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Technical Paper
Advanced Generator Sets for Distributed and Premium Power Generation
Page 2
Turbine Power Products for DPG
The benefits of DPG are well understood. The evidence is the strong interest in the marketplace in emerging technologies that have the potential to compete favorably with the grid, provide for grid robustness and improve grid reliability experienced in various areas of the globe. The market prospects for micro turbines and mini turbines for distributed power, and their associated high-grade heat, are extremely encouraging. The growth in this area is likely to accelerate as the deregulation of electric power markets is finalized, and as the utilities start to realize that DPG can effectively defer capital cost, reduce maintenance costs of infrastructure and improve network performance.
Recent years have seen a strong interest in distributed generation (DG), and thus, an increase in turbine system development activities. A number of companies, including TGC, are currently field-testing demonstration units, and commercial units are available in the marketplace. Small turbine-based generating systems are available from 30 kW to 400 kW, and soon they will be available in levels exceeding the megawatt as recently announced by the partnership between Turbo Genset, Magellan Aerospace and Altek Power Inc.
A typical turbine-based power system consists of a compressor, combustor, turbine and a direct-driven generator. The turbine can be a single or two-shaft design, and uses high-speed, permanent-magnet alternators to produce variable voltage, high frequency, alternating current. An on-board inverter converts high-frequency ac power produced by the alternator to an output power with the appropriate voltage and frequency required by the applications.
Distributed generation resources can be optimally deployed within the distribution system to meet the power and reliability requirements of the customers served by the utility, and they can be installed on either side of the utility metering equipment.
As for the technologies, some DG solutions are already well established. For example, these include the synchronous generators driven by reciprocating diesel engines. These technologies are mature with well-known cost, size and performance characteristics. The newer technologies, such as micro turbines, were adapted mainly from aerospace and defense industries, and they are already demonstrating gains in cost, reliability and performance when compared to the reciprocating engine solution. Additionally, as the DG market grows, these technologies will benefit from cost reduction associated with industrialization and manufacturing volumes.
Most of the turbine-based generating sets are base loaded and serve a portion of the load, or are used as peaking units during high-cost periods, while the utility serves the remainder of the load and performs the load following function. Although this mode of operation is simplistic, the resultant standby charge from the utility and the fuel and investment charges often make this mode of operation uneconomical.
The mini turbine being developed by TGC and its partners has four modes of operation:
- Grid-parallel export
- Grid-parallel import
- Isolated operation, single unit
- Isolated operation, multiple units
If the standby rates are relatively high, the system can be operated as a stand-alone island (without standby) with its own reserve margin, and as such can provide the reliability the customer requires.