JPH11233137A - Sodium-sulfur battery system, and its operation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sodium-sulfur battery system suitable for utilization of a peak shift in an electric power system, an operation method, and an electric power system using it. SOLUTION: In a sodium-sulfur battery system composed of a battery module 1 storing a sodium-sulfur battery 3 in a heat-insulated container 2, a possible electric power peak shift quantity by the battery module 1 is calculated from a day load characteristic of electric power, a discharge characteristic of the battery module 1, an allowable battery heating value and an allowable discharge quantity, to control discharge of the battery module 1 based on the calculated result. By this manner, a peak shift in an electric power system is effectively conducted without impairing reliability of the sodium-sulfur battery 3, and efficiency of the sidium-sulfur battery system and a system for the electric power system using it are kept high.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power storage system used for load leveling and peak shift of power,
In particular, the present invention relates to a sodium-sulfur battery system, an operation method thereof, and a power system using the same.

[0002]

2. Description of the Related Art A sodium-sulfur battery using sodium as a negative electrode and sulfur as a positive electrode has attracted attention because of its high efficiency and energy density, and is expected to be used for power storage devices and electric vehicles. These sodium-sulfur batteries are housed in an insulated container to form a battery module in order to keep the operating temperature at about 300 to 350 ° C., and convert AC to DC and AC to DC converter for converting AC to DC. Driven in combination with

[0003] Such a battery module is usually used for load leveling, and is repeatedly operated in a cycle of storing power at night and discharging at a constant power during the day.

[0004] For this reason, the heat insulation container has been heat-designed so that the battery temperature does not exceed an allowable temperature in consideration of heat generation at the time of discharging with constant power. However, when this battery module is used for the purpose of peak shifting of the power system, the load pattern required in the power system differs depending on the season, weather, etc. If the battery temperature is too high, the battery temperature exceeds a predetermined temperature, thereby deteriorating the reliability of the battery. If the discharge current is small, there is a problem that the electric energy stored in the battery cannot be fully utilized for the peak shift. In particular, when the battery temperature exceeds a predetermined temperature, corrosion of the positive electrode container containing sulfur and sodium polysulfide proceeds, and there is a problem that the battery capacity and efficiency are reduced.

[0005]

To cope with the above-mentioned problems, Japanese Patent Application Laid-Open Nos. 5-112,092 and 8-17464 disclose a method in which the heat radiation characteristics of an insulated container are changed according to the temperature of a battery, and the battery temperature is controlled within a predetermined range. It has been proposed to put it inside. However, in this case, a new problem arises in that the structure of the heat-insulating container becomes complicated, the heat-insulating container becomes large, and the reliability is easily impaired. If the heat dissipation of the heat insulating container is designed to be large in consideration of various discharge patterns, it is possible to prevent the battery temperature from exceeding the predetermined temperature at the time of discharge. In order to keep the battery temperature within a predetermined range, it is necessary to input a large amount of energy to the heater provided in the heat insulating container, and there is a problem that the efficiency of the sodium sulfur battery system is reduced.

An object of the present invention is to provide a sodium-sulfur battery system suitable for use in peak shifting of power, an operation method thereof, and a power system using the same.

[0007]

To achieve the above object, a sodium-sulfur battery system of the present invention comprises a battery module containing a sodium-sulfur battery in an insulated container, an AC / DC converter, and a daily load characteristic of a power system. The peak shift amount of the power system is calculated using the discharge characteristics of the battery module so that the calorific value or / and discharge amount of the battery module does not exceed the allowable battery calorific value and / or the allowable discharge amount of the battery module. And calculating means for controlling the discharge of the battery module based on the calculation result of the peak shift amount. Means for temporarily determining the peak shift amount; means for calculating the discharge current of the battery module using the daily load characteristics of the power system, the discharge characteristics of the battery module, and the temporarily determined peak shift amount. Means for calculating the calorific value and / or discharge amount of the battery module using the calculated value of the discharge current, calculating the calculated value of the calorific value of the battery and the allowable calorific value of the battery, and / or calculating the discharge amount Means for comparing the value with the allowable discharge amount, and a calculated value of the battery heat value or /
And the calculated value of the discharge amount exceeds the allowable battery heat value or / and / or the allowable discharge amount, respectively, or the calculated value of the battery heat amount and / or the calculated value of the discharge amount respectively corresponds to the allowable battery heat value. It is preferable to include means for correcting the tentatively determined peak shift amount when the amount or / and the allowable discharge amount is significantly lower. Further, the calculating means calculates the discharge current and the discharge amount for each discharge time step of the battery module,
It is preferable to include means for repeating this calculation until a discharge end time determined by the provisionally determined peak shift amount, and means for feeding back the calculated value of the discharge amount to the calculation of the discharge current. Further, the calculation means may include means for approximating a daily load characteristic of the power system as a function. Further, the calculation means may include means for taking in the heat radiation characteristic of the battery module and / or the temperature dependency of the discharge characteristic of the battery module.

