EP2777126A1

EP2777126A1 - Method for providing control power, taking into account a variable target frequency

Info

Publication number: EP2777126A1
Application number: EP12781078.6A
Authority: EP
Inventors: Georg Markowz; Carsten Kolligs; Holger BREZSKI; Anna FLEMMING; Dennis GAMRAD; Sébastien COCHET
Original assignee: Evonik Industries AG
Current assignee: Evonik Operations GmbH
Priority date: 2011-11-10
Filing date: 2012-10-30
Publication date: 2014-09-17
Also published as: WO2013068267A1; US20140368039A1; DE102011055251A1

Abstract

The current invention relates to a method for providing control power in order to stabilize an alternating current network, the alternating current network operating at a variable target frequency and comprising at least one decentrally controlled provider of control power which regulates the network frequency to a specified frequency, the specified frequency being adjusted to the target frequency.

Description

Method for providing control power taking into account a variable setpoint frequency

The present invention relates to a method for the provision of control power taking into account a variable nominal frequency and to an apparatus for carrying out such a method.

Electricity grids are used to distribute electricity from many energy generators in large areas to many users and to supply households and industry with energy. Energy producers, usually in the form of power plants, provide the required energy. As a rule, power generation is planned and provided based on the forecasted consumption.

Both the generation and the consumption of energy can lead to unplanned fluctuations. These can arise on the energy producer side, for example, in that a power plant or part of the power grid fails or, for example, in the case of renewable energies such as wind, that the energy production is higher than predicted. Consumers may also experience unexpectedly high or low consumption. For example, the failure of a portion of the grid, which cuts off some consumers from the power supply, can lead to a sudden reduction in power consumption. This generally results in power network fluctuations due to unplanned and / or short-term variations in power generation and / or consumption. The desired AC frequency is, for example, 50 Hz in Europe. A reduction in consumption compared to the plan results in an increase in the frequency at planned power fed in by the energy producers, as well as an increase in electricity production compared to the planned consumption plan. On the other hand, a reduction in the output of the energy producers compared to the plan leads to a reduction of the network frequency at scheduled consumption, as well as to an increase in consumption compared to the plan at scheduled production. For reasons of network stability, it is necessary to keep these deviations within a defined range. For this purpose, depending on the amount and direction of the deviation, it is necessary to provide specifically positive control power by connecting additional generators or switching off consumers, or negative balancing power by shutting down generators or adding consumers. There is a general need for economical and efficient provision of these control powers, where the requirements for the capacities to be kept and the dynamics of the control power sources or sinks can vary depending on the characteristic of the power grid. In Europe, for example, there is a set of rules (UCTE Handbook) that describes three different categories of control power. This also defines the respective requirements and the control power types. The types of balancing power differ, among other things, in the demands on the dynamics and the duration of the service provision. In addition, they are used differently with respect to the boundary conditions. Primary control power (PRL) is to be provided by all integrated sources throughout Europe, regardless of the location of the disturbance, substantially in proportion to the actual frequency deviation. The absolute maximum power is to be provided at frequency deviations of minus 200 mHz and (absolute) below, the absolute minimum power is to be provided at frequency deviations of plus 200 mHz and above. With regard to dynamics, it is necessary to provide the (maximum) performance within 30 seconds from hibernation. In contrast, secondary control power (SRL) and minute reserve power (MRL) are to be provided in the balancing rooms in which the fault has occurred. Their task is to compensate for the disturbance as quickly as possible and thus to ensure that the frequency is back within the desired range as quickly as possible, preferably at the latest after 15 minutes. In terms of dynamics, the SRLs and the MRLs have lower requirements (5 or 15 minutes to full service delivery after activation), and at the same time these services must be provided for longer periods than primary control capacity. In the power grids operated so far, a large part of the control power is provided by conventional power plants, in particular coal and nuclear power plants. Two fundamental problems result from this. On the one hand, the conventional power plants providing control power are not operated at full load and thus maximum efficiencies, but slightly below them in order to be able to provide positive control power if required, if necessary over a theoretically unlimited period of time. On the other hand, with increasing expansion and increasing preferential use of renewable energies, fewer and fewer conventional power plants are in operation, which is often the prerequisite for the provision of balancing services.

For this reason, approaches have been developed to use more memory to store negative control power and provide it as a positive control power when needed.

The use of hydro pumped storage plants to provide control power is state of the art. In Europe, all of the above three types of control are provided by pumped storage. However, hydropumps are also often referred to as the currently most economical technology for the injection and withdrawal of preferably renewable energies, in order to be able to better match the energy supply and demand in terms of time. The potential for expanding storage capacity - especially in Norway - is a matter of controversy, as significant capacity in power lines needs to be approved and installed for use. Consequently, the use for the energy management of load management is in competition with the provision of control power.

Against this background, in the area of primary control power in the recent past, approaches have repeatedly been explored and described for the use of other storage technologies, such as flywheel mass and battery storage, for the provision of control power.

From US 2006/122738 A1 an energy management system is known, which comprises a power generator and an energy store, wherein the energy store can be charged by the power generator. This should be an energy producer, which does not guarantee a uniform power generation in normal operation, such as For example, the increasingly favored renewable energy sources, such as wind power or photovoltaic power plants, will be able to distribute their energy more evenly into the power grid. The disadvantage of this is that in this way a single power plant can be stabilized, but all other disturbances and fluctuations in the power network can not be intercepted or only to a very limited extent.

It is known from WO 2010 042 190 A2 and JP 2008 178 215 A to use energy storage to provide positive and negative control power. When the grid frequency leaves a tolerance range around the desired grid frequency, either energy is provided from the energy store or added to the energy store to regulate the grid frequency. DE 10 2008 046 747 A1 also proposes operating an energy store in an island power grid in such a way that the energy store is used to compensate for consumption peaks and consumption minima. The disadvantage hereof is that the energy stores do not have the necessary capacity to compensate for a longer disturbance or a plurality of disturbances rectified with respect to the frequency deviation one after the other.

In the article "Optimizing a Battery Energy Storage System for Primary Frequency Control" by Oudalov et al., In IEEE Transactions on Power Systems, Vol. 22, No. 3, August 2007, dependency of the capacity of a rechargeable battery of technical and operational It is shown that due to the injection and withdrawal losses in the long term at different time intervals repeatedly charging or discharging the memory is unavoidable, the authors suggest the time periods Although the frequency may be in the deadband (ie in the frequency range where there is no control power available), it may happen temporarily or temporarily that the memory becomes overloaded, and the authors suggest that (limited Use) of loss-generating resistors, which extremal the complete negative nominal Regelei record, so have to be interpreted. In addition to the additional investment required for the resistors and their cooling, however, this leads, as of The authors themselves already called, to a more or less unwanted energy depreciation, the resulting waste heat can not be used in the rule. The authors point out that a lower utilization of loss production is only possible through a higher storage capacity, combined with higher investment costs.

