Advanced SCADA – Extending the Function of the Solar Plant SCADA System

Introduction
All monitoring and SCADA systems provide basic device information to allow detection of offline and malfunctioning equipment. This includes data from: Meters, Inverters, Weather Stations, Trackers, Strings, and Substation Equipment. At a basic level, these systems provide actionable information to determine if equipment at a solar power plant is performing as expected. The analysis of this information has traditionally been the responsibility of system operators and performance engineers. Technicians were then deployed to investigate and resolve any identified issues. As the number of sites under management increases, plant owners need to utilize more automated methods for identifying and addressing performance issues. Further, as operating margins are compressed, more economic solutions are needed for analyzing and investigating root causes.

While additional performance management systems and analytic systems could be licensed and implemented to help with the volume of sites, this does not necessarily reduce the cost of operation. In fact, in most cases, this approach increases the management costs. As SCADA systems improve in functionality to include advanced analytics and integration, plant owners and operators are leveraging these additional capabilities to improve their operations while not increasing their costs. This paper outlines how Trimark Associates is advancing its premier SCADA system to help this effort.

SCADA Data
Traditional SCADA systems continuously monitor plant devices and record sampled data in a local historian. The real-time data is used to present status information to operator screens and to evaluate for alarm conditions. The collected data is available for review and reporting as needed. Most systems will provide summary analysis of the collected data to show trends and identify anomalies as well as design queries and reports to summarize the data for operational maintenance and management.

The data is often exported from the historian regularly for further analysis in other performance management and asset management systems where the data is augmented with other data such as rate schedule details, outage management data, modeled data, weather data, etc.

Since the SCADA system has the plant operational data, adding additional support to the SCADA system directly allows the analysis to happen on the SCADA system, eliminating/reducing the need for external systems and analysis. Data collected and available in real-time allows for more timely review and handling of performance issues and plant anomalies. The results of the analysis can be used as a basis for alarms and workflow automation leading to improved plant operation efficiency. Additionally, since the data no longer needs to be exported to external systems for analysis, the operational data transformation tasks can be simplified and external systems requirements reduced/eliminated. This reduces the overall operation complexities and costs.

By incorporating advanced analytics and performance management functionality into the SCADA system, plant operators and managers gain technically advanced capabilities without the need to license and incorporate additional systems.

Performance Management
Most sites undergo a full engineering analysis prior to and immediately following construction to provide a baseline expectation on how the site should perform. This baseline is used in subsequent months/years of operation to track and report on actual and projected performance. This information is used as part of the overall financial management reporting of the plant. To allow the SCADA system to provide useful performance management information, the Trimark team added support for customers to provide the plant’s performance expectations from the engineering analysis to the SCADA system. The Trimark SCADA system can then analyze the measured performance and provide immediate feedback on how the plant is performing relative to the expectations. In addition, comparing the expected weather information against the measured meteorological data provides weather adjusted context to the site’s performance and availability measurements. Regular reports show the site’s performance relative to expectations without the need for external systems or additional analysis.

The Trimark team also integrated weather forecast service support into the SCADA system, allowing the system to have insight into projected weather conditions. This weather forecasted information, combined with the expected performance information, provides accurate energy forecasts. Furthermore, the collected weather service data can validate the on-site weather sensors, allowing for valuable insight to data and sensor calibration issues.

Trimark also extended the performance analysis down to the individual device level. Customers can provide device details including designed individual inverter capacity, string counts and installed solar panels’ specifications. The information is used by the system to provide device level performance information in real-time. This allows the system to alert operators and maintenance technicians of detailed device performance issues in addition to the level of impact for quick analysis.

The Trimark team has even added calculated tracker angle details into the system based on the site’s location, tracker specifications and installation details. The calculated tracker angles allow customers to know when the trackers are not tracking to the optimal angles, resulting in reduced energy production.

When the performance of all of the plant’s devices are monitored by the SCADA system, lost energy analysis is simply a matter of calculating the amount of energy that would have been produced if the devices were operating at optimal performance levels. Lost energy reporting can provide historical detail for targeted analysis of the underperformance incidents.

With the site and the contributing devices monitored and performance analyzed in real-time, customers can manage the site by exception rather than having to constantly monitor and analyze plant information to identify issues. The SCADA system provides performance based-alarms to alert operators when the site or individual devices are not performing optimally. With a growing number of sites under management, resource owners and operators need automation and exception handling to manage the fleet efficiently.

