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Battery Energy Storage System Design

Design of battery energy storage system iEngineering design, manufacture, and supply a wide range of BESS for power and storage capacity from small-sized household devices to large-scale systems for utilities and industrial applications. 

We design off the self and custom-based BESS’s for our clients. 

Whatever the practical application, batteries are widely used technology to store an electrical energy. Other than storage purposes, batteries are extensively used to provide voltage support for weaker electric power systems like very long transmission lines.  

The battery storage system is having the primary importance in insuring the satisfactory operation of generation station, substation and in other stationary application. Batteries are the lifeline of substation. Substations are a part of every power grid. They convert voltage from high to low, and vice versa. Without substations, power grids around the world could not operate. Now, why do substations need batteries? Batteries ensure all critical substation loads will always operate. In a substation, the primary source of power comes from your AC power supply. But you cannot completely rely on your AC power supply. If a substation’s transmission line or generation source goes offline, you’ll lose power. So, we use a battery as an alternate DC power source in case we lose the AC power source to feed the critical loads such protection relays, circuit breakers, etc. 

Battery sizing is crucial to ascertain that it can supply power to the connected loads for the time it is designed. Unsuitable sizing of the battery can pose many serious problems such as permanent battery damage because of over-discharge, low voltages to the load, insufficient backup times. 

Based on BESS type we can Store in different ways:

Due to spread of mobile Information Technology the increased mass production of Lithium battery and its lowest cost has boosted demand for energy storage device (BESS) 

Design of Energy Storage device (BESS) is based on:

  • Maximum depth of discharge – Depth of discharge (DoD) is the fraction or percentage of the capacity which has been removed from the fully charged battery. It is an alternative method to indicate a battery’s state of charge (SoC). The depth of discharge is the complement of state of charge as one increases, the other decreases. 
  • Temperature correction factorThe battery cells capacity is generally provided for a standardized temperature which is 250C and if it varies somewhere with the installation temperature, a correction factor is needed to implement.
  • Aging factorCapacity decreases gradually during the life of the battery, with no sudden capacity loss being encountered under normal operating conditions. Since the rate of capacity loss being encountered under normal operating conditions. Since the rate of capacity loss is dependent upon factors such as operating temperature, electrolyte-specific gravity, depth, and frequency of discharge. The aging factor is chosen based on the required service life.Design marginIt is prudent design practice to provide capacity margin to allow for unforeseen additions to the DC systems and less than optimum operating conditions of the battery due to improper maintenance, recent discharge, ambient temperature lower than anticipated, or a combination of these factors. A method of providing this design margin is to add a percentage factor to the cell size determined by calculations. If the various loads are expected to grow at different rates, it may be more accurate to apply the expected grow at different rates, it may be more accurate to apply the expected growth rate to each load for a given time and to develop a duty cycle from the results 
  • Capacity rating factor (kt) – The capacity rating factor KT, is the ratio of rated ampere hour capacity (at a standard time rate, at 250C and to a standard end of discharge voltage) of a cell, to the amperes that can be supplied by that cell for t minutes at 250C and to a given end of discharge voltage. KT factors value should be provided by the reference battery manufacture KT = Period (Hour) x Gradient + Intercept. 
  • Section capacity – Capacity determine for each section is the section capacity. Section capacity is equal to the change in load scaled by the capacity rating factor for the specific section. The total section capacity is equal to the sum of all the section capacities. Section Capacity = Change in load x K 

Schematic of battery energy storage system