Five considerations for deploying Ethernet in wind farms

Diane Davis, Director of Product Management, Ethernet Networking, Red Lion Controls


Maximize uptime and limit effects of single-point failures with robust network design for harsh wind-farm environments

Click image to enlarge

Figure 1: A network topology for wind-farm applications makes use of redundant devices and cabling to maximize system uptime and minimize the operational consequences of single points of failure.

Data is a key element to the successful operation of a wind farm. Real-time data access allows operators to monitor wind turbine uptime, performance, and power output—even from remote locations. This data can track efficiency and trends, which are essential in the era of the Smart Grid. But how can you capture this data under the rugged conditions of wind-farm environments? Industrial-grade Ethernet networks can seamlessly provide access to real-time data and maximize overall wind farm uptime. First, it is important to note that conditions at wind farms are not suitable for traditional commercial grade communications and networking equipment. In fact, their conditions are far from normal. Extreme high and low temperatures, humidity, dust, vibration, and EMI from rotating generators and radio transmitters all make for a challenging environment in which to build an Ethernet network. Maximizing uptime and preventing failures is important because wind farms are often built in remote areas where IT staff is not on site, so the labor expenses to fix technical issues (or to replace an entire switch) are even higher. Additionally, since the wind farm operator sells to consumers every kilowatt a wind generator produces, network downtime is very costly, so it is important to keep wind farms running as much as possible. As a result, wind farm operators need maximum uptime and high fault tolerance from their networks, and should use devices with high MTBF (mean time between failure) rates. Industrial-grade Ethernet switches are specifically designed to operate in harsh conditions such as those described above, with high and low temperatures, dust, and vibration and wind farms are a classic example of an environment with these extreme conditions. Wind farms are often in areas where the weather can be very hot or very cold, and the wind turbines create vibration. When selecting industrial Ethernet equipment and deploying it in a wind farm, it is important to consider the following five key characteristics: Redundancy Because you need to keep the network that supports the wind farms up and running at all times, redundancy is a key element in an industrial Ethernet switch. There are several ways to implement redundancy in these products. Since the power supply is one of the most common points of failure in any piece of electronics, be sure to look for an industrial Ethernet switch with redundant power supplies. There are some key differences that should be noted within power supplies. While standard commercial-grade switches usually use low-cost, wall-mounted AC-DC power supplies that plug into standard wall receptacles, industrial Ethernet switches hard-wire two redundantly independent power supply connections to the DC-power bus and backup power system. Industrial Ethernet switches also use dual-power inputs that accept AC, DC, or both voltage options, which helps protect against a single point of failure. This not only helps to protect wind farm networks from downtime caused by equipment failure, but also from lightning and voltage surges. Another issue that can cause network outages is cable breaks, which can be the result of human or natural causes, or connector or transceiver failures. To help prevent this, use a redundant ring configuration for cabling to help assure network uptime until an IT or maintenance crew can deploy on site to fix the issue. Wind farms typically use a ring topology to connect turbines to a central location with fiber-optic cable. This configuration is superior because the ring lets the network re-route information if a failure occurs in one of its links. Wind farm operators might also use RSTP (rapid spanning tree protocol), a design that finds alternate and backup routes to redirect network traffic around failures in a mesh topology. The ideal network configuration supports both ring configurations and RSTP, and this would be the best option for a wind farm network. Scalability With global energy demand continuously increasing, many nations are turning to renewable energy sources like wind power. As demand continues to grow, the ability to scale up and expand will be essential. Ring configurations have the flexibility to expand as wind farms grow, and support up to 50 industrial Ethernet switches per turbine, which provides significant scalability. Industrial Ethernet switches also offer a variety of port counts, depending on the number of devices that need to attach to the switch, so additional turbines can connect to the network as the wind farm grows. Support for multiple types of fiber-optic cable Fiber-optic cable is the ideal cable type to use in wind farms. It is important to note that there are two primary types of fiber cabling: MMF (multi-mode fiber) and SMF (single-mode fiber). MMF is appropriate for short to medium distances—up to 4 km—while SMF is suitable for longer distances, ranging from 20 to 60 km. The industrial Ethernet switch should support both MMF and SMF, providing the maximum number of options to connect wind farms at different distances, depending on both immediate needs and how the wind farm expands over time. This will also help reduce costs by preventing you from having to buy different or additional switches to support one cable type versus another. Temperature Rating Power consumption directly relates to temperature ratings, which, in turn, can affect the reliability of a switch, making this a critical consideration when selecting an Ethernet switch. The temperature swings in wind farms—both hot and cold—can be extreme. The temperature range can be as low as ?40 °C or as high as 75 ° C when there are no external cooling devices in place. It is important to note that some manufacturers will build a standard grade product and then test the lot to find some units that work in extreme temperatures. In cases like this, the manufacturer did not specifically design and build the product to withstand extreme temperatures the way that manufacturers of industrial-grade Ethernet switches do. These standard products will often fail in the field, even though they tested successfully for a short time interval. For wind farms, it is vital to use only reputable, industrial-grade Ethernet switches that the manufacturer has designed, tested, and proven in the field to handle fluctuating temperatures and power consumption. Management Protocols Advanced management protocols, such as multicast and VLAN support, help to improve wind farm operation by providing real-time access to key network data that can be used to improve the efficiency of the network. Industrial Ethernet switches that deliver enterprise-class management features, combined with industrial-grade ruggedness, give a complete package that enables automated monitoring and management of network uptime, performance, traffic patterns and power output. As an added benefit, this monitoring and management can even be done from remote areas to avoid the high costs and resources that would otherwise be required to reach wind farms in distant locations. Red Lion Controls