Energy Value
The Power Purchase Agreement (PPA) for each plant outlines the value of the energy generated. Some PPAs have complex schedules where the energy is valued differently depending on the time of day, day of the week, month of the year, or a holiday. Trimark has included Rate Schedule awareness in the SCADA system, allowing the SCADA system to know the value of the energy produced by the plant, or in the case of lost energy, the value of the energy not produced. This financial information is extremely useful to operation staff when defining priorities of issue resolution. In addition, the information is useful to asset managers in evaluating and reporting a plant’s financial performance.

With the energy value awareness, the SCADA system can prepare reports outlining the value of the production over time and even assist in the billing and settlement activities. In the case of Trimark’s SCADA system, they can provide billing and settlement information directly to a customer’s financial systems, streamlining the billing and settlement processes. This reduces man-hours as well as the likelihood of costly mistakes. As organizations grow and the number of assets increase, leveraging the SCADA system to help automate the invoicing processes are vital.

Integration Services
A standard function of a SCADA system is to provide integration into a utility energy management system, allowing the utility to monitor critical plant function in real-time and to provide Automated Generation Control (AGC) signals as needed to control the plant output. Increasingly, advanced SCADA systems are extending integration capabilities to enhance the capabilities of the SCADA system and provide additional automation and control.

Satellite Weather / Forecasting
By integrating into one or more weather services, the SCADA system can augment plant information with area weather observations and forecasts, used to forecast energy production from the solar plant.

Meter Settlement
Most SCADA and monitoring systems read plant energy generation from the plant’s main meter. Accumulated energy read from the meter is used for generation totals. However, this is not the value that is used for settlement by the off-taker or utility. The settlement value is often the recorded values in the meters memory. Accessed using specialized meter reading systems, this settlement information is used to reconcile the plant’s generation for billing purposes. In large plants, the difference between the accumulated energy and the meter’s settlement value is significant. Trimark’s SCADA system is integrated with meter reading systems to provide the additional settlement energy values.

Billing Systems
The process of billing can be tedious for customers, especially considering the increasingly complex rate schedules. Typically, customers will export the data from their SCADA systems and import it into separate systems or complex spreadsheets to divide the energy data into separate time of day buckets to match the plant’s PPA rate schedule. The information is then entered into the customer’s accounting system where additional details are added, eventually producing a sales order and invoice that is sent to the off-taker for billing. Advanced SCADA systems are adding support for integration into billing systems to automate the process. For example, Trimark’s SCADA system allows customers to review and automatically create Sales Orders in their accounting system without any manual manipulation.

Document Management Systems
Plant owners and operators contend with a large number of documents; engineering documents, contract documents, compliance documents, operation procedure documents, and a host of others outlining every aspect of the management of the plant. Traditionally, these documents are maintained in a document management system for ease of organization and control. By integrating into the document management systems, plant documents can be accessed from within the SCADA system without the need to maintain multiple copies and risk having outdated details. Trimark’s SCADA system allows customers to access their plant documents from key areas in the system for operations and maintenance as well as asset and compliance management.

Advanced Analytics
Analytics of a solar facility can provide insight into the plants operation that regular review and system alerts cannot, providing a higher level of visibility to not only a plant’s operation, but the relationship of the plant’s operation to other plants of similar size and design. Visualizing the plant data with analytic reports and dashboards can be helpful in maximizing the production and providing details behind performance anomalies. Traditionally, this kind of analysis is done in separate systems by importing the SCADA data and other operational data into advanced analytic systems for analysis. Increasingly, advanced analytics are being integrated into the SCADA systems directly to provide the visualization in more real-time and with a more cost-effective solution. With the advanced capabilities of the SCADA system detailed in earlier sections, advanced analytics are easy to support and use from within the SCADA system without the need to export data or purchase costly analytic systems.

Performance across the entire fleet can be reviewed and compared. Fleet information can be organized in a variety of ways including type, equipment, performance, etc. Details on performance and losses can be visualized across the fleet to provide insight into patterns and trends as well as measured improvements for maintenance activities.

With the addition of advancing predictive analysis and machine learning, the SCADA system can provide insight into past, current, and future operation.

Conclusion
The SCADA system is at the core of a plant’s monitoring and control. By design, all of the plant’s details and information is stored in the plant’s SCADA system. Historically the plant’s SCADA system was limited purely to data collection and control. Increasingly, it is becoming a management system, providing broad support services in all aspects of the plant’s management and life cycle.

As technology continues to advance, it is important that SCADA systems continue to advance the usage and availability of this technology. SCADA systems are no longer regarded as purely engineering systems to be used and managed by the operation engineers. They are becoming advanced business systems used by all areas of management. It will be exciting to see this continue to develop. Who knows what the future may bring.

SCADA Bob’s article screen capture
Sample Analytic Dashboard from Trimark’s SCADA system, showing actual and predictive analytics of a site’s inverters.

 

 

 

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