The advent and evolution of the Smart Grid initiative to improve the electric utility power infrastructure has brought with it a number of opportunities for improving efficiencies, but along with those benefits come challenges in the effort to assure safety, security, and reliability for utilities and consumers alike. One of the considerations in designing the capabilities of the Smart Grid is the integration of Supervisory Control and Data Acquisition (SCADA) systems to allow the utility to remotely monitor and control network devices as a means of achieving reliability and demand efficiencies for the utility as a whole. Given the ability of these systems to control the flow of electricity throughout the network, additional planning and forethought is required to ensure all possible measures for preventing compromise are considered. This work discusses the overall architecture(s) used today and some of the measures currently implemented to secure those architectures as they evolve. More importantly, it considers simplifying the complexity of implementing the many standards put forth by applicable standards and regulatory bodies as a means to achieve realistic governance.
Utility infrastructures represent privileged targets for cyber terrorists or foreign state-sponsored hackers. There are a number of challenges to achieve a base-level security across the utility spectrum. The challenges are due to limited budgets, privately owned control systems in utility infrastructures, and the complexity in decomposing the myriad sets of requirements from competing regulatory bodies each with their own frameworks. The process of developing a functional, secure infrastructure requires technology skills and understanding how and why all applied technologies interact with each other.
In this section, the SCADA and smart grid are explained to discuss the efficacy and challenges in the integration process.
Supervisory Control and Data Acquisition (SCADA) systems are basically Process Control Systems (PCS) that are used for monitoring, gathering, and analyzing real-time environmental data from a simple office building or a complex nuclear power plant. PCSs are designed to automate electronic systems based on a predetermined set of conditions, such as traffic control or power grid management. Some PCSs consist of one or more remote terminal units (RTUs) and/or Programmable Logic Controllers (PLC) connected to any number of actuators and sensors, which relay data to a master data collective device for analysis. Gervasi (2010) described SCADA systems with the following components:
- Operating equipment: pumps, valves, conveyors, and substation breakers that can be controlled by energizing actuators or relays.
- Local processors: communicate with the site’s instruments and operating equipment. This includes the Programmable Logic Controller (PLC), Remote Terminal Unit (RTU), Intelligent Electronic Device (IED), and Process Automation Controller (PAC). A single local processor may be responsible for dozens of inputs from instruments and outputs to operating equipment.
- Instruments: in the field or in a facility that sense conditions such as pH, temperature, pressure, power level, and flow rate.
- Short-range communications: between local processors, instruments, and operating equipment. These relatively short cables or wireless connections carry analog and discrete signals using electrical characteristics such as voltage and current, or using other established industrial communications protocols.
- Long-range communications: between local processors and host computers. This communication typically covers miles using methods such as leased phone lines, satellite, microwave, frame relay, and cellular packet data.
- Host computers: act as the central point of monitoring and control. The host computer is where a human operator can supervise the process, as well as receive alarms, review data, and exercise control.
Figure 1 displays a high-level overview of SCADA architecture, where the Remote Stations might be an Electric Substation, the SCADA network on one network segment, with other organization network on differing network segments. With advancements in the computing field, the integration of digital electronics devices play an important role in the manufacturing industry, wherein manufacturing plants utilize PLCs/RTUs to control the devices, and develop distributed and large complicated systems in which intelligent systems are part of the manufacturing control systems processes.
Figure 1: SCADA Network (Source: www.buraq.com)
“Most often, a SCADA system will monitor and make slight changes to function optimally; SCADA systems are considered closed loop systems and run with relatively little human intervention. One of the key processes of SCADA is the ability to monitor an entire system in real time. This is facilitated by data acquisitions including meter reading, checking statuses of sensors, etc. that are communicated at regular intervals depending on the system” (Abawajy & Robles, 2010).