Candidate
Fatima Binte Zia
Title
Coordinated Volt/Var Control in Smart Distribution System with Distributed Generators
Supervisor
Ehab El-Saadany
Abstract
The high penetration level of Distributed Generation (DG) is one of the most attractive features of the smart grid aside from being automatic, modern, reliable and efficient. However, high penetration comes with more challenges to deal with such as the voltage and reactive power (Volt/Var) control and increased power loss. Modifying conventional control techniques by moving to a smart technique is a core requirement to mitigate these issues. Voltage control is hard if it is solely handled by on load tap changer transformer (OLTC) and switched shunt capacitors (SC) due to the high penetration and unpredictable behaviors of DGs. The ability to inject the reactive power of the DGs with the proper coordination of SC and OLTC can contribute to control Volt/Var besides minimizing the power loss efficiently. To incorporate DGs in the power distribution system, two methods are presented for Volt/Var control and power loss concerns caused by the random behavior of DGs. The distributed control scheme based on fuzzy logic combined with the automated agent technology known as the multi-agent based system is attempted as the first solution to the Volt/Var control problem. Assuming the existence of proper communication medium and protocols, each agent i.e. OLTC, DG unit, SC and loads without the knowledge of the whole system, can contribute to control Volt/Var. This method demonstrates an optimized voltage and loss profile as well as reduces number of tap operations of OLTC. As second solution, centralized genetic algorithm based control method is introduced in the system. To get optimum voltage and realize reactive power control, this method shows 24 hours lead time coordination among the OLTC, SC and DGs. Certain level of DG penetration no longer imposes a significant effect on the voltage fluctuations and power loss profile in the distribution system and keeps the number of operation for OLTC and SC within permitted limits.It also demonstrates that adaptive control technique which updates switching time and number every 6 hours of the day gives a better loss profile compared to day ahead control since the forecasted DG data becomes more accurate with time. Both approaches are simple, straightforward and efficient.