavior of a conventional power plant.
With regard to the disposition of the components, it is considered to be advantageous that the energy storage units and the energy-generating units are disposed at a distance from each other, and may be distributed in an urban area or a larger rural area. The distance between the two components of the power plant installation that are most distant from each other is preferably at least 5 km. The problem of the local distribution of regenerative infeed is thereby remedied, or at least alleviated.
Despite the spatial distribution of the energy storage units and energy-generating units, in comparison with the prior connection practice the requirement for new electricity lines is not substantially increased since at present, already, longer line sections are frequently required for grid connection, and these can be used for constructing a power plant installation according to at least one embodiment of the invention.
At least one embodiment of the invention additionally relates to a method for operating a power plant installation that is connected to an external energy supply grid via an infeed connection and that has at least one energy-generating unit.
With regard to such a method, it is provided according to at least one embodiment of the invention that the energy of the at least one energy-generating unit and/or energy of at least one energy storage unit of the power plant installation is fed into an own sub-grid of the power plant, wherein the energy of the at least one energy-generating unit is fed into the external energy supply grid either directly, via the infeed connection, or via a converter and the infeed connection, or -entirely or at least in part—stored intermediately in the at least one energy storage unit.
Preferably, the energy of the at least one energy storage unit is fed into an own sub-grid of the power plant that that is connected to the infeed connection via a converter of the power plant installation, and that is electrically decoupled from the infeed connection and the external energy supply grid by the converter.
With regard to the advantages of the method according to at least one embodiment of the invention, reference may be made to the explanations above concerning the power plant installation according to at least one embodiment of the invention.
It is considered to be advantageous if the proportion of energy that is stored intermediately is determined in dependence on a predefined infeed schedule or a predefined grid service.
Preferably, the controlling of the converter, the energy-generating units and the energy storage units is effected in such a manner that the infeed behavior of the power plant installation emulates the infeed behavior of a conventional power plant.
Furthermore, the power plant installation 5 according to
The controlling of the energy-generating units and of the energy storage units of the sub-grids 10 and 11, and the controlling of the converters 20 of the sub-grids 10 is effected by a controller 50, which is connected to the energy-generating units, the energy storage units and the converters 20, whether via communication modules, not shown, or via droop controllers, not shown.
In the case of the example embodiment according to
On the one hand, in the case of the example embodiment according to
Furthermore, in the case of the example embodiment according to
It can additionally be seen from both
In particular, the decoupled sub-grids 10 enable the problems of a spatially distributed generation of regenerative energy that fluctuates with time to be significantly alleviated.
For the purpose of decoupling as fully as possible the infeed behavior of the power plant installation 5 at the infeed connection 30 from the fluctuating energy generation of its energy-generating units, various storage technologies are advantageous, which have differing characteristics in respect of storage capacity, dynamics, efficiency, etc. Thus, for example, lithium-ion and redox flow batteries are more suitable as minute and hour storages, whereas P2G systems are more suitable as long-duration storages, having a large storage capacity. The overall behavior can be optimized by corresponding dimensioning and coordination of the individual storages.
The problems of a spatially distributed infeed are solved, or at least alleviated, by the grouping of generating installations in the decoupled sub-grids 10, and by the infeeding at the central infeed connection 30 via the converters 20. As a result, the structure and functioning of the existing energy supply grid can be almost entirely retained. The need for grid expansion measures is significantly reduced.
A further significant aspect of the example embodiment according to
In addition to the hydrogen reconversion in gas turbines or engine-based cogeneration systems (BHKW), it is also optionally possible to use further conventional energy conversion systems that work sequentially (e.g. diesel generators, gas turbines, engine-based cogeneration systems), as well as easily controllable energy loads (e.g. power-to-heat systems, e.g. for generating district heating) in the power plant installation 5 according to
Overall, the power plant installation 5 according to
In the case of the example embodiment for a power plant installation according to an embodiment of the invention in
By contrast, the power plant installations 5 of the example embodiments in
In
The energy-generating units and/or energy storage units connected to the directly coupled sub-grid 11 are controlled by the controller 50, preferably via communication paths, not shown; for this purpose, the energy-generating units and/or energy storage units connected to the directly coupled sub-grid 11, and the controller 50, preferably each have a suitable communication module.
In a manner similar to conventional power plants, the power plant installations 5 according to
A further function of the energy storages resides in evening out the energy generation fluctuations of the fluctuating photovoltaic installations PV, and in evening out the energy generation fluctuations of the wind power installations WKA. Biogas installations BIO are conceivable as further flexible generating installations that may be used.
In
In the case of the example embodiment according to
In the case of the example embodiment according to
Irrespective of the internal realization, with direct current or alternating current, various embodiment types may exist for power plant installations 5, which differ in the extent to which the infeed at the infeed connection 30 is decoupled from the generation of the renewable energies. An overview relating to this is given in the following table, divided according to type:
Accordingly, in the case of a Type 1 power plant installation, the grid infeed and the renewable-energy generation are still coupled to a relatively great extent, despite a decoupled sub-grid, only discrepancies between infeed forecasts and actual renewable-energy generation being evened out.
In the case of a Type 2 power plant installation, grid infeed and renewable-energy generation are partly decoupled, i.e. a limited shifting of the fluctuating generation is possible. The power plant installation is only on the grid at certain times, and therefore is similar to a medium-load or peak-load power plant.
Represented by way of example in
Although the invention has been illustrated more fully and described in detail on the basis of preferred example embodiments, the invention is not limited by the disclosed examples, and other variations may be derived therefrom by persons skilled in the art, without departing from the scope of protection of the invention.
This application is the national phase under 35 U.S.C. § 371 of PCT International Application No. PCT/EP2014/070545 which has an International filing date of Sep. 25, 2014, which designated the United States of America, the entire contents of which are hereby incorporated herein by reference.
Filing Document | Filing Date | Country | Kind |
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PCT/EP2014/070545 | 9/25/2014 | WO | 00 |