Method of controlling a tap changer of a transformer

• US 5,821,716 A
• Filed: 07/29/1996
• Issued: 10/13/1998
• Est. Priority Date: 08/05/1995
• Status: Expired due to Fees

• Current Assignee: Maschinenfabrik Reinhausen GmbH (Richard Scheubeck Beteiligungs-Gmbh & Co. KG)
• Original Assignee: Maschinenfabrik Reinhausen GmbH (Richard Scheubeck Beteiligungs-Gmbh & Co. KG)
• Inventors: Okanik, Peter
• Primary Examiner(s): Masih, Karen
• Application Number:
  US08/688,061
• Time in Patent Office: 806 Days
• Field of Search: 318/478, 364/483, 323/355, 323/260, 323/256, 323/247, 323/255
• US Class Current: 318/478
• CPC Class Codes: G05F 1/147 with motor driven tap switch

Abstract

A tap-changer transformer operated by the step-by-step principle in which its motor drive receives a signal to raise or lower the tap, has a voltage regulator in which the switching delay times and sensitivity values are freed matrix-like the respective tap changes. The actual voltage value of the transformer is compared with the preselected voltage setpoint and, based upon the control deviation, a value pair of delay and sensitivity are read out. This allows asymmetric response of the system as contrasted with the symmetrical response required by earlier systems.

Claims

1. A method of controlling a tap changer of a transformer having a motor drive for effecting tap changing, said method comprising the steps of:

(a) storing in nonvolatile memory in value pairs an individual sensitivity value E(n) and a switching delay value T(n) for each positive and negative value n corresponding to a respective voltage tap of the transformer, wherein n can assume a value . . . , -3, -2, -1, +1, +2, +3, . . . , ;

(b) measuring an actual voltage value of said transformer and comparing the measured actual voltage value with a preselected voltage setpoint;

(c) generating a control deviation n_akt from the comparison of the measured actual voltage value with said preselected voltage setpoint and with a sign representing direction of deviation of the measured actual voltage value from said preselected voltage setpoint;

(d) reading out of said nonvolatile memory a value pair of a sensitivity value E(n_akt) and a switching delay value T(n_akt) for n=n_akt ; and

(e) issuing an actuating command to said motor drive when, after a switching delay of said switching delay value T(n_akt), the control deviation exceeds said sensitivity value E (n_akt).

2. The method defined in claim 1 comprising the step of storing said value pairs of an individual sensitivity value E(n) and a switching delay value T(n) for each positive and negative value n corresponding to a respective voltage tap of the transformer in said nonvolatile memory in a matrix form.

3. A method of controlling a tap changer of a transformer having a motor drive for effecting tap changing, said method comprising the steps of:

(a) storing in nonvolatile memory in value pairs an individual sensitivity value E(n) and a switching delay value T(n) for each positive and negative value n corresponding to a respective voltage tap of the transformer, wherein n can assume a value . . . , -3, -2, -1, +1, +2, +3, . . . , ;

(b) measuring an actual voltage value of said transformer and comparing the measured actual voltage value with a preselected voltage setpoint;

(c) generating a control deviation n_akt from the comparison of the measured actual voltage value with said preselected voltage setpoint and with a sign representing direction of deviation of the measured actual voltage value from said preselected voltage setpoint;

(d) reading out of said nonvolatile memory a value pair of a sensitivity value E (n_akt) and a switching delay value T(n_akt) for n=n_akt ;

(e) determining if the control deviation during a preselected fraction a2 of a switching delay period corresponding to said switching delay value T(n_akt) exceeds said sensitivity value E(n_akt); and

(f) issuing an actuating command to said motor drive when the control deviation exceeds said sensitivity value E(n_akt) during said preselected fraction a2 of said switching delay period.

4. The method defined in claim 3 comprising the step of storing said value pairs of an individual sensitivity value E(n) and a switching delay value T(n) for each positive and negative value n corresponding to a respective voltage tap of the transformer in said nonvolatile memory in a matrix form.