WO2019112527A1 - An energy storage system and a control method for the energy storage system - Google Patents

An energy storage system and a control method for the energy storage system Download PDF

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Publication number
WO2019112527A1
WO2019112527A1 PCT/TR2017/050675 TR2017050675W WO2019112527A1 WO 2019112527 A1 WO2019112527 A1 WO 2019112527A1 TR 2017050675 W TR2017050675 W TR 2017050675W WO 2019112527 A1 WO2019112527 A1 WO 2019112527A1
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Prior art keywords
energy
storage element
present
predicted
time slot
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PCT/TR2017/050675
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French (fr)
Inventor
Mustafa Fikret OTTEKIN
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Ottekin Mustafa Fikret
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Publication of WO2019112527A1 publication Critical patent/WO2019112527A1/en

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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/28—Arrangements for balancing of the load in a network by storage of energy
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
    • H02J2203/20—Simulating, e g planning, reliability check, modelling or computer assisted design [CAD]
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y04—INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
    • Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
    • Y04S40/00—Systems for electrical power generation, transmission, distribution or end-user application management characterised by the use of communication or information technologies, or communication or information technology specific aspects supporting them
    • Y04S40/20—Information technology specific aspects, e.g. CAD, simulation, modelling, system security

Definitions

  • the present invention relates to energy storage systems for storing electrical energy and control methods for controlling the operation of said energy storage systems.
  • the users are encouraged by the electricity market regulatory authorities and electricity distribution companies to consume electricity at the hours when the total consumption is relatively low. This encouragement is provided by determining the unit price of the electrical energy in proportion to the total energy consumption through multi-time tariffs.
  • residential users may shift the use of some of their electrical household appliances to the hours when the unit price of electrical energy is low. In this manner, daily power consumption is more homogenously distributed over time.
  • an energy storage system for storing electrical energy, and a control method for the energy storage system.
  • Said energy storage system comprises at least two energy storage units, wherein each unit has at least one storage element for storing electrical energy, at least one local control unit for providing at least one network connection and controlling the operation thereof, at least one mains input to obtain electrical energy from an electricity grid, at least one mains switch for controlling the supply of the electrical energy obtained from the mains input to the storage element, and at least one output for the electricity outlet; and at least one central control unit which is adapted to exchange data with each energy storage unit by means of the local control unit and which transmits, according to the information received from the energy storage units and at least one current time information, at least one control data to the energy storage units.
  • Said control method comprises the steps of transmitting the fullness level data of at least one storage element that is present in the energy storage unit to the central control unit by at least one local control unit; generating control data by the central control unit to control operation of each energy storage unit by using the current time information and the fullness level data of the storage element that are transmitted for each energy storage unit to the central control unit; transmitting each of the generated control data to the corresponding energy storage unit; controlling in each energy storage unit, according to the control data transmitted to the energy storage unit, whether or not electrical energy will be stored in the storage element through at least one mains input and whether or not the stored energy will be supplied for consumption through the output.
  • operation of different energy storage units is controlled by a central control unit.
  • a central control unit it is ensured that operation of each energy storage unit is controlled without any error, thereby the energy storage units are prevented from negatively affecting the operation of the electricity distribution systems, the transmission system and the generation/consumption balancing process.
  • An object of the present invention is to provide an energy storage system for storing electrical energy, and a control method for controlling the operation of said energy storage system.
  • Another object of the present invention is to provide an energy storage system for storing electrical energy obtained from different sources, and a control method for controlling the operation of said energy storage system.
  • Yet another object of the present invention is to provide an energy storage system for controlling the operation of a plurality of energy storage units, and a control method for controlling the operation of said energy storage system.
  • Still another object of the present invention is to provide a reliable and practical energy storage system, and a control method for controlling the operation of said energy storage system.
  • FIG. 1 is a block diagram of the energy storage system according to the present invention.
  • Figure 2 is a block diagram of an energy storage unit that is used in the energy storage system according to the present invention
  • Figure 3 is a flow diagram of an operation of the developed control method during night hours.
  • Figure 4 is a flow diagram of an operation of the developed control method during daylight hours.
  • an energy storage system for enabling the storage of electrical energy at the convenient times and the use of the stored energy at the desired time, and a control method for the said energy storage system.
  • the energy storage system comprises at least two energy storage units (U), wherein each unit has at least one storage element (1) (e.g. a battery) for storing electrical energy, at least one local control unit (2) for providing at least one network connection and controlling the operation thereof (for example comprising a network card), at least one mains input (3) for obtaining electrical energy from an electricity grid, at least a first bypass switch (23) for controlling the flow of the electrical energy obtained from the mains input (3), at least a second bypass switch (24), and at least one output (4) for the electricity outlet; and at least one central control unit (C) which is adapted to exchange data (for example over the internet) with each energy storage unit (U) by means of the local control unit (2) and which transmits, according to the information received from the energy storage units (U) and at least one current time information, at least one control data to the energy storage units (U).
  • each unit has at least one storage element (1) (e.g. a battery) for storing electrical energy
  • at least one local control unit (2) for providing at least one network connection and
  • the control method of the energy storage system developed with the present invention comprises the steps of transmitting by the local control unit (2) the fullness level data of the storage element (1) that is present in the energy storage unit (U) and the information indicating whether or not energy is available at the mains input (3) to the central control unit (C); generating control data by the central control unit (C) to control the operation of each energy storage unit (U) by using the fullness level data of the storage element (1) that are transmitted for each energy storage unit (U) to the central control unit, the information indicating whether or not energy is available at the mains input (3) and the current time information; transmitting each of the generated control data to the corresponding energy storage unit (U); controlling in each energy storage unit (U), by adjusting the state of the first bypass switch (23) and the second bypass switch (24) according to the control data transmitted to the energy storage unit, whether or not electrical energy will be stored in the storage element (1) through the mains input (3) and whether or not the stored electrical energy will be supplied for consumption through the output (4).
  • the energy storage unit (U) in the form of an uninterruptible power supply (UPS) is used for storing electrical energy.
  • the energy storage unit (U) of the present invention is connected by means of the local control unit (2) comprised therein to the central control unit (C), and the operation of a plurality of different energy storage units (U) is controlled by the said central control unit (C).
  • said control operation is performed by controlling whether or not electrical energy will be stored in the storage element (1) that is located in the energy storage unit (U) (in other words, whether or not it is to be charged).
  • the central control unit (C) mainly uses two parameters to determine whether or not electrical energy will be stored in the storage element (1) that is located in each energy storage unit (U).
  • One of these parameters is the fullness level data of the storage element (1), which is transmitted to the central control unit (C) by the local control unit (2).
  • the fullness level data is used for the purpose of determining whether or not the storage element (1) needs to be charged (in other words, whether or not the energy storage unit (U) has enough energy to meet the user needs).
  • the other of said parameters is the current time information.
  • using the current time information it is determined at which times the storage element (1) is to be charged. For example, charging of the storage element (1) is performed as much as possible at the period of time when the total consumption is low.
  • energy storage operation is performed at times when the unit price of the electrical energy is relatively low.
  • energy may be stored according to different scenarios. For example, if the unit price of the electrical energy is at the lowest level (in other words, the total amount of energy drawn from the electricity generation facilities is at the lowest level) at a time when the storage element (1) is not fully stored, then the storage element (1) may be fully charged even if there is no such need.
  • the storage element (1) is charged in order to meet the user needs.
  • direct current is used while electrical energy is stored in storage elements (1) such as batteries.
  • the electrical energy obtained from the mains input (3) is generally in the form of alternating current, the alternating current needs to be converted to direct current.
  • said energy storage unit (U) comprises at least a first rectifier (9) for the conversion of the alternating current that is obtained from the mains input (3) to the direct current.
  • the energy storage unit (U) further comprises at least a first measuring element (11) for measuring the voltage and / or current value of the electrical energy output from the first rectifier (9). By virtue of measuring the electrical energy transmitted to the storage element (1) by the said first measuring element (11), the total energy transferred to the storage element (1) is determined.
  • the energy storage unit (U) further comprises at least one mains measuring element (10) for measuring the voltage and / or current value of the electrical energy obtained from the mains input (3).
  • the energy storage unit (U) further comprises at least one mains switch (12) that is provided between the measuring element (11) and the storage element (1).
  • said energy storage unit (U) comprises at least one inverter (6) for the conversion of the direct current that is obtained from the storage element (1) to alternating current.
  • the energy storage unit (U) further comprises at least one storage output measuring element (8) for measuring the voltage and / or current value of the electrical energy obtained from the storage element (1).
  • energy efficiency of the storage element (1) may be determined for example by comparing the values measured by the first measuring element (11) with those measured by the storage output measuring element (8).
  • said energy storage unit (U) comprises at least a first bypass switch (23) for connecting the mains input (3) to the output (4) in a controlled manner, and at least a second bypass switch (24) for connecting the mains input (3) to the storage element (1) in a controlled manner.
