A robust decentralised linear AC operation for integrated transmission and distribution networks
Zeraati, Sasan (2021)
Diplomityö
Zeraati, Sasan
2021
School of Energy Systems, Sähkötekniikka
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Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi-fe2021052431353
https://urn.fi/URN:NBN:fi-fe2021052431353
Tiivistelmä
The power grid is developing from a traditional one-way network to a more integrated, complicated structure because of the penetration of electric vehicles, large distributed generators, and renewable energy sources into the grid. Renewable energy sources (RESs) extensive integration into the distribution network causes difficulties that Distribution System Operator (DSO) and Transmission System Operator (TSO) can face. In overcoming the issues such as active and reactive power, voltage profile, congestion management, as well as frequency control, it is urgent to provide a power delivery system based on flexibility to ensure safe, resilient and cost-effective utilisation of the grid. Thus, to overcome the network constraints, the optimal power flow (OPF) is considered in most of today’s grids to facilitate the TSOs, and DSOs to operate and benefit most from the grid.
More importantly, in today’s transmission networks (TNs), the sudden outage of some generation units (GUs) from the generation cycle can cause significant problems such as imbalance between generation and demand-side (consumption) and thus increase the cost of operating the power system. On the other hand, distributed generators (DGs) with their ability to react quickly in distribution networks (DNs) can be a relatively good alternative to the disconnected fast generation units (FGUs). Therefore, a robust cooperation problem for integrated TN&DN is essential. However, it is unattainable to solve the cooperation of the TN&DN problem without considering the AC optimal power flow (ACOPF), the operators' independence, and the information privacy.
On the other hand, the robust cooperation of TN & DN based on ACOPF model is a Mixed-Integer Nonlinear Programming (MINLP), which is impractical to solve with existing solvers. Thus, in this thesis, a linearised ACOPF (LACOPF) model for robust cooperation of TN & DN problem is presented. And also, an efficient hierarchical decentralised solution method is represented to solve robust cooperation of integrated TN & DN in which the information privacy is maintained for both network operators. Furthermore, the standard IEEE 30-bus TN and an IEEE 33-bus standard DN are utilised to implement the proposed problem simulation.
Finally, the thesis validates through simulations that the accuracy and computational efficiency of the proposed robust optimisation problem and hierarchical decentralised method and the advantage and efficiency of the optimisation method and the proposed solution methodology.
More importantly, in today’s transmission networks (TNs), the sudden outage of some generation units (GUs) from the generation cycle can cause significant problems such as imbalance between generation and demand-side (consumption) and thus increase the cost of operating the power system. On the other hand, distributed generators (DGs) with their ability to react quickly in distribution networks (DNs) can be a relatively good alternative to the disconnected fast generation units (FGUs). Therefore, a robust cooperation problem for integrated TN&DN is essential. However, it is unattainable to solve the cooperation of the TN&DN problem without considering the AC optimal power flow (ACOPF), the operators' independence, and the information privacy.
On the other hand, the robust cooperation of TN & DN based on ACOPF model is a Mixed-Integer Nonlinear Programming (MINLP), which is impractical to solve with existing solvers. Thus, in this thesis, a linearised ACOPF (LACOPF) model for robust cooperation of TN & DN problem is presented. And also, an efficient hierarchical decentralised solution method is represented to solve robust cooperation of integrated TN & DN in which the information privacy is maintained for both network operators. Furthermore, the standard IEEE 30-bus TN and an IEEE 33-bus standard DN are utilised to implement the proposed problem simulation.
Finally, the thesis validates through simulations that the accuracy and computational efficiency of the proposed robust optimisation problem and hierarchical decentralised method and the advantage and efficiency of the optimisation method and the proposed solution methodology.