Accumulators and other energy stores can absorb or release energy very quickly, making them basically suitable for providing PRL. A disadvantage, however, is that very large capacities of the batteries must be provided in order to deliver the control power over a longer period or repeatedly. However, very large capacity batteries are also very expensive.

Due to the losses during storage and withdrawal of energy takes place at statistically symmetrical deviation of the mains frequencies from the setpoint by the operation sooner or later a discharge of the energy storage, such as a battery. It is therefore necessary to recharge the energy storage more or less regularly targeted. It may be necessary to pay for this charging current separately.

The relatively constant network frequency of AC networks, which are regulated, for example, according to the methods set out above, can be used as a timer for determining a so-called network or synchronous time or for the operation of clocks. However, due to the fact that the frequency deviations are distributed statistically, especially over shorter periods of a few hours to days not ideal symmetric around the value zero, it comes to deviations of the network time from the coordinated world time, which is determined today by means of atomic clocks. If, for example, positive frequency deviations from the setpoint value over a period of time prevail, the mains time is ahead of the world time. Conversely, the network time runs after mostly negative frequency deviations of the world time. In order to have the network time determined via the AC mains deviate only to a limited extent from the world time or to provide the possibly subsequently regulated clocks with a high accuracy, the nominal frequency at which the AC grids are operated, as required of time deliberately slightly changed at the time. However, this change has so far only been taken into account by the centrally controlled control power suppliers, who usually provide the secondary control power (SRL) or the minute reserve power (MRL) set out above. In this regard, it should be noted that these control power suppliers can generally, in particular, provide higher power than the usual locally controlled primary control power (PRL) sources.

It has been found within the scope of the invention that sometimes considerable quantities of energy are monotonously fed in or out, as shown by an analysis of real frequency characteristics of the inventors. For a given storage capacity, this leads to a correspondingly high charge state change. In turn, large state of charge changes tend to cause faster aging than low state of charge changes. Either the energy store thus reaches its end of life rather than having to be replaced, or the capacity is to be increased a priori in order to reduce the relative state of charge change. Both lead to an increase in investment costs.

In addition, a consistent adherence to the guidelines for the prequalification of primary control technologies requires the availability of sufficient power reserves at any operating time and thus the state of charge of the energy storage. This requirement (currently in Germany: the marketed primary control power over a period of 15 minutes) means that in addition a corresponding, increase in investment costs capacity must be maintained. In fact, such a reserve would be used very rarely (statistically).

In view of the prior art, it is therefore an object of the present invention to provide a technically improved method for providing control power for stabilizing an AC network, which does not involve the disadvantages of conventional methods.

In particular, the process should be as simple and inexpensive as possible. In particular, the installations with which the procedure can be carried out should be associated with the least possible investment in terms of the provision of control power. It should be possible to provide control power at a high efficiency of the components used.

Another object of the invention is to be seen in that the capacity of the energy storage device should be as low as possible in order to provide the required control power.

In addition, it would also be advantageous if a lower aging load could be achieved. Furthermore, the provision of primary control power while avoiding intermediate charging or discharging would also be desirable. Alternatively, it would be desirable to at least reduce the number of charging or discharging operations required to maintain operability.

Furthermore, it is an object of the present invention to find a method in which the described disturbances of the power network and at the same time trading operations are avoided or reduced. Furthermore, the process should be as simple and inexpensive as possible.

In addition, the energy producers and energy consumers should have the most efficient possible energy yield as control power suppliers.

The inventive method should also be able to provide the necessary control power as needed as quickly as possible. Furthermore, the process should be able to be carried out with as few process steps as possible, whereby they should be simple and reproducible.

Other tasks not explicitly mentioned emerge from the overall context of the following description and the claims. These are solved as well as other tasks that are not explicitly mentioned, but which are readily derivable or deducible from the contexts discussed in the introduction, by a method having all the features of patent claim 1. Expedient modifications of the method according to the invention for the provision of control power for a power supply are provided in the subclaims 2 to 15 under protection. Furthermore, claim 16 and 17 have an apparatus for performing such a method to the subject.

The subject of the present invention is accordingly a method for the provision of control power for stabilizing an AC network, wherein the AC mains operates at a variable setpoint frequency, and the AC mains comprises at least one decentralized regulated power supplier controlling the mains frequency to a default frequency, characterized in that the default frequency is adjusted to the nominal frequency. By means of the method according to the invention, it is possible in an unforeseeable manner to provide a method for the provision of control power for the stabilization of an AC network, which does not involve the disadvantages of conventional methods.

In particular, the present invention allows to provide control power with a high efficiency of the components used.

Furthermore, with the use of galvanic elements, such as accumulators, the capacity of the energy storage can be kept very low in order to provide a required control power.

Furthermore, the energy producers and energy consumers have a very efficient energy yield as a control power suppliers.

The inventive method is also suitable to provide the necessary control power very quickly.

In particular, the method can be carried out as simply and inexpensively as the storage capacity required for full availability can be reduced or the number of charging and discharging, which must be made to adjust the state of charge of the energy storage with external energy sources or sinks are reduced can. It should be noted that the energy storage through the power network through energy trading performance can relate. This service must be purchased and recalled at a specific time, otherwise the system will malfunction. Actual grid frequency is insignificant for this process as it does not affect the frequency of the grid in the case of a planned, simultaneous feed-in and take-out of a power. Rather, it is important that the feed-in and the removal of this power take place as synchronously as possible. With a constant capacity of the energy storage, as a result of the reduced charging / discharging cycles, the operational life of the storage can be increased, this being an important consideration, in particular for accumulators, which can be surprisingly improved by the present invention.

Furthermore, the control power suppliers, in particular the energy producers and / or energy consumers, independently of the height and direction of the deviation of the network frequency, can purposefully provide a sufficient amount of positive or negative control power. Moreover, the process can be carried out with very few process steps, the same being simple and reproducible.

The present method serves to provide control power for stabilizing an AC network. As already explained in the introduction, the frequency changes in an AC grid if the balance between energy consumption and energy supply is not maintained.

The control energy or control power is delivered to the power grid (positive control energy or positive control power) or taken from the mains (negative control energy or negative control power). Positive control power can be supplied by energy supply, such as energy input of an energy storage or by connecting a power plant, or by throttling a consumer in the network. Negative control power may be supplied to the grid by absorbing energy from an energy store, throttling an energy source, such as a power plant, or by connecting a load to the grid. Further important information can be found in the prior art, with particular reference to the documents discussed in the introduction Reference is made. In this context, it should be noted that the terms control power and control power have similar meaning for purposes of this invention.

Normally, control power for a given nominal power is provided by the provider to the network operator. In this case, the nominal power is to be understood as meaning the power with which the control power source, which is operated by a method according to the invention, is at least prequalified. However, the prequalification performance may be higher than the nominal power provided to the network operator at maximum. This nominal power can also be referred to as contracted maximum power, as this power is provided to the grid at maximum.