  • the energy storage unit (U) is able to operate in Bypass mode. For example, at a time slot when there is sufficient energy in the storage element (1) and the demand for the electrical energy is low, the electrical energy, which is obtained from the mains input (3) is directly transmitted by means of the first bypass switch (23) to the output (4), while the second bypass switch (24) is opened to disable energy transfer to the storage element (1).
  • said energy storage unit (U) comprises at least one output measuring element (5) for measuring the voltage and / or current value of the electrical energy transferred to the output (4).
  • operating performance of the energy storage unit (U) may be determined based on the values measured by the output measuring element (5).
  • said energy storage unit (U) is also able to obtain electrical energy from at least one renewable energy source in addition to the mains inlet (3).
  • the energy storage unit (U) comprises at least one solar panel input (21) which is suitable for connection to a solar panel; at least one regulator (19) for regulating the voltage value of the electrical energy obtained from the said solar panel input (21); at least a first storage input switch (13) for transferring the electrical energy, the voltage value of which is regulated by the regulator (19), to the storage element (1) in a controlled manner (in other words, the operation thereof is controlled by the local control unit (2)).
  • the energy storage unit (U) further comprises at least a first storage input measuring element (17) for measuring the voltage and / or current value of electrical energy, the voltage value of which is regulated by the regulator (19), and at least a first storage safety switch (15) for controlling the transfer of the electrical energy, the voltage value of which is regulated by the regulator (19), to the storage element (1) according to the fullness level data of the storage element (1).
  • the values measured by the first storage input measuring element (17) may be sent to the central control unit (C) by the local control unit (2). In this way, for example, the central control unit (C) is able to predict the amount of energy that can be obtained through the solar panel for the next day.
  • the energy storage unit (U) comprises at least one wind turbine input (22) which is suitable for connection to a wind turbine; at least a second rectifier (20) for converting the electrical energy obtained from the wind turbine input (22) to direct current; and at least a second storage input switch (14) for transferring the energy obtained from the second rectifier (20) to the storage element (1) in a controlled manner (in other words, the operation thereof is controlled by a local control unit (2)).
  • the energy storage unit (U) further comprises at least a second storage input measuring element (18) for measuring the voltage and / or current value of electrical energy obtained from the second rectifier (20), and at least a second storage safety element (16) for controlling the transfer of the electrical energy obtained from the second rectifier (20) to the storage element (1) according to the fullness level data of the storage element (1).
  • the values measured by the second storage input measuring element (18) may be sent to the central control unit (C) by the local control unit (2). In this way, for example, the central control unit (C) is able to predict the amount of energy that can be obtained through the wind turbine for the next day.
  • the central control unit (C) takes into account the amount of electrical energy that may be obtained through the renewable energy sources as well.
  • the control method mentioned in this embodiment comprises the steps of receiving by the central control unit (C) the weather forecast information in the geographical location where each energy storage unit (U) is located; calculating the amount of electrical energy that may be obtained through the renewable energy sources by using the features (e.g. capacity, size, location etc.) of the renewable energy source utilized together with each energy storage unit (U) and the information of weather forecast; using the information of the calculated amount of electrical energy that may be obtained through the renewable energy sources in the step of generating control data for controlling the operation of each energy storage unit (U).
  • the information of the amount of energy that is consumed through the output (4) can also be used.
  • the control method comprises the steps of comparing the times when the storage elements (1) of different energy storage units (U) are to begin charging through the mains input (3); and delaying the start time of charging for at least one energy storage unit (U) if said start time of charging is the same for at least two energy storage units (U).
  • the control method prevents an uncontrolled increase in the total drawn instantaneous current level caused by the coincident loading of the plurality of energy storage units (U) on the grid.
  • Said delay operation is preferably performed with a shifting method.
  • the energy storage units (U) are divided into at least two groups (for the systems comprising a large number of energy storage units (U), it can be more than two).
  • a group number is assigned to each energy storage unit (U).
  • Said assigning operation is preferably determined according to the MAC address of the local control unit (2).
  • the delay time for the energy storage unit (U) in each group is determined according to the formula of “group number - (total number of groups / 2)”. Therefore, the start time of charging for the energy storage units (U) that are in different groups differs from each other. Here, it may not be appropriate in terms of equality of opportunity that, the start time of charging for the energy storage units (U) in each group is constant every day. For that reason, the delay time for each group can be changed on a daily basis. In a preferred embodiment of the invention, the delay time for each group is changed according to an amount of change every day. Here, the amount of change is obtained for example by dividing the total number of groups by the number of change steps.
  • the number of change steps is preferably not selected as 7 or one of the multiples of 7.
  • the delay time of the current day is obtained by adding, every day, said amount of change to the delay time of the day before.
  • the sign of the amount of change is reversed. In other words, the amount of change is subtracted from the delay time of the day before. This subtraction operation is continued until half of the total number of groups is exceeded in negative direction. Afterwards, the sign of amount of change is reversed again.
  • said control method comprises the steps of dividing a day (24 - hour period of time) into three periods of time, namely night time period, daytime period and peak time period, and controlling the operation of energy storage unit (U) with different methods in each time period.
  • each time period is divided into and consists of time slots of, for example, 15 minutes.
  • n denotes the time slot at which the calculation is to be made
  • ns denotes the first time slot of the daytime period
  • PreBatt[n ⁇ denotes the energy that is predicted to be present in the storage element at the end of the n th time slot
  • PreRnwbl[i] denotes the total amount of renewable energy that is predicted to be obtained at the i th time slot
  • PreConsump[i] denotes the total amount of energy that is predicted to be consumed at the i th time slot.
  • the average amount of energy that is predicted to be present in the storage element at the daytime and peak time periods is preferably calculated by averaging the maximum energy that is predicted to be present in the storage element at the daytime and peak time periods and the minimum energy that is predicted to be present in the storage element at the daytime and peak time periods.
  • the energy that is desired to be present in the storage element at the end of the night time period is calculated by subtracting the average energy which is predicted to be in the storage element at the daytime and peak time periods from the average of maximum value and minimum value of the storage element (1).
  • ns denotes the first time slot of the daytime period, now denotes the current time slot
  • BPs denotes the energy that is predicted to be present in the storage element at the end of the night time period
  • Bait denotes the stored energy in the storage element (1)
  • PreRnwbl[i] denotes the total amount of renewable energy that is predicted to be obtained at the i th time slot.
  • Bd Batt + (Bs - BPs) wherein, Bs denotes the energy value that is desired to be present in the storage element at the end of the night time period, Batt denotes the stored energy in the storage element (1), BPs denotes the energy that is predicted to be present in the storage element at the end of the night time period.
  • Bd Batt + a PreRnwbl[now] wherein, Bd denotes the energy that is desired to be present in the storage element at the end of the current time slot, Batt denotes the stored energy in the storage element (1), PreRnwbl[now] denotes the total amount of renewable energy that is predicted to be obtained at the current time slot, and a denotes the coefficient.
  • n denotes the time slot for which the calculation is to be made, now denotes the current time slot
  • PreBatt[n ⁇ denotes the energy that is predicted to be present in the storage element at the end of the n th time slot
  • Bait denotes the stored energy in the storage element (1)
  • PreRnwbl[i] denotes the total amount of the renewable energy that is predicted to be obtained at the i th time slot
  • PreConsump[i] denotes the total amount of energy that is predicted to be consumed at the i th time slot.
  • a (BMAX-Batt)/(BPmax-Batt) wherein, a denotes the coefficient, BMAX denotes the maximum energy value that may be present in the storage element (1), Batt denotes the stored energy in the storage element (1), and BPmax denotes the maximum energy that is predicted to be present in the storage element at the daytime and peak time periods.
  • a (Batt-BMIN)/(Batt-BPmin) wherein, a denotes the coefficient, Batt denotes the stored energy in the storage element (1), BMIN denotes the minimum energy value that must be present in the storage element, and BPmin denotes the minimum energy that is predicted to be present in the storage element at the daytime and peak time periods.
  • Bd Batt + a(PreRnwbl[now] - PreConsump[now]) wherein, Bd denotes the energy that is desired to be present in the storage element at the end of the current time slot, Batt denotes the stored energy in the storage element (1), PreRnwbl[now] denotes the total amount of the renewable energy that is predicted to be obtained at the current time slot, a denotes the coefficient, PreConsump[now] denotes the total amount of energy that is predicted to be consumed at the current time slot.
  • Peak time period is a time period in which the electrical energy consumption is at its highest (and thus the most expensive), and therefore, powering the storage element (1) through the mains input (3) within this time period is not preferred as far as possible. In fact, if there is enough energy stored in the storage element (1) within this time period, the loads connected to the output (4) are powered by said stored energy.
  • the minimum energy, which must be present in the storage element (1) of the energy storage units (U), is hold in reserve for use in case the distribution grid fails to supply energy to the mains inputs (3) of the storage units, and thus said minimum energy cannot be used in the cycle of daily energy storage/consumption. Since the storage capacity of the energy storage units (U) is limited, the efficiency from the energy storage units (U) will be increased by reducing the minimum energy value that must be present in the storage element (1) in the regions and periods in which the grid power failure is rarely experienced and by increasing the minimum energy value that must be present in the storage element (1) in the regions and periods in which the grid power failure is frequently encountered.
