Optimal management of voltage conditions in power distribution systems

Al-Abri, Waleed ORCID: 0000-0003-1046-1516 (2022). Optimal management of voltage conditions in power distribution systems. University of Birmingham. Ph.D.

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Abstract

Power distribution systems are currently experiencing an increased connection of Renewable Energy Technologies (RETs) such as Photovoltaics (PVs) and Electric Vehicles (EVs), mainly due to the widespread awareness of global warming. The massive diffusion and intermittent nature of these technologies can exacerbate the voltage unbalance level and pose additional operational stresses to the existing voltage regulation devices, such as power transformers. These conditions can introduce components failure, capacity waste, energy losses and restrict further integration of RETs. To address these obstacles, novel and effective control techniques and management strategies of various power distribution assets are required. However, developing adequate and practical approaches can be challenging due to the size, unbalance, and complexity of typical power distribution systems. Therefore, this thesis proposes a novel methodology for optimal unbalanced voltage management in modern power distribution systems integrated with the expanded penetration of RETs.

The thesis presents an innovative Three-phase Power and Current Injection Mismatch (TPCIM) method as an alternative and more robust unbalanced load flow calculation method by implementing a new voltage-controlled bus model. This involves guaranteed convergence modelling of modern power distribution system assets, particularly Static Var Compensator (SVC) and STATic synchronous COMpensator (STATCOM). The developed models and mathematical formulation of load flow calculation improve the convergence characteristics and are computationally efficient, providing a superior method that can be better suited for the applications of real-time control and management in a power distribution system. The proposed load flow calculation methodology is utilised to establish a comprehensive and accurate assessment of RET integration impacts on power distribution systems. The investigation underlines that the unbalanced voltage level can be significantly high in a power distribution system, and with ordinary control and spread of RETs, it can be further intensified due to the inter-phase coupling of distribution lines. The thesis then presents an effective approach to limit voltage unbalance and prevent overvoltage problems by proposing an innovative reactive power control of PV inverters, which could also limit the ageing of PV inverters.

In order to facilitate the massive deployment of RETs and obtain an effective unbalanced voltage regulation, this thesis also proposes an advanced mathematical framework for the optimal coordination of RETs under modern power distribution system operating conditions. The advanced framework has been innovated with an Advanced Hybrid Particle Swarm Optimization (AHPSO) algorithm to further enhance the accuracy, convergence, and effectiveness of the multi-objective optimisation solution. The development of the coordination scheme and AHPSO provides a key tool for real-time voltage management that requires highly accurate solutions with a fast and scalable formulation. Thus, the thesis offers a significant knowledge advancement for the formation of mathematical frameworks of voltage management in modern power distribution systems.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):