The wind industry has grown to the point where it is now the fourth largest source of electrical power in North America after natural gas, coal, and nuclear. Industry reports indicate that global electricity generation from wind energy reached 60 GW in 2016. The U.S. Department of Energy’s Wind Vision report says the United States may be able to meet 10 percent of its electricity needs through wind power by 2020, 20 percent by 2030, and 35 percent by 2050. Further, according to the American Wind Energy Association (AWEA), there are now 13,759 MW under construction, and 15,875 MW in advanced development. The combined 29,634 MW represents a 27 percent year-over-year increase, the highest level reported since AWEA began tracking both categories at the beginning of 2016.
However, it takes power to make power, and the unpredictability of extreme weather conditions can cause disruptions to onshore and offshore construction projects.Against this backdrop, and to stay on schedule, many wind energy developers are turning to temporary power generation solutions that provide for a wider, more flexible, and durable power capability across each stage of the wind farm lifecycle.
Temporary power generation solutions can be deployed at various stages of a wind farm development project to maintain productivity from both an economical, and operational standpoint…regardless of the waves Mother Nature makes.
Compared to onshore wind energy projects, planning for offshore wind farms presents a new learning curve. Much of the testing can be done at the manufacturing facility on both high and low voltage systems, but additional onsite testing is required for all projects.
For example, in order to progress from the planning phase into the construction phase, a project needs a reliable power source for LIDAR. LIDAR ensures the collection of a constant stream of information on wind, birds, and other wildlife. In this phase, the operation cannot lose power, even when challenged by turbulent waves and extreme wind. Any temporary power generation equipment must be waterproof to keeping the planning stage on track.
A reliable source of power is also required throughout the construction phase. Temporary power for large and small loads can be supplied with a wide range of generators designed to withstand any climate condition.
Testing the high voltage (HV) cable and substation requires a temporary power source. Per offshore construction, an HV cable soak test is conducted for building the substation so that the developer can test all the relays and transformers on the substation prior to floating out. This prevents potential failures that will be costly to rectify offshore. For onshore projects, the cable soak is the first step in the commissioning process for each circuit of a wind farm. When the circuit is energized, this is the first time that cable has received power. The developer then has the entire circuit inspected prior to energizing the transformers.
Offshore, generators are used to commission or condition the turbines. This often includes use of generators on the MAP that power the essential equipment, followed by a greater amount of power to pitch and yaw the turbines. Failure to provide this motion could result in damage to the turbine.
Novel offshore power solutions have been created for this requirement, with the operating environment in mind; generators that are lightweight, durable and can synch together work to minimize the load. LV and HV back feeding solutions can also be provided for the offshore substation (OSS), further minimizing cost for the developer.
The past 20 years have seen certain variability and induction problems with wind-farm projects, and continues to make connecting to the utility grid a major challenge. This is where temporary power suppliers have played a pivotal role. The average size of wind driven generators has increased from 0.5 MW in the mid-1990s, up to 8-MW in the latest offshore models. Commissioning these systems into service is expedited with mini-grid solutions, which provides the capability to manage power from the turbines, along with an associated array of scalable generators and transformers.
Onshore, generators are used to commission turbines prior to grid interconnection. This is often required because the transmission line is not complete or the interconnection will occur and leave to short a timeline to commission all the turbines prior to the sites Commercial Operation Date (COD). To complete the function on a large scale, the power from the turbines must be absorbed and managed by technically trained personnel with the correct equipment.
The generators and load banks supplied to the industry enable turbines to be commissioned prior to connecting to the power grid; this benefits return on investment (ROI) by letting the developer begin production as soon as the project completes the wind farm’s substation. Saving time with reliable power equipment is important, given the tax incentives and credits available once the wind energy system is fully operational.
Operations and maintenance phase
In the post-commissioning phase, low-voltage power generators at the base of each turbine can power ancillary equipment such as lighting, and the hydraulic pumps to turn the rotor (to prevent bearing lock up). Alternatively, a central high voltage package can power the integrated system from one point of connection, keeping transformers and switchgear running, in addition to the turbines.
Maintenance typically uses temporary power from standard generators, while transformers are available for the higher voltages, such as 690V (the industry standard for many years). In fact, transformers have been supplied for multiple uses; to connect the circuits in the field, 480 V/34.5 transformers in the 2,500-to 5,000 kVa range are provided. To keep the system operational, power has been supplied to the field when the main transformer has failed or the utility has to take the distribution system out of service. Whether it is a maintenance issue or an emergency situation, sometimes an entire wind farm must be taken offline. When this occurs a temporary mini-grid solution can support the entire wind farm providing enough power for all the turbines to pitch and yaw correctly and protect all warranties associated.
Offering unique designs and reliable models that weather severe conditions, temporary power generators can significantly reduce the costs and risks of downtime across the lifecycle of a project. While Mother Nature never stops, the capabilities of such generators continue to expand as the industry transitions into offshore projects in North America and elsewhere.
Bill Cook is a Renewable Energy Sector Manager for Aggreko, an international provider of power generation and temperature control solutions. In his role, Bill is focused on driving the company’s business strategies and relationships within the renewables market. He has been leading Aggreko’s business in the renewables sector for the last 12 years. Bill spends most of his time traveling and working with industry experts to develop solutions to their individual challenges. He lives in Chicago with his wife and four children.
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