DE19805267A1 - Method and arrangement for optimizing the energy management of autonomous power supply systems supplied from batteries - Google Patents

Abstract

The method involves measuring the change in the capacity of the batteries as a function of time. When a selectable critical reference value is exceeded for the battery supplying the load the supply is changed over to another, i.e. the one with the maximum capacity compared to the remaining batteries. The disconnected battery is not made available again until its self recovery effect is complete.

Description

The invention relates to a method and an arrangement for optimizing the energy managements of autonomous energy supply systems, their energy supply via battery lators is done. Such autonomous energy supply systems are used in mobile or stationary facilities or systems where an energy supply is used stationary networks are not technically possible or economically unprofitable.

Well-known examples are lighting devices on remote streets and sidewalks or Parking ticket machines that are located at a greater distance from energy supply networks are so that a connection of these consumers to a local or regional Energiever bundnetz would be economically unprofitable due to the distances. This consumption So there are autonomous energy production facilities such as solar cells and wind power generators, etc. equipped. Excess energy is transferred to storage units (Ni-Cd Accumulators, lead-acid accumulators) passed and can by an energy control system to the consumer as required (e.g. at night).

The state of the art also includes solutions for mobile systems such as solar vehicles, where electrical energy to power the vehicles using the photovoltaic Effect is obtained from light energy. DE 33 47 054 A1 describes an electric vehicle described with an electric motor and a rechargeable battery, in which the re Charging takes place by means of solar cells, which are arranged on a body roof.

To avoid overloading the rechargeable battery when loading or unloading In addition, DE 195 39 695 A1 avoids a battery handling device for Electric vehicle described, which the determination of the current state of charge of the Battery serves regardless of whether the battery is in a load state or in a Resting phase.

Based on the knowledge that a previously heavily loaded battery is switched off The condition serves a permanent discharge after a temporary recovery phase  Battery handling device to the remaining usable capacity of a battery in one to signal separate state from the consumer. This should ensure timely reloading or an exchange of the battery in question is made possible.

So it is proposed, with the help of a sensor that is located on or in the battery Intervals to determine the current actual capacity. For this purpose, measuring arrangements proposed that only a low energy requirement for performing the measurements need. It is also proposed to include an autonomous battery with the help of an auxiliary battery Realize the voltage supply of the sensors. This auxiliary battery serves to falsify of the measurement results on the battery to be monitored by an autonomous power supplier elimination. The proposed circuit arrangement for monitoring a Accumulator is complex and causes increased procurement costs.

The known solutions are characterized by a number of disadvantages.

This means that stationary or mobile facilities and systems can meet their energy needs is finally covered by wind or solar energy, only with appropriate meteorology conditions are safely and reliably supplied with electrical energy. Currently at regions with changing climates, such as in Northern and Central Europe, are therefore reliable ger use of such systems over long periods of time hardly possible. Add to that the comparatively high procurement costs and the low electrical power more well known Wind turbines and solar cells.

The alternative, exclusive use of lead, nickel-cadmium, or silver-cadmium Lithium-sulfur accumulators for the energy supply of autonomous systems encountered on the other hand, to economic limits, since high-performance accumulators do not behave are reasonably expensive and have a relatively limited lifespan.

Known lead-acid batteries, which are characterized by a more favorable price-performance ratio have the disadvantage that the absorption capacity of the cells is comparatively low and the mass or specific density of these batteries when used in mobile  Facilities (motor vehicles, submarines) the possible payload and the radius of action of the vehicle is very limited.

The object of the invention is to provide a method and an arrangement for optimizing the To create energy management of autonomous energy supply systems, their energy supply supply via batteries. Through the energy management, the average duration of use and the availability of autonomous facilities and systems increased become. At the same time, the reliability of the energy supply device and thus the of the entire system and the expected service life of the used Accumulators are increased.

This object is achieved by the characterizing features of the main claim solved. Further developments are preferably set out in the subclaims.

Increasing the duration and availability of autonomous facilities and Systems is brought about by the fact that the surprising effect of "self-recovery" existing accumulators are used in a targeted manner.

For this purpose, the change in capacity (state of charge) of each individual accumulator in the system is determined at intervals. As soon as the change in the instantaneous capacity of the accumulator over time exceeds a selectable, critical setpoint, the energy flow is separated from the previously used storage (accumulator) S _i to the consumer and at the same time another storage S _{k is} selected, from which energy is obtained. This next memory S _k is selected with the proviso that that memory S ₁ . . . S _{n is} selected that has the optimal conditions for delivering energy to the consumer.