  • the information indicating whether or not energy is available at the main inputs (3) of the storage units and the amount of energy that is present in the storage element (1) of the storage units are transmitted from the energy storage units (U) to the central control unit (C).
  • the central control unit (C) adjusts the minimum energy value that must be present in the storage element. For example, if there is no energy at the mains input (3) and the energy in the storage element (1) is also about to run out, the minimum energy value that must be present in the storage element (1) is increased. In this way, it is ensured that the users are more prepared for the next power failure.
  • Increasing the minimum energy value that must be present in the storage element is performed by the following formula;
  • BMIN (BMIN + BMINmax)/2 wherein, BMIN denotes the minimum energy value that must be present in the storage element (1), and BMINmax denotes an upper limit of the minimum energy value that must be present in the storage element (1).
  • the minimum energy value that must be present in the storage element (1) is decreased in certain periods (for example 48 hours). Said decrease is performed by the following formula;
  • BMIN (BMIN + BMINmin)/2 wherein, BMIN denotes the minimum energy value that must be present in the storage element (1), and BMINmin denotes a lower limit of the minimum energy value that must be present in the storage element.
  • the central control unit (C) makes a comparison of the information about the power failures that are received from different energy storage units (U) so as to determine the correlation between the energy storage units (U). In this manner, for example, when there is power failure in an energy storage unit (U), it is determined that power failure will also occur in another energy storage unit (U) associated with said energy storage unit (U), and thus it is ensured that the minimum energy value that must be present in the storage element (1) of the other energy storage unit (U) is also updated.
  • the central control unit (C) in the energy storage system developed according to the present invention comprises at least one status manager for changing the status of operation of the energy storage units (U) according to the different situations.
  • Said status manager controls the status of operation of the energy storage units (U) according to the following parameters.
  • REQ denotes the message containing the input data which is sent by the energy storage unit (U) and received by the central control unit (C);
  • Time Period denotes the time period to which the time information specific to the energy storage unit (U) sending the input data belongs at the moment the input data is received;
  • Present state denotes status information which is obtained through the input data and which is specific to the energy storage unit (U) that indicates one of the states from“Bat- 0”,“Battery”,“Bypass” or“Charge”;
  • Bat-0 denotes the state in which the energy in the storage element (1) is used (external system is powered) when no electrical energy is available at the mains input (3);
  • Battery denotes the state in which the energy in the storage element (1) is used although electrical energy is available at the mains input (3);
  • Bypass denotes the status in which the electrical energy obtained from the mains input (3) is consumed;
  • Charge denotes charging the storage element (1) with the electrical energy obtained from the mains input (3) while consuming the electrical

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Abstract

With the present invention, there is provided an energy storage system for storing electrical energy, and a control method for the energy storage system. Said energy storage system comprises at least two energy storage units (U) and at least one central control unit (C) which controls the operation of the energy storage units (U) by exchanging data with said energy storage units (U). Said control method comprises the steps of transmitting the fullness level data of at least one storage element (1) that is present in the energy storage unit (U) to the central control unit (C) by at least one local control unit (2); generating control data by the central control unit (C) to control the operation of each energy storage unit (U) by using the current time information and the fullness level data of the storage element (1) that are transmitted for each energy storage unit (U) to the central control unit; transmitting each of the generated control data to the corresponding energy storage unit (U); controlling in each energy storage unit (U), according to the control data transmitted to the energy storage unit, whether or not electrical energy will be stored in the storage element (1) through at least one mains input (3).

Description

AN ENERGY STORAGE SYSTEM AND A CONTROL METHOD FOR
THE ENERGY STORAGE SYSTEM
Field of Invention
The present invention relates to energy storage systems for storing electrical energy and control methods for controlling the operation of said energy storage systems.
Background of the Invention
Nowadays, many devices are powered by electrical energy, and thus there is a need for uninterrupted electrical energy. For example, since devices used in daily life such as computers, televisions, music players etc. are powered by electrical energy, these devices may not be used at the times when there is no electrical energy due to reasons such as power grid failure. Users’ daily routines are negatively affected by this situation. Other than the residential electrical energy use, electrical energy is also used to power various devices and systems in work places such as factories, offices and shopping centers.
As electrical energy is used to meet different needs in different fields, for example, not only the amount of energy consumed at different hours during a day but also the total amount of energy that electricity generation facilities (such as thermal and hydroelectric power plants) must generate vary. For example, the total amount of energy consumed between the hours of 18:00 and 23:00 is very high, whereas the amount of consumption between the hours of 23:00 and 07:00 is significantly reduced. This fluctuation during the day complicates the control of electricity generation facilities, and capacity problems can be encountered particularly when the total amount of energy consumed is very high. It is preferred that the total amount of energy drawn from the electricity generation facilities be as constant as possible during the day in order to reduce said fluctuation and solve the capacity problem in order to balance the distribution of daily power consumption, the users are encouraged by the electricity market regulatory authorities and electricity distribution companies to consume electricity at the hours when the total consumption is relatively low. This encouragement is provided by determining the unit price of the electrical energy in proportion to the total energy consumption through multi-time tariffs. Thus, in order to pay less for the electrical energy, residential users may shift the use of some of their electrical household appliances to the hours when the unit price of electrical energy is low. In this manner, daily power consumption is more homogenously distributed over time.
The use of electrical energy at a higher cost during certain hours may restrict residential users from using electrical household appliances. Therefore, in the prior art, there are used energy storage units which store electrical energy at the time when the price is low and enable users to use the electrical energy at any time the user desires. In these units, electrical energy, which is obtained from the grid at the times when the unit price of electrical energy is low, is stored in a storage unit such as a battery. Stored energy may be used on demand by the user (for example, at the times when the unit price of electrical energy is high) in this way, it is ensured that the amount of energy that must be generated during the day by electricity generation facilities is as homogeneous as possible, while the users are allowed to use electrical energy at any time they desire. But, in such applications, the charging of energy storage unit and the use of the stored energy are managed by the control unit of the energy storage unit.
In the applications where an energy storage unit is used, external conditions such as tariffs etc. and user preferences determine when the energy storage unit will store the electrical energy supplied by the grid, and the control unit of the storage unit that may further comprise a timer unit manages the storage operation. In the units having a timer, the timer may possibly make an error due to any reason. Furthermore, as the connection or disconnection of a plurality of energy storage units comprising a timer to the grid at the same time will dramatically change the amount of instantaneous power that is drawn from the grid, instantaneous power fluctuations in the grid may turn into a problem. In addition to this problem, when errors resulting from the software running on the control unit of the storage unit are found, said software must be updated, and it is a risky process to update the software of the control unit of a plurality of storage units. Brief of the Invention
With the present invention, there is provided an energy storage system for storing electrical energy, and a control method for the energy storage system. Said energy storage system comprises at least two energy storage units, wherein each unit has at least one storage element for storing electrical energy, at least one local control unit for providing at least one network connection and controlling the operation thereof, at least one mains input to obtain electrical energy from an electricity grid, at least one mains switch for controlling the supply of the electrical energy obtained from the mains input to the storage element, and at least one output for the electricity outlet; and at least one central control unit which is adapted to exchange data with each energy storage unit by means of the local control unit and which transmits, according to the information received from the energy storage units and at least one current time information, at least one control data to the energy storage units.
Said control method comprises the steps of transmitting the fullness level data of at least one storage element that is present in the energy storage unit to the central control unit by at least one local control unit; generating control data by the central control unit to control operation of each energy storage unit by using the current time information and the fullness level data of the storage element that are transmitted for each energy storage unit to the central control unit; transmitting each of the generated control data to the corresponding energy storage unit; controlling in each energy storage unit, according to the control data transmitted to the energy storage unit, whether or not electrical energy will be stored in the storage element through at least one mains input and whether or not the stored energy will be supplied for consumption through the output.
According to the energy storage system and the control method for said system developed with the present invention, operation of different energy storage units is controlled by a central control unit. Thus, it is ensured that operation of each energy storage unit is controlled without any error, thereby the energy storage units are prevented from negatively affecting the operation of the electricity distribution systems, the transmission system and the generation/consumption balancing process. Furthermore, in different embodiments of the invention, it will be possible to evaluate the data of consumption and generation that may be obtained through renewable energy sources, which can be transmitted from the energy storage units to the central control unit, using big data analysis and machine learning methods in the central control unit, and thereby efficiency of the energy storage units would be maximized.
Object of the Invention
An object of the present invention is to provide an energy storage system for storing electrical energy, and a control method for controlling the operation of said energy storage system.
Another object of the present invention is to provide an energy storage system for storing electrical energy obtained from different sources, and a control method for controlling the operation of said energy storage system.
Yet another object of the present invention is to provide an energy storage system for controlling the operation of a plurality of energy storage units, and a control method for controlling the operation of said energy storage system.
Still another object of the present invention is to provide a reliable and practical energy storage system, and a control method for controlling the operation of said energy storage system.
