Modeling the battery parameters that effect the fault current of a feeding BESS in LV grids
Poppe, Mathieu (2023)
2023
Master's Programme in Electrical Engineering
Informaatioteknologian ja viestinnän tiedekunta - Faculty of Information Technology and Communication Sciences
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Hyväksymispäivämäärä
2023-01-26
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tuni-202301181541
https://urn.fi/URN:NBN:fi:tuni-202301181541
Tiivistelmä
The popularity of renewable energy makes the use of battery energy storage systems (BESS) in the grid very attractive. BESS can support the intermittent power output of renewable energy sources. BESS can also provide a support during and after grid failure and even provide black-start capability in case of a blackout. Li-ion batteries are mainly used for these BESS because of their high energy density.
In this thesis, the parameters affecting on the fault current of the battery in a BESS are modeled. In most studies around BESS, the inverter has gotten more attention than the battery part. However, the battery part behaves different than a simple DC voltage source. It is evaluated to what extent the behaviour of the battery affects the fault current fed by a BESS. The focus is on the open-circuit voltage (OCV) and internal resistance (Rint) of the battery. The state of charge (SoC), operating temperature, C-rate and state of health (SoH) of the battery affect this voltage and resistance. The behavior of the inverter is also taken into account to get a realistic BESS model. The developed model uses only data available in the manufacturer’s datasheets and information from existing studies.
Today, a general fault model already exists for conventional generators, e.g., synchronous generators, but for inverter-based distributed energy resources (IBDER), e.g. BESS, there is not yet a generally accepted model for fault current calculations. There is a great need for simplified fault current models in the industry. These fault models are needed to get the overall dynamic fault response. One possible application is the sizing of overcurrent protection devices. If a BESS feeds in island mode, the available fault current will often be smaller due to the sensitive components that can handle less fault current than robust synchronous or asynchronous machines. These robust generators can provide high short-circuit currents for a short amount of time.
The BESS model is incorporated into a simulation software program, here Matlab Simulink, to perform simulations
In this thesis, the parameters affecting on the fault current of the battery in a BESS are modeled. In most studies around BESS, the inverter has gotten more attention than the battery part. However, the battery part behaves different than a simple DC voltage source. It is evaluated to what extent the behaviour of the battery affects the fault current fed by a BESS. The focus is on the open-circuit voltage (OCV) and internal resistance (Rint) of the battery. The state of charge (SoC), operating temperature, C-rate and state of health (SoH) of the battery affect this voltage and resistance. The behavior of the inverter is also taken into account to get a realistic BESS model. The developed model uses only data available in the manufacturer’s datasheets and information from existing studies.
Today, a general fault model already exists for conventional generators, e.g., synchronous generators, but for inverter-based distributed energy resources (IBDER), e.g. BESS, there is not yet a generally accepted model for fault current calculations. There is a great need for simplified fault current models in the industry. These fault models are needed to get the overall dynamic fault response. One possible application is the sizing of overcurrent protection devices. If a BESS feeds in island mode, the available fault current will often be smaller due to the sensitive components that can handle less fault current than robust synchronous or asynchronous machines. These robust generators can provide high short-circuit currents for a short amount of time.
The BESS model is incorporated into a simulation software program, here Matlab Simulink, to perform simulations