The sodium-sulfur battery system of the present invention further includes means for calculating the value of the discharge current of the battery module at each time using the calculation result of the peak shift amount, wherein the calculating means includes: Includes means for controlling the discharge of the battery module according to the value of the discharge current, or the calculation means includes means for determining a reference power level using a calculation result of the peak shift amount, and the control means includes It is desirable to include means for controlling the discharge of the battery module following a load power exceeding a reference power level. Further, in the latter, means for measuring the temperature of the sodium-sulfur battery or / and the discharge amount of the battery module, the measured temperature or / and the measured discharge amount and the permissible temperature of the sodium-sulfur battery or / and the battery module Means for comparing the allowable discharge amount, respectively, the battery when the measured temperature or / and the measured discharge amount respectively reach the allowable temperature or / and the allowable discharge amount or when the measured temperature or / and / or the allowable discharge amount exceeds the allowable temperature or / and the allowable discharge amount Means for stopping the discharge of the module may be included.

The sodium-sulfur battery system of the present invention comprises a battery module containing a sodium-sulfur battery in a heat insulating container, an AC / DC converter, and control means for controlling discharge of the battery module. The maximum output of the AC / DC converter is determined by using the daily load characteristic of the power system and the discharge characteristic of the battery module, and the calorific value and / or discharge amount of the battery module is determined by the allowable battery calorific value and / or allowable discharge of the battery module. The peak shift amount of the power system determined not to exceed the amount is equal to or larger than the peak shift amount.

[0010] Further, a power system according to the present invention is characterized in that it is a power system using the above-mentioned sodium-sulfur battery system.

On the other hand, the method for operating a sodium-sulfur battery system according to the present invention is a method for operating a sodium-sulfur battery system comprising a battery module in which a sodium-sulfur battery is housed in an insulated container. Calculating a peak shift amount of the power system so that a battery heat value and / or a discharge amount of the battery module does not exceed an allowable battery heat value and / or an allowable discharge amount of the battery module, using the characteristic; The discharge of the battery module is controlled based on the calculation result of the shift amount. The calculation of the peak shift amount includes the step of temporarily determining the peak shift amount, the discharge current of the battery module using the daily load characteristic of the power system, the discharge characteristic of the battery module, and the temporarily determined peak shift amount. Calculating the battery calorific value or / and the discharge amount of the battery module using the calculated value of the discharge current, calculating the battery calorific value and the allowable battery calorific value, and / or Comparing the calculated value of the discharge amount with the allowable discharge amount, and the calculated value of the battery heat value or / and the calculated value of the discharge amount respectively exceed the allowable battery heat value or / and the allowable discharge amount. Or if the calculated value of the calorific value of the battery and / or the calculated value of the discharge amount is significantly less than the allowable calorific value of the battery and / or the allowable discharge amount, respectively. , The step of correcting the peak shift amount the temporarily determined, it is preferable to include a. The calculation of the peak shift amount includes calculating the discharge current and the discharge amount for each discharge time step of the battery module, and repeating the calculation until the discharge end time determined by the provisionally determined peak shift amount. And a step of feeding back the calculated value of the discharge amount to the calculation of the discharge current. Further, the calculation of the peak shift amount may include a step of functionally approximating the daily load characteristic of the power system. Further, the calculation of the peak shift amount may include a step of taking in the heat radiation characteristic of the battery module and / or the temperature dependence of the discharge characteristic of the battery module.

