Means and method for controlling elecrical transformer voltage regulating tapchangers

A method of automatically controlling operation of tapchangers for step-down transformers at an electrical power substation where each transformer is a part of a circuit including distribution bus means and bus tie breaker means comprising:

• monitoring in real time distribution voltage across a secondary winding of each step-down transformer which reduces voltage from a high power transmission line;
• monitoring in real time electrical power flow, including real and reactive power, in said distribution bus means connected to the secondary windings of the step-down transformers, and converting monitored power flow measurements into digital bit values;
• monitoring in real time each bus tie breaker means to determine interconnection status of each transformer in the substation, and communicating the interconnection status of each transformer to a processing means;
• converting, in approximately real time, the digital bit values of real power and reactive power into engineering units representing said power flow through said distribution bus means;
• communicating said engineering units to the processing means;
• communicating predetermined desired limit values for power substation operation to the processing means, and criteria for analyzing acceptable power substation operation;
• comparing actual power substation operation with the desired limit values;
• and
• generating a control signal if the comparison does not meet the criteria, the control signal causing one or more selected tapchangers for one or more selected transformers to alter its position to alter operation of said one or more selected transformers.

A supervisory means for automatically operating a transformer tapchanger control of an underload tapchanger for an electrical power substation transformer comprising:

• bus means for connecting the transformer to other circuitry, which can include other transformers;
• bus breaker means for opening or closing electrical contact between parts of the circuitry;
• transducer means for monitoring parameters associated with the transformer, including but not limited to load voltage, real power and reactive power;
• status means for monitoring whether the bus breaker means has opened or closed electrical contact between parts of the circuitry;
• programmable means for establishing desired values including but not limited to desired output voltage of the transformer and allowable range for output voltage of the transformer;
• processing means for reading the transducer means, the status means, and programmable means, and analyzing whether instructions should be generated to change the transformer tapchanger;
• and
• output means for communicating any instructions from the processing means to the tapchanger control, the instructions causing the tapchanger control to adjust the transformer tapchanger.

A method for controlling tapchangers for a plurality of electrical substation power transformers each connectable by secondary breaker means to a distribution bus means from which distribution feeder lines extend, and each connectable individually or in parallel by bus tie breaker means with another transformer to distribution feeder lines comprising the steps of:

• loading operation information in digital form onto an information storage means, the operation information relating to desired operational parameters of the transformers individually and collectively, including instructions regarding alteration of operational parameters based on certain changing conditions experienced by the transformers individually or collectively;
• communicating a digital processor means through an analog/digital converter with a tapchanger control means for the tapchanger of each transformer, the tapchanger control means adjusting the position of the tapchanger to raise or lower the transformer output according to an analog instruction signal;
• installing the information storage means onto the processor means which can read and perform operations in response to the digital operation information on the storage means;
• monitoring actual operation of the transformers by using transducer means to derive at least voltage, real power, and reactive power values associated with the transformers for any given time;
• monitoring the bus tie and secondary breaker means associated with the transformers to determine interconnection status of the transformers with the distribution bus and each other at any given time;
• reading the actual operation data for a given time or time period and processing the data according to the calculations contained in the operation information to derive engineering quantities which can be related to the operation parameters of the operation information;
• checking for system errors;
• scanning the operation of all transformers, including the monitoring of actual operation of the transformers and the monitoring of bus tie and secondary breaker means, and storing the data in a memory means;
• calculating operation parameters based on the scanning to determine present conditions of the system;
• comparing the present condition data in the processing means with the operation parameters on the information storage means;
• altering the operation parameters with respect to the preset conditions;
• and
• issuing instruction signals to each tapchanger control means to control and regulate the transformer output of each transformer to automatically control individual and composite transformer output.