Description of the Drawings
Exemplary embodiments of energy storage system developed according to the present invention are illustrated in the attached drawings, wherein:
Figure 1 is a block diagram of the energy storage system according to the present invention;
Figure 2 is a block diagram of an energy storage unit that is used in the energy storage system according to the present invention; Figure 3 is a flow diagram of an operation of the developed control method during night hours.
Figure 4 is a flow diagram of an operation of the developed control method during daylight hours.
All the parts illustrated in the drawings are individually assigned a reference numeral and the corresponding terms of these numbers are listed as follows:
Energy storage unit (U)
Central control unit (C)
Storage element (1)
Local control unit (2)
Mains input (3)
Output (4)
Output measuring element (5)
Inverter (6)
Storage output measuring element (8)
First rectifier (9)
Mains measuring element (10)
First measuring element (11)
Mains switch (12)
First storage input/output switch (13)
Second storage input/output switch (14)
First storage safety switch (15)
Second storage safety switch (16)
First storage input measuring element (17)
Second storage input measuring element (18)
Regulator (19)
Second rectifier (20)
Solar panel input (21)
Wind turbine input (22)
First bypass switch (23) Second bypass switch (24)
Start (100)
Receiving parameters (101)
Calculating the energy that is predicted to be present in the storage (102) element at time slots
Calculating other parameters (103)
Determining whether or not the energy desired to be present in the (104) storage element at the end of the night time period is between the maximum energy value that may be present in the storage element and the minimum energy value that must be present in the storage element
Comparing the energy desired to be present in the storage element (105) at the end of the night time period with the maximum energy value that may be present in the storage element
Setting the energy desired to be present in the storage element at (106) the end of the night time period to the minimum energy value that must be present in the storage element
Setting the energy desired to be present in the storage element at (107) the end of the night time period to the maximum energy value that may be present in the storage element at the end of the night time period
Calculating the energy that is predicted to be present in the storage (108) element at the end of the night time period
Comparing the energy that is predicted to be present in the storage (110) element at the end of the night time period with the energy desired to be present in the storage element at the end of the night time period
Calculating with a formula the energy that is desired to be present in (111) the storage element at the end of the current time slot
Calculating the coefficient value with a first formula (112)
Calculating the coefficient value with a second formula (113)
Calculating the energy that is desired to be present in the storage (114) element at the end of the current time slot with a first formula according to the coefficient value Controlling the operation of the storage unit by taking into account (115) the energy that is desired to be present in the storage element at the
end of the current time slot
Comparing the maximum energy and minimum energy predicted to (116) be present in the storage element in the daytime and peak time
periods with the maximum energy value that may be present in the
storage element and the minimum energy value that must be present
in the storage element
Comparing the current time slot with the time slot at which the (117) maximum energy is predicted to be present in the storage element
Comparing the current time slot with the time slot at which the (118) minimum energy is predicted to be present in the storage element
Controlling that the time slot at which the minimum energy is (119) predicted is smaller than the time slot at which the maximum energy
is predicted and that minimum energy predicted to be present in the
storage element in the daytime and peak time periods is less than
the minimum energy vaiue that must be present in the storage
element
Controlling that maximum time slot is smaller than the minimum time (120) slot and that maximum energy predicted to be present in the storage
element in the daytime and peak time periods is more than the
maximum vaiue of the storage eiement
Calculating the coefficient value with a third formula (121)
Calculating the energy that is desired to be present in the storage (122) element at the end of the current time slot with a second formula
according to the coefficient value
Description of the Invention
As electrically powered devices are extensively used in everyday life and business life, electrical energy is constantly needed. Total consumption of all the electrical devices and systems that are connected to a transmission system varies significantly during the day, and thus there occurs significant changes in the amount of energy drawn from electricity generation facilities connected to said transmission system at different hours during a day. This situation can lead to difficulties in controlling electricity generation facilities and inefficient operation thereof. In order to prevent said imbalance, it is necessary to reduce the use of mains electricity of some of the users, particularly at the hours when the total consumption is intense. Therefore, with the present invention, there is provided an energy storage system for enabling the storage of electrical energy at the convenient times and the use of the stored energy at the desired time, and a control method for the said energy storage system.
The energy storage system, the exemplary views of which are illustrated in Figures 1-2, according to the present invention, comprises at least two energy storage units (U), wherein each unit has at least one storage element (1) ( e.g. a battery) for storing electrical energy, at least one local control unit (2) for providing at least one network connection and controlling the operation thereof (for example comprising a network card), at least one mains input (3) for obtaining electrical energy from an electricity grid, at least a first bypass switch (23) for controlling the flow of the electrical energy obtained from the mains input (3), at least a second bypass switch (24), and at least one output (4) for the electricity outlet; and at least one central control unit (C) which is adapted to exchange data (for example over the internet) with each energy storage unit (U) by means of the local control unit (2) and which transmits, according to the information received from the energy storage units (U) and at least one current time information, at least one control data to the energy storage units (U).
The control method of the energy storage system developed with the present invention comprises the steps of transmitting by the local control unit (2) the fullness level data of the storage element (1) that is present in the energy storage unit (U) and the information indicating whether or not energy is available at the mains input (3) to the central control unit (C); generating control data by the central control unit (C) to control the operation of each energy storage unit (U) by using the fullness level data of the storage element (1) that are transmitted for each energy storage unit (U) to the central control unit, the information indicating whether or not energy is available at the mains input (3) and the current time information; transmitting each of the generated control data to the corresponding energy storage unit (U); controlling in each energy storage unit (U), by adjusting the state of the first bypass switch (23) and the second bypass switch (24) according to the control data transmitted to the energy storage unit, whether or not electrical energy will be stored in the storage element (1) through the mains input (3) and whether or not the stored electrical energy will be supplied for consumption through the output (4).
In an exemplary embodiment of the invention, the energy storage unit (U) in the form of an uninterruptible power supply (UPS) is used for storing electrical energy. Unlike the uninterruptible power supplies in conventional applications, the energy storage unit (U) of the present invention is connected by means of the local control unit (2) comprised therein to the central control unit (C), and the operation of a plurality of different energy storage units (U) is controlled by the said central control unit (C). Here, said control operation is performed by controlling whether or not electrical energy will be stored in the storage element (1) that is located in the energy storage unit (U) (in other words, whether or not it is to be charged). The central control unit (C) mainly uses two parameters to determine whether or not electrical energy will be stored in the storage element (1) that is located in each energy storage unit (U). One of these parameters is the fullness level data of the storage element (1), which is transmitted to the central control unit (C) by the local control unit (2). The fullness level data is used for the purpose of determining whether or not the storage element (1) needs to be charged (in other words, whether or not the energy storage unit (U) has enough energy to meet the user needs). The other of said parameters is the current time information. Here, using the current time information, it is determined at which times the storage element (1) is to be charged. For example, charging of the storage element (1) is performed as much as possible at the period of time when the total consumption is low. in this way, while the amount of energy drawn from the electricity generation facilities during the day is ensured to be as homogenous as possible, energy storage operation is performed at times when the unit price of the electrical energy is relatively low. By virtue of using said parameters together, energy may be stored according to different scenarios. For example, if the unit price of the electrical energy is at the lowest level (in other words, the total amount of energy drawn from the electricity generation facilities is at the lowest level) at a time when the storage element (1) is not fully stored, then the storage element (1) may be fully charged even if there is no such need. In another example, if the unit price of the electrical energy is at the highest level (in other words, the total amount of energy drawn from the electricity generation facilities is at the highest level) when the storage element (1) is almost empty, the storage element (1) is charged in order to meet the user needs. Generally, direct current is used while electrical energy is stored in storage elements (1) such as batteries. As the electrical energy obtained from the mains input (3) is generally in the form of alternating current, the alternating current needs to be converted to direct current. For that reason, in a preferred embodiment of the invention, said energy storage unit (U) comprises at least a first rectifier (9) for the conversion of the alternating current that is obtained from the mains input (3) to the direct current. In this embodiment, the energy storage unit (U) further comprises at least a first measuring element (11) for measuring the voltage and / or current value of the electrical energy output from the first rectifier (9). By virtue of measuring the electrical energy transmitted to the storage element (1) by the said first measuring element (11), the total energy transferred to the storage element (1) is determined. The energy storage unit (U) further comprises at least one mains measuring element (10) for measuring the voltage and / or current value of the electrical energy obtained from the mains input (3). The energy storage unit (U) further comprises at least one mains switch (12) that is provided between the measuring element (11) and the storage element (1).
As the input power of electronic devices is generally alternating current, the direct current obtained from the storage elements (1) needs to be converted to alternating current. For that reason, in another preferred embodiment of the invention, said energy storage unit (U) comprises at least one inverter (6) for the conversion of the direct current that is obtained from the storage element (1) to alternating current. In this embodiment, the energy storage unit (U) further comprises at least one storage output measuring element (8) for measuring the voltage and / or current value of the electrical energy obtained from the storage element (1). Here, energy efficiency of the storage element (1) may be determined for example by comparing the values measured by the first measuring element (11) with those measured by the storage output measuring element (8).
