Metodologias para análise de impactos emergentes na qualidade de energia dos modernos sistemas de distribuição de energia elétrica

Author(s)

Ricardo Torquato Borges

• Document type: Doctoral Thesis
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Engenharia Elétrica e de Computação
• Defense date: 2017-12-14

Examining board members

Walmir de Freitas Filho; Denis Vinicius Coury; Nelson Kagan; José Antenor Pomilio; Cesar Jose Bonjuani Pagan

• Advisor: Walmir de Freitas Filho

Abstract

Modern power distribution systems (MPDS) are migrating from a passive, non-supervised structure to an active, supervised structure due to the integration of distributed generators, distributed metering and monitoring devices, new types of loads, such as electrical vehicles and modern electronic appliances, and energy storage devices. Such changes are not limited to the utility system (e.g., extensive network monitoring), but are also extended to customer devices (e.g., modern power electronic based appliances, photovoltaic generators, electric vehicles). In spite of many technical (e.g., loss reduction, energy efficiency improvement) and environmental (e.g., reduction on air pollution) advantages, these developments may potentially create a number of new adverse power quality (PQ) impacts on distribution systems. This scenario has attracted the attention of distribution utilities around the world, especially due to the lack of information on how to evaluate and manage these new PQ concerns. In such context, the main goal of this PhD thesis is to investigate in detail two new PQ concerns: the impact of excessive neutral-to-earth voltage rise at customer service panel and of high frequency waveform distortions on distribution systems. A passive, measurement-based, method for determining the contributors to a customer¿s neutral-to-earth voltage (the main cause of stray voltage incidents) has been developed. The proposed method has three main advantages over existing methods. First, the test can be performed without switching off any load and, therefore, without causing inconvenience to the customer. Second, the obtained results can be employed to monitor the grounding conditions of the system involved, such as broken neutral and poor customer grounding. Third, the method does not require measuring neutral voltages and, therefore, the difficult task of establishing a voltage reference point is eliminated. Regarding the high frequency distortions (HFD), analytical studies, computer simulations, lab experiments and field measurements have been conducted to provide the scientific community and distribution utilities with a comprehensive understanding of the behavior of high frequency waveform distortions and of their propagation characteristics into the utility grid. Furthermore, an equivalent circuit model is proposed, validated, and subsequently employed to analyze some of the phenomena associated with HFD propagation. These studies associated with high frequency waveform distortions are conducted mainly with HFD emitted by inverters found in photovoltaic generators (AU)

• FAPESP's process: 14/09538-6 - Methodologies for assessment of emerging power quality impacts on modern power distribution systems
• Grantee: Ricardo Torquato Borges
• Support Opportunities: Scholarships in Brazil - Doctorate