The method according to the invention serves to stabilize an AC network. AC grids are characterized by a change in the polarity of the electrical current, with positive and negative instantaneous values complementing each other so that the current is zero on average over time. These networks are generally used for the transmission of electrical energy.

Usually, the AC grids are operated at a nominal frequency that is currently in Europe, especially in Germany, at 50,000 Hz. In contrast, in North America the nominal frequency is 60,000 Hz. As stated earlier, this nominal frequency is currently not fixed, but is slightly varied in order to adapt the so-called network time, which inter alia serves as a clock timer, to the coordinated world time. Consequently, such an alternating current network operates at a variable nominal frequency. According to current standards in Europe, with a deviation of ± 20 seconds between mains time and world time, the setpoint frequency is lowered or increased by 10 mHz, depending on the grid time deviation, so that the setpoint frequency is currently 49,990 Hz, 50,000 Hz or 50,010 Hz can take. This adjustment is made centrally by the grid operator and taken into account when using secondary control power (SRL) and minute reserve power (MRL). In this context, it should be noted that the setting of the setpoint frequency when using secondary control power or minute reserve power does not necessarily require a measurement of the mains frequency in the control power sources and must be made by the latter itself. At present, for example, the current account is used to control the use of the named service providers. Thus, the primary service is provided in solidarity throughout the European network, whereas the secondary control power and the minute reserve power are each requested for parts of the network by the responsible network operator. Accordingly, the transmission of power between the different networks of the European interconnected network and a deviation between forecast and actual values for generation and consumption is determined and used to request the secondary control power and / or the minute reserve power. Previously, there is generally a correction of the balance sheet with regard to the primary control power provided at the time in question. The power level to be corrected is determined on the basis of the deviation of the mains frequency from the current setpoint. This regulation requires an adjustment of the nominal frequency of the network by the network operator.

The data set forth above with regard to the reference frequencies and the data for adapting the network time to the world time are merely illustrative, without the invention being restricted thereto. If necessary, these values may differ.

Furthermore, the network frequency of decentralized regulated power supplier is regulated to a default frequency. In this case, the network operator usually defines frequency ranges around this predefined frequency beyond which positive or negative control power must be provided. In this case, these frequency ranges are of relevance, in particular for providers of primary control power, since primary control power is generally controlled in a decentralized manner by the provider of the primary control power. Exact details can be found in European standards (Handbook), which are used to operate the European network system UCTE (Union for the Co-ordination of Transmission of Electricity). were developed and implemented in national guidelines (eg Transmission Code for Germany).

At present, there are two tolerances for sources of primary control power that are relevant to frequency deviations. First, this is the frequency measurement accuracy. This must not exceed +/- 10 mHz. In addition, there is a so-called insensitivity range of a maximum of +/- 10 mHz, which is granted to the primary control power sources. In order to avoid operating the control power sources in any case contrary to the desired direction, the transmission system operators in Germany have specified in their framework contracts, for example, a band of +/- 10 mHz around the setpoint of 50 Hz, in which no primary control power is to be provided. Even at maximum frequency accuracy of + 10 mHz or - 10 mHz, the provision of control power against the desired direction is excluded. Outside these limits, reserve power must be provided in accordance with the terms of the contract.

However, changing the set frequency to match the mains time to world time may cause decentralized control power suppliers to act against the desired direction to adjust the grid time, thereby extending the time required to adjust the grid time to world time, though the relevant provision of the standard power to stabilize the network is not yet required. For example, if the world time's network time is more than 20 seconds ahead, an overall reduction in frequency is required to achieve an adjustment. The setpoint is set to 49.990 Hz for this purpose. For example, if the current frequency is 49.985 Hz, a decentralized control power generator will provide a positive control power according to the deviation from the standard target frequency (50,000 Hz) since the deviation is more than 10 mHz. This positive control power tends to increase the frequency and thus speed up the grid time. On the basis of the new setpoint and taking into account the frequency band of +/- 10 mHz, however, there would still be no reason for the provision of positive control power (deviation from the new setpoint below 10 mHz), the frequency would be exceeded by providing Control power does not tend to be raised and thus adapt the grid time to the world time faster.

The frequency to which decentralized control power suppliers regulate, preferably primary control power generators, is referred to here as the default frequency in order to distinguish it from the nominal frequency explained in more detail above. This default frequency has been kept constant, with this value currently around 50,000 Hz in Europe. According to the present invention, since the decentralized control power suppliers can now apply a default frequency adapted to the variable set frequency, the term "common default frequency" is used to distinguish the standard value of the frequency with which the AC power network operates For a deliberate, targeted influencing of the course of the network frequency, for example, to adapt the network time to the coordinated world time, the standard target frequency is varied.

In general, a dead band is set by the default frequency required for the contractual provision of control power, as stated above.

In this context, it should be noted that less the type of control power is essential to the invention, but rather the centralized or decentralized control thereof. The terms decentralized and centralized should clarify that the regulation takes place in two fundamentally different ways, whereby in one case, in general, the operator of the respective network or a corresponding entity is responsible for activating part of the provision of control power. By contrast, the regulation of a further part of the control power supply is controlled by one or more further entities, for example one or more providers of primary control power, in any case independently of the grid operator. In this case, an instance can control one or more primary control power sources, which can, for example, form a network. According to a preferred variant, the control power supplier operating at the default frequency can provide primary control power. For centralized control of the setpoint frequency, the AC network can include at least one supplier for secondary control power and / or minute reserve power, wherein the activation of the supplier for secondary control power and / or minute reserve power taking into account the variable target frequency.

The invention is based on the surprising finding that an adaptation of the default frequency to which a decentralized regulated power supplier regulates the grid frequency to the nominal frequency with which the AC grid is operated leads to unexpected improvements, in particular during operation of energy stores.

Thus, surprisingly, the number of charging / discharging cycles during operation for the required adaptation of the state of charge can be reduced and / or the required capacity of energy stores can be minimized, whereby a lower aging load can be achieved. For this purpose, it should be noted that when the default frequency is adapted to the current setpoint frequency, an action contrary to the desired direction of adaptation of the network time to the world time is excluded.