In another preferred embodiment of the invention, said energy storage unit (U) comprises at least a first bypass switch (23) for connecting the mains input (3) to the output (4) in a controlled manner, and at least a second bypass switch (24) for connecting the mains input (3) to the storage element (1) in a controlled manner. In this embodiment, the energy storage unit (U) is able to operate in Bypass mode. For example, at a time slot when there is sufficient energy in the storage element (1) and the demand for the electrical energy is low, the electrical energy, which is obtained from the mains input (3) is directly transmitted by means of the first bypass switch (23) to the output (4), while the second bypass switch (24) is opened to disable energy transfer to the storage element (1).
In another preferred embodiment of the invention, said energy storage unit (U) comprises at least one output measuring element (5) for measuring the voltage and / or current value of the electrical energy transferred to the output (4). In this embodiment, operating performance of the energy storage unit (U) may be determined based on the values measured by the output measuring element (5).
In a further preferred embodiment of the invention, said energy storage unit (U) is also able to obtain electrical energy from at least one renewable energy source in addition to the mains inlet (3). In an exemplary embodiment, the energy storage unit (U) comprises at least one solar panel input (21) which is suitable for connection to a solar panel; at least one regulator (19) for regulating the voltage value of the electrical energy obtained from the said solar panel input (21); at least a first storage input switch (13) for transferring the electrical energy, the voltage value of which is regulated by the regulator (19), to the storage element (1) in a controlled manner (in other words, the operation thereof is controlled by the local control unit (2)). In this embodiment, the energy storage unit (U) further comprises at least a first storage input measuring element (17) for measuring the voltage and / or current value of electrical energy, the voltage value of which is regulated by the regulator (19), and at least a first storage safety switch (15) for controlling the transfer of the electrical energy, the voltage value of which is regulated by the regulator (19), to the storage element (1) according to the fullness level data of the storage element (1). Here, the values measured by the first storage input measuring element (17) may be sent to the central control unit (C) by the local control unit (2). In this way, for example, the central control unit (C) is able to predict the amount of energy that can be obtained through the solar panel for the next day. In another exemplary embodiment, the energy storage unit (U) comprises at least one wind turbine input (22) which is suitable for connection to a wind turbine; at least a second rectifier (20) for converting the electrical energy obtained from the wind turbine input (22) to direct current; and at least a second storage input switch (14) for transferring the energy obtained from the second rectifier (20) to the storage element (1) in a controlled manner (in other words, the operation thereof is controlled by a local control unit (2)). In this embodiment, the energy storage unit (U) further comprises at least a second storage input measuring element (18) for measuring the voltage and / or current value of electrical energy obtained from the second rectifier (20), and at least a second storage safety element (16) for controlling the transfer of the electrical energy obtained from the second rectifier (20) to the storage element (1) according to the fullness level data of the storage element (1). Here, the values measured by the second storage input measuring element (18) may be sent to the central control unit (C) by the local control unit (2). In this way, for example, the central control unit (C) is able to predict the amount of energy that can be obtained through the wind turbine for the next day. In the applications where renewable energy sources are used, while sending a control signal to each energy storage unit (U), the central control unit (C) takes into account the amount of electrical energy that may be obtained through the renewable energy sources as well. For that reason, the control method mentioned in this embodiment comprises the steps of receiving by the central control unit (C) the weather forecast information in the geographical location where each energy storage unit (U) is located; calculating the amount of electrical energy that may be obtained through the renewable energy sources by using the features (e.g. capacity, size, location etc.) of the renewable energy source utilized together with each energy storage unit (U) and the information of weather forecast; using the information of the calculated amount of electrical energy that may be obtained through the renewable energy sources in the step of generating control data for controlling the operation of each energy storage unit (U). In this way, for example, it may be ensured that no electrical energy is obtained from the mains input (3) at the times when it is possible to fully charge the storage element (1) through the renewable energy sources. Here, In addition to the information about the calculated amount of the electrical energy that may be obtained through the renewable energy sources, the information of the amount of energy that is consumed through the output (4) can also be used.
In another preferred embodiment of the invention, in the step of generating control data by the central control unit (C) to control the operation of each energy storage unit (U) by using the fullness level data of the storage element (1) that are transmitted for each energy storage unit (U) to the central control unit and the current time information, the control method comprises the steps of comparing the times when the storage elements (1) of different energy storage units (U) are to begin charging through the mains input (3); and delaying the start time of charging for at least one energy storage unit (U) if said start time of charging is the same for at least two energy storage units (U). In this embodiment, for example, if charging of a plurality of energy storage units (U) is to begin at the same time through the mains input (3) at a time when the unit price of the electrical energy changes, the start time of charging is delayed for at least one energy storage unit (U). In this way, the control method prevents an uncontrolled increase in the total drawn instantaneous current level caused by the coincident loading of the plurality of energy storage units (U) on the grid. Said delay operation is preferably performed with a shifting method. In the shifting method, the energy storage units (U) are divided into at least two groups (for the systems comprising a large number of energy storage units (U), it can be more than two). Here, a group number is assigned to each energy storage unit (U). Said assigning operation is preferably determined according to the MAC address of the local control unit (2). Here, the delay time for the energy storage unit (U) in each group is determined according to the formula of “group number - (total number of groups / 2)”. Therefore, the start time of charging for the energy storage units (U) that are in different groups differs from each other. Here, it may not be appropriate in terms of equality of opportunity that, the start time of charging for the energy storage units (U) in each group is constant every day. For that reason, the delay time for each group can be changed on a daily basis. In a preferred embodiment of the invention, the delay time for each group is changed according to an amount of change every day. Here, the amount of change is obtained for example by dividing the total number of groups by the number of change steps. In order to assure weekly variations, the number of change steps is preferably not selected as 7 or one of the multiples of 7. The delay time of the current day is obtained by adding, every day, said amount of change to the delay time of the day before. When the delay time so obtained exceeds half of the total number of groups, the sign of the amount of change is reversed. In other words, the amount of change is subtracted from the delay time of the day before. This subtraction operation is continued until half of the total number of groups is exceeded in negative direction. Afterwards, the sign of amount of change is reversed again.
In another preferred embodiment of the invention, in the step of generating control data by the central control unit (C) to control the operation of each energy storage unit (U) by using the fullness level data of the storage element (1) that are transmitted for each energy storage unit (U) to the central control unit and the current time information, said control method comprises the steps of dividing a day (24 - hour period of time) into three periods of time, namely night time period, daytime period and peak time period, and controlling the operation of energy storage unit (U) with different methods in each time period. Here, each time period is divided into and consists of time slots of, for example, 15 minutes.
The method to control the operation of the energy storage unit (U) when the current time period is night is explained in the flo diagram shown in Figure 3. According to said flow diagram, when the current time period is detected as night, the steps of the method are initiated (100). Following the start step (100), said method comprises the steps of receiving parameters of the energy storage unit (U) (e.g. information of the amount of renewable energy that is predicted for the current time slot, information of the estimated amount of energy consumption that is predicted for the current time slot, and information of the minimum amount of energy that must be present in the storage element (1)) (101); calculating, by using the received parameters, the energy that is predicted to be present in the storage element (1) at all the time slots of daytime and peak time periods (102); calculating other parameters such as maximum energy that is predicted to be present in the storage element at the daytime and peak time periods, minimum energy that is predicted to be present in the storage element at the daytime and peak time periods, average energy that is predicted to be present in the storage element at the daytime and peak time periods, the energy desired to be present in the storage element at the end of the night time period (103); determining whether or not the energy desired to be present in the storage element at the end of the night time period is between the maximum energy value that may be present in the storage element and the minimum energy value that must be present in the storage element (104); comparing the energy desired to be present in the storage element at the end of the night time period with the maximum energy value that may be present in the storage element, if the energy desired to be present in the storage element at the end of the night time period is not between the maximum energy value that may be present in the storage element and the minimum energy value that must be present in the storage element (105); setting the energy desired to be present in the storage element at the end of the night time period to the minimum energy value that must be present in the storage element, if the energy desired to be present in the storage element at the end of the night time period is less than the maximum energy value that may be present in the storage element (106); setting the energy desired to be present in the storage element at the end of the night time period to the maximum energy value that may be present in the storage element, if the energy desired to be present in the storage element at the end of the night time period is more than the maximum energy value that may be present in the storage element (107); calculating the energy that is predicted to be present in the storage element at the end of the night time period (108); comparing the energy that is predicted to be present in the storage element at the end of the night time period with the energy desired to be present in the storage element at the end of the night time period (110); calculating the energy that is desired to be present in the storage element at the end of the current time slot, if the energy that is predicted to be present in the storage element at the end of the night time period is not more than the energy desired to be present in the storage element at the end of the night time period (1 11); calculating a coefficient value with a first formula, if the energy that is predicted to be present in the storage element at the end of the night time period is more than the energy desired to be present in the storage element at the end of the night time period (112); calculating the energy that is desired to be present in the storage element at the end of the current time slot with a first formula according to the coefficient value (114); controlling the operation of the storage unit (U) according to the energy that is desired to be present in the storage element at the end of the current time slot (115).
