Battery are used to stored energy basically its convert chemical energy into electrical energy or vice versa. This property of battery is very useful in power system. It has used everywhere for availability of energy. Some of its main applications are grown in last decade of year, these are
• Battery is in Electrical vehicle.
• For the energy storage in plant we use Battery Energy Storage Plants. In this we compensate the flow active or reactive power.
• Batteries are used in Uninterrupted Power Supplies.
Main types of battery are available for use i.e. primary and secondary. Primary batteries are used for a single time until they discharged because they are not rechargeable like zinc–carbon batteries, alkaline batteries etc. but secondary batteries are rechargeable they can be used again and again like nickel–cadmium (NiCd), lithium-ion (Li-ion) cell etc.
2. DIFFERENT TYPES OF BATTERY MODEL
There are many techniques of battery modelling are present. Few of them are mentioned here with their merits and demerits are given below:
1. SIMPLE BATTERY MODEL
It is the most common model of the battery. This model is having a terminal voltage and internal resistance of battery which is equivalent to constant internal resistance ESR with open circuit voltage . It is consisting of ideal battery which having unlimited power is assumed shown in fig. 1.
Fig. 1: Circuit of the simple Battery model
At fully charged condition, the terminal voltage is obtained from open circuit measurement. ESR can be obtained by connecting a load and by measuring the voltage and current across the load. This model seems very simple but it is does not depend upon the state of charge (SOC), changes in internal resistance ESR due to temperature and electrolyte concentration. This model never is used for monitoring of battery in Electric vehicle. It is applicable in specific circuit simulation where power is assume to be unlimited.
2. MODIFIED BATTERY MODEL
It is the improve model of simple battery model. In this model, the disadvantages of above model was considered and make a propagate model. Here battery internal resistance ESR changes according to changes occur in state of charge over the time. A common formula is set and given as:
At fully charged condition, internal resistance of battery was calculated and
Where, is 10 hour battery capacity(Ah) at reference temperature ( it may be change according to battery age). S is changes from 0 when battery is completely discharge or 1 when battery is completely charge. The Coefficient k is function of discharge rate of battery and it is calculated by , and basis which can be determined by curve given by manufacture.
3. THEVENIN BASED ELECTRICAL MODEL
This model is consisting of ideal no load battery voltage , capacitance C occur due to capacitance of parallel plate, internal resistance and over voltage resistance occur due to the contact resistance of plate to electrolyte shown in...