Abstract
A method to secure the generator reactive power reserve by adjusting the transformer tap to improve the power system penetration of renewable energy has been proposed in this study. The tap is adjusted based on the voltage and reactive power sensitivity in the power system network. That is, the transformer tap sensitivity is calculated and analyzed to adjust the tap variation to gain sufficient or the least necessary amount of reactive power reserve. This method can be effective for generators without any margins in the reserves. The optimization problem based on the calculated sensitivities and effectiveness are presented. The optimum solution derived from such a problem provides the minimum control amount necessary to maintain the system voltage and dynamic reactive power reserve at their pre-specified levels to improve the power system acceptability of renewable energy. To demonstrate the effectiveness of the method proposed, a simulation has been performed for an IEEE-25 bus system. The results from simulations prove that the voltage has been well maintained while securing a dynamic reactive power reserve through optimal control based on the sensitivity analysis.
Highlights
The share of renewable energy in power systems is increasing with the growing concern for environmental problems [1]
The increase in renewable energy is making the operation of power systems more difficult due to the variability of renewable energy that changes power generation according to changes in nature [2]
Many studies have been conducted to improve the acceptability of renewable energy in power systems until now [8,9], but studies focusing on voltage and reactive power have been insufficient compared to studies focusing on active power and frequencies [10]
Summary
The share of renewable energy in power systems is increasing with the growing concern for environmental problems [1]. Investment in facilities is difficult worldwide due to the social atmosphere and economic factors In this situation, the improvement of power system operation technology can be the cheapest and most efficient way to improve renewable energy supply [7]. Many studies have been conducted to improve the acceptability of renewable energy in power systems until now [8,9], but studies focusing on voltage and reactive power have been insufficient compared to studies focusing on active power and frequencies [10]. The difference from the previous research and this paper is that this paper proposes a method to secure the generator reactive power reserves that have a faster dynamic response characteristic than OLTC using optimal control of OLTC in steady-state.
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