In this method, in the step of calculating the energy that is predicted to be present in the storage element at all the time slots of daytime and peak time periods (102), preferably the following formula is used for each time slot;
Figure imgf000017_0001
wherein n denotes the time slot at which the calculation is to be made, ns denotes the first time slot of the daytime period, PreBatt[n\ denotes the energy that is predicted to be present in the storage element at the end of the nth time slot, PreRnwbl[i] denotes the total amount of renewable energy that is predicted to be obtained at the ith time slot, and PreConsump[i] denotes the total amount of energy that is predicted to be consumed at the ith time slot.
In the step of calculating other parameters (103), the average amount of energy that is predicted to be present in the storage element at the daytime and peak time periods is preferably calculated by averaging the maximum energy that is predicted to be present in the storage element at the daytime and peak time periods and the minimum energy that is predicted to be present in the storage element at the daytime and peak time periods. Here, the energy that is desired to be present in the storage element at the end of the night time period is calculated by subtracting the average energy which is predicted to be in the storage element at the daytime and peak time periods from the average of maximum value and minimum value of the storage element (1).
In the step of calculating the energy that is predicted to be present in the storage element at the end of the night time period (108), the following formula is used;
Figure imgf000018_0001
wherein, ns denotes the first time slot of the daytime period, now denotes the current time slot, BPs denotes the energy that is predicted to be present in the storage element at the end of the night time period, Bait denotes the stored energy in the storage element (1), and PreRnwbl[i] denotes the total amount of renewable energy that is predicted to be obtained at the ith time slot.
In the step of calculating the energy that is desired to be present in the storage element at the end of the current time slot (111), the following formula is used;
Bd = Batt + (Bs - BPs) wherein, Bs denotes the energy value that is desired to be present in the storage element at the end of the night time period, Batt denotes the stored energy in the storage element (1), BPs denotes the energy that is predicted to be present in the storage element at the end of the night time period.
In the step of calculating a coefficient value with a first formula (112), the first formula is as follows; a = (Bs-Batt)/(BPs-Batt) wherein, a denotes the coefficient, Bs denotes the energy value that is desired to be present in the storage element at the end of the night time period, Batt denotes the stored energy in the storage element (1), and BPs denotes the energy that is predicted to be present in the storage element at the end of the night time period.
In the step of calculating the energy that is desired to be present in the storage element at the end of the current time slot with a first formula according to the coefficient value (114), the following formula is used;
Bd = Batt + a PreRnwbl[now] wherein, Bd denotes the energy that is desired to be present in the storage element at the end of the current time slot, Batt denotes the stored energy in the storage element (1), PreRnwbl[now] denotes the total amount of renewable energy that is predicted to be obtained at the current time slot, and a denotes the coefficient.
The method to control the operation of the energy storage unit (U) when the current time period is daytime, is explained in the flow diagram shown in Figure 4. According to said flow diagram, when the current time period is detected as daytime, the steps of the method are initiated (100). Following the start step (100), said method comprises the steps of receiving parameters of the energy storage unit (U) (e.g. information of the amount of renewable energy that is predicted for the daytime and peak time periods, information of the estimated amount of energy consumption that is predicted for the daytime and peak time periods, and information of the minimum amount of energy that must be present in the storage element (1)) (101); calculating, by using the received parameters, the energy that is predicted to be present in the storage element (1) at a desired time slot (102); calculating other parameters such as maximum energy that is predicted to be present in the storage element at the daytime and peak time periods, minimum energy that is predicted to be present in the storage element at the daytime and peak time periods, time slot at which maximum energy is predicted, time slot at which minimum energy is predicted (103); comparing the maximum energy and minimum energy that are predicted to be present in the storage element at the daytime and peak time periods with the maximum energy value that may be present in the storage element and the minimum energy value that must be present in the storage element (116); comparing the current time slot with the time slot at which the maximum energy is predicted, if the maximum energy that is predicted to be present in the storage element at the daytime and peak time periods is more than the maximum energy value that may be present in the storage element or if the minimum energy that is predicted to be present in the storage element at the daytime and peak time periods is less than the minimum energy value that must be present in the storage element (117); comparing the current time slot with the time slot at which the minimum energy is predicted, if the current time slot is not equal to the time slot at which the maximum energy is predicted (118); controlling that the time slot at which the minimum energy is predicted is smaller than the time slot at which the maximum energy is predicted and the minimum energy that is predicted to be present in the storage element (1) at the daytime and peak time periods is less than the minimum energy that must be present in the storage element (1), if the current time slot is not equal to the time slot at which the minimum energy is predicted (119); controlling that the time slot at which the maximum energy is predicted is smaller than the time slot at which the minimum energy is predicted and the maximum energy that is predicted to be present in the storage element at the daytime and peak time periods is more than the maximum value of the storage element, if the time slot at which the minimum energy is predicted is not smaller than the time slot at which the maximum energy is predicted or if the minimum energy that is predicted to be present in the storage element at the daytime and peak time periods is not less than the minimum energy value that must be present in the storage unit (120); determining the coefficient as 1 , if the time slot at which the maximum energy is predicted is not smaller than the time slot at which the minimum energy is predicted or if the maximum energy that is predicted to be present in the storage element at the day time and peak time periods is not more than the maximum value of the storage element;
calculating the coefficient value with a second formula, if the current time slot is equal to the time slot at which the minimum energy is predicted or if the time slot at which maximum energy is predicted is smaller than the time slot at which minimum energy is predicted and the maximum energy that is predicted to be present in the storage element at the daytime and peak time periods is more than the maximum value of the storage element, as a result of the comparison (118) of the current time slot with the time slot at which the minimum energy is predicted (113); calculating the coefficient value with a third formula, if the current time slot is equal to the time slot at which the maximum energy is predicted or if the time slot at which minimum energy is predicted is smaller than the time slot at which maximum energy is predicted and the minimum energy that is predicted to be present in the storage element at the daytime and peak time periods is less than the minimum energy value that must be present in the storage element, as a result of the comparison (117) of the current time slot with the time slot at which the maximum energy is predicted (121); calculating the energy that is desired to be present in the storage element at the end of the current time slot with a second formula according to the coefficient value (122); controlling the operation of the storage unit (U) according to the energy that is desired to be present in the storage element at the end of the current time slot (115).
In this method, in the step of calculating the energy that is predicted to be present in the storage element at a desired time slot of daytime and peak time periods (102), preferably the following formula is used;
Figure imgf000021_0001
wherein, n denotes the time slot for which the calculation is to be made, now denotes the current time slot, PreBatt[n\ denotes the energy that is predicted to be present in the storage element at the end of the nth time slot, Bait denotes the stored energy in the storage element (1), PreRnwbl[i] denotes the total amount of the renewable energy that is predicted to be obtained at the ith time slot, and PreConsump[i] denotes the total amount of energy that is predicted to be consumed at the ith time slot.
In the step of calculating the coefficient value with a second formula (113), preferably the following formula is used; a = (BMAX-Batt)/(BPmax-Batt) wherein, a denotes the coefficient, BMAX denotes the maximum energy value that may be present in the storage element (1), Batt denotes the stored energy in the storage element (1), and BPmax denotes the maximum energy that is predicted to be present in the storage element at the daytime and peak time periods.
In the step of calculating the coefficient value with a third formula (121), preferably the following formula is used; a = (Batt-BMIN)/(Batt-BPmin) wherein, a denotes the coefficient, Batt denotes the stored energy in the storage element (1), BMIN denotes the minimum energy value that must be present in the storage element, and BPmin denotes the minimum energy that is predicted to be present in the storage element at the daytime and peak time periods.
In the step of calculating the energy that is desired to be present in the storage element at the end of the current time slot with a second formula according to the coefficient value (122), preferably the following formula is used;
Bd = Batt + a(PreRnwbl[now] - PreConsump[now]) wherein, Bd denotes the energy that is desired to be present in the storage element at the end of the current time slot, Batt denotes the stored energy in the storage element (1), PreRnwbl[now] denotes the total amount of the renewable energy that is predicted to be obtained at the current time slot, a denotes the coefficient, PreConsump[now] denotes the total amount of energy that is predicted to be consumed at the current time slot.
Peak time period is a time period in which the electrical energy consumption is at its highest (and thus the most expensive), and therefore, powering the storage element (1) through the mains input (3) within this time period is not preferred as far as possible. In fact, if there is enough energy stored in the storage element (1) within this time period, the loads connected to the output (4) are powered by said stored energy.
