SCADA’s Role in Utility-Scale PV Plants

Utility-scale power producers face a demanding and multifaceted mission: Meet contract commitments, operate safely, support grid stability and maximize profits. Supervisory control and data acquisition (SCADA) systems play an essential role in meeting these objectives. SCADA systems monitor and control a variety of devices at utility-scale PV sites, including inverters, meters, trackers, meteorological stations, storage systems and other smart devices. Properly designed SCADA systems provide total site control to optimize power generation, control voltage, maximize revenue, ensure accurate settlements and satisfy utility compliance requirements.

Here I look at the role of SCADA systems in utility-scale PV power plants for compliance, operations management, asset management and revenue optimization. I conclude with an overview of design and deployment considerations.

Compliance, Grid Support and Security

On the regulatory compliance front, power producers use SCADA technology to honor contracts, meet regulatory compliance or both. For example, a power-producing site may have either a contractual or a compliance requirement to operate at a certain production level, a condition that effectively requires SCADA capabilities. Plant operators need to have not only visibility into how the site is performing currently, but also foresight into how it will perform in the future. SCADA systems can be invaluable in reviewing historical performance and correlating past values to projected weather patterns. These systems enable operators to provide accurate forecasts to address operational and compliance requirements.

SCADA systems also enable utility-mandated grid support functionality. With the right technology, the site can not only react to and counter the impact of variations in voltage, frequency or reactive power, but also can ride through transient events to avoid exacerbating a grid disturbance. The SCADA system evaluates grid conditions in real time and can make grid-support decisions automatically.

Site security is another important consideration with compliance implications. Technology plays a vital role in protecting large-scale power generation sites from those who intend to do harm, from unwanted access and control, or from unintended human error. Although physical security systems can limit perimeter access, operators must also implement cybersecurity systems to limit access to sensitive information and control activities. For large sites, the North American Electric Reliability Corporation (NERC) explicitly outlines cybersecurity requirements for low-, medium- and high-impact sites in its critical infrastructure plan (CIP) standards. Even if regulators do not require that a site meet these NERC CIP levels, operators must still address cybersecurity, as it is essential to successful plant operations.

Operations, Performance and Safety

To optimize operational management activities, plant operators need accurate and timely information. SCADA systems collect, analyze and present site information clearly and concisely so operators know how to prepare for and react to site events. Operators can leverage this technology to automatically react to values that exceed defined thresholds by adjusting how the site operates, by raising alarms or both. For example, an on-site SCADA system can compare actual production to expected production and raise an alarm if the site is not performing optimally. This ensures that restricted performance does not negatively impact overall revenue and profitability.

Operators can use a well-designed SCADA system to establish key performance indicators (KPIs) with the goal of streamlining operational activities. These KPIs allow operators to focus quickly on the actionable information they need to operate the site rather than having to review thousands of pieces of information. For example, rather than rely on an arbitrary washing schedule, operators can use SCADA systems to calculate the soiling impacts, and then present these data as a metric that indicates when to schedule panel washing. Ideally, the SCADA system identifies any gaps or anomalies in the data and makes the adjustments necessary to ensure data integrity. A customized SCADA solution can provide this extra level of data analysis.

To improve operational safety, SCADA systems can proactively identify events that may affect a plant’s safe operation. If a power transformer shows signs of overheating, for instance, the SCADA system can raise an alarm so that the operator can dispatch a maintenance crew to investigate the problem. As an additional layer of protection, a well-implemented SCADA system can also vary plant behavior to compensate for this type of event before it becomes more serious and harmful. In the event of a transformer temperature alarm, for example, the SCADA system could automatically reduce or curtail the power flowing through the transformer to lessen or eliminate the risk of equipment damage.

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