A tap changer configured to be coupled to an on-load tap changing, OLTC, transformer of an electric power distribution system controlled by a Supervisory Control and Data Acquisition, SCADA, system, the OLTC transformer including a plurality of primary windings and a plurality of secondary windings, the OLTC transformer further including a plurality of taps, each tap of the plurality of taps coupled to a different portion of at least one of the plurality of primary windings and the plurality of secondary windings, the secondary windings of the OLTC transformer coupled to a plurality of buses, said tap changer comprising: a tap selection device configured to selectively engage a portion on one side of the transformer; a drive device coupled to said tap selection device; and at least one processor coupled to said drive device, said at least one processor configured to generate estimated voltage values of at least one bus of the plurality of buses, said at least one processor further configured to regulate a voltage bandwidth of said on-load tap changer as a function of the estimated voltage values of at least one bus of the plurality of buses based on: real-time measurements proximate the secondary windings; and characterized by a priori values of one of power and current transmitted through each bus of the plurality of buses, wherein the a priori values of one of power and current are substantially based on one of measured power and measured current transmission through the OLTC transformer; and first covariance data, Q, of process noise within electric power distribution system, said first covariance data, Q, modelling a likelihood that the current in a given bus of the plurality of buses will change from one interval step to another to facilitate uncertainty evaluations; and second covariance data, R, of observed variables to model an uncertainty of such observed variables, including, without limitation, a noise expected from real-time measurements from the SCADA system of voltage and current at OLTC transformer and an uncertainty around the a priori knowledge collected on the values of the individual bus currents within electric power distribution system downstream of OLTC transformer; wherein said processor is further configured to generate estimations of voltages for each bus of the plurality of buses, and further to generate tap position commands for said tap changer at least partially based on the regulated voltage bandwidth of said on-load tap changer. a tap selection device configured to selectively engage a portion on one side of the transformer; a drive device coupled to said tap selection device; and at least one processor coupled to said drive device, said at least one processor configured to generate estimated voltage values of at least one bus of the plurality of buses, said at least one processor further configured to regulate a voltage bandwidth of said on-load tap changer as a function of the estimated voltage values of at least one bus of the plurality of buses based on: real-time measurements proximate the secondary windings; and characterized by a priori values of one of power and current transmitted through each bus of the plurality of buses, wherein the a priori values of one of power and current are substantially based on one of measured power and measured current transmission through the OLTC transformer; and first covariance data, Q, of process noise within electric power distribution system, said first covariance data, Q, modelling a likelihood that the current in a given bus of the plurality of buses will change from one interval step to another to facilitate uncertainty evaluations; and second covariance data, R, of observed variables to model an uncertainty of such observed variables, including, without limitation, a noise expected from real-time measurements from the SCADA system of voltage and current at OLTC transformer and an uncertainty around the a priori knowledge collected on the values of the individual bus currents within electric power distribution system downstream of OLTC transformer; real-time measurements proximate the secondary windings; and characterized by a priori values of one of power and current transmitted through each bus of the plurality of buses, wherein the a priori values of one of power and current are substantially based on one of measured power and measured current transmission through the OLTC transformer; and first covariance data, Q, of process noise within electric power distribution system, said first covariance data, Q, modelling a likelihood that the current in a given bus of the plurality of buses will change from one interval step to another to facilitate uncertainty evaluations; and second covariance data, R, of observed variables to model an uncertainty of such observed variables, including, without limitation, a noise expected from real-time measurements from the SCADA system of voltage and current at OLTC transformer and an uncertainty around the a priori knowledge collected on the values of the individual bus currents within electric power distribution system downstream of OLTC transformer; wherein said processor is further configured to generate estimations of voltages for each bus of the plurality of buses, and further to generate tap position commands for said tap changer at least partially based on the regulated voltage bandwidth of said on-load tap changer. generate estimations of voltages for each bus of the plurality of buses, and further to generate tap position commands for said tap changer at least partially based on the regulated voltage bandwidth of said on-load tap changer.