Methodologies for evaluating the collective impact of residential loads in modern power distribution systems

• Grant number: 08/07000-8
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: November 01, 2008
• End date: June 30, 2012
• Field of knowledge: Engineering - Electrical Engineering - Power Systems
• Principal Investigator: Walmir de Freitas Filho
• Grantee: Diogo Salles Correa
• Host Institution: Faculdade de Engenharia Elétrica e de Computação (FEEC). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
• Associated research grant: 04/14531-9 - Short-term operation planning of power systems including electric constraints, AP.TEM

Abstract

The mass penetration of both energy efficient and consumer electronic devices in homes are resulting in noticeable distortions to the voltage and current waveforms in modern distribution systems. There is an urgent need for techniques that can determine the collective harmonic impact of these modern residential loads. Such techniques can be used, for example, to predict the harmonic effects of mass adoption of compact fluorescent lights. In response to the need, this work developed a probabilistic harmonic assessment technique for residential feeders. The method models the random harmonic injections of home appliances by simulating the random operating statuses of the appliances. This is done through determining the switching-on probability of an appliance based on the load research results. The result is a randomly varying harmonic equivalent circuit representing a residential house. By combining multiple residential houses supplied with a service transformer, a probabilistic model for service transformers was also derived. Measurement results have confirmed the validity of the proposed technique. Then, the proposed methodology was applied to investigate the potential impact of such modern residential loads on the power quality of both secondary and primary distribution systems. Impacts such as harmonic voltage and current distortions, transformer loading, neutral voltage and current rise, telephone interference, harmonic-caused stray voltages etc. were evaluated. The evolution of the impacts over the next several years as affected by the market trends of home appliances was also determined. This work has further conducted effectiveness studies on two potential solutions for managing the situation, namely, adopting the IEC device-level harmonic emission limits and installing harmonic filters in primary distribution systems. The main findings of this work are (1) modern residential loads have a significant impact on feeder harmonic distortion levels, harmonic current injection into the transmission system, feeder neutral current, service transformer loading and telephone interference, (2) the annual growth rate of the indices characterizing these impacts are in the range of 10% to 15%. If uncontained, it could lead to other potential problems such as revenue meter errors. (3) Adopting the IEC limits can reduce the impacts significantly and decrease the growth rate by about half. The option of installing feeder level filters is also effective in reducing the harmonic impacts in the system.

Academic Publications

(References retrieved automatically from State of São Paulo Research Institutions)

CORREA, Diogo Salles. Metodologias para a avaliação do impacto harmônico coletivo de cargas residenciais em modernos sistemas de distribuição de energia elétrica. 2012. Doctoral Thesis - Universidade Estadual de Campinas (UNICAMP). Faculdade de Engenharia Elétrica e de Computação Campinas, SP.