A memory S _k is considered to be optimal if the actual capacity

C _cost = I _k .t

corresponds to the maximum nominal capacity C _{kNenn of} this memory (state of charge full) or when an already partially discharged memory S _k has reached its instantaneous maximum charging capacity after completion of the "recovery phase".

The parameter for reaching this maximum state of charge is the point C _tmax in the course of the characteristic curve of the accumulator used in each case. After the point C _{tmax is reached,} the rise in the characteristic curve I _k = f (t) flattens out. This indicates the end of the self-recovery phase of the battery in question (memory S _k ). After this characteristic point, there is no significant increase in storage capacity over time.

At this time t _max , the memory S _{k in} question can be used again for delivering energy to the consumers of the system. A prolonged absence of a Stromabnah me from this memory S _k (extension of the "conservation phase" of the battery for the purpose of Refreshings) would from this point t _max disproportionate to the otherwise necessary larger number of stores S _n to the capacitive total requirements Systems to cover electrical energy.

In the manner mentioned above, the temporal changes in the capacitances C ₁ become in differently small time intervals dt. . .C _n all memories S ₁ . . .S _{n of} the system recorded over time t and compared. It is therefore possible to choose a next partial storage S _{n if} the residual capacity C _{iRest of} a storage S _{i falls below} the critical limit, which _{temporarily provides} the optimal energetic requirements C _i (t) = opt for the energy delivery to the consumers! having.

An arrangement for implementing the method in a stationary or mobile system essentially consists of a number of memories S ₁ . . .S _n , which may have the same or different nominal capacities. The memory used can be identical or differ in size and structure. All stores S ₁ . . .S _n are connected to the consumer (s) in an electrically conductive manner via an energy supply network. A memory S _{i is connected} to the consumer via a circuit device (I) which is connected to a computer ( 2 ). The on-board computer ( 2 ) determines the current capacity C ₁ (t) permanently or cyclically. . .C _N (t) of all memories S ₁ . . .S _n .

If the instantaneous capacity C _i (t) of a memory i has reached the lower permissible discharge _limit C _iRest , the switch is made to a memory which is most suitable for the power consumption.

After each storage unit has been discharged, there is a load-free rest phase that lasts until takes to reach the effective setpoint for the regeneration (refreshing). Successor This storage can be used again for energy delivery.

The suitability of the memory S ₁ . . .S _n for renewed energy consumption can be checked using different control mechanisms:

1. Active system

The suitability of the memory S ₁ . . .S _n is determined by an on-board computer which determines the rate of change of current and / or voltage and / or resistance of the memories over time t in all memories S _i at stochastic or determined intervals and detects the memory concerned when the value falls below a predefinable limit value and released for subsequent energy extraction.

2. Passive system

The permissible change of current, voltage and / or resistance or of the product or quotient of the aforementioned parameters over time is determined for the respective memory (as a memory-specific characteristic). The associated switchover points (switch-on points EP _1. .EP _n and switch-off points AP _1. .AP _n ) are stored in a memory of the computer before the stationary or mobile device is started up. When a determined changeover point of the characteristic curve of a memory is reached, the computer determines the subsequent memory which has the optimal energy requirements for energy delivery.

Both systems are used with the same functional principle to determine the storage S _i , which is currently suitable for energy extraction or charging.

Energy gained externally, such as energy from air movement, solar energy, etc. is used in Depends on the power supplied to the memory that is used for the energy are most suitable or - depending on the current energy requirement - used directly for the operation of the facility.

If the externally generated energy is supplied in a jerky manner (e.g. feed-in of electrical energy from a wind generator), this is preferably not introduced directly into the storage unit, but is initially used to charge one or more optional intermediate storage units SZ ₁ . . .SZ _i (e.g. flywheel storage), which subsequently deliver the supplied energy to the individual storage for optimal charging. As a result, the amount of energy offered is optimally used and, at the same time, harmful overloading of the operating memories S ₁ to S _{n is} avoided.

_Ges due to the division of the effective total capacitance C of the entire system into a plurality of partial capacitances (storage _S1.. .S _n) occurs after the extracting electrical energy from the respective memory S _i and the switching to a new memory S recovery _k of the memory (accumulator ) S _i , as a result of which, surprisingly, a significant increase in capacity C _i (t +1) <C _i (t) is recorded in the previously discharged memory S _i . This "recovery effect" of the unloaded memory S _i , which occurs after each load cycle, increases the current capacity of this memory by approximately 10%.