Further, in the method for operating a sodium-sulfur battery system according to the present invention, a value of a discharge current of the battery module at each time is obtained by using the calculation result of the peak shift amount, and the battery is charged according to the value of the discharge current. Controlling the discharge of the module, or determining a reference power level using the calculation result of the peak shift amount, and controlling the discharge of the battery module following a load power exceeding the reference power level. I have. In the latter, the temperature of the sodium-sulfur battery or / and the discharge amount of the battery module are measured, and the measured temperature or /
And comparing the measured discharge amount with the allowable temperature of the sodium-sulfur battery and / or the allowable discharge amount of the battery module, respectively, so that the measured temperature and / or the measured discharge amount is the allowable temperature and / or the allowable temperature, respectively. The discharge of the battery module can be stopped when the discharge amount is reached or when the temperature exceeds the allowable temperature and / or the allowable discharge amount.

According to the present invention, an appropriate peak shift amount is calculated within a range of a battery allowable temperature and / or an allowable discharge amount of the battery module, and the discharge of the battery module is controlled based on the calculated peak shift amount. The reliability of the power system is not impaired, and the peak shift of the power system is possible by effectively utilizing the electric energy stored in the sodium-sulfur battery. Also, since it is not necessary to increase the heat radiation from the battery module more than necessary, there is no need for large energy to maintain the battery temperature during charging or standby, and the efficiency of the sodium-sulfur battery system is kept high. be able to. Furthermore, since the maximum output of the AC / DC converter is appropriately selected, there is no waste in the equipment, and
The peak shift of the power system is effectively achieved. As a result, a highly reliable and efficient power system can be realized while peak shifting can be performed effectively.

The allowable amount of heat generated and the allowable amount of discharge of the battery module differ depending on the structural design and required life of the battery module, and the former is determined by the allowable temperature of the battery determined from the heat capacity, the amount of heat radiation and the required life of the battery module. For example, the temperature of a sodium-sulfur battery needs to be about
The maximum value of the battery temperature during standby must be 3
If the temperature is set to 20 ° C., the allowable temperature rise becomes 50 ° C. When the influence of the heat release amount is small, the product of the heat release amount and the heat capacity of the battery module substantially becomes the allowable battery heat generation amount. On the other hand, the allowable discharge amount is determined mainly by the amount of active materials such as sodium and sulfur. In the structure of a general sodium-sulfur battery, the utilization rate of the active material is about 80 to 90%, and the value obtained by multiplying the utilization rate by the amount of the active material is used. Is determined.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments.

FIG. 1 shows a configuration example of a sodium-sulfur battery system of the present invention. In the figure, reference numeral 1 denotes a battery module having a structure in which a plurality of sodium-sulfur batteries 3 are housed inside a heat insulating container 2. As the heat insulating container 2, a vacuum heat insulating container is generally used because of its excellent heat insulating performance, and a heater (not shown) is provided inside to heat the battery at the time of starting up the system, charging, and waiting. I have. Insulating materials 4 and 5 are provided for electric insulation of the battery and the electric wiring, respectively. Reference numeral 6 denotes an AC / DC converter which converts DC power from a battery into AC power and supplies (discharges) it to a power system or a load, and conversely converts AC power from a power system or a generator into DC power. Supplying (charging) the battery. An IGBT (Insulated Gate Bipolar Transistor) is commonly used as a semiconductor element used in the AC / DC converter. Reference numeral 7 denotes a transformer for electrical insulation and boosting. The AC / DC converter 6 is connected to a power system (not shown) via the transformer 7. Reference numeral 8 denotes control means such as a control device, which is calculated by calculation means 9 such as a computer.
The discharge of the battery module 1 is controlled by the AC / DC converter 6 based on the result of calculating the peak shift amount of the power system that can be performed by the electric module. Further, the peak shift amount of the power system is calculated by using the daily load characteristic of the power required in the power system or the load and the discharge characteristic of the battery module, and calculating the battery heat generation amount and / or the discharge amount of the battery module. The calculation is performed by the calculation means 9 so as not to exceed the allowable battery heat generation amount and / or the allowable discharge amount of the battery module.

