Optimisation of point of connection and effects of power electronic distributed energy resources on harmonic levels in low voltage power distribution networks

Gissing, Graham Peter (2024) Optimisation of point of connection and effects of power electronic distributed energy resources on harmonic levels in low voltage power distribution networks. PhD thesis, University of Glasgow.

Abstract

As of 2022, National Grid ESO stated that there were over one million electric vehicles (EVs) on United Kingdom (UK)’s roads, with an expectation that there will be approximately thirty-three million by 2050 under a ‘falling short’ scenario. Additionally, the Department for Energy Security and Net Zero (DESNZ) states that, as of November 2023, there were over 1.24 million 0 ≤ 4 kW photovoltaic (PV) generators connected to the low voltage electricity distribution network (LV EDN). Despite this, substantial physical upgrades to the LV EDN have not yet been carried out. In addition, within existing literature, consensus is that power-electronic loads such as electric vehicle chargers (EVCs) and distributed energy resources (DERs), such as PV generation and vehicle to grid (V2G), can lead to voltage, overloading, and power quality issues including harmonic distortion and flicker. Although each of these issues present significant engineering concerns, this thesis shall focus on harmonic distortion and aim to fulfil the identified research gaps.

The majority of supply points are connected to the LV EDN; therefore, changes in harmonics at this voltage level will directly affect these consumers. Harmonics can increase the risk of transformer, motor, and cable overheating, metering and computer errors, failure of electronic equipment, circuit breaker malfunction, and communication interferences. This thesis has two main purposes. Firstly, the effect that increased numbers of EVCs and PV generators have on the steady-state voltage total harmonic distortion (THDv) of a UK LV EDN under steady-state cable faults will be investigated using MATLAB simulations. In conjunction with the voltage harmonic limits stipulated within Engineering Recommendation G5/5, violation of harmonic limits, maximum penetration levels and the increase in individual limiting voltage harmonics after cable faults will be investigated. In addition, the impact of harmonics on infrastructure lifespan and voltage imbalances on risk of death to members of the public will be explored. Secondly, the optimal point of coupling for EVCs, PV generation and V2Gs to minimise the steady-state THDv on a radial LV EDN under a range of both normal and steady-state fault conditions will be ascertained using a combination of two algorithms, Elephant Herding Optimisation and Monarch Butterfly Optimisation, using simulations in MATLAB. This expansion of knowledge is critical for network operators. When implemented, this will ensure that voltage harmonic noncompliance under previously unconsidered fault scenarios can be identified, the design of LV EDNs can be optimised with respect of voltage harmonics, the risk of asset failure which leads to financial loss can be reduced and the risk of death can be mitigated.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Subjects: T Technology > T Technology (General)
• Colleges/Schools: College of Science and Engineering > School of Engineering
• Supervisor's Name: Yang, Dr. Jin
• Date of Award: 2024
• Depositing User: Theses Team
• Unique ID: glathesis:2024-84654
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 05 Nov 2024 11:32
• Last Modified: 05 Nov 2024 11:35
• Thesis DOI: 10.5525/gla.thesis.84654
• URI: https://theses.gla.ac.uk/id/eprint/84654

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