Due to the gentle charging and discharging of the individual memories S ₁ monitored by the computer. . .S _n increases their service life by about 20%.

Total failures of storage due to rapid discharge or falling below the permissible The lower limit voltage of the batteries is largely prevented.

The drift behavior of the individual memories can also be monitored by the temporally determined or stochastic determination of the instantaneous capacitances C _ist and their change within differentially small time periods dt. In this way, memories are recognized early on, whose charging and discharging behavior is not in accordance with the standards. This defective memory can thus be replaced preventively. This increases the reliability and availability of the system.

If such deviant charging or discharging characteristics of a memory is detected during the operation of a mobile or stationary device, a switch is made to another memory by the onboard computer (2), which _is at this time the optimality criterion C = opt. ! corresponds.

Due to the preferably temporary storage of energy supplied in pulses (e.g. from a wind power generator) to one or more intermediate storage ZS ₁ . . .ZS _n can advantageously be an optimized charging process for the individual memories (accumulators) S ₁ . . .S _n corresponding to the respective discharge state [instantaneous capacity C _1act (t). . .C _nist (t)].

The computer controls that there is no direct change from discharge to charge in any storage S _i , since otherwise the regenerative energy would not be used due to the "recovery effect" of the storage.

It was surprisingly found that the memory, which is in a regeneration phase (Recovery phase), which absorb energy more effectively than storage, which energy during an energy extraction phase (e.g. in the form of solar energy) is fed.

The mode of operation of the method and the arrangement for optimizing the energy management of autonomous energy supply systems is subsequently carried out on different Embodiments explained and shown in the accompanying figures.

Embodiment 1

Show it:

Fig. 1 shows the schematic structure of a bound gauge boot with the main assembly in a sectional view,

Fig. 2 shows the exemplary diagram of a cycle of operation of the gauge boot,

Fig. 3 shows the characteristic curve of U (t) and I (t) of a used lead-acid battery,

Fig. 4 shows the characteristic curve U (t) and I (t) of a nickel-cadmium battery used.

An arrangement to optimize energy management is based on an unmanned Instrument carrier used, which is used in marine research. Depending on the measuring task, instrument carriers are used freely drifting or tied up. Conditionally The extreme operating conditions place high technical demands on all components mechanical and chemical resilience. The energy ver Care system of the measuring instrument carrier is designed so that a cyclical, preventive off the batteries are replaced by supply vessels in the area of operation. Quasi-stationary instrument carriers are used to monitor the marine environment and the Monitoring of environmental changes, especially in heavily polluted areas near the coast Waters such as the North and Baltic Seas. For this purpose, the measuring device carriers are on the sea floor anchored. The devices installed on board record climatic, chemical and biological Measurement data that is archived or passed on directly to ground stations via weather satellites be tested.

The measuring instrument holder has 3 memories S ₁ . . .S ₃ with different nominal capacity C _nominal , which are arranged near the center of gravity of the equipment carrier and connected to the consumers via the electrical system. All stores S ₁ . . .S ₃ are fully charged when the device carrier is started up.

On the surface of the device carrier, solar panels ( 18 ) and a wind generator ( 19 ) for external generation of electrical energy are arranged, the energy of which is fed into the vehicle electrical system.

When the device carrier is started up (state 1) and the control is activated, the on-board computer ( 20 ) begins with the permanent control of the capacities C1 actual. . .C _{3 is} all storage S ₁ . . . S ₃ . For this purpose, the temporal change in current and / or voltage and / or resistance or the product or the quotient of the aforementioned parameters is determined over time for each memory S _i . The time interval between the check intervals is selected depending on the battery type, the current power consumption (load situation) and, if applicable, other parameters and can be between several hours (for unloaded storage systems, from which no energy is currently being drawn) and fractions of a second.

The on-board computer ( 20 ) controls the energy supply from the solar panels ( 18 ) and the wind generator ( 19 ) and makes them available to the memory S ₁ , which is most suitable from its capacitive state for charging. In the present case, the supplied solar and / or wind energy is used to maintain the storage S ₁ . If all memories S ₁ . . .S ₃ currently have no absorption capacity, the energy is fed in directly for the consumer at the start of the work interval (cf. actual state in FIG. 2).

At the start of the measuring processes (cf. switch-on point EP1 of the storage characteristic according to FIG. 3), energy for supplying the consumers ( 12 ), ( 15 ), ( 17 ) (cf. state 2 in the working cycle according to FIG. 2) is first of all generated from the storage S1 taken.

