EP2936423A1

EP2936423A1 - Management of high-temperature batteries

Info

Publication number: EP2936423A1
Application number: EP13821885.4A
Authority: EP
Inventors: Nicolas Martin
Original assignee: Commissariat a lEnergie Atomique CEA; Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
Current assignee: Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
Priority date: 2012-12-20
Filing date: 2013-12-20
Publication date: 2015-10-28
Also published as: FR3000264A1; US20150349393A1; JP2016506715A; FR3000264B1; WO2014096739A1

Abstract

The invention relates to a method for the management of at least one high-temperature electrochemical battery (30) comprising the following steps: evaluating (32) the production capacities of an electrical network and/or evaluating (31) the consumption needs of the users of this network, for a future period; deciding (33) whether or not to use the battery during the future period, according to the result of the evaluation step; and bringing (36) the battery to an operating temperature or restoring (38) the battery to an idle state at an ambient temperature according to the decision made.

Description

HIGH TEMPERATURE BATTERY MANAGEMENT

Field of the invention

The present invention generally relates to the management of energy in an electrical distribution network and, more particularly, the management of high temperature electrochemical batteries for storing electricity.

Presentation of the prior art

The so-called high temperature batteries are electrochemical batteries used in power distribution networks. This type of battery is also known as "Sodium Beta" batteries, which include sodium / nickel chloride batteries (Zebra batteries) as well as sodium / sulfur batteries. All these batteries are batteries of high capacity (several tens of kilowatt hours) and are generally located on the distribution grid, that is to say between the high voltage or medium voltage transformer stations to the low voltage, and subscribers.

Energy storage means such as batteries are generally desirable in power grids to absorb peaks in consumption or production. Indeed, in the absence of such storage elements, it is necessary to size the production and distribution so that it is able to meet demand and production, including in periods of high consumption / production peaks are usually only a few hours for a few days per year.

High temperature batteries are practical storage means to the extent that they can be easily placed near the consumption sites, which is not the case for other hydraulic storage type power distribution control means. However, a diffi ^¬ culty is that these batteries should be brought to a temperature of several hundred degrees (typically around 300 ° C) to operate (charge and discharge). The need to carry these batteries at high temperatures for them to work means that they are in practice kept permanently at operating temperature.

This increases the cost of energy, not only because of the need to heat the batteries permanently, but also because it limits the life of these batteries. Indeed, high temperature type batteries have a limited lifetime of about ten years in high temperature operation.

The document "Analysis and Operational Records of NAS Battery" by K. Iba et al, R. Ideta and Suzuki K. - Universities Power Engineering Conference, 2003 - UPEC '06. Proceedings of the 41st International, IEEE, PI, September 1, 2006, pages 491-495, describes a method of temperature regulation of NAS type batteries.

GB-A-2081000 also discloses a method of regulating the temperature of NAS batteries.

The document "Overview of the Sodium-Sulfur Battery for the IEEE Stationary Battery Committee" of A. Bito - Power Engineering General Society Meeting, 2005 - IEEE San Francisco, USA - June 12-16, 2005 - pages 2346-2349, makes an inventory of NAS type batteries. The document "Battery Storage System Sizing Distributed Feeders with Distributed Photovoltaic Systems" by C. Venu et al. Powertech 2008 IEEE Bucharest, IEEE, Piscataway, NJ, USA - June 28, 2009 - pages 1-5, describes a system combining batteries and photovoltaic production.

All of the above documents emphasize the importance in NAS batteries of regulating the temperature in order to avoid temperature variations that are detrimental to the life of these batteries.

summary

Thus, an object of an embodiment of the present disclosure aims at overcoming all or part of the drawbacks associated with the use of high tempera ^¬ erasure batteries.

Another object of an embodiment is to increase the service life of high temperature batteries and, more particularly, batteries able to withstand temperature variations.

Another object of an embodiment is to optimize the use of high temperature batteries in an electrical network.

Another object of an embodiment is to propose a solution more particularly adapted to Sodium-Beta type batteries.

To achieve all or part of these objects as well as others, there is provided a method of managing at least one high temperature electrochemical battery, wherein the battery is brought to a nominal operating temperature after detection of a need. use.

According to one embodiment, there is provided a method of managing at least one high temperature electrochemical battery comprising the following steps:

to evaluate the production capacities of an electricity network and / or to evaluate the consumption needs of the users of this network, for a future period; decide whether or not to use the battery in the future period, depending on the outcome of the evaluation step;

bring the battery to an operating temperature or bring the battery to rest at room temperature according to the decision taken; and

repeat the steps above.