According to this method, the battery module is appropriately controlled to discharge so as to fall within the range of the allowable battery calorific value and / or the allowable discharge amount of the battery module, so that the reliability of the sodium-sulfur battery is not impaired. Thus, the peak shift of the power system can be effectively performed. In addition, since it is not necessary to design the heat radiation characteristics of the heat insulating container larger than necessary, the efficiency of the sodium sulfur battery system can be increased. In addition,
When discharging the battery module, it is necessary to control so that both the calorific value and the discharge amount of the battery fall within the allowable values, but if one of the calorific value of the battery and the discharge amount falls within the allowable values, the other is automatically controlled. It is possible to design the battery module so as to fit within the allowable value. In this case, one of the battery calorific value and the discharge amount may be calculated, and the peak shift amount of the power system may be determined so that the calculation result does not exceed the allowable value.

FIG. 2 shows an example of a calculation flow of the peak shift amount of electric power used in the sodium-sulfur battery system of the present invention. As shown in the figure, first, the peak shift amount ΔW is provisionally determined based on the daily load characteristics of the electric power. Figure 3 shows an example of the power of daily load characteristics, the power W of the portion exceeding the reference power level W ₀ shown only lowered dashed ΔW from the power peak (t) and financed by the discharge from the battery module, It is assumed that the peak shifts. In addition,
The electrical energy required for discharging is provided by nighttime charging. Instead of using the daily load characteristics estimated based on the past load patterns as shown in FIG. 3, it is also possible to approximate the time change of the load power by a trigonometric function, a triangular wave, a trapezoid, or the like.

Next, a discharge start time t ₁ , a discharge end time t ₂ and a discharge amount W (t) at each time are obtained from the daily load characteristics and the temporarily determined peak shift amount. Next, from these values and the discharge characteristics of the battery module, the discharge current I (t) of the battery module at each time is calculated according to Equation 1.

[0020]

W (t) = η × [E ₀ −I (t) × R] × I (t) (1) where η is the DC-to-AC conversion efficiency of the AC / DC converter, E ₀ Is the electromotive force of the battery module, and R is the internal resistance of the battery module. In the actual calculation, the interval between the discharge end time t ₂ and the discharge start time t ₁ is divided into steps at intervals of Δt, and this calculation is performed for each step from t ₁ to t
The discharge current in each time step may be obtained by repeating the process in the range of ₂ .

FIG. 4 schematically shows the charge / discharge characteristics of the battery module. As can be seen from this figure, the discharge characteristic is the electromotive force E
It is obtained by subtracting the voltage drop IR due to the internal resistance R from ₀ . When a sodium-sulfur battery is used as the battery module, as shown in FIG. 4, the electromotive force E ₀ changes according to the discharge amount Q, and the value of the internal resistance is not strictly constant, but changes according to the discharge amount Q. I do. In this case, the amount of discharge Q (t) at each time is obtained from Equation _2, and the electromotive force E ₀ and the internal resistance R at each time are obtained from this value and the charge / discharge characteristics of the battery module shown in FIG. The discharge current I (t) may be calculated by feeding back the equation (1). According to this method, the discharge current can be calculated with high accuracy.

[0022]

(Equation 2)

Here, t '= t ₁ + nΔt, n = 1 to
(T−t ₁ ) / Δt Next, the calorific value H (t ₂ ) of the battery module is calculated by Equation 3 using the discharge current and the internal resistance obtained for each time step.

[0024]

H (t ₂ ) = ΣR × I ² (t ′) Δt (3) where t ′ = t ₁ + nΔt, n = 1 to (t ₂ −t ₁ ) /
Δt Finally, the allowable battery calorific value H ₀ obtained from the heat capacity of the battery module and the allowable temperature rise amount, and / or the allowable discharge amount Q ₀ obtained from the active material amount of the battery module, and the calorific value obtained from Equation 3 H (t ₂ ) and / or the discharge amount Q (t ₂ ) obtained from Equation ₂ are compared. Here, if H (t ₂ )> H ₀ and / or Q (t ₂ )> Q ₀ , it is determined that the discharge is excessive, and the process returns to the beginning of the calculation to set a new slightly smaller peak shift amount. The above calculation is performed by calculating H (t ₂ ) ≦ H ₀ and Q (t ₂ ) ≦ Q ₀
Repeat until you have. Note that H (t ₂ ) and Q (t
If ₂₎ is too small compared to H _0, Q _0, respectively, and a little larger set value of the peak shift amount, perform calculations again, peak shift amount in the range of allowable discharge amount and the allowable battery heating value Should be optimized. By such a method, an appropriate peak shift amount ΔW can be determined, and the discharge of the battery module can be appropriately controlled using the discharge current I (t) at each time obtained based on the amount. Becomes As a result, the peak shift of the electric power system can be performed by effectively utilizing the electric energy stored in the battery module without impairing the reliability of the sodium-sulfur battery constituting the battery module. In addition, by controlling the discharge of the battery module so that the peak shift amount becomes as large as possible within the range of the allowable battery heat generation amount and the allowable discharge amount, the electric energy stored in the battery module can be effectively used, which is advantageous. Needless to say.

