Wind power is increasingly becoming an established source of energy. High oil prices, global warming concerns and the nuclear disaster in Fukushima have all contributed to more people looking at renewable energy sources such as wind power. Germany, for example, has decided to gradually phase-out nuclear power by 2022. Wind power will be the backbone of this energy transition — by the year 2050 it should cover about half of German electricity.
The energy transition in Germany shows that the successful integration of renewable energy into utility portfolios is increasing. Still, owners and operators of wind farms face many business challenges: optimizing operations, effective maintenance and increasing the accuracy and timeliness of decisions all affect the bottom line. Other critical issues include utility integration, accurate data analysis as well as forecasting and scheduling energy output. All these business aspects require reliable real time data for making effective decisions.
Guaranteed Data Delivery Required
Such issues are illustrated by those encountered at a wind farm in Spain, operated by a major energy company.
The energy company, which has 650,000 power distribution/retail customers, faced the challenge of providing centralized data access to three remote wind farms in Spain. The wind farms contain turbines and control systems from different vendors with varying, low bandwidth communication mediums. In order to have access to real-time information for equipment monitoring as well as making production decisions, the energy company needed guaranteed data delivery for its wind farms.
To do this, the company needed to establish bidirectional communications between three wind parks with approximately 26 megawatts per park and a control and a dispatch center (both located in Madrid). In addition, the company required: real time and historical data collection for periodical reports to its headquarters in Germany, technical diagnostic and real time supervision, centralized information for every project manager, manufacturer warranty, and outsourcing maintenance supervision.
Open Connectivity with OPC
The energy company decided to use OPC, which is a series of open standard specifications for control automation data connectivity. OPC can be deployed to communicate between devices, controllers, and/or applications without getting caught up in the usual custom driver-based connectivity problems.
The most widely used variations of the classic OPC standard are: OPC Data Access (OPC DA) to move real-time data between control devices to HMIs, historians, and other display clients; OPC Historical Data Access (OPC HDA) to provide a standard way to share historical data; and OPC Alarms & Events (OPC A&E) for the transmission of alarms and events. These OPC specifications rely on Microsoft Windows' binary communication services implemented in the Component Object Model (COM) and Distributed Component Object Model (DCOM) which enable Windows applications to share data locally or remotely respectively. Thanks to this, all control systems, machine interfaces, automation applications etc, which run on a Windows platform, can easily take advantage of the data sharing offered by OPC Classic.
In order to deliver vendor-independent communications, OPC abstracts the Data Source (such as a PLC), Data Sink (such as a HMI) and implementation details from each side so data can be exchanged between the data source and the data consumer without requiring them to know anything about each other's native communications protocol and internal data organization. This is in contrast to the custom driver approach of writing applications that, by definition, must natively communicate between each other.
The ability to flexibly choose any SCADA, Historian or analysis tool on the market is set to be a key consideration as wind parks grow and technology evolves.
Implementation: Challenges and Solutions
While implementing its OPC solutions, various technical challenges had to be addressed on behalf of the energy operator, both in the wind farms and the control center.
One main challenge for almost every wind park operator is the connectivity with different control systems; in this case three different controllers from two different providers were involved. OPC allowed seamless communications to be established to all of them and all necessary data collected.
The data coming from the turbines in the Spanish wind farms, however, were quite basic, such as generated electricity or the pitch angle of the wind turbine blades. To give the energy company more insightful information, a tailored solution was devised, combining a proprietary Data Calculator with a ‘funnel’ system.
The Data Calculator is an OPC tool designed to combine any number of real time OPC inputs, condition them, and generate create real time OPC outputs, while the Funnel collects all process data from the wind farms into a single gateway. This way, the OPC Data Calculator only had to make one simple connection (to Funnel) to access data from all the data sources. The Data Calculator can then turn raw data into information: for example, by combining generated energy with the mechanical stress a turbine is exposed to provide data that shows how efficiently the wind turbine is working.
Data Transmission from Wind Farm to Historian
In order to be able to analyze the collected real-time data for the long term, it was important for the energy company to store the information in a data archiving tool. For that, rather than a centralized data historian, OPC Desktop Historians were used at each wind farm. This technology, a lightweight Historian solution that provides efficient high speed data archiving, was installed, configured, and administered at each wind farm, allowing engineers access to all required information locally.
This solution was augmented by the addition of a system used to automatically transmit archived data at each wind farm to the centralized data historian in the control center. Called Historylink, it uses OPC HDA to perform the transfer from data source to destination while ensuring that no data is lost. While wind farms sometimes generate and capture large amounts of local data, they often operate in low bandwidth network environments, which make it difficult to move the data to a centralized location. Historylink allowed the energy company, where required, to select the most critical data for transfer to the central data historian. To avoid security and DCOM issues, a reliable data delivery mechanism was added to ensure secure transmission paths from the wind parks.
Confronted by problems such as multiple locations, proprietary components from multiple vendors, and the necessity for reliable communication channels over unreliable network environments, the energy company had found data consolidation from its different wind farms highly challenging.
In partnering with experts dedicated to provide a vendor-neutral solution, OPC could be implemented as a corporate standard for communication. Thanks to this, the energy company achieved a scalable and robust architecture based on an open standard which enables the creation of a vendor neutral hardware and software architecture. As a result, the connectivity between the remote wind farms and the control center allowed for reliable data transition and reduced project costs.
Lead image: Wind turbines via Shutterstock