According to one embodiment, the difference between the ambient temperature and the operating temperature is at least 100 ° C.

According to one embodiment, the aging of the battery at ambient temperature is at least twice as slow as its aging at operating temperature.

According to one embodiment, the transition from the ambient temperature to the operating temperature and vice versa takes several hours.

According to one embodiment, the evaluation steps are performed in advance taking into account the time required to bring the battery or batteries to their operating temperature.

According to one embodiment, the evaluation steps are performed daily for the following day.

There is also provided a power management method in an electric network, wherein the high temperature electrochemical batteries are used to store the ener gy ^¬ produced by decentralized solar power plants.

There is also provided an electrical network adapted to the implementation of the energy management method.

Brief description of the drawings

These and other objects, features, and advantages will be set forth in detail in the following description of particular embodiments in a non-limitative manner with reference to the accompanying figures in which: Figure 1 is a schematic representation of an electrical network of the type to which the embodiments to be described apply;

Figures 2A, 2B and 2C are timing diagrams illustrating very schematically an example of function ^¬ ment of energy management method; and

Figure 3 is a simplified block diagram of one embodiment of the energy management method.

detailed description

The same elements have been designated by the same references to the different figures that have been drawn without respect of scale. For simplicity, only the steps and elements useful for understanding the described embodiments have been shown and will be detailed. In particular, the power generation facilities have not been detailed, the described embodiments being compatible with the usual installations equipping the networks. In addition, the constitution of a high temperature electrochemical battery has also not been detailed, the embodiments described being again compatible with the usual batteries.

FIG. 1 is a very schematic representation of an example of an electrical network of the type to which the embodiments which will be described apply.

Such a network is generally found in any region or country. Typically, an electricity network comprises production units 11, for example of the nuclear power station, thermal, hydraulic, wind farm, etc., a transport network for example air 12 (towers and cables) or buried between the production units and substation transformers very high voltage to medium voltage or low voltage 13. Downstream of these transformers or substations source, there is a distribution network 14 responsible for conveying the medium or low voltage to users, for example industries 15, collective or individual dwellings 20, where appropriate through secondary transformation 17. Production units (for example of the solar power plant type 18) can also supply energy directly to a secondary transformer station 17. In addition, there are more and more mini-or micro-power plants. energy production, for example, solar panels 21 installed on the roof of houses or buildings, which are likely to reinject energy on the network.

To facilitate the regulation and management of distributed energy based on demand, the power grid incorporates increasingly decentralized storage systems, for example, batteries electro ^¬ high temperature chemical 30. In the example 1, a single battery 30 has been shown associated with a transformer 17, but such decentralized storage elements can be distributed to multiple locations of the network.

FIGS. 2A, 2B and 2C are timing diagrams illustrating an example of energy management in an electrical network using a high temperature electrochemical battery storage element. Figure 2A illustrates an example of the power generation (PROD) rate provided by the various plants over time, for example over the course of a day. Figure 2B illustrates the power demand of the network (POWER), that is, the consumption requirements. Figure 2C illustrates the pace of energy (BAT) in the battery.

It is assumed that at the beginning of the time period considered, the power demanded by the network does not exceed the maximum capacity MAX of production of the power stations. We take this opportunity to recharge the battery (between times tl and t2). The energy stored in the battery then serves for another period for example of the day (between instants t3 and t4) during which the energy requirements of the distribution network exceed the maximum production that can be provided by the power stations. . Such energy management avoids having to oversize the network according to peaks of episodic consumption. FIGS. 2A to 2C have been described in connection with the use of a storage element but, in practice, using decentralized storage elements, this operation can be reproduced at these various storage elements.

The life of high temperature electrochemical batteries is however limited. This lifetime depends on the number of cycles (charge-discharge) of use of the battery (aging in cycling), as well as time (calendar aging).

Most of the high temperature batteries used today are NAS (sodium sulfide) batteries. As indicated in particular by the documents mentioned at the beginning of the present description, it is sought to regulate the temperature of these batteries in order to preserve them. This regulation aims to limit temperature variations around their nominal operating temperature (several hundred degrees). Indeed, the NAS-type batteries are not adapted to withstand cycling in terms of rise-fall in temperature between the nominal operating temperature and the ambient temperature (typically a few tens of degrees, of the order of 20-25 degrees). This is why we usually try to keep them at their nominal operating temperature, whether they are used or not. This cycling in terms of rise-fall in temperature is different from the cycling in charge-discharge.