Further, in order to further increase the calculation accuracy in the above calculation, it is necessary to consider the influence of temperature rise due to heat generation of the battery module and heat radiation from the battery module. Specifically, the electromotive force E ₀ and the internal resistance R of the battery module slightly decrease as the temperature rises. Further, heat is radiated from the battery module during the discharge time, and the temperature decreases slightly. By incorporating these effects into the above-described calculations, highly accurate calculations can be performed. On the other hand, when calculating by ignoring these effects, there is an advantage that the calculation is relatively simple, and the appropriate amount of peak shift to be obtained is smaller than when considering these effects. Since the module is operated, there is no fear that the reliability of the sodium-sulfur battery constituting the battery module is impaired. Furthermore, according to this method, even when the heat radiation at the time of discharge is negligibly small, appropriate discharge control can be performed, the heat radiation from the battery module can be reduced, and the efficiency of the sodium sulfur battery system can be kept high.

The daily load characteristics shown in FIG. 3 can be approximated by a function and used for the above calculation. In this case, instead of using the calculation flow of FIG. 2, it is also possible to directly calculate an appropriate peak shift amount by using the values of Equations 1, 2, and 3 and the allowable battery heat generation amount and / or allowable discharge amount. It is. According to this method, there is an advantage that the calculation time can be shortened as compared with the case where the calculation flow of FIG. 2 is used.

Furthermore, reference power level W ₀ as shown in FIG. 2 with the peak shift amount ΔW obtained from the calculation
It is also possible to determine (a value obtained by subtracting the peak shift amount from the power peak) and control the discharge of the battery module following the actual load power exceeding the reference power level. FIG. 5 shows a configuration example of the sodium-sulfur battery system in this case, and the components denoted by the same reference numerals as those in FIG. 1 have the same contents. In the figure, 10 is a battery temperature measuring means such as a thermocouple, 11 is a discharging amount measuring means of a battery module, 12 is a power system for supplying power to a load (not shown), and 13 and 14 are PT, CT and the like. This is a load power measuring means.

According to this method, the power actually required by the load is measured, and the power is supplied from the battery module based on the measured power. Therefore, compared to the case where the discharge control is performed according to the calculated value of the discharge current, the peak shift is performed. Can be performed with high accuracy. In the case of this method, when the actual load power is larger than the power required by the expected daily load characteristic shown in FIG. 3, during the discharge, particularly in the latter half, the allowable battery calorific value and / or the allowable discharge amount are exceeded. It is expected that a case in which the discharge continues will occur. In this case, a temperature measuring means is attached to the sodium-sulfur battery constituting the battery module, the battery temperature at the time of discharge is measured, and this is compared with the battery allowable temperature determined by the battery life, etc., to determine whether the measured temperature reaches the allowable temperature. If it exceeds this, control may be performed to stop the discharge. Also, regarding the discharge amount, a discharge amount measuring means, for example, a discharge current measuring device and an integrating device are attached to the battery module, and the measured discharge amount and the allowable discharge amount are compared to determine whether the measured discharge amount reaches the allowable discharge amount. Control may be performed so that the discharge is stopped when the voltage exceeds this. By this method, peak shift can be effectively performed, and the reliability of the sodium-sulfur battery can be kept high.

