Substation Automation in Smart Grid

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What is Substation Automation?

Substation Automation is a fundamental concept that represents a transition from traditional electric grid to an intelligent and more efficient electric grid. The substation automation can be defined as a process of using data from intelligent electronic devices (IEDs) to control and automate the grid operations.

Substation automation is primarily meant for automating the power system operations like switching, control, monitoring, protection, etc. so that we can get an electric substation with high reliability, efficiency, and security.

The core component involved in substation automation to transform this manual operation to automated one is the digital communication and control system.

Components of Substation Automation

A substation automation system consists of several smart components for real-time monitoring and automated control of power system operations.

Some of the main components of a substation automation system and their functions are given here −

Intelligent Electronic Devices (IEDs)

The IEDs are the core components of a substation automation system. These devices perform continuous monitoring of the substation equipment in real-time and collect the data for analysis and decision making. IEDs used in substation automation can be smart relays, sensors, circuit breakers, etc.

SCADA System

SCADA (Supervisory Control and Data Acquisition) system is a software program used for remote monitoring and control of substation operations. This system receives data about grid operation from the IEDs and sends it to a central control center for analysis and processing. SCADA is the most fundamental elements in the substation automation, thus without SCADA, the substation automation is almost impossible.

Remote Terminal Unit (RTU)

In substation automation, RTU is a microprocessor-based device used to create an interface between the hardware components i.e., IEDs and the SCADA system for data transmission.

Programmable Logic Controller (PLC)

PLCs are nothing but microcontrollers used in substation automation to perform a specific set of operations. The PLCs can be pre-programmed to perform the automation task.

Human-Machine Interface (HMI)

HMI is a graphical user interfacing device used to provide a communication medium for substation operators. Using HMI, the substation operators can interact with the substation systems to control the operations and monitor the system parameters.

Configuration of Substation Automation

The configuration of the substation automation in smart grid consists of the following three levels of equipment function −

• Station Level Functions
• Bay Level Functions
• Process Level Functions

These three functions of substation automation configuration are explained here.

Station Level Functions

At this level, the substation computer, HMI, and the gateway to control center are the main devices involved in the substation automation. Here, the message specification network acts as a communication link between the SCADA system, IEDs, and the central control center.

Bay Level Functions

This level consists of controllers and intelligent electronic devices (IEDs) as the main substation automation devices. These devices provide protection for different utilities of the system and performs a real-time evaluation of the distribution network.

Process Level Functions

In this level of substation automation configuration, optical voltage and current sensors are used as the core element. This level also comprises of current transformers, potential transformers, sensors, and switchgear control and monitoring system. At this level, the analog signals received from the CTs and PTs are converted into optical signals using a merging unit and then transferred to protection and control devices through fiber optic links.

Advantages of Substation Automation

Substation automation is aimed for automated operation of the power system with minimal human intervention. It results in the following benefits −

• Substation automation improves the reliability of the power system by faster fault detection and isolation and reduced power outages duration.
• Substation automation makes the grid operations faster and less dependent on human intervention. This results in reduced chances of accidents and fires in the system and hence improve safety.
• Substation automation minimizes the human involvement and errors and results in enhanced operational efficiency of the power system.
• Substation automation also allows for automatic adjustment of grid parameters depending on the load requirements and provides a stable power supply.
• Substation automation uses SCADA system and hence allows to control the grid operations from a distant location.

Challenges in Substation Automation

The following are some major challenges or barriers coming in the implementation of substation automation −

• Substation automation involves the use of smart electronic devices and modern advanced technologies. Hence, it requires a high initial investment.
• Substation automation uses digital communication technologies which are vulnerable to cyber threats and thus requires a robust security system.
• The electronic devices used in substation automation can be from different manufacturers and may have compatibility issues.
• Substation automation is a technology intensive task and therefore requires technically skilled personnel for erection, operation, and maintenance.

Conclusion

Substation automation is an important technological implementation required for efficient, reliable, and secure power system. Substation automation is nothing but an integration of power grid with a digital communication network for automated monitoring and control of power flow.

Substation automation system is essential for achieving desired efficiency and reliability in the power system. Proceed to the next chapter to learn about Feeder Automation in Smart Grid.