Electric power systems are responsible for generating, transmitting, and distributing electrical energy from power generating plants to end consumers, including households, businesses, and industries.
This article will present a way to map the conditions under which an inductive voltage transformer, especially those of the 36 kV class, can operate under the condition of ferroresonance and how it is possible to prevent the equipment from experiencing thermal and electrical collapse in the event of this occurrence.
Transfer Function
The pioneering work in hydroelectric power generation in Brazil was made possible by the construction of the Marmelos Power Plant in Juiz de Fora. Over 120 years ago, this milestone inaugurated the era of electromechanical energy conversion through the hydraulic method, becoming the most widespread form of energy generation in Brazil due to its high hydraulic potential and unique geography, paving the way for Brazil to become one of the leading producers of hydroelectric power in the world.
The Marmelos Power Plant accelerated the development of hydroelectric power generation techniques in Brazil, opening the doors to a sector that would become essential for the country's economic growth. The project utilized the force of the waters of the Paraibuna River, which runs through the Minas Gerais Zona da Mata and flows into the coast of Rio de Janeiro. The use of turbines imported from the United States at the Marmelos Power Plant marked the first significant conversion of mechanical energy into electrical energy in the country.
Stages of EPS
1. Generation of Energy
The electric power generation subsystem is the starting point of electric power systems. Power plants are the basis of this process and can be classified according to the energy sources they use. In Brazil, the installed capacity of EPS is 211,000 megawatts, and this capacity is divided into different sources:
Hydroelectric Power Plants: Responsible for 51.4% of the installed capacity.
Thermal Power Plants: Contributing 19.7%.
Wind Power Plants: With 12.9% of the installed capacity.
Solar Power Plants: Contributing 5% of the installed capacity.
Micro/Mini Distributed Generation: 11%
2. Energy Transmission
Transmission lines can be overhead or underground, designed to minimize energy losses.
There is a great effort in the design of transmission lines through electrical and mechanical projects, seeking robust structure and minimization of losses. Transmission lines usually operate at high and extra-high voltage, the reason being to minimize losses, given that the primary electrical relationship is that the passage of current through a conductor causes power loss through the heating of that conductor, and increasing the voltage results in a decrease in current. Other analyses are necessary, such as interaction of electric fields, mutual inductances, external influences, short-circuit level, definition of tower shapes, all for the system to operate as efficiently as possible.
This subsystem is responsible for transporting electrical energy from power plants to consumption centers. Transmission lines are key elements in this process and play a fundamental role in system efficiency.
In Brazil, the total length of EPS transmission lines is impressive, covering about 1.2 million kilometers. The use of high electrical conductivity materials and the selection of routes that minimize length are strategies adopted to achieve this objective.
Transmission lines, given their extension, have also allowed the interconnection of the entire country's electric power system, forming the National Interconnected System, through which it is possible to make a smarter and improved energy balance, improving energy utilization and efficiency. Given that the balance between generation and load is the fundamental basis of EPS operation.
3. Energy Distribution
The distribution subsystem is the final stage of EPS. This is where electricity reaches end consumers. Distribution grids are responsible for meeting the specific needs of consumers, whether overhead or underground. These distribution grids are divided into primary grids, which supply energy to large consumers, and secondary grids, which supply energy to residential and commercial consumers.
Distribution, usually the responsibility of local utilities, consists of the entire structure of delivering energy demand at all consumption levels. Transmission lines arrive at distribution centers, usually via distribution substations, where transformers regulate voltage levels for energy delivery, and from where feeders derive, and subsequently, branches; the energy still circulates at a higher voltage in the primary distribution grid, and smaller transformers regulate the voltage level again to reliably and efficiently deliver energy to consumers.
4. Consumption
After all these stages, electricity is delivered to consumers, meeting considerable demand. In 2023, electricity consumption in Brazil reached 625.6 billion kilowatt-hours.
How do they work?
The operation of EPS is based on the principles of electricity and electromagnetism. Electricity is produced by a driving force due to the rotation of a primary machine, which can be a hydraulic turbine, an internal combustion engine, or a wind turbine. This driving force rotates a generator, which produces alternating electric current. The electric current is then transmitted through transmission lines to consumption centers.
In transmission substations, the voltage of the electric current is raised, allowing it to be transported over long distances with lower losses. In distribution substations, the voltage is reduced to levels suitable for residential and commercial consumption.
Control and Monitoring
Electric power systems are complex and highly integrated, requiring an advanced level of control and monitoring. A computer system monitors the performance of EPS and takes corrective actions when necessary. Additionally, a grid of sensors collects data about the system's condition, contributing to the maintenance and improvement of the electrical grid.
Importance of Electric Power Systems
Electric power systems are essential for economic and social development. They enable access to electricity, a clean and efficient energy source, for people and businesses. Without robust electric power systems, modern life as we know it would be impossible.
Statistical Data from ONS (National System Operator)
Statistical data from the National System Operator (ONS) provide an accurate view of electric power system (EPS) generation in Brazil in 2023.
National Generation
The installed capacity of the Brazilian EPS is truly remarkable, reaching 211,141 megawatts. This capacity is divided into various generation sources, with hydroelectric power playing a dominant role, representing 51.4% of the total capacity.
Closely following, we have thermal origin with 19.7%, while wind and solar contribute with 12.9% and 5%, respectively.
In addition to Distributed Generation consisting of micro and mini generators, which can be installed by residential consumers assisting in the system's generation through the dispatch of surplus energy. At the moment, distributed generation represents 11% of the total capacity, with most of the distributed generation coming from wind and solar energy through residential projects with bidirectional metering devices that allow power flow in both directions, i.e., allowing injection of power from the consumer to the grid.
This balance between different generation sources demonstrates the diversification of the Brazilian electrical matrix and its growing commitment to renewable sources.
Statistical Data from ANEEL (National Electric Energy Agency)
Statistical data from the National Electric Energy Agency (ANEEL) offer a comprehensive view of electric power systems (EPS) in Brazil in 2023.
Infrastructure
The Brazilian EPS is a giant in terms of transmission infrastructure. With an impressive extension of 1.2 million kilometers of transmission lines, Brazil ensures that electricity is effectively conveyed from generating plants to consumption centers throughout the country.
Distribution grids also cover about 10 million kilometers, ensuring that electricity reaches end consumers efficiently. Its vast extension is essential to meet the varied needs of consumers, from residences to large industries.
Energy Consumption
Electricity consumption in Brazil in 2023 reached the milestone of 625.6 billion kilowatt-hours. This reflects the fundamental role of electricity in modern life and the Brazilian economy. Additionally, electricity accounts for about 30% of total energy consumption in Brazil, highlighting its relevance in the national energy scenario.
Brazil not only stands out as one of the world's largest electricity producers, ranking 8th globally, but also as the 5th largest electricity consumer in Latin America.
Itaipu Transmission Line:
Recognized as the world's largest, it stretches for about 750 kilometers connecting the Itaipu Hydroelectric Power Plant to the Brazilian electrical system. With an installed capacity of 14,000 megawatts, Itaipu is truly an engineering marvel, located on the border between Brazil and Paraguay.
São Paulo Energy Distribution Grid:
With the mission of serving a population of 12 million people, this is the largest electricity distribution grid in Brazil. It plays a vital role in ensuring that electricity is effectively delivered to a densely populated and industrialized area.