The minimum energy, which must be present in the storage element (1) of the energy storage units (U), is hold in reserve for use in case the distribution grid fails to supply energy to the mains inputs (3) of the storage units, and thus said minimum energy cannot be used in the cycle of daily energy storage/consumption. Since the storage capacity of the energy storage units (U) is limited, the efficiency from the energy storage units (U) will be increased by reducing the minimum energy value that must be present in the storage element (1) in the regions and periods in which the grid power failure is rarely experienced and by increasing the minimum energy value that must be present in the storage element (1) in the regions and periods in which the grid power failure is frequently encountered. For that reason, in a preferred embodiment of the invention, the information indicating whether or not energy is available at the main inputs (3) of the storage units and the amount of energy that is present in the storage element (1) of the storage units are transmitted from the energy storage units (U) to the central control unit (C). By using said information, the central control unit (C) adjusts the minimum energy value that must be present in the storage element. For example, if there is no energy at the mains input (3) and the energy in the storage element (1) is also about to run out, the minimum energy value that must be present in the storage element (1) is increased. In this way, it is ensured that the users are more prepared for the next power failure. Increasing the minimum energy value that must be present in the storage element is performed by the following formula;
BMIN = (BMIN + BMINmax)/2 wherein, BMIN denotes the minimum energy value that must be present in the storage element (1), and BMINmax denotes an upper limit of the minimum energy value that must be present in the storage element (1).
In case no power failure is experienced at the mains input (3) for a while, the minimum energy value that must be present in the storage element (1) is decreased in certain periods (for example 48 hours). Said decrease is performed by the following formula;
BMIN = (BMIN + BMINmin)/2 wherein, BMIN denotes the minimum energy value that must be present in the storage element (1), and BMINmin denotes a lower limit of the minimum energy value that must be present in the storage element. In this embodiment, the central control unit (C) makes a comparison of the information about the power failures that are received from different energy storage units (U) so as to determine the correlation between the energy storage units (U). In this manner, for example, when there is power failure in an energy storage unit (U), it is determined that power failure will also occur in another energy storage unit (U) associated with said energy storage unit (U), and thus it is ensured that the minimum energy value that must be present in the storage element (1) of the other energy storage unit (U) is also updated.
The central control unit (C) in the energy storage system developed according to the present invention comprises at least one status manager for changing the status of operation of the energy storage units (U) according to the different situations. Said status manager controls the status of operation of the energy storage units (U) according to the following parameters.
Figure imgf000024_0001
According to the table given above, REQ denotes the message containing the input data which is sent by the energy storage unit (U) and received by the central control unit (C); “Time Period” denotes the time period to which the time information specific to the energy storage unit (U) sending the input data belongs at the moment the input data is received; “Present state” denotes status information which is obtained through the input data and which is specific to the energy storage unit (U) that indicates one of the states from“Bat- 0”,“Battery”,“Bypass” or“Charge”; Bat-0 denotes the state in which the energy in the storage element (1) is used (external system is powered) when no electrical energy is available at the mains input (3); Battery denotes the state in which the energy in the storage element (1) is used although electrical energy is available at the mains input (3); Bypass denotes the status in which the electrical energy obtained from the mains input (3) is consumed; Charge denotes charging the storage element (1) with the electrical energy obtained from the mains input (3) while consuming the electrical energy obtained from the mains input (3); Batt denotes the amount of stored energy in the storage element (1); BMIN denotes the minimum energy value that must be present in the storage element (1); Bd denotes the amount of energy that is desired to be stored in the battery at the end of the current time slot; dB denotes an adjustable energy value such as 3% - 5% of the usable storage capacity of the storage element (1);“Next state” denotes state information, which is calculated specifically for the energy storage unit (U) providing the input data and indicates any one of the states from “Bat-0”, “Battery”, “Bypass” or“Charge”; CNF denotes the message which is sent by the central control unit (C) to the energy storage unit (U) and contains the information of“Next State”.
In the energy storage system and the control method for the said system developed according to the present invention, operation of different energy storage units (U) is controlled by a central control unit (C). In this way, it is ensured that operation of each energy storage unit (U) is controlled in a safer manner, thereby the plurality of energy storage units (U) are prevented from negatively affecting the electrical energy generation / consumption balancing process.

Claims

1. An energy storage system for storing electrical energy, characterized by comprising: at least two energy storage units (U), wherein each unit has at least one storage element (1) for storing electrical energy, at least one local control unit
(2) for providing at least one network connection and controlling the operation thereof, at least one mains input (3) for obtaining electrical energy from an electricity grid, at least a first bypass switch (23) and at least a second bypass switch (24) for controlling the transfer of electrical energy obtained from the mains input (3) to the storage element (1), and at least one output (4) for the electricity outlet; and
at least one central control unit (C) which is adapted to exchange data with each energy storage unit (U) by means of the said local control unit (2) and which transmits, according to the information received from the energy storage units (U) and at least one current time information, at least one control data to the energy storage units (U).
2. A control method for an energy storage system that comprises at least two energy storage units (U) and at least one central control unit (C) for controlling the operation of the energy storage units (U) by exchanging data with said energy storage units (U), characterized by comprising the steps of:
- transmitting by at least one local control unit (2) the fullness level data of at least one storage element (1) that is present in the energy storage unit (U) and the information indicating whether or not energy is available at the mains input
(3) of the energy storage unit (U) to the central control unit (C);
generating control data by the central control unit (C) to control the operation of each energy storage unit (U) by using the fullness level data of the storage element (1) that are transmitted for each energy storage unit (U) to the central control unit, the information indicating whether or not energy is available at the mains input (3) and the current time information;
- transmitting each of the generated control data to the corresponding energy storage unit (U); controlling in each energy storage unit (U), according to the control data transmitted to the energy storage unit, whether or not electrical energy will be stored in the storage element (1) through at least one mains input (3) and whether or not the stored energy will be supplied for consumption through the output (4).
3. A control method according to Claim 2, characterized by comprising the steps of: receiving weather forecast information in the region where each energy storage unit (U) is located; calculating the amount of electrical energy that may be obtained through the renewable energy sources by using the features of the renewable energy source utilized together with each energy storage unit (U) and the information of weather forecast; using the information of the calculated amount of electrical energy that may be obtained through the renewable energy sources in the step of generating control data for controlling the operation of each energy storage unit (U)
4. A control method according to Claim 3, characterized in that in addition to the information of the calculated amount of electrical energy that may be obtained through the renewable energy sources, the amount of energy that is consumed through the output (4) is also used.
5. A control method according to Claim 2, characterized by comprising, in the step of generating control data by the central control unit (C) to control the operation of each energy storage unit (U) by using the fullness level data of the storage element (1) that are transmitted for each energy storage unit (U) to the central control unit, the information indicating whether or not energy is available at the mains input (3), and the current time information, the steps of comparing the times when the storage elements (1) of different energy storage units (U) are to begin charging through the mains Input (3) or such charging process is to be ended; and delaying the start time of charging or the end time of charging for at least one energy storage unit (U) if said start time of charging or the end time of charging is the same for at least two energy storage units (U).
6. A control method according to Claim 2, characterized in that, in the step of generating control data by the central control unit (C) to control the operation of each energy storage unit (U) by using the fullness level data of the storage element (1) that are transmitted for each energy storage unit (U) to the central control unit, the information indicating whether or not energy is available at the mains input (3), and the current time information, a day is divided into three periods of time, namely night time period, daytime period and peak time period, and the operation of the energy storage unit (U) at each time period is controlled in different ways.
7. A control method according to Claim 6, characterized in that when the current time period is detected as night, the method comprises the steps of:
receiving parameters of the energy storage unit (U) (101);
calculating, by using the received parameters, the energy that is predicted to be present in the storage element (1) at all the time slots of daytime and peak time periods (102);
calculating other parameters such as maximum energy that is predicted to be present in the storage element at the daytime and peak time periods, minimum energy that is predicted to be present in the storage element at the daytime and peak time periods, average energy that is predicted to be present in the storage element at the daytime and peak time periods, the energy desired to be present in the storage element at the end of the night time period (103); determining whether or not the energy desired to be present in the storage element at the end of the night time period is between the maximum energy value that may be present in the storage element and the minimum energy value that must be present in the storage element (104);
comparing the energy desired to be present in the storage element at the end of the night time period with the maximum energy value that may be present in the storage element, if the energy desired to be present in the storage element at the end of the night time period is not between the maximum energy value that may be present in the storage element and the minimum energy value that must be present in the storage element (105);
setting the energy desired to be present in the storage element at the end of the night time period to the minimum energy value that must be present in the storage element, if the energy desired to be present in the storage element at the end of the night time period is less than the maximum energy value that may be present in the storage element (108); setting the energy desired to be present in the storage element at the end of the night time period to the maximum energy value that may be present in the storage element, if the energy desired to be present in the storage element at the end of the night time period is more than the maximum energy value that may be present in the storage element (107);
calculating the energy that is predicted to be present in the storage element at the end of the night time period (108);
comparing the energy that is predicted to be present in the storage element at the end of the night time period with the energy desired to be present in the storage element at the end of the night time period (110);
calculating the energy that is desired to be present in the storage element at the end of the current time slot, if the energy that is predicted to be present in the storage element at the end of the night time period is not more than the energy desired to be present in the storage element at the end of the night time period (111);
calculating a coefficient value with a first formula, if the energy that is predicted to be present in the storage element at the end of the night time period is more than the energy desired to be present in the storage element at the end of the night time period (112);
calculating the energy that is desired to be present in the storage element at the end of the current time slot with a first formula according to the coefficient value (114);
controlling the operation of the storage unit (U) according to the energy that is desired to be present in the storage element at the end of the current time slot (115).