The inventors have found that other types of batteries withstand a cycle in terms of rise-fall in temperature between the ambient temperature (typically 25 ° C.) and a nominal operating temperature (of the order of

300 ° C). This is, for example, the case of Sodium-Beta type batteries.

Moreover, for Sodium-Beta type batteries, it is considered that the number of charge-discharge cycles that the battery is likely to support is of the order of 3000 and that the calendar aging at the nominal operating temperature (of the order of 300 ° C) is about 10 years.

The inventor has also found that the batteries could be used to absorb peaks of consumption that of the order of one cycle per day and for a few months per year. By estimating the number of months as four, this means that the life of the battery will be limited by calendar aging while it could support a greater number of cycles. High temperature batteries of this type are therefore generally underused.

However, the calendar aging of a high temperature electrochemical battery is not the same depending on whether the battery is at rest at its normal operating temperature or at rest at ambient temperature. It ages less quickly at room temperature, where its life span is several decades.

The inventor has found that by using batteries in periods when they are really useful from the point of view of the electricity grid, that is to say in periods when there are significant peaks in consumption, It was possible to increase the life of the batteries by bringing them back to room temperature outside the operating periods. It then takes advantage of the fact that some batteries support a cycle in terms of rise-fall in temperature to control a heating system and / or cooling of the battery. A difficulty, however, is that it takes several hours or even a day to carry a high temperature electrochemical battery to its operating temperature. Therefore, the responsiveness of the system is problematic.

It is proposed to use power prediction and prediction tools to determine periods during which electrochemical batteries are placed at operating temperature. We then exploit the possibility of predicting, from weather forecasts, production periods by the mini-decentralized plants (in particular the production by mini-solar power plants) of the network. We also use the consumption forecast based on the history of consumption as well as various parameters such as the weather, the news (for example a major sporting event tele ^¬ broadcast) to optimize the management of batteries.

Such a solution is particularly suited to the existence of decentralized production sites whose production capacities are of the same order of magnitude as the storage capacity of electrochemical batteries (a few tens of kilowatts). It is therefore now possible to disseminate these storage elements over an entire territory in order to optimally optimize and adjust energy management by minimizing transport, a source of losses.

FIG. 3 is a simplified flow diagram of an embodiment of the method of managing a battery. This figure will be described in connection with an example of use of a single battery but it will be noted that it transposes without difficulty regardless of the number of batteries.

By way of example, it is considered that the time required to place a battery in its operating conditions (time required to bring the battery to operating temperature by several hundred degrees) is of the order of one day. The method described will be able to adapt to other durations but the example of a day corresponds to a realistic example which, moreover, adapts perfectly to the periodicity of production of the solar power stations (production during the day where the energy demand is lower) and the frequency of consumption peaks (maximum consumption at the beginning and end of the day where solar production is low or non-existent).

In the example of Figure 3, was evaluated daily ^¬ ment consumption requirements (block 31 CONS D + l) and the capacity (block 32 PROD D + l), in particular decentralized production capacities. Of estimated consumption ^¬ tools from the weather forecast, the time of year, expected current events, etc. are known and used for this purpose. Similarly, tools for estimating energy production and in particular decentralized generation by solar mini-power plants spread across a territory according to their location and, in particular, weather forecasts, are also available and likely to be used. to be used to estimate the production of the next day.

It is then assessed whether the need for instantaneous consumption, in a future period (for example, the next day) will exceed the production capacity (block 33, CONS (D + 1)> PROD (D + 1)?) Of this period future. In the affirmative (output Y of block 33), this means that the battery must be put into operation, that is to say, be able to be charged during the time slots of the following day when the production will exceed the consumption and then be discharged at the peak of consumption that will follow. Here we take advantage of the fact that there are always, in a daily period, time intervals where production is greater than consumption (see Figures 2).

We start (block 34, BAT ON?) By detecting the state of the battery (rest at room temperature (BAT OFF) or at high temperature (BAT ON)), that is to say if it is already at its operating temperature for example because it is being used for the current day.

In the negative (output N of block 34), the battery is preheated to bring it to operating temperature (block 35, PRE HEAT). If the battery was already at operating temperature (output Y of block 34), step 35 is obviously skipped. The difference between the operating temperature and the ambient temperature is, in practice, at least 100 degrees. It is not a question of regulating the temperature of the battery around a value but "switch" its temperature between two values distant from each other, to take advantage of different aging conditions.

The battery is then usable (BAT ON state, block 36).

In the case where the expected consumption conditions for the next day are not likely to exceed the instantaneous production capacities (output N of block 33), the battery can then be placed at rest at ambient temperature (of the order of 25 ° C) to limit aging.