The adjustment of the default frequency can be carried out according to a preferred embodiment, that the target frequency is transmitted to the decentralized control power supplier. In this case, the network operator can actively send this data to the control power supplier. Alternatively, the nominal frequency of the AC network can be queried by the control of the decentralized control power provider. Optionally, both methods can be used in a coordinated fashion to ensure greater reliability. For this purpose, the target frequency can be transmitted, for example, by telecommunications to the control power suppliers, and this can also be done automatically, for example, using computers and corresponding data transmission, for example via the Internet. The transmission of the nominal frequency should take place as soon as possible, so that the setpoint frequency currently set by the network operator can be used in the adaptation thereto by the decentrally controlled control power supplier. It should be noted that currently planning for a possible adjustment of the network time to the coordinated world time takes place several hours before the actual changeover and then applies for the minimum period of 24 hours. Accordingly, the term "near real-time" means that the decentralized control power supplier the necessary information about the duration and the time of switching the standard target frequency to a deviating target frequency is notified in sufficient time that this information can be taken into account when setting the default frequency The necessary information is communicated to the control power supplier for at least 15 minutes, particularly preferably at least 1 hour, especially preferably at least 6 hours before the actual changeover. The necessary information includes, for example, the level of the change of the frequency setpoint, the time and the duration of the changeover of the setpoint frequency ,

In a preferred embodiment it can be provided that, in the case of transmission errors, for example a failure of the data transmission, the primary control power sources default to the usual default frequency, that is, as before.

Furthermore, it can be provided that a deviation between the nominal frequency and the preset frequency is determined by a permanent frequency deviation of the network frequency outside a frequency band over a defined period of time.

The bandwidth of the frequency band, which is used to assess a permanent frequency deviation is not critical to the present invention and can be adapted accordingly to the requirements of the network operator. In this case, the frequency band used according to the invention for determining a deviation between the nominal frequency and the preset frequency may differ from the frequency range which serves to describe the provision of control power in accordance with the standard specifications. So will be in the following the term deadband is used to demonstrate the provision of a control power according to the standard specifications, whereas the term frequency band describes a range of frequencies used to determine whether there is a deviation between desired frequency and default frequency, as described below.

In this case, the frequency band which is defined by the predefined frequency can correspond to the dead band; it can alternatively be larger than the dead band. According to a preferred alternative, the deadband may be larger than the frequency band. In this context, it should be noted that the primary control power generators generally control to a fixed default frequency, while the secondary control power providers, when adjusting the mains time to the coordinated world time, control to a target frequency that differs by ± 10 mHz from the default frequency. It should be remembered that at least a portion of the primary control power provider can provide control power against the control by the secondary control power provider. Accordingly, the average network frequency will generally deviate less from the default frequency than the target frequency if no unexpected network disturbances occur.

For example, the frequency band may preferably have a width of at most 18 MHz, preferably at most 16 MHz, particularly preferably at most 14 MHz and especially preferably at most 12 MHz. This results in frequency bands which, for example, in Europe preferably in the range from 49.991 Hz to 50.009 Hz, preferably m range from 49.992 Hz to 50.008 Hz, more preferably m range from 49.993 Hz to 50.007 Hz and especially preferably m range from 49.994 Hz to 50.006 Hz lie.

Depending on the variation of the standard target frequency, this frequency band may also be larger than the deadband. For example, if the deadband is defined to be narrower than the values set forth above, but the values set forth above for equalizing the network time to the coordinated world time are preserved, it may be desirable to choose the frequency band broader. It should be noted that the previously described values for explaining the present invention, without being limited thereto. Much less is therefore the deadband, but rather the range of variation of the nominal frequency.

Preferably, a unit with a high measuring accuracy can be used to determine the network frequency, in particular the average network frequency. A particularly preferred embodiment of the invention may provide that the frequency deviation is measured with an inaccuracy of a maximum of ± 8 mHz, more preferably of a maximum of ± 4 mHz, most preferably of a maximum of ± 2 mHz, even more preferably of a maximum of ± 1 mHz. According to the present invention, with a permanent frequency deviation outside the frequency band over a fixed period of time, an adaptation of the default frequency to the nominal frequency can be undertaken. Accordingly, it is checked whether the network frequency is permanently outside the frequency band defined by the default frequency. In the event of a permanent deviation of the mains frequency over a defined period of time, it is possible to adapt the default frequency to the nominal frequency.

The specified period of time depends on the requirements of the network operator and can accordingly be variable. According to the regulations currently in force in Europe, a primary balancing power source must be able to provide the primary balancing power for a minimum of 15 minutes. In America, other rules apply, and the present invention should not be limited to a particular region or a specific set of rules. Advantageously, the specified period may for example be in the range of 0 minutes to 24 hours, preferably 1 minute to 8 hours, preferably 2 minutes to 1 hour and more preferably 5 minutes to 30 minutes.

A permanent frequency deviation outside the frequency band is given if, over the predetermined period of time set out above, the network frequency is at least 60%, preferably at least 80%, preferably at least 90%, especially preferably at least 95% and particularly preferably at least 99% on one side above or below the frequency band lies. According to a special preferred embodiment means a permanent frequency deviation outside the frequency band, that the frequency is outside the frequency band over the entire period.

If there is a permanent frequency deviation outside the frequency band over a specified period of time, a change in the preset frequency of the energy store to a variable control frequency, in particular a variable nominal frequency, can take place after this specified period of time. In this case, it is possible to control to a previously defined frequency which, depending on the deviation, can be above or below the predetermined frequency band. For example, when one of the previously defined conditions, a control frequency can be set, for example, by 5 mHz, 8 mHz, 10 mHz higher or lower than the usual default frequency, depending on the type of previously determined permanent deviation of the mains frequency. Preferably, it is possible to control to an assumed variable target frequency currently in Europe at 49.990 Hz or 50.000 Hz or 50.010 Hz, which values may be adjusted if necessary.

According to a preferred embodiment, it is possible to determine via a moving average of the network frequency whether an adaptation of the default frequency to a variable nominal frequency can take place. Guiding averaging means that not all data points are used to calculate the mean, but only part of it. Preferably, the moving average is calculated by taking into account the data determined over a period not exceeding three times, preferably not more than twice that of the previously defined period. In particular, it may also only be part of the defined period of time defined above. For example, the time period over which the values for determining the conducting average are collected may be in the range of 3 minutes to 2 hours, preferably 5 minutes to 1 hour and more preferably 10 minutes to 30 minutes. Here, the mean values can be formed in a variety of ways, such as a simple shift, without weighting the data (simple moving average (SMA)). According to a preferred embodiment, a weighted moving average (WMA) in which the younger data is preferably of a higher weight than the older one may be used to determine the variable frequency. Here, a simple weighting can be done or an exponential smoothing can be performed. The number of data points depends on the frequency of the frequency measurement, whereby the average values of the data can be used to reduce the memory space. According to a preferred embodiment, within a period of 1 minute at least 10 data points are formed, which can be used to determine the mean value.

According to a preferred embodiment, an adjustment of the default frequency, preferably operating on a primary control power source to a target frequency, which is preferably used in the activation of a secondary control power source or a source for a minute reserve power, not mandatory, but optional.

According to this embodiment, it can be checked whether a change in the control power supply to a variable setpoint frequency leads to an optimization of the state of charge. In this context, in a corresponding state of charge and a standard control can be maintained, according to the control power is provided at a deviation from the default frequency, although a change to a variable target frequency would be possible. In this case, within a period for which the variable setpoint frequency is changed from a default value to a value deviating therefrom, a multiple adjustment of the default frequency from the original value to a variable setpoint can be made if the adjustment of the default frequency was temporarily canceled during this period.

