Position angle transducer for tap changing transformers
First Claim
1. An improved position angle transducer for voltage compensating tap changing transformers which have a rotatable shaft for changing the secondary tap of the transformer to different secondary tap positions or tap numbers by rotation of the shaft, a shaft motor for rotating the shaft through different tap changing shaft angles, a shaft angle sensor operatively coupled for generating shaft angle analog signals corresponding to the tap changing shaft angles, wherein each transformer is characterized by a transfer function or functional relationship of tap changing shaft angle to tap number, the improvement comprising:
- analog-to-digital converter means having a plurality of inputs operatively coupled to receive the shaft angle analog signals from the shaft angle sensor and a plurality of outputs for delivering digital words, said analog to digital converter means being programmed to deliver shaft angle digital words at the outputs corresponding to the shaft angle analog signals and tap changing shaft angles of the shaft of a tap changing transformer;
computer program means operatively programmed for automatically converting empirically determined transfer function data correlating shaft angle and tap number for a particular tap changing transformer to a digitally encoded table correlating shaft angle and tap number digital words for said tap changing transformer;
digital-to-digital converter means having a plurality of inputs coupled to receive the shaft angle digital words and a plurality of outputs for delivering tap number digital words, said digital-to-digital converter means being operatively programmed with said digitally encoded table for the tap changing transformer for converting the shaft angle digital words to tap number digital words according to the transfer function or functional relationship of tap changing shaft angle to tap number for the particular tap changing transformer.
1 Assignment
0 Petitions
Accused Products
Abstract
A position angle transducer for voltage compensating tap changing transformers provides secondary tap number or tap position analog output signals which accurately reflect the secondary tap position even if a non-linear relationship obtains between the shaft angle and tap number. A shaft angle sensor generates shaft angle analog signals and an analog-to-digital converter converts the shaft angle analog signals to shaft angle digital words. A digital-to-digital converter receives the shaft angle digital words and provides at its output tap number digital words according to the transfer function or functional relationship of tap changing shaft angle to tap number for the particular transformer. A programmable read-only memory performs the digital-to-digital conversion and is flexibly programmed according to the transfer function of the transformer and in order to establish any desired transfer functional relationship. The tap number digital words may then be converted to tap number analog signals at the output truly representative of the secondary tap position for input to a utility company SCADA System.
12 Citations
23 Claims
-
1. An improved position angle transducer for voltage compensating tap changing transformers which have a rotatable shaft for changing the secondary tap of the transformer to different secondary tap positions or tap numbers by rotation of the shaft, a shaft motor for rotating the shaft through different tap changing shaft angles, a shaft angle sensor operatively coupled for generating shaft angle analog signals corresponding to the tap changing shaft angles, wherein each transformer is characterized by a transfer function or functional relationship of tap changing shaft angle to tap number, the improvement comprising:
-
analog-to-digital converter means having a plurality of inputs operatively coupled to receive the shaft angle analog signals from the shaft angle sensor and a plurality of outputs for delivering digital words, said analog to digital converter means being programmed to deliver shaft angle digital words at the outputs corresponding to the shaft angle analog signals and tap changing shaft angles of the shaft of a tap changing transformer; computer program means operatively programmed for automatically converting empirically determined transfer function data correlating shaft angle and tap number for a particular tap changing transformer to a digitally encoded table correlating shaft angle and tap number digital words for said tap changing transformer; digital-to-digital converter means having a plurality of inputs coupled to receive the shaft angle digital words and a plurality of outputs for delivering tap number digital words, said digital-to-digital converter means being operatively programmed with said digitally encoded table for the tap changing transformer for converting the shaft angle digital words to tap number digital words according to the transfer function or functional relationship of tap changing shaft angle to tap number for the particular tap changing transformer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
-
-
13. An improved position angle transducer for voltage compensating tap changing or variable tap transformers having a rotatable shaft for changing the secondary tap of the transformer in response to load demand to different secondary tap positions or tap numbers, a prime mover for rotating the shaft through different tap changing shaft angles in response to control signals, a synchronous generator having rotor and stator coils for generating synchro rotor and stator signals, said synchronous generator rotor coil being mechanically coupled to the rotatable shaft of the variable tap transformer for generating reference rotor signals and variable stator signals according to the tap changing shaft angle, each tap changing transformer being characterized by a transfer function or functional relationship of the tap changing shaft angle to tap number, the improvement comprising:
-
synchro to digital converter means having inputs coupled to receive the synchro signals from the synchronous generator and programmed to generate at the output digital word addresses corresponding to and representing the tap changing shaft angles of the rotatable shaft of a variable tap transformer; computer program means operatively programmed for automatically converting empirically determined transfer function data correlating shaft angle and tap number for a particular variable tap transformer to a digitally encoded transfer function table correlating shaft angle and digital word tap numbers for said variable tap transformer; transfer function memory means comprising a plurality of digital word address inputs and corresponding digital word address memory locations, said transfer function memory means being operatively programmed with said digitally encoded transfer function table for the variable tap transformer for storing the digital word tap numbers at said digital word address memory locations corresponding to the different tap changing shaft angles of the rotatable shaft of the particular variable tap transformer, said transfer function memory means comprising a plurality of outputs for delivering said digital word tap numbers according to the transfer function or functional relationship of tap changing shaft angle to tap number for said particular variable tap transformer; and digital to analog converter means operatively coupled for converting the tap number digital words at the output of the transfer function memory means to tap number analog signals corresponding to the tap number selected by the tap changing angle of the rotatable shaft of the variable tap transformer. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
-
-
21. An improved method for generating tap number or tap position data output signals for a tap changing transformer from tap changing shaft angle analog signals, where the transformer has a rotatable shaft for changing the secondary tap to different secondary tap positions or tap numbers, a shaft motor for rotating the shaft through different tap changing shaft angles, a shaft angle sensor operatively coupled for generating shaft angle analog signals corresponding to the tap changing shaft angle, and wherein the transformer is characterized by a transfer function or functional relationship of the tap changing shaft angle to tap number, the improved method comprising:
-
empirically determining transfer function data correlating shaft angle and tap number for a particular tap changing transformer; automatically converting the empirically determined transfer function data to a digitally encoded transfer function table correlating shaft angle and tap number digital words for the tap changing transformer; converting the shaft angle analog signals from the shaft angle sensor of the tap changing transformer to shaft angle digital words; converting the shaft angle digital words to tap number digital words representing tap numbers corresponding to the shaft angle digital words and tap changing shaft angles, according to the digitally encoded transfer function table for the particular tap changing transformer; converting the tap number digital words to tap number output signals; and buffering said output signals to provide low impedance substantially constant current tap number output signals. - View Dependent Claims (22, 23)
-
Specification