Further, the maximum output of the AC / DC converter shown in FIGS. 1 and 5 is calculated by using the daily load characteristic of the electric power required by the electric power system and the load and the discharge characteristic of the battery module.
The battery calorific value or / and / or the discharge amount of the battery module is the allowable battery calorific value or /
And the peak shift amount of the power system determined so as not to exceed the allowable discharge amount, that is, ΔW in FIG.
Alternatively, it is desirable to make it larger. If the maximum output of the AC / DC converter is made to coincide with the value determined as the peak shift amount of the power system, there is an advantage that the device can be efficiently and effectively peak-shifted. On the other hand, when the maximum output is made larger than this, when the battery module is operated following the load power as shown in FIG. 5 and the actual load power is larger than the power required by the expected daily load characteristic, This also makes it possible to effectively shift the peak of the power system. When determining the peak shift amount of the power system, determine the peak shift amount so that the battery calorific value is equal to or does not exceed the allowable battery calorific value, and the discharge capacity of the battery module has a margin with respect to the allowable discharge amount. If the battery module is designed so as to have the electric energy remaining in the battery module even during the standby after the end of the discharge, the electric energy corresponding to this can be used as an emergency power supply.

As a specific example, the capacity per one piece is about 480 W
h, using a sodium-sulfur battery having a rated output of about 60 W, 216 batteries were arranged in a vacuum insulated container having a length of about 1 m, a width of about 1.5 m, and a height of about 0.6 m in a planar direction, and stored in FIG. A battery module having a capacity similar to that shown and having a capacity of about 100 kWh DC was obtained. In addition, an aluminum bus bar was used as an electric terminal, insulated with glass wool, and taken out of the heat insulating container. Further, a vacuum heat insulating container was used as the heat insulating container. Further, as the AC / DC converter, a converter using an IGBT element and having a conversion efficiency of 95% and a maximum output of 50 kW AC was used.

Using this sodium-sulfur battery system,
The peak shift amount, the discharge start time, the discharge end time, and the discharge current at each time were calculated for the daily load characteristics shown in FIG. 3 in the calculation flow shown in FIG. 2, and the discharge of the battery module was controlled based on this. As a result, it was found that the operation was performed with a discharge duration of about 4 hours and a discharge peak output of AC 45 kW, and a peak shift of AC 45 kW was possible. The temperature of the sodium-sulfur battery at the start of discharging was 320 ° C., and the temperature of the battery at the end of discharging was 370 ° C., so that the sodium-sulfur battery could be operated in a temperature range without any problem in reliability.
Further, the efficiency of the sodium-sulfur battery system is 75% or more, which is not less than that of the 8-hour constant power discharge, 8-hour constant current charging, and 8-hour standby operation pattern used for general load leveling operation. Met. Further, it has been found that the peak shift of the power system can be effectively performed and the system efficiency can be increased by using the sodium-sulfur battery system.

[0032]

According to the present invention, the peak shift of electric power can be effectively performed by using an AC / DC converter that does not impair the reliability of the sodium-sulfur battery and that has no waste in equipment capacity. Further, the efficiency of the sodium sulfur battery system and the power system using the same can be kept high.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a configuration example of a sodium-sulfur battery system of the present invention.

FIG. 2 is a flowchart showing an example of a calculation flow for discharge control of the sodium-sulfur battery system of the present invention.

FIG. 3 is a pattern diagram showing an example of a daily load pattern of electric power.

FIG. 4 is a characteristic diagram showing an example of charge / discharge characteristics of a battery module.

FIG. 5 is a configuration diagram showing a configuration example of a sodium-sulfur battery system of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Battery module, 2 ... Insulated container, 3 ... Sodium-sulfur battery, 4, 5 ... Insulating material, 6 ... AC / DC converter, 7 ... Transformer, 8 ... Control means, 9 ... Calculation means, 10 ... Battery temperature measurement means , 11 ... discharge amount measuring means, 12 ... power system, 13,
14: Load power measuring means.

Claims (10)