In a particularly preferred embodiment, the adjustment of the default frequency from the original value to a modified setpoint can be repeated and reversed, even though the setpoint has not been changed during that time. For example, the setpoint can be reduced from 50,000 Hz to 49,990 Hz for the duration of a day and the default frequency can be adjusted at least once to the new value during the same day and reset to the original preset frequency before the end of the day. In a preferred embodiment, the change from the original default frequency to the new setpoint occurs more than once back and forth, at least twice, and at least once back. According to a particular embodiment, the supply of energy in the energy storage may be dependent on the time of day. As a result, a high stability of the network can be ensured even at a high load at certain times of the day. Thus, at peak loads, a regeneration of the energy storage, which would be useful due to the deviation of the mains frequency from the default frequency over a longer period, are excluded.

In a particularly preferred embodiment, the change between the original default frequency and a different desired frequency can be excluded under certain boundary conditions. For example, this can be made dependent on the current frequency gradients (change in frequency deviation with time), the absolute frequency deviation and / or the time of day. In the latter case, a high stability of the network can be ensured even at a high load at certain times of the day. Thus, for example, at peak loads, a regeneration of the energy storage, which would be useful due to the deviation of the mains frequency of the default frequency over a longer period, are excluded.

The deviating from the usual default frequency control can be maintained over any period. A return to the provision of control power according to the standard specifications, in which is regulated to the usual default frequency, can be achieved, for example, that at a given state of charge of a preferred as a control power supplier to be used energy storage, the control is terminated on the variable target frequency.

Furthermore, it can be checked whether the network frequency is without special measures over a longer period in the frequency band, which is defined by the usual default frequency. In this embodiment, the average network frequency can be determined, for example, by a weighted averaging. If this check results in that the average mains frequency is in the frequency band over a longer period of time, the control can be reversed to a variable set frequency, so that it is regulated to the usual default frequency.

This longer period is not subject to any special conditions, so that it can be chosen arbitrarily. For example, this longer period of time may be identical to the specified period of time determined with respect to the permanent frequency deviation. Furthermore, this longer period may also be significantly shorter, so that this period may for example be in the range of 1 second to 1 hour, preferably 1 minute to 30 minutes.

Furthermore, it can be provided that, when the frequency enters the previously defined frequency band or another frequency value, the control is terminated to a variable nominal frequency. Alternatively, it can be provided that after a predetermined period of time, was regulated by the variable to a desired frequency, this exception rule is reversed and is regulated according to the regulations on the usual default frequency. For example, the network operator can provide a time limit for changing the control frequency, so that, for example, after a maximum of 2 days, preferably after at most 1 day, preferably after a maximum of 6 hours and more preferably at most 2 hours, the usual default frequency is regulated.

A further preferred embodiment consists in that the method according to the invention is applied only by a part of the primary control power generator, in particular storing, or is practiced up to a maximum total primary control power to be provided by these sources.

In another embodiment, the periods of time set forth above and the adjustment of the default frequency for longer duration deviations of the frequency are set differently than for longer deviations of the frequency down.

In this context, it should be noted that the method can contribute to the stabilization of the network even with a relatively small capacity of the energy store, since provision of control power can also take place if the network frequency is outside the deadband for a very long period of time, within which no regulation is necessary.

According to a particular embodiment, a regeneration of the energy storage even then take place when the measured frequency is longer term on one side outside a deadband. This embodiment is particularly suitable in connection with the manner of exploiting tolerances, which, for example, with regard to the amount of control power delivery, the time within which the control power is to be provided, and the frequency tolerances, are able to optimize the state of charge.

For example, more negative control power can be provided if the state of charge of the energy storage is very low due to a network frequency, which is on average over a longer period below the default frequency. In this case, tolerances, for example the tolerances granted to the control power provider by the network operator, with regard to the mains frequency, the amount of control power depending on the frequency deviation, the insensitivity to the frequency change, and the period within which the control power is to be provided, can be exploited adjust the state of charge of the energy storage to the requirements. Thus, for example, at least 105%, preferably at least 1 10% and particularly preferably at least 1 15% of this control power can be provided instead of the planned negative control power. If at a low state of charge now positive In this case, the contractually provided service is provided as exactly as possible in this case. Furthermore, the energy intake can take place immediately in the case of a low charge state, while the energy is fed in at the latest possible time according to the regulations or with a rise which is as slow as possible according to the regulations. Furthermore, the frequency tolerance granted by the network operator can be used by carrying out a measurement with a higher accuracy, whereby the difference thus obtained is specifically used for the given inaccuracy of measurement in order to minimize the power in accordance with the regulations, ie within the given tolerance range to feed in the network or to record as much power as possible from the network. In a high state of charge can be mirrored procedure. For example, a high energy output when providing a positive control power and a low power consumption while providing a negative control power is possible or realized.

The tolerance with regard to the amount of the control power provided and the tolerance in determining the frequency deviation, etc., is to be understood by the network operator to be certain deviations between an ideal nominal power due to technical conditions, such as the measurement accuracy in determining the control power supplied or the grid frequency and the actual control power actually delivered. The tolerance may be granted by the network operator, but could also comply with a legal requirement.

According to a particular embodiment, the supply of energy in the energy storage may be dependent on the time of day. As a result, a high stability of the network can be ensured even at a high load at certain times of the day. Thus, at peak loads, a regeneration of the energy storage, which would be useful due to the deviation of the mains frequency from the default frequency over a longer period, are excluded. Furthermore, it can be provided that a plurality of energy stores are used in accordance with the present method. In a particular embodiment, in this case, all or only a part of these energy stores can provide a control power adapted to the state of charge of the energy store, as has been explained above.

The size of the energy storage within the pool can vary. In a particularly preferred embodiment, in the various energy stores of a pool in the use of tolerances, in particular the choice of bandwidth in the deadband, the change from one parameter setting to another not synchronously, but deliberately offset in time to minimize any disturbances in the network or at least tolerable.

In a further preferred embodiment, the tolerances used in the various methods, in particular the choice of bandwidth in the dead band, vary depending on the time of day, the day of the week or the season. For example, within a period of 5 minutes to 5 minutes after the hour change, tolerances may be more narrowly defined. This is due to the fact that often very rapid frequency changes take place here. It may be in the interest of transmission system operators that there are lower tolerances and thus the control energy supply is more secure in the sense of sharper. According to a further embodiment, it can be provided within the framework of the specifications for the provision of control power that, on average, more energy is absorbed from the network than fed in by the decentrally regulated reserve power supplier. This can be done by providing very much negative control power in accordance with the regulations including the procedure outlined above, whereas according to the regulations including the procedure set out above, preferably only the at least guaranteed power is provided at positive control power. Preferably, an average of at least 0.1% more energy is withdrawn from the network than is supplied, in particular at least 0.2%, preferably at least 0.5%, more preferably at least 1.0%, especially preferably 5%, these values being based on a Average over a period of at least 15 Minutes, preferably at least 4 hours, more preferably at least 24 hours and especially preferably at least 7 days, and relates to the energy fed in.

