Station Service Voltage Transformer (SSVT) is a special class of single-phase high voltage instrument transformer with a power winding and optional metering winding at the secondary. The SSVT is capable of being connected directly to the transmission line and providing 120 to 480 V at the secondary power terminals and 115 V at the metering terminals. The power rating of the secondary is normally anywhere from 25 kVA up to 333 kVA. The SSVT was initially developed as a means to provide control power in a substation without the need for stepdown and distribution transformers. Over time, the properties of the SSVT made it an ideal power source for many different applications. Today the SSVT is being installed in numerous applications around the world. Some typical applications include but are not limited to: remote cell towers, transmission tower lighting, oil and gas, mining projects, substation auxiliary power and rural electrification. In any of the listed applications, it is still necessary to acquire accurate revenue metering for the power companies to charge for power usage. In many cases this requires the installation of instrument transformers to perform the metering. Unfortunately, the metering and power windings of the SSVT cannot be operated simultaneously. When a load is applied to the power winding on the SSVT, a load current is reflected back into the primary winding. This current generates a drop in voltage through the primary reactance and resistance. It is these values which are reflected back into the metering winding. The accuracy of the metering winding will fall out of acceptable limits when the voltage drop is present. This research proposes a new method to provide both power and accurate metering, simultaneously, in a dual secondary SSVT. The accuracy of the metering winding remains essentially unaffected by the load on the power winding if the load is less than the maximum rating of the compensator. The result is a single transformer capable of replacing the functionally of two separate transformers. This new approach will have a broad impact in the development of future substation designs.
| Identifer | oai:union.ndltd.org:MSSTATE/oai:scholarsjunction.msstate.edu:td-2466 |
| Date | 07 August 2020 |
| Creators | Wallace, David |
| Publisher | Scholars Junction |
| Source Sets | Mississippi State University |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Theses and Dissertations |
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