[Claims] 1. A battery module for accommodating a sodium-sulfur battery in an insulated container, an AC / DC converter for converting DC power obtained by the battery module into AC power, and a heat generation amount and / or heat release amount of the battery module. A sodium-sulfur battery system comprising: calculating means for calculating a peak shift amount of an electric power system; and control means for controlling discharge of the battery module based on the peak shift amount obtained by the calculating means. 2. The calculating means according to claim 1, wherein said means for temporarily determining said peak shift amount uses a daily load characteristic of said power system, a discharge characteristic of said battery module and a temporarily determined peak shift amount. Means for calculating the discharge current of the battery module by using the calculated value of the discharge current, means for comparing the calorific value of the battery of the battery module and / or the calculated value of the discharge amount with the allowable discharge amount, the battery When the calorific value and / or the calculated value of the discharge amount are lower than the allowable battery heat value and / or the discharge amount, respectively,
A sodium-sulfur battery system having means for correcting the tentatively determined peak shift amount. 3. The sodium-sulfur battery system according to claim 1, wherein said control means is means for controlling discharge of said battery module according to a value of said discharge current. 4. The sodium-sulfur battery system according to claim 1, wherein said control means is means for controlling discharge of said battery module following a load power exceeding said reference voltage level. 5. A battery module containing a sodium-sulfur battery in a heat insulating container, an AC / DC converter for converting DC power obtained by the battery module into AC power, and control means for controlling discharge of the battery module. Wherein the maximum output of the AC / DC conversion device is such that a battery calorific value and / or a discharge amount of the battery module is determined using a daily load characteristic of a power system and a discharge characteristic of the battery module. Setting means for determining the peak shift amount of the power system so as not to exceed the allowable battery heat value and / or the allowable heat value of the battery module; and comparing the peak shift amount of the power system by the setting device with the maximum output. A sodium-sulfur battery system for controlling a peak shift amount of the power system so as not to exceed the maximum output. . 6. The power supply system according to claim 5, wherein the setting means for determining the peak shift amount of the power system includes a means for temporarily determining the peak shift amount, a daily load characteristic of the power system, a discharge characteristic of the battery module, Means for calculating the discharge current of the battery module using the determined peak shift amount; means for calculating the calorific value and / or calorific value of the battery module using the calculated value of the discharge current; Means for comparing the calculated value of the battery with the allowable battery calorific value, and / or the calculated value of the discharge amount with the allowable discharge amount, and the calculated value of the battery calorific value and / or the calculated value of the discharge amount are respectively When the allowable battery calorific value and / or the allowable discharge amount is exceeded, or the calculated value of the battery calorific value and / or the calculated value of the discharge amount are respectively equal to the allowable battery calorific value and / Or if lower than the allowable amount of discharge, the sodium-sulfur battery system characterized in that it comprises means for correcting the peak shift amount the temporarily determined. 7. A power system using the sodium-sulfur battery system according to any one of claims 1 to 6. 8. A method for operating a sodium-sulfur battery system comprising a battery module in which a sodium-sulfur battery is housed in an insulated container, wherein the daily load characteristic of the power system and the discharge characteristic of the battery module are used for the battery of the battery module. A calculating step of calculating a peak shift amount of the power system such that a heat generation amount and / or a discharge amount does not exceed an allowable battery heat generation amount and / or an allowable discharge amount of the battery module, respectively; A method for operating a sodium-sulfur battery system, comprising: a control step of controlling discharge of the battery module using a calculation result of a peak shift amount. 9. The calculating step according to claim 8, wherein the peak shift amount is temporarily determined, and the daily load characteristic of the power system, the discharge characteristic of the battery module, and the temporarily determined peak shift amount are determined. Calculating the discharge current of the battery module by using the calculated value of the discharge current; calculating the calorific value and / or the amount of discharge of the battery module by using the calculated value of the discharge current; calculating the calorific value of the battery and the allowable battery The calorific value, and / or the calculated value of the discharge amount and the calculated value of the allowable discharge amount respectively exceed the allowable battery heat amount and / or the allowable discharge amount, or the calculated value of the battery heat amount and / or A step of correcting the tentatively determined peak shift amount when the calculated value of the discharge amount is less than the allowable battery heat value and / or the allowable discharge amount, respectively. The method of operating the sodium-sulfur battery system comprising. 10. A method for operating a sodium-sulfur battery system comprising a battery module in which a sodium-sulfur battery is housed in an insulated container, wherein the temperature of the sodium-sulfur battery and / or the heat release of the battery module are measured. The temperature and / or the measured heat release amount is compared with the allowable temperature of the sodium sulfur battery and / or the measured heat release amount, respectively, to reach the measured temperature and / or the measured heat release amount and the allowable temperature of the sodium sulfur battery. And / or when the temperature exceeds the allowable temperature and / or the measured heat radiation, the discharging of the battery module is stopped.