In this case, the control power provision described above can be used selectively to extract a maximum of energy from the network, the maximum possible negative control power is provided, whereas only a minimum of positive control power is provided.

In the embodiments for the preferred and especially for the maximum energy consumption, the energy thus extracted from the network can be sold via the energy trade described above, preferably at times when the highest possible price is to be achieved. For this purpose, forecasts of the price development based on historical data can be used.

Furthermore, the state of charge at the time of a planned sale of energy may preferably be at least 70%, more preferably at least 80%, and most preferably at least 90% of the storage capacity, the state of charge after sale being preferably at most 80%, in particular at most 70% and most preferably at most 60% of the storage capacity is.

In the case of a permanent frequency deviation outside the frequency band, the control power can be provided in accordance with the usual regulations, which are also provided for a short-term regulation of the network frequency. In Europe, according to current regulations, the amount of the service to be provided is to be increased largely linearly with increasing frequency deviation from the default frequency. Thus, with a deviation of 100 mHz, a control power is usually provided which amounts to 50% of the maximum power. This maximum power is provided at a deviation of 200 mHz and corresponds to the previously defined rated power or contracted maximum power, for which the energy storage is at least prequalified. With a deviation of 50 mHz, accordingly, 25% of the rated power is provided. This regulation can, however, be maintained with the change of the usual default frequency to a variable setpoint frequency set out above. In this case, the frequency values at which the maximum power or nominal power is to be provided can be shifted accordingly. Alternatively, these frequencies can be maintained.

According to the invention, the method is carried out with a control power provider. Control power providers are in particular energy storage, energy producers and energy consumers.

It can be inventively provided that a power plant is used as an energy generator, preferably a coal power plant, a gas power plant or a hydroelectric power plant and / or a plant for producing a substance is used as an energy consumer, in particular an electrolysis plant or a metal -Werk, preferably one Aluminum plant or a steel plant.

Such energy producers and consumers are well-suited to providing longer-term balancing services. Their inertia, according to the invention, does not constitute a hindrance if suitably combined with dynamic storage.

Preferably, an energy store is used to carry out the method, which can absorb and deliver electrical energy. The type of energy storage is not essential to the practice of the present invention.

Preferably, it can be provided that as energy storage a flywheel, a heat storage, a hydrogen generator with fuel cell, a natural gas generator with gas power plant, a pumped storage power plant, a compressed air storage power plant, a superconducting magnetic energy storage, a redox flow element and / or a galvanic element is preferably used, an accumulator or combinations ("pools") of memories or memories with conventional control power sources or of memories with consumers and / or power generators. A heat storage device operated as an energy store must be operated together with a device for producing electricity from the stored heat energy.

Battery storage systems (accumulators) are distinguished from conventional technologies for providing primary and / or secondary control functions, inter alia, in that they can change the services provided much faster. In most cases, however, is disadvantageous in battery storage that they have a relatively small storage capacity, so can provide the required services only over a limited period. In a statistical evaluation of the frequency deviations over time, it has surprisingly been found in the context of the present invention that the requested powers in more than 75% of the active time (that is to say a power deviating from zero) are less than 20% of the maximum power. Performance or marketed performance. It also follows from this finding according to the invention that the capacity of the energy store and thus the stored reserve power amount to be kept can be selected to be lower and it is particularly well possible with a method according to the invention to keep the capacity of the energy store small. Specific and particularly preferred embodiments of the approaches are that the energy store is an accumulator or battery store that is used to provide primary control power.

In a further specific embodiment, the energy absorbed into the energy store in the case of negative PR power can be sold on the spot market, in particular if the conditions there are advantageous.

Accumulators include in particular lead-acid batteries, sodium-nickel-chloride accumulators, sodium-sulfur accumulators, nickel-iron accumulators, nickel-cadmium accumulators, nickel-metal hydride accumulators, nickel-hydrogen accumulators, nickel-zinc accumulators, Tin-sulfur lithium ion batteries, sodium ion batteries and potassium ion batteries.

Here, accumulators are preferred, which have a high efficiency and a high operational and calendar life. The preferred accumulators accordingly include, in particular, lithium ion accumulators (for example lithium polymer accumulators, lithium titanate accumulators, lithium manganese accumulators, lithium iron phosphate accumulators, lithium iron manganese phosphate Accumulators, lithium-iron-yttrium-phosphate accumulators) and developments thereof, such as lithium-air accumulators, lithium-sulfur accumulators and tin-sulfur lithium-ion accumulators.

In particular, lithium-ion secondary batteries are particularly suitable for methods according to the invention because of their rapid reaction time, that is, both in terms of the response time and the rate at which the power can be increased or reduced. In addition, the efficiency is good, especially for Li-ion batteries. Furthermore, preferred accumulators exhibit a high power to capacity ratio, this characteristic being known as the C rate.

It can also be provided that an energy of at least 4 kWh can be stored in the energy store, preferably of at least 10 kWh, particularly preferably at least 50 kWh, very particularly preferably at least 250 kWh.

According to a further embodiment, the energy storage device can have a capacity of 1 Ah, preferably 10 Ah and particularly preferably 100 Ah.

When using memories based on electrochemical elements, in particular accumulators, this memory can advantageously be operated with a voltage of at least 1 V, preferably at least 10 V and particularly preferably at least 100 V.

Depending on the course of the frequency deviation, the supply of control power to the AC grid can be constant, via pulses or via ramps which are characterized by an increase in power supply over a defined period of time. An over Pulse (pulses) provided control power allows an improvement in the efficiency of the device and the method for providing control power, as this, the, in particular when using accumulators, necessary power electronics can be operated at a higher efficiency. A pulse is to be understood as a time-limited, jerky current, voltage or power curve, whereby these pulses can also be used as a repetitive series of pulses. The duty cycle according to DIN IEC 60469-1 can be selected here from the type of power electronics and the control power to be provided, wherein this in the range of greater than zero to 1, preferably in the range of 0.1 to 0.9, particularly preferably in the range of 0.2 to 0.8.

In the case of changes in power required, it may preferably be provided that the power of the energy store is increased over a period of at least 0.5 s, preferably over a period of at least 2 s, particularly preferably over a period of time, depending on the level of the required power change at least 30 s.

These slower ramps ensure that there are no suggestions of unwanted disturbances or oscillations in the power network or in the connected consumers and generators by a too steep power gradient.