8. A control method according to Claim 6, characterized in that when the current time period is detected as daytime, the method comprises the steps of:
receiving parameters of the energy storage unit (U) (101);
calculating, by using the received parameters, the energy that is predicted to be present in the storage element (1) at a desired time slot (102);
calculating other parameters such as maximum energy that is predicted to be present in the storage element at the daytime and peak time periods, minimum energy that is predicted to be present in the storage element at the daytime and peak time periods, time slot at which maximum energy is predicted, time slot at which minimum energy is predicted (103);
comparing the maximum energy and minimum energy that are predicted to be present in the storage element at the daytime and peak time periods with the maximum value of the storage element and the minimum energy value that must be present in the storage element (116);
comparing the current time slot with the time slot at which the maximum energy is predicted, if the maximum energy that is predicted to be present in the storage element at the daytime and peak time periods is more than the maximum value of the storage element or if the minimum energy that is predicted to be present in the storage element at the daytime and peak time periods is less than the minimum value that must be present in the storage element (117);
comparing the current time slot with the time slot at which the minimum energy is predicted, if the current time slot is not equal to the time slot at which the maximum energy is predicted (118);
controlling that the time slot at which the minimum energy is predicted is smaller than the time slot at which the maximum energy is predicted and the minimum energy that is predicted to be present in the storage element at the day time and peak time periods is less than the minimum value that must be present in the storage element (1), if the current time slot is not equal to the time slot at which the minimum energy is predicted (119);
controlling that the time slot at which the maximum energy is predicted is smaller than the time slot at which the minimum energy is predicted and the maximum energy that is predicted to be present in the storage element at the day time and peak time periods is more than the maximum value of the storage element, if the time slot at which the minimum energy is predicted is not smaller than the time slot at which the maximum energy is predicted or if the minimum energy that is predicted to be present in the storage element at the daytime and peak time periods is not less than the minimum energy value that must be present in the storage unit (120);
determining the coefficient as 1 , if the time slot at which the maximum energy is predicted is not smaller than the time slot at which the minimum energy is predicted or if the maximum energy that is predicted to be present in the storage element at the daytime and peak time periods is not more than the maximum value of the storage element;
calculating the coefficient value with a second formula, if the current time slot is equal to the time slot at which the minimum energy is predicted or if the time slot at which maximum energy is predicted is smaller than the time slot at which minimum energy is predicted and the maximum energy that is predicted to be present in the storage element at the daytime and peak time periods is more than the maximum value of the storage element, as a result of the comparison (118) of the current time slot with the time slot at which the minimum energy is predicted (113);
calculating the coefficient value with a third formula, if the current time slot is equal to the time slot at which the maximum energy is predicted or if the time slot at which minimum energy is predicted is smaller than the time slot at which maximum energy is predicted and the minimum energy that is predicted to be present in the storage element at the daytime and peak time periods is less than the minimum energy value that must be present in the storage element, as a result of the comparison (117) of the current time slot with the time slot at which the maximum energy is predicted (121);
calculating the energy that is desired to be present in the storage element at the end of the current time slot with a second formula according to the coefficient value (122);
controlling the operation of the storage unit (U) according to the energy that is desired to be present in the storage element at the end of the current time slot (115).
9. A control method according to Claim 7, characterized in that in the step of calculating the energy that is predicted to be present in the storage element at a desired time slot of daytime and peak time periods (102), the following formula is used;
Figure imgf000031_0001
wherein n denotes the time slot at which the calculation is to be made, ns denotes the first time slot of the daytime period, PreBatt[n\ denotes the energy that is predicted to be present in the storage element at the end of the nth time slot, PreRnwbl[i] denotes the total amount of renewable energy that is predicted to be obtained at the ith time slot, and PreConsump[i] denotes the total amount of energy that is predicted to be consumed at the ith time slot.
10, A control method according to Claim 7, characterized in that in the step of calculating the energy that is predicted to be present in the storage element at the end of the night time period (108), the following formula is used;
Figure imgf000032_0001
wherein, ns denotes the first time slot of the daytime period, now denotes the current time slot, BPs denotes the energy that is predicted to be present in the storage element at the end of the night time period, Bait denotes the stored energy in the storage element (1), and PreRnwbl[i] denotes the total amount of renewable energy that is predicted to be obtained at the ith time slot.
11. A control method according to Claim 7, characterized in that in the step of calculating the energy that is desired to be present in the storage element at the end of the current time slot (111), the following formula is used;
Bd = Batt + (Bs-BPs) wherein, Bs denotes the energy value that is desired to be present in the storage element at the end of the night time period, Batt denotes the stored energy in the storage element (1), and BPs denotes the energy that is predicted to be present in the storage element at the end of the night time period.
12. A control method according to Claim 7, characterized in that in the step of calculating the coefficient value with a first formula (112), the first formula is as follows; a = (Bs-Batt) / (BPs-Batt) wherein, a denotes the coefficient, Bs denotes the energy value that is desired to be present in the storage element at the end of the night time period, Batt denotes the stored energy in the storage element (1), and BPs denotes the energy that is predicted to be present in the storage element at the end of the night time period.
13. A control method according to Claim 7, characterized in that in the step of calculating the energy that is desired to be present in the storage element at the end of the current time slot with a first formula according to the coefficient value (114), the following formula is used;
Bd = Batt + a PreRnwbl[now] wherein, Bd denotes the energy that is desired to be present in the storage element at the end of the current time slot, Batt denotes the stored energy in the storage element (1), PreRnwbl[now] denotes the total amount of renewable energy that is predicted to be obtained at the current time slot, and a denotes the coefficient.
14. A control method according to Claim 8, characterized in that in the step of calculating the energy that is predicted to be present in the storage element at a desired time slot of daytime and peak time periods (102), the following formula is used;
Figure imgf000033_0001
wherein, n denotes the time slot at which the calculation is to be made, now denotes the current time slot, PreBatt[n\ denotes the energy that is predicted to be present in the storage element at the nth time slot, Batt denotes the stored energy in the storage element (1), PreRnwbl[i] denotes the total amount of renewable energy that is predicted to be obtained at the ith time slot, and PreConsump[i] denotes the total amount of energy that is predicted to be consumed at the ith time slot.
15. A control method according to Claim 8, characterized in that in the step of calculating the coefficient value with a second formula (113), the following formula is used; a = (BMAX-Batt) / (BPmax-Batt) wherein, a denotes the coefficient, BMAX denotes the maximum energy value that may be present in the storage element (1), Batt denotes the stored energy in the storage element (1), and BPmax denotes the maximum energy that is predicted to be present in the storage element at the daytime and peak time periods.
16, A control method according to Claim 8, characterized in that in the step of calculating the coefficient value with a third formula (121), the following formula is used; a = (Batt-BMIN) / (Batt-BPmin) wherein, a denotes the coefficient, Batt denotes the stored energy in the storage element (1), BMIN denotes the minimum energy value that must be present in the storage element, and BPmin denotes the minimum energy that is predicted to be present in the storage element at the daytime and peak time periods.
17. A control method according to Claim 8, characterized in that in the step of calculating the energy that is desired to be present in the storage element at the end of the current time slot with a second formula according to the coefficient value (122), the following formula is used;
Bd = Batt + a (PreRnwbl[now] - PreConsump[now]) wherein, Bd denotes the energy that is desired to be present in the storage element at the end of the current time slot, Batt denotes the stored energy in the storage element (1), PreRnwbl[now] denotes the total amount of renewable energy that is predicted to be obtained at the current time slot, PreConsump[now] denotes the total amount of energy that is predicted to be consumed at the current time slot, and a denotes the coefficient.
18. A control method according to Claim 2, characterized in that the minimum energy value that must be present in the storage element (1) is updated according to the stored energy in the storage element (1) and whether or not energy is available at the mains input (3).
19. A control method according to Claim 18, characterized by comprising the steps of determining the correlation between the energy storage units (U) by comparing the information indicating whether or not energy is available at the mains input (3) of different energy storage units (U), and updating, according to the status of the mains electricity in an energy storage unit (U), the minimum energy value that must be present in the storage element (1) of at least another energy storage unit (U) associated with said energy storage unit (U).
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Citations (2)

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Publication number Priority date Publication date Assignee Title
EP2713463A1 (en) * 2012-09-28 2014-04-02 Enrichment Technology Deutschland GmbH Energy storage system
US20160172899A1 (en) * 2013-09-09 2016-06-16 Fujitsu Limited Operation schedule generating apparatus, operation schedule generating method, and storage battery system

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2713463A1 (en) * 2012-09-28 2014-04-02 Enrichment Technology Deutschland GmbH Energy storage system
US20160172899A1 (en) * 2013-09-09 2016-06-16 Fujitsu Limited Operation schedule generating apparatus, operation schedule generating method, and storage battery system

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