For this, it is checked whether the battery is in an operating state (block 37, BAT ON?). In the affirmative (output Y of block 37), the battery is brought back to ambient temperature (block 38, BAT OFF), that is to say that the heating elements of the battery are stopped and it goes down again. itself at room temperature (or activate a cooling system if you want to speed up the process). If the battery is already at room temperature (output N of block 37), nothing is changed.

Steps 31 to 38 are repeated daily

(block 39, NEXT D) or with a periodicity corresponding to the periodicity chosen to place the battery in operation. This periodicity may depend, in particular, on the time required to carry an electrochemical battery at operating temperature. The choice of the time to implement steps 31-38 is not important, but the same time will always be chosen from one day to the next.

FIG. 4 is a simplified flowchart illustrating an alternative embodiment of the method. Compared to Figure 3, the difference is that the test 33 is replaced by a test 33 '(CONS (D + 1) ≠ PROD (D + 1)?) In which it is evaluated whether the consumption expected for the future period will be different from the expected production for this future period. If so, put the battery in its operating condition (blocks 34, 35 and 36), whether to charge it (lower consumption than production) or to unload it (consumption greater than production). If not, the battery is brought back to room temperature (blocks 37 and 38).

According to other simplified variants not shown, only the production expected for the future period or only the expected consumption is evaluated. The battery is then placed in its operating condition if the expected production (or consumption) is greater than a threshold. This prepares the battery, either to be charged or to be discharged.

The method described above can be implemented using computer equipment commonly present in the control centers of the electrical network. The control of the batteries and in particular their preheating are easily carried out remotely, the equipment of an electrical network is now almost all remote controllable.

It will be noted that, during the periods when the battery is at its operating temperature, it will be possible to implement a temperature regulation mechanism of the type described in the aforementioned documents.

By implementing such a power management method, the lifetime of the electrochemical batteries is considerably increased while optimizing the management of the network and the use of the decentralized storage elements.

One advantage of using high temperature batteries is to help maintain the voltage plan

(average voltage level) of the distribution network on which production units such as solar power plants can have a significant impact. Indeed, during periods of high solar production, the level of the network voltage is difficult to regulate, especially if the consumption is not important, the voltage then tends to increase. Charging the batteries during these periods generates consumption which contributes to an improvement of the voltage plan. In a similar way, the discharge of the batteries at the moment when the consumption becomes important and where the production photovoltaic falls and could thus cause a collapse of the voltage, provides energy to avoid or reduce this phenomenon.

Various embodiments have been described, various variations and modifications will be apparent to those skilled in the art. In addition, the practical implementation of the embodiments described is within the abilities of those skilled in the art based on the functional indications given above and using standard production and consumption estimation tools and computer tools. adapted. In addition, the choice of batteries to which the described embodiments can be applied depends on their aging conditions at ambient temperature and at operating temperature. Preferably, one will select types of batteries whose aging ratio between the two temperatures is at least 2. This is the case of Sodium-Beta type batteries. Furthermore, although a solution has been described for batteries whose operating temperature is higher than the ambient temperature, these embodiments could be transposed to batteries whose nominal operating temperature is lower than the ambient temperature by applying cooling instead of reheating.

Claims

A method of managing at least one high temperature electrochemical battery (30) comprising the steps of:

evaluate (32) the generation capacity of an electricity grid and / or evaluate (31) the consumption needs of the users of this network, for a future period;

deciding (33; 33 ') whether or not to use the battery in the future period, depending on the result of the evaluation step;

carry (36) the battery to an operating temperature or return (38) the battery to rest at ambient temperature depending on the decision taken; and

repeat the steps above.

The method of claim 1, wherein the difference between the ambient temperature and the operating temperature is at least 100 ° C.

3. The method of claim 1 or 2, wherein aging of the battery at room temperature is at least twice as slow as aging at operating temperature.

4. Method according to any one of claims 1 to 3, wherein the passage from room temperature to the operating temperature (35) and vice versa takes several hours.

5. Method according to any one of claims 1 to 4, wherein the evaluation steps (31, 32) are performed in advance taking into account the time required to bring the battery or batteries to their operating temperature.

The method of any one of claims 1 to 5, wherein the evaluation steps (31, 32) are performed daily for the next day.

7. A method for power management in a network ^¬ elec tric wherein high electrochemical batteries temperature (30) are used to store the energy produced by decentralized solar power plants (18, 21), by carrying out the method according to any one of claims 1 to 6.

8. Electrical network adapted to the implementation of the method according to claim 7.