The desired state of charge of the energy store may preferably be in the range from 20 to 80% of the capacity, more preferably in the range from 40 to 60%. Compliance with and / or the return to these state of charge areas can be achieved, for example, by using the mode of operation on which this invention is based and / or via the energy trade, which was explained in more detail above, via the power grid. The state of charge corresponds in particular in the case of accumulators as an energy storage the state of charge (engl.:State-of-Charge ", SoC) or the energy content (English:" State-of-Energie ", SoE).

The desired state of charge of the energy store may depend on forecast data. In particular, consumption data can be used to determine the optimum state of charge depending on the time of day, the day of the week and / or the season are used.

It can also be provided that the output of the power storage of the energy storage or recorded from the power grid power of the energy storage after a permanent frequency deviation outside the frequency band at several times, in particular continuously measured and the state of charge of the energy storage at several times, preferably continuously calculated is set, wherein the output or absorbed power of the energy storage in response to this state of charge is set such that the variable target frequency is taken into account in the power consumption or Abgäbe.

According to a particular embodiment of the present invention, the method can be carried out with an additional energy generator and / or energy consumer. Additional energy producers and / or energy consumers in this context are devices that can provide control power, but that do not constitute energy storage.

In particular, those additional energy producers and / or energy consumers are preferred, which can also be used in connection with renewable energies, such as electrolysis plants or metal works whose production can be reduced to provide positive control power.

By this configuration, the nominal power of the energy storage can be surprisingly increased without the capacity of the same must be increased. In this case, the energy storage can be provided by the additional power generator and / or energy consumers even at a high network load in a very short time, if necessary, without a lengthy energy trading is necessary. Surprisingly, therefore, a relatively high capacity can be delivered at a relatively low capacity of the memory, which can generally be delivered only for a short period of time. Due to the direct access to the additional power generator and / or energy consumer, this can after a short time actually from the Energy storage to provide available control power or substitute. Thus, in particular, a regeneration of the energy storage by the energy or power of the additional energy generator and / or energy consumers take place. Here, the energy storage contributes to the quality of the control power delivery, as a result, a fast response time is achieved. In contrast to this, the additional energy producer and / or energy consumer contributes above all to the quantity, since at relatively low costs, this can provide control power for a significantly longer period of time due to the type of construction.

Furthermore, it may be provided that the energy generator and / or the energy consumer has or have a power of at least 10 kW individually or in the pool, preferably at least 100 kW, more preferably at least 1 MW and most preferably at least 10 MW.

The ratio of rated power of the energy storage device to maximum power of the additional control power supply may preferably be in the range of 1: 10000 to 100: 1, more preferably in the range of 1: 1000 to 40: 1.

The method of the present invention may preferably be carried out with a device comprising a controller and an energy store, wherein the device is connected to a power grid and the controller is connected to the energy store, wherein the controller is provided with a unit for determining the duration and a Unit for determining a mean network frequency is connected.

It can be provided that the device comprises a frequency meter for measuring the mains frequency of the power network and a data memory, wherein in the memory at least one limit value (eg default frequency ± 10 mHz, default frequency ± 200 mHz, etc.) of the network frequency is stored, the controller is designed to compare the mains frequency with the at least one limit value and to control the power of the energy store and possibly the energy consumer and / or the energy generator as a function of the comparison. Under a control according to the invention is understood in the present case a simple control. It should be noted that each control comprises a control, as in a control, a control in dependence on a difference of an actual value to a desired value takes place. Preferably, the controller is thus designed as a control, in particular with respect to the state of charge. Particularly preferably, the controller is a control system.

Furthermore, it can be provided that the unit for determining the time duration has a data memory, wherein at least historical data about the deviation and the duration of the network frequency from the default frequency are recorded in the data memory, this historical data having a period of preferably at least a day, preferably at least one week, more preferably at least one month and especially preferably at least one year. The unit for determining an average network frequency may be designed according to the type of averaging. In general, the control unit will include a data memory containing the variable target frequencies that are set to adjust the network time to the coordinated world time.

Alternatively, the data is collected at a remote location and evaluated as set forth above, and the appropriate signal is appropriately transmitted to the memory (s) for control power provision. In a particularly preferred embodiment, this can be done via the known methods of remote data transmission and communication.

Embodiments of the invention will be explained below with reference to three schematically illustrated figures, without, however, limiting the invention. 1 shows a schematic representation of a device according to the invention for the provision of control power;

FIG. 2 shows a flowchart for a first embodiment of a method according to the invention and FIG

FIG. 3 shows a flow chart for a second embodiment of a method according to the invention. FIG. 1 shows a schematic structure of a preferred embodiment of a device 10 according to the invention for a method according to the invention comprising a controller 1 1 and an energy store 12, the device being connected to a power grid 13. In particular, even in such cases, a particularly fast-reacting and easy to charge and discharge energy storage 12 is particularly advantageous. Batteries are best suited for this purpose. In particular, Li-ion batteries are quickly and frequently charged and discharged with little harmful effects on the battery, so that they are particularly suitable and preferred for all embodiments according to the invention. This requires the provision of considerable capacity Li-ion batteries. For example, these can be easily accommodated in one or more 40-foot ISO containers.

Here, the controller 1 1 is connected to the energy storage 12. Furthermore, the controller 1 1 is connected to a unit for determining the time duration 14 and a unit for determining a mean power frequency 15. Of course, these units can be accommodated spatially in a housing with the controller. The connection between the unit 14 for determining the time duration 14 and the unit for determining a mean power frequency 15 with the controller 1 1 allows communication of the determined data, which are processed in the control unit. Furthermore, the controller 1 1 may be connected to the power grid 13, this connection, not shown in Figure 1, a transmission of requests for required control power, both positive and negative, may allow.

The embodiment set forth in Figure 1 comprises an additional power generator and / or power consumer 16, which in the present invention is an optional component. The additional power generator and / or energy consumer 16 is connected both to the power grid 13 and to the energy store 12, so that the control power provided by the additional power generator and / or energy consumer can be fed directly into the power grid 13 or used for regeneration of the energy store 12 can be. The control of the additional power generator and / or energy consumer 16 may by conventional Components that can be connected to the controller 1 1 of the device 10 according to the invention.

Please refer to the Forum Netztechnik / Netzbetrieb in the VDE (FNN) "TransmissionCode 2007" of November 2009 for details on the regulation of control power and the exchange of information with the network operators.

Figure 2 shows a flow chart for a first embodiment of a preferred method according to the present invention. In this embodiment, no information is transmitted to the current setpoint frequency by the network operator, and this information can not be queried by the control power provider. Rather, in this embodiment, the applicable nominal frequency is determined by measuring the mains frequency. In the method set out in FIG. 2, an energy store is used. In step 1, the grid frequency of the power grid is measured. In decision step 2, it is then checked whether the network frequency lies within or outside the frequency band which was previously determined. This frequency band can be identical to a deadband, which is predetermined by the network regulations or by the network operator. Preferably, this frequency band may be smaller than the dead band determined by the network operators or by the network regulations.

