Facing challenges in planning the quality of electricity supply distribution.
The availability of electricity is fundamental for improving the quality of life of the population, as electricity becomes an integral part of people's daily lives and industries, the need to discuss its quality as a commercial product arises.
Maintaining the supply of electricity is directly related to the reliability of generation, transmission, and distribution systems. The concept of reliability refers to the probability of a component, element, or system performing its functions continuously, without failures over a specified period under specific conditions.
Although events in generation and transmission may impact extensive areas, failure rates in transmission tend to be lower than in distribution. Generally, distribution systems are complex, composed of various elements such as transformers, overhead lines, and protective devices, decreasing their reliability. Additionally, due to their typically radial layout, the failure of a single element can result in supply interruption for a high number of consumers.
Assessment of Supply Quality
The quality of electricity supply is assessed via continuity indicators, which are calculated based on the frequency and duration of interruptions. Companies monitor these indicators not only to plan their operation and investments but also to report them to regulatory authorities. Furthermore, consumers are increasingly demanding regarding the quality of service offered and show greater rigor in their demands.
In this scenario, it is crucial for companies to invest in improving service quality to avoid fines and compensations, as the availability of electricity supply is often one of the first aspects evaluated when choosing to install new industrial units, for example.
Service Continuity
Primarily, the concern is with service continuity, as any interruption can cause significant disruptions. However, the quality of electricity as a commercial product is also an important consideration, even in the absence of visible interruptions. This often only becomes evident through failures in electrical equipment.
The continuous growth of electrical grids and their interconnection to facilitate energy distribution across the country between generation and consumers is a common scenario. Furthermore, this reality is directly linked to the technological advancement of smart grids and electrical equipment. Since they mostly introduce loads with non-linear characteristics and greater sensitivity to disturbances, resulting in increased challenges related to the quality and safety of electricity supply.
Causes of Interruptions in the Electrical System
Interruptions in electricity supply consist of disconnecting one or more consumers from the electrical system, being defined as the discontinuity of the neutral or voltage in any phase of an electrical circuit serving a consumer unit.
These interruptions can be caused by improper operation of switching devices, short circuits, intentional disconnections for maintenance, or electrical and mechanical failures, forced and scheduled interruptions are distinguished based on their causes.
Additionally, faults leading to the opening of protective devices can be caused by various factors, such as tree branch contact, winds, lightning strikes, equipment failures, grids breakdowns, among others, with distribution grids being more susceptible to adverse weather conditions.
Determining Variables
The factors influencing continuity indicators in electricity supply can be due to various variables, such as weather, environmental conditions, load density, circuit length, circuit configuration, equipment status, and interruption recording method.
It is worth noting that distribution companies do not have control over many of these variables, making the comparison of indicators between grid procedures and systems challenging. However, investments in grid layout, installation of protective, control, monitoring devices, preventive maintenance, and other measures are essential to improve reliability and systemic safety.
Weather conditions and lightning strikes have a significant impact on the indicators by increasing the chances of failures. Additionally, the configuration of distribution systems and the condition of the equipment are also direct influences.
Longer circuits tend to have lower reliability due to their greater exposure; on the other hand, in areas with higher load density, consequently arranged in smaller circuits, the indicators tend to be better due to the greater availability of grid restoration by adjacent circuits.
Furthermore, another variable that directly influences the supply quality is the equipment's condition; therefore, in this context, preventive maintenance is essential to prolong asset life and ensure greater safety and reliability.
Actions to Improve Continuity Indicators
Several measures are adopted to enhance continuity indicators in electricity supply. Among these measures are:
Improvement of resources for fault location and restoration:
Investments in fault indicators and locators, implementation of interruption management systems, real-time monitoring equipment, adequate sizing, are examples of measures that can reduce service restoration time and consequently promote service quality improvement.
Limitation of the number of disconnected consumers:
The use of devices such as fuse switches, reclosers, and switches allows for selective and efficient disconnection, minimizing the impact on consumers.
Disconnection of consumers only in cases of permanent failures:
The use of reclosers instead of fuse switches, together with coordinated and intelligent protection schemes, avoids unnecessary interruptions of electricity supply, promoting the continuity of a larger region.
Continuity indicators also consider the number of consumers affected by interruptions. In this regard, the installation of sectionalizing devices, which allow the division of long circuits into smaller sections, can significantly contribute to the improvement of these indicators. By adopting coordinated protection schemes, the aim is to avoid prolonged interruptions caused by temporary faults, ensuring selective disconnection of consumers only when necessary.
The time required to restore service has a significant impact on the duration of interruptions. To reduce this period, companies can invest in improving communication systems and implementing fault location and monitoring devices. Additionally, the automation of distribution systems has been increasingly explored as a way to minimize the system's recomposition time, through the use of sensors and smart devices.
Finally, it is essential for companies to invest in interruption management systems, aiming to obtain reliable real-time statistics that support planning and more effectively direct system operation. Thus, it is possible to identify with greater precision the circuits with the most significant problems, their cause and consequence, allowing for a more efficient allocation of available resources.