The parallelism system for power transformers equipped with shunt taps under load has traditionally been done by an electro-mechanic panel, with analog indication of TAP position and manual tap change.…
WAPA (Western Area Power Administration) transmits power to the 15 States in the Central and West regions of the United States, as we can see in the side map. The company is one of the four administrations of the electrical power market of the country, reporting to the Department of Energy of the United States (DOE-USA). According to the last annual report, in the accounting year closed on September 31, 2008, WAPA sold total 36 billion kWh (kilowatts/hour) and reported gross operational income of US$ 1.2 billion.
Characteristics of the Electrical Power System
By counting on 296 substations and more than 27,000 km of lines, WAPA distributes the power produced by 57 hydroelectric power plants, which together are responsible for an installed capacity of approximately 10,395 MW. The dimensions and characteristics of the park installed require continuous and reliable monitoring of all the functions of transformers in operation in their substations, among which the “temperature” is one of the most significant of them.
In function of these characteristics, WAPA holds the leading position in technology in its performance segment. Its planning includes the gradual replacement of mechanical thermometers currently installed by digital temperature monitors, in order to optimizing the operations, achieving efficiency in technical training, reducing the diversity of spare equipment, and consequently the cost of stock maintenance.
For the implementation of the project for replacement of mechanical thermometers, in 2006, WAPA evaluated the digital temperature monitors manufactured by the following companies: Qualitrol Inc.; Advanced Power Technologies; Barrington Consultants Tech Inc.; Transformer Advantage; Dynamic Ratings; Schweitzer Engineering Laboratories (SEL) and Treetech Sistemas Digitais (the only foreigner company).
As a result of this evaluation, it determined the application of Treetech equipment in the new transformers produced by large traditional and multinational manufacturers, such as Hyundai and Waukesha Electric. In addition, in October 2007, the WAPA unit of the Rock Mountain Region defined Treetech as its “Sole Source” to supply the temperature monitors. Provided that duly justified, the Sole Source releases WAPA from carrying out public bids for purchase of equipment that, due to exclusive technical characteristics, are produce by one manufacturer only. The “Sole Source” justification report prepared by Wapa is available in the web site of the Department of Energy of the United States.
Among the evaluation criteria of the customer, weight and facility/simplicity of replacement of the previous thermometers by the Temperature monitors (Mod. TM1 and TM2) can be listed, by considering aspects, such as mechanical and electrical adaptations. As they are miniaturized and compatible with the spaces released by the former equipment, Treetech monitors exhibited great advantage before other brands.
The easy parameterization and simple operation, which result in greater efficacy of the training provided to operators, also favor the Treetech equipment. Finally, the multiple communication protocols of Treetech monitors – Modbus and DNP 3.0 made them more competitive.
Shown below are the characteristics evaluated by Wapa and the characteristics of the TM1 and TM2 temperature monitors by Treetech:
|Analysis Criteria||Wapa Requirements||Treetech Equipment Characteristics|
|Universal application in transformers of different manufacturers and characteristics||Reduced dimensions, which enable the installation on the control panels of any existing transformer||Miniaturized equipment with front side with 96x96mm only|
|Embedded installation on the panel door||Embedded installation with connection terminals on the back side of the equipment and front keyboard/display|
|Transformer settings programmed in the own equipment, with no hardware changes||Totally programmable on the front panel|
|Standardization of stock and spare parts||The same equipment can be reconfigured according to the application, standardizing and reducing stocks.|
|Power supply 38-160Vdc and 120/240Vac||Universal power supply 38 to 265Vdc or Vac 50/60Hz|
|Integration with the existing data collection systems at the substations||Standard and open communication interface and protocol - RS232 and DNP 3.0||Open protocols DNP3.0 and Modbus. Interfaces RS232 and RS485.|
|Remote management||Immediate detection of defects and remote configuration||Self-diagnosis of failures. Data gathering and remote configuration management.|
|Operation conditions||Operating temperature: -40°C to 85°C||Tested and approved in climatic, vibration and electric tests|
|Display, high brightness, legible from -40°C to 85°C||LED display, high brightness from -40°C to 85°C|
|Inputs||Temperature measurement on 3 windings||Temperature measurement on up to 3 windings|
|Inputs for 3 temperatura sensors Pt100||Inputs for up to 4 temperature sensors|
|Absence of mechanical parts for calibration||Calibration and configuration totally by software|
|Outputs||Minimum 7 output contacts||Eight output contacts|
|Start of timed mechanical ventilation, even in case of power outage||Mechanical ventilation with timed start in case of power outage|
|Functions||Expert functions, Pre-cooling, Fan test, Temperature Difference of OLTC, Expected Final Temperature Gradient and Alternance of VF groups||Além das funções especificadas, possui ainda Memória de Massa, Redundância no Acionamento da VF e Acionamento de Desligamento com Segurança Dupla|
WAPA already specifies these technical requirements for the purchase of new transformers. Other energy companies, such as HHIC-PHIL Subic of the Philippines, and US companies Kansas City, Power & Light and Detroit Edson are also adopting the technology on the recommendation of South Korea’s Hyundai manufacturer.