If the measured network frequency is within the frequency band, according to the present embodiment of the method, a control power supply is performed according to the standard specifications, as shown in step 8.

If the mains frequency deviates from the default frequency, decision step 3 checks to see if there is a permanent frequency deviation over a specified period of time. Here it can also be checked whether there is another restriction which excludes a deviation from the standard specifications. For example, it may be provided that a regulation to the default frequency is mandatory at certain times of the day. If no permanent frequency deviation is given or regulation to a variable setpoint frequency is excluded, control power is provided in accordance with the usual specifications, being regulated to the default frequency. If a permanent Frequency deviation is present and no exception rule applies, is continued with decision step 4.

In decision step 4 it is checked whether an abort criterion is present, so that a transition from a control with a variable set frequency must be made to a control with the default frequency. These termination criteria may, for example, be given by a period to which a provision of control power is limited with a variable target frequency. Furthermore, a state of charge can be achieved by a regeneration of the energy storage, which allows a control to the default frequency. In this case, in the present embodiment, according to step 5, the time measurement is restarted with respect to the predetermined time period for which a permanent frequency deviation must be present before a control to a variable target frequency is allowed. Subsequently, control power is provided according to the usual specifications using the default frequency, as shown schematically in step 8. If this abort criterion is not met, it is checked in the present embodiment in decision step 6, whether the application of a control power application using a variable target frequency is appropriate to convert the state of charge of the energy storage in the shortest possible time in a desired state of charge. If this is not the case, the usual default frequency is used to provide the control power.

For example, the target frequency may be at a value of 49.990 Hz to match the network time to the coordinated world time. If the energy store now has a relatively high state of charge and the energy store should accordingly preferably deliver energy, it makes sense to leave the default frequency at 50,000 Hz and to provide increased or higher positive control power.

Otherwise, the procedure according to step 7, and the default frequency is adjusted to the desired frequency. Similar to the case described above, the energy store may have a relatively high state of charge. However, the setpoint frequency should this time be at a value of 50.010 Hz. In this case, it makes sense to adapt the default frequency to the changed setpoint frequency in order to provide as much positive control power as possible. Subsequently, the grid frequency is measured again, so that a cycle is given. This also applies in the event that the provision of control services is performed in accordance with the standard requirements, as described in step 8.

The order of the steps set forth in Figure 2 may be partially changed. In particular, decision step 6 can take place before decision step 4, so that the check is made on the desirability of a regulation to a variable control frequency before the presence of a termination criterion.

FIG. 3 shows a flow chart for a second embodiment of a preferred method according to the present invention. In this embodiment, information about the current setpoint frequency is transmitted by the network operator. This can be done on the initiative of the network operator. Alternatively, this information can also be queried by the decentrally controlled control power provider.

In step 1 ', the current setpoint frequency is transmitted to the control power provider. In decision step 2 'it is checked whether this setpoint frequency corresponds to the usual default frequency. If this is the case, control power is provided according to the specifications using the usual default frequency according to step 4 '.

If the nominal frequency deviates from the usual default frequency, it is tested in decision step 3 'whether the application of the control power application using a variable nominal frequency is appropriate to convert the state of charge of the energy storage in the shortest possible time in a desired state of charge. If this is not the case, the usual default frequency is used to provide the control power according to step 4 '.

Otherwise, the procedure according to step 5 'and the default frequency is adjusted to the target frequency. Similar to the case described above, the Energy storage have a relatively high state of charge. However, the setpoint frequency should this time be at a value of 50.010 Hz. In this case, it makes sense to adapt the default frequency to the changed setpoint frequency in order to provide as much positive control power as possible. The features of the invention disclosed in the foregoing description as well as the claims, figures and embodiments may be essential both individually and in any combination for the realization of the invention in its various embodiments.

Claims

claims

Method of providing control power to stabilize a

AC network, wherein the AC mains at a variable

Setpoint frequency operates and the AC power network includes at least one decentralized regulated power supplier, which regulates the grid frequency to a default frequency, characterized in that the default frequency is adapted to the variable target frequency.

A method according to claim 1, characterized in that the control power supplier operating at the default frequency provides primary control power.

A method according to claim 1 or 2, characterized in that the AC network comprises at least one supplier of secondary control power and / or minute reserve power, which is centrally controlled, the activation of the secondary control power supplier and / or

Minute reserve power taking into account the variable target frequency takes place.

Method according to at least one of the preceding claims, characterized in that the operating at the default frequency

Control power supplier is an energy storage device that can absorb and release electrical energy.

A method according to claim 4, characterized in that the

Charging state of the energy storage is taken into account when adjusting the default frequency to the variable target frequency.

A method according to claim 4 or 5, characterized in that the energy store is an accumulator.

A method according to claim 6, characterized in that the accumulator is a lithium-ion accumulator.

8. The method according to at least one of the preceding claims, characterized in that the variable nominal frequency is transmitted to the decentralized control power supplier.

9. The method according to at least one of the preceding claims, characterized in that a deviation between variable nominal frequency and

Preset frequency by a permanent frequency deviation of the

Mains frequency outside a frequency band over a fixed period of time.

10. The method according to claim 9, characterized in that a

Deviation between variable target frequency and default frequency is determined by a sliding average of the mains frequency.

1 1. Method according to at least one of the preceding claims, characterized in that a deadband is specified by the default frequency.

12. The method according to claim 1 1, characterized in that a

Deviation between variable setpoint frequency and default frequency due to a permanent frequency deviation of the mains frequency outside of one

Frequency band is detected over a predetermined period of time, wherein the deviation of the mains frequency is measured by the default frequency with a higher accuracy than the width of the dead band. 13. The method according to claim 12, characterized in that the

Frequency band, which is used to determine a permanent

Frequency deviation of the mains frequency is used, is smaller than the dead band.

14. The method according to at least one of the preceding claims, characterized in that in the context of the specifications for the provision of

On average, more energy is taken in from the network than fed in by the decentralized regulated power supplier.

5. The method according to any one of the preceding claims, characterized in that within a period for which the variable

If the reference frequency is changed from a standard value to a value deviating therefrom, a multiple adaptation of the preset frequency from the original value to a variable nominal value is undertaken if the adjustment of the predefined frequency was temporarily reversed during this period.

6. A device for carrying out a method according to claims 1 to 15, characterized in that the device (10) comprises a controller (1 1) and an energy store (12), wherein the device to a

Power supply (13) is connected and the controller (1 1) with the

Energy storage (12) is connected, wherein the controller (1 1) with a unit for determining the time duration (14) and a unit for determining a mean power frequency (15) is connected.

7. The device according to claim 16, characterized in that the unit for determining a mean power frequency (15) has a higher

Measurement accuracy has as a defined by the default frequency dead band.