Comparison of the performance of sensitivity-based voltage control algorithms in DG-integrated distribution systems

Conference ProceedingsThe integration of renewable energy generators in distribution grids has increased the complexity of the voltage control problem. Reactive power control (RPC) algorithms based on sensitivity analysis have been proposed in the literature for the management of the voltage problem. Sensitivity methods are computationally complex for practical real-time analysis and this has led to use of de-coupled and other simplified load flow models. However, algorithms based on decoupled models have been shown to be inefficient for analysis of distribution systems with low X/R ratio. This paper uses a simplified line modelling approach recently proposed in the literature to facilitate the development of computationally simple distributed, non-decoupled, load flow equations that completely capture the characteristics of the radial distribution feeder, removing the need to use the decoupled models. Results show that the simple algorithm based on this new line modelling approach gives better voltage control performance compared to the decoupled models

Exploring The Gaps In Renewable Energy Integration To Grid

ArticleThe continued integration of diverse renewable energy sources into the power grid has led to a significant decrease in power system inertia, thus resulting in several challenges in the electric power system such as frequency instability and sharp rise in rate of change of frequency (rocof). In order to combat these challenges, several technologies such as the use of energy storage systems, hybrid energy storages system and hybrid systems have been used to provide fast frequency response and regulation. This paper gives a comprehensive review of these technologies thus highlighting their applications, merits and demerits for frequency regulation in renewable energy sourced grid. Furthermore, the research reveals that hybridized system provides better characteristics than singly sourced renewable energy system, therefore the best suited hybrid system can be formed based on the desired power grid characteristics and specific power requirement. Finally, it was revealed that FESS, SMES and SCES have similar characteristics, nonetheless, their characteristics is complimentary to that of BESS, CAES and PHES technology, and so a hybrid combination comprising of BESS and SCES could be best suited for fast frequency response in renewable energy sourced grid

Assessing the role of hybrid energy storage in generation expansion planning for enhanced frequency stability

As the power grid transforms towards a renewable energy dominant grid, which are associated with frequency stability challenges, it is important to combat these challenges through proper power system planning. This paper therefore investigates the impact of hybrid energy storage (HES) in enhancing the frequency stability of the modern grid. The optimization problem is formulated as a mixed integer quadratic constrained programming model to minimize the system cost, while maximizing system inertia. The proposed model is then implemented on an IEEE 6-bus system, and solved using CPLEX solver in GAMS, with its performance evaluated using two study cases. Case 1 considers only the economic objective (cost), while case 2 considers both the economic objective (cost) and the technical objective (system inertia). The result show that the incorporation of HES in the generation planning model improved the overall system inertia of the system by 11% (from 6.199s in case 1, to 6.901s in case 2), however the total system cost increased by 3% (from 218M$in case 1 to 2.25M$ in case 2)