After reaching a residual capacity of about 30% of this lead-acid battery, characterized by a significant drop in voltage and current by about 20% within a time interval of one second compared to the previous measuring cycle, the on-board computer ( 2 ) switches when it reaches it of the switch-off point AP1 (cf. FIG. 3) to the memory S ₂ by (state 3).

In the time after the switch from memory S ₁ to S ₂ , an increase in the voltage occurs in memory S ₁ due to the refreshing effect (state 3). The on-board computer ( 2 ) monitors the initially steep rise in voltage until it flattens out and occurs at an empirically determined level.

During the refreshing process, additional external energy (solar and / or wind energy) is fed into the memory S _{1 in} accordance with the current energy absorption capacity (state 3).

After completion of the measuring processes (switch-off point AP1 of memory S ₁ has been reached, switching to memory S ₂ has been carried out, see state 3), during the subsequent pause (state 4), the memory suitable for reloading is carried out by the on-board computer ( 20 ) by the Diagnosis of the current state of the memory S ₁ . . .S ₃ determined.

In the present example, the refreshing is completed in the memory S _1; there is a further supply of solar and / or wind energy. The refreshing process has not yet been completed in memory S ₂ . Due to the current energy absorption capacity of the storage S ₂ , this storage is also supplied with solar and / or wind energy. The optimum charging current I _opt is specified by the on-board computer ( 20 ) on which the characteristic curves I (t), U (t), R (t) of all the accumulators (memories S ₁ ... S ₃ ) of the device carrier are stored (cf. State 4 of the working interval).

In the event of a short-term change in the environmental data relevant for the measurements (air temperature, wind speed, salinity), a further measurement process is initiated via sensors, the energy required for the consumer being taken from the store S ₂ . At the same time, the store S ₁ is recharged further by solar and / or wind energy (state 5).

Due to the peculiarity of the determined measurement results, an immediate forwarding of the data via a directional radio transmitter is necessary parallel to further measurements. This increased load leads to the switch-off point AP2 (cf. FIG. 3) and causes the on-board computer ( 20 ) to switch to the memory S ₃ (state 6).

At the same time, the store S ₁ is recharged with solar and / or wind energy and the refreshing effect occurs in the store S ₂ .

After data transmission by the transmitter ( 14 ) has ended, the normal measuring operations are continued (state 7). At this point in time, the refreshing effect has already ended in the memory S ₂ . The stores S ₁ and S ₂ are loaded with solar and / or wind energy in accordance with their current energy absorption capacity.

The gentle charging takes place on the basis of the known characteristic curve of the individual accumulators. Changes in the characteristic behavior, which the on-board computer ( 20 ) registers, lead to the charging current for the relevant memory being changed.

In the following measurement pause (state 8), the refreshing effect and the recharging in memory S _{1 are} completed.

The refreshing effect is also completed in memory S ₂ . It is in the phase of recharging through solar and / or wind energy.

The refreshing effect sets in in memory S ₃ . Due to the current energy absorption capacity of the storage S ₃ , additional energy is already being supplied by solar and / or wind energy.

This process is repeated until all memories S ₁ . . .S ₃ can no longer increase their permissible, minimum residual capacity C _Rest even through refreshing and / or recharging of solar and / or wind energy.

The mother station of the measuring device carrier is now signaled via data radio that a reloading of the memories S ₁ . . .S ₃ from an external energy source or an exchange of the batteries within a safety period is necessary. A defined reserve capacity of a memory S ₁ is available for the further operation of the measuring device carrier. . .S ₃ ) is available.

Embodiment 2

The arrangement for optimizing the energy management is in the energy supply of traffic signs, traffic warning and guidance systems. These plants are often far away from energy supply networks and have to be extended Period can be operated reliably and with as little maintenance as possible.

Traffic warning devices are tasked with autonomously measuring data about local weather conditions collect conditions, evaluate this information and with the help of optical and / or to transmit acoustic signaling devices to the drivers. For this it is necessary that permanent or at intervals certain data, such. B. the humidity and the Air temperature can be measured.

A special application is the permanent visual range monitoring using phototech nik in latent fog-prone areas to prevent the driver from suddenly warning deterioration. The electrical necessary to acquire this measurement data Measuring devices and the amplifiers required to transmit and display the information and displays or signal boards are electrical consumers with a relatively high lei need.

Such devices are supplied with energy by local batteries Energy generators in the form of solar cells or wind generators can be recharged.

