461 Example Interface Standard State of Texas

The state of Texas was the first to establish an interconnection standard for DG. Although a national consensus standard will ultimately be adopted by most of the states, this early standard draft indicates what considerations are involved. The following is a condensation of the Texas standard with key points that will be present in any interconnection standard. Note that a standard is required because heretofore only a national guide for the interconnection of emergency power generators existed, issued in the 1980s by the IEEE. In the U.S., only standards can be referenced in building codes, for example; guides cannot be referenced. At the time this book was written, the IEEE was midway through its DG standards writing activity under working group 1547.

Selections from the Texas Draft Standard (with editing by the author)*

The size of DG units considered is generally ten megawatts or less. DG (the generator and any associated interface equipment) operating in parallel with the distribution utility will be required to operate and maintain equipment such that there is no adverse effect on other customers, or on the utility's ability to maintain voltage and frequency in compliance with P.U.C. SUBST. R. 25.51, relating to power quality.

* These extracts are for illustrative purposes only and are taken from a standard draft. The final standard was not complete at the time of publication of this book. The reader is referred to the final standard or to the IEEE standard when it is completed (scheduled for 2001).

Standardization of interconnection criteria should recognize that many features to protect safety and meet reliability needs can be, and are, integrated within electrical conversion units. These electric conversion units can comply with independent testing requirements, can be tested on the production line, and can then be installed in a streamlined fashion at multiple sites. Protection functions and the interrupting device should have some way of being individually function-tested during commissioning and on a periodic basis.

These guidelines are not intended for generation that would interface directly with secondary network systems (anything below 2.4 kilovolts) due to the special characteristics of these systems. These guidelines are not intended for generation that would interface directly with the transmission system (at or above 60 kilovolts). Transmission system interconnection is governed by P.U.C. SUBST. R. 23.67 and 23.70 and any successor regulations. (See Project No. 18703, Proposed Changes to P.U.C. Subst. R. §23.67 and §23.70 relating to transmission access and pricing.)

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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