What you need to know about SCADA
July 19, 2016
By Tom Tate
Next time you find yourself in the company of engineers, wow them with your knowledge of SCADA. You say you don’t know anything about SCADA? Well, you have come to the right place!
Let’s begin with the basis of the acronym: Supervisory Control And Data Acquisition. Basically, SCADA systems help electric co-ops quickly spot and solve power outages – this means safer, more reliable electricity for you, the co-op member.
Believe it or not, most of us use a SCADA system every day. Do you drive? Consider the dashboard your car’s Personal SCADA system. From the driver’s seat, you can instantly gauge your speed, fuel level and engine diagnostics. Utility-scale SCADA is exactly the same, only much bigger. The system is bigger because there are more things that need to be monitored and controlled.
Now that the baseline is set, let’s discuss the components of a SCADA system. Both hardware and software are used. The software provides the intelligence. It processes the data gathered, allows operators to program automated responses to particular situations and displays the data in a graphical format for the operators so they can easily interpret what is happening in the co-op’s service territory. The hardware consists of sensors that collect data, remote terminal units (RTUs) that monitor the sensors and transmit the data on the SCADA network, actuators that perform actions based on data and system commands, and communications gear.
So how do SCADA systems impact members of South Central Power? South Central Power is undertaking a large project to integrate its facilities and equipment with a SCADA system. While parts of the system are active now, it will be several years before SCADA is integrated into the bulk of our transmission and distribution system. As new facilities are added, a determination will be made on how to best utilize this technology to offer the most cost effective, safe and reliable benefits to the SCP system and membership.
How will this work in the future? Let’s walk through an example. We want to ensure that everything is operating correctly at our substations. Inside the substation, sensors and actuators that are connected to an RTU are installed. A secure communication link is created between the devices and the co-op’s engineering office by using wireless, hardwired or fiber optic connections.
Our engineers program the operating characteristics they want to monitor and control – in this example, let’s say it’s voltage and frequency. This is to ensure that the power leaving the substation meets power quality standards. A diagram of the substation is created and displayed on a computer so the engineers can see what is happening inside.
Everything is powered up and the SCADA system goes into action. Suppose the voltage from a transformer goes too far out of its range, creating a potentially dangerous situation. The sensor sends this data to the RTU. The RTU sends this to the SCADA software and an alarm is generated in our engineering office.
When an alarm is received, a couple of actions are possible. An automated response can be programmed into the system that tells the RTU to use actuators to implement a particular corrective measure. These types of automated actions provide immediate response to a situation while alerting the engineers that it has occurred. Or, the alarm allows engineers to assess the situation and issue commands from their computer to correct the problem. The system is flexible, so the engineers can automate what they want and opt for human intervention for especially important actions.
Since the data is supplied in near real-time, these systems are extremely valuable to ensuring the safe, reliable and stable operation of the grid. They are also becoming important in the creation of the Smart Grid. At its most basic, it involves two-way communication between devices installed within the grid. At its most advanced, it automates major portions of grid operations to provide immediate response to grid conditions that can lead to problems for co-op members.
So, the next time you find yourself in the company of engineers, you can impress them with your knowledge of SCADA systems.
Tom Tate writes on cooperative issues for the National Rural Electric Cooperative Association, the Arlington, Va.-based service arm of the nation’s 900-plus consumer-owned, not-for-profit electric cooperatives.