Method for calculating the average value of a noise corrupted signal

Claim 1

In a sampled data system the method for automatically modifying the control signal for a power distribution system which includes an electric steel refining furnace as part of its load so that the control signal will not change significantly as a result of loss of arc in the furnace, comprising the steps of: automatically computing the average value of the furnace load as a linear average of the sampled furnace load measurements after the sampled value deviates from the previously calculated average by an amount which is greater than a preset meximum representing the expected maximum value from furnace melting noise, automatically computing the average as an exponential average of the values of the furnace load after said linear average attains a value substantially equal to the value which would be computed as the exponential average for the last sampled value and the previously calculated average so long as the deviation of the value from the previously calculated average is less than said preset maximum, and automatically maintaining the average at its last value and changing the value of the control signal by a weighted value directly related to the difference between the last sampled furnace load measurement and the previous average value of the furnace load so as to modify said control signal in magnitude and polarity so that the change In furnace load, due to the loss of arc, will not produce a comparable change in the control signal, said maintenance of the average and changing of the value of the control signal being carried out during a preset maximum time period representing the expected maximum time duration of a loss of arc when that period follows a deviation of the sampled value of the furnace load beyond a preset maximum and so long as that deviation exceeds said preset maximum.

Claim 3

The method for automatically modifying the control signal for a power distribution system which includes an electric steel refining furnace as a part of its load so that the control signal will not change significantly as a result of loss of arc in the furnace, comprising the steps of: automatically comparing a previous average value for periodic samples of the furnace load with the presently sampled value for the furnace load; automatically incrementing a timer when said comparison indicates that the change in the furnace load from its previous average constitutes a decrease beyond that preset deviation limit which when exceeded indicates a loss of arc in the furnace; automatically setting the average at the present sampled value of load when, said comparison indicates a change in furnace load from the previous average of magnitude sufficient to constitute an increase beyond a deviation limit set to be comparable to the change in load expected from furnace melting noise, and said timer has incremented to a preset value representing the expected maximum time duration of a loss of arc; automatically averaging the furnace load values sampled since restarting the average at the sampled value when said comparison indicates that the change in the furnace load from its previous average constitutes a change of insufficient magnitude to exceed either said increase or decrease limit; and automatically holding the average at the previous average and changing the value of the control signal by a weighted value directly related to the difference between the presently sampled furnace load and the previous average value of the furnace load so as to modify said control signal in magnitude and polarity so that the change in furnace load due to the loss of arc will not produce a comparable change in the control signal when said timer has not incremented to said preset value.

Claim 4

The method for automatically modifying the control signal for a power distribution system which includes an electric steel refining furnace as a part of its load so that the control signal will not change significantly as a result of loss of arc in the furnace, comprising the steps of: automatically comparing a previous average value for periodic samples of the furnace load with the presently sampled value for the furnace load; automatically incrementing a timer when said comparison indicates that the change in the furnace load from its previous average constitutes a decrease beyond that preset deviation limit which when exceeded indicates a loss of arc in the furnace; automatically setting the average at the present sampled value of load when, said comparison indicates a change in furnace load from the previous average of magnitude sufficient to constitute an increase beyond a deviation limit set to be comparable to the change in load expected from furnace melting noise, and said timer has incremented to a preset value representing the expected maximum time duration of a loss of arc; automatically averaging the furnace load values sampled since restarting the average at the sampled value when said comparison indicates that the change in the furnace load from its previous average constitutes a change of insufficient magnitude to exceed either said increase or decrease limit; and automatically holding the average at the previous average and changing the value of the control signal by a weighted value directly related to the difference between the presently sampled furnace load and the previous average value of the furnace load so as to modify said control signal in magnitude and polarity so that the change in furnace load due to the loss of arc will not produce a comparable change in the control signal when said timer has not incremented to said preset value.