The accumulator capacity required for long-term operation of the traffic warning system ren is divided into several partial capacities. Depending on the respective time of day fluctuating energy requirements, only those partial capacities are activated which cover the current energy requirements are necessary. The partial capacities not used will be reloaded or are in the recovery phase. The accumulators, according to which a recovery period, the recovery phase is completed by the procedure appropriate energy management, energy-efficient and gentle recharging.  

If the critical storage capacity falls below a critical lower limit, is over a connected digital mobile radio device sends a warning message to the person responsible Traffic monitoring device directed, which causes an exchange of the batteries.  

Reference list

10th

Carrier unit (float)

11

anchoring

12th

sensor

13

antenna

14

Transmitter-receiver

15

sensor

16

Sampler

17th

Temperature sensor

18th

Solar panels

19th

Wind generator

20th

On-board computer

21

Storage (accumulators)
AP ₁

. . .AP _n

Switch-off points (points in time when a store is switched off by the consumer)
C capacity
C ₁

. . .C _n

Capacities of the first to nth memory S ₁

. . .S _n

C _total

Total capacity
C _Is

current actual capacity
C _iRest

Remaining capacity of the i-th memory
C _is

current actual capacity of the kth memory S _k

C _can

nominal nominal capacity of the kth memory S _k

C _tmax

current maximum actual capacity
EP switch-on point (time at which a store was connected to the consumer)
n Number of memories
S ₁

. . .S _i

, S _k

, S _n

Storage (accumulators)
S _Res

Reserve memory
SZ buffer
t time
t _max

Time of reaching the current maximum actual capacity of a memory
UP switchover point (switch-on or switch-off point of the characteristic curve of a memory)

Claims (10)

1. Method and arrangement for optimizing the energy management of autonomous energy supply systems, the energy supply of which is provided by accumulators, characterized in that
that the temporal change in the capacity dC / dt of the memory S ₁ . . .S _{n of} the energy supply system is determined,
that when a selectable, critical setpoint of the temporal change in the capacitance dC / dt of a memory S _{i is separated} over time, the energy flow is separated from the previously used memory S _i to the consumer and another memory S _{k is} selected, from which the energy is supplied to the consumer ,
the selection of this memory S _{k is carried out} on the condition that the current actual capacitance C _kist = I _k .t of the memory S _k compared to the other memories S ₁ . . .S _{n is} a maximum
that the previously used memory S _{i is} not selected again for energy delivery during a determinable time interval in order to use the refreshing effect of the memory S _i and that the memory S _{i is} not used until the next switch-on point EP _{i of} the U (t) - or I ( t) or R (t) characteristic curve or a characteristic curve determined from the aforementioned parameters is released for renewed energy delivery. 2. Arrangement for realizing the method according to claim 1, characterized in that
that the energy supply system n memory S ₁ . . .S _n ,
that all memory S ₁ . . .S _{n are} electrically connected to the consumer,
that the connection of a memory S _i to the consumer takes place via a circuit device ( 1 ) which is connected to a computer ( 2 ), the computer ( 2 ) being the current actual capacity C _1actual (t). . .C _nist (t) of all memories S ₁ . . .S _{n is} determined and the stores selected that are optimally suited for energy extraction and energy supply,
that the energy supply system has facilities for generating energy which are stored on the computer ( 2 ) with the memories S ₁ . . .S _n and / or the consumer are in operative connection. 3. Arrangement according to claim 2, characterized in that the memory S ₁ . . .S _n same or different nominal _capacities C _1Nom . . .C _can own. 4. Arrangement according to claim 2 or 3, characterized in that the memory S ₁ . . .S _{n are} identical. 5. Arrangement according to claim 2 or 3, characterized in that the memory S ₁ . . .S _{n have} a different structure and / or different nominal capacity S _iNenn . 6. Arrangement according to claim 2, characterized, that the facilities for energy production as solar cells or wind power generators are trained. 7. Arrangement according to claim 2, characterized in that the device for generating energy as a rotating flywheel storage ( 4 ) with a generator ( 6 ) is formed, which absorbs the kinetic energy of the mobile device with the integrated energy supply system with delayed movements, stores and to the consumer and / or loadable memories S ₁ . . .S _n delivers. 8. Arrangement according to one of claims 2 to 7, characterized, that the arrangement for optimizing energy management is part of a traffic or Means of transport, such as a motor vehicle, a watercraft or a flying object is. 9. Arrangement according to one of claims 2 to 7, characterized, that the arrangement for optimizing energy management is part of an autonomous lighting system device or traffic facility. 10. Arrangement according to one of claims 2 to 7, characterized, that the arrangement for optimizing energy management is part of a mobile or stationary measuring or monitoring device.