53 Power Electronics and Controls

Microturbines produce high frequency AC power. Development of the power electronics and control systems (PECS) required to convert this unregulated power into a usable form (e.g., 60 Hz, 480 VAC) has proven to be a significant but achievable hurdle in the commercial deployment of MTs. Figure 5.10 depicts a modern DG power system. Although the details depend on the specific power generation technology, the same basic principles apply.

FIGURE 5.10

Modern MT power system architecture.

FIGURE 5.10

Modern MT power system architecture.

The unregulated power from the energy source must be processed (or converted) before it is consumed. In the case of an MT, the power produced by the generator is variable both in terms of voltage and frequency and is, therefore, not directly usable. The PECs that perform this power processing and regulation function are often specific to the generation technology. For example, in the case of an MT, the first stage of power electronics may contain a diode rectifier that converts the high frequency AC power produced by the generator into DC. After the power produced by the energy source has been converted to DC, it can easily be combined with power from the element at the bottom of Figure 5.10, labeled "Power Source" (Energy Storage). Energy storage is an important aspect of many DG power systems, often required for supplying starting power to the system as well as for supplying rapid transients demanded by the load. This power source is coupled to the DC bus through another power electronic converter, the details of which are dependent on the energy storage technology employed. For example, if an electrochemical battery is used, a DC-to-DC converter is used to couple the energy from the battery to the DC bus. In the case of a flywheel, an AC-to-DC converter would be used.

Finally, a PEC is required to convert electricity into a form consumable by the load. Once again, the details of this converter are dependent on the specifics of the application. For example, in the case of an electric utility (or stand-alone AC load), the power electronics would take the form of a DC-to-AC inverter. In the case of a hybrid electric vehicle (HEV), the power electronics would take the form of a DC-to-DC converter. Other power electronic elements are not shown in this simple diagram but are essential for realization of a practical DG power system. For example, motor controllers and power supplies are commonly employed in ancillary systems.

Solar Stirling Engine Basics Explained

Solar Stirling Engine Basics Explained

The solar Stirling engine is progressively becoming a viable alternative to solar panels for its higher efficiency. Stirling engines might be the best way to harvest the power provided by the sun. This is an easy-to-understand explanation of how Stirling engines work, the different types, and why they are more efficient than steam engines.

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