# US 9,753,067 B2 · Determining a phase and a frequency of an electric quantity of an operating electrical device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,753,067 B2 - Document ID: US9753067B2 - Status: Granted - Kind: B2 - Application number: 14/359,585 - Filed: 2013-02-01 - Published: 2014-12-18 - Granted: 2017-09-05 - Earliest claimed: 2012-02-03 - Assignees: Siemens Aktiengesellschaft - Applicants: Siemens Aktiengesellschaft - Inventors: Heng Deng - Web page: https://patentgrep.com/patent/US9753067B2 ## CPC - G01R 23/02: Arrangements for measuring frequency, e.g. pulse repetition rate; Arrangements for measuring period of current or voltage - G01R 25/00: Arrangements for measuring phase angle between a voltage and a current or between voltages or currents - H02J 3/381: {Dispersed generators} - H02J 3/40: Synchronisation of generators for connection to a network or to another generator - H02M 5/42: by static converters - H02J 2101/28: Wind energy - Y02E 10/76: Power conversion electric or electronic aspects - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) - H02J: ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY - H02M: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF (transformers H01F; dynamo-electric converters H02K47/00; controlling transformers, reactors or choke coils, control or regulation of electric motors, generators or dynamo-electric converters H02P) - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION ## Abstract A method and an apparatus for determining a phase and a frequency of an electric quantity being associated with an operation of an electrical device are described. The method comprises extracting a fundamental component of the electric quantity, calculating a positive sequence component of the electric quantity based on the extracted fundamental component, and determining the phase and the frequency of the electric quantity based on the calculated positive sequence component. ## Claims ### Claim 1 A method for determining a phase and a frequency of an electric quantity being associated with an operation of an electrical device, the method comprising: providing an electric machine or a power grid; providing an AC-to-DC stage for converting a first AC power signal being generated by the electric power machine into a DC power signal; providing a DC-to-AC stage for converting the DC power signal into a second AC power signal being received from the power grid; extracting a fundamental component of the electric quantity from the electric machine or power grid, wherein the electric quantity is a counter electromotive force; calculating a positive sequence component of the counter electromotive force based on the extracted fundamental component of the electric machine or power grid; determining the phase and the frequency or oscillation of the counter electromotive force based on the calculated positive sequence component of the electric machine or power grid; providing a feedback loop providing the determining unit and the calculating unit with the determined frequency so as to improve an accuracy of the determined phase, frequency or oscillation; and performing a change in the phase, the frequency or the oscillation of the electric machine or power grid based upon the determined phase, frequency, or oscillation. ### Claim 2 (depends on 1) The method according to claim 1, further comprising: determining the counter electromotive force by a Kalman filter. ### Claim 3 (depends on 1) The method according to claim 1, further comprising: determining the counter electromotive force by an observer. ### Claim 4 (depends on 1) The method according claim 1, wherein the fundamental component is extracted by an adaptive band pass filter and/or a low pass filter. ### Claim 5 (depends on 1) The method according to claim 1, wherein: calculating the positive sequence component comprises obtaining a phase shifted component which has a 90 degree phase shift to the extracted fundamental component. ### Claim 6 (depends on 1) The method according to claim 1, wherein the phase and the frequency of the electric quantity are determined by a Phase Lock Loop. ### Claim 7 (depends on 1) A computer program product, comprising a computer readable hardware storage device having computer readable program code stored therein, said program code executable by a processor of a computer system to implement a method for determining a phase and a frequency of an electric quantity being associated with an operation of an electrical device, wherein the computer program product, when executed by the processor, is adapted to perform a method according to claim 1. ### Claim 8 An apparatus for determining a phase and a frequency of an electric quantity being associated with an operation of an electrical device, the apparatus comprising: an extracting unit configured for extracting a fundamental component of the electric quantity; a calculating unit configured for calculating a positive sequence component of the electric quantity based on the extracted fundamental component; a determining unit configured for determining the phase and the frequency of the electric quantity based on the calculated positive sequence component; an AC-to-DC stage for converting a first AC power signal being generated by an electric power generating machine into a DC power signal; a DC-to-AC stage for converting the DC power signal into a second AC power signal being received from a power grid; and a feedback loop providing the determining unit and the calculating unit with the determined frequency so as to improve an accuracy of the determined phase and frequency. ### Claim 9 (depends on 8) The apparatus according to claim 8, further comprising: a further determining unit configured for determining the electric quantity, wherein the electric quantity is a counter electromotive force being associated with the electrical device. ### Claim 10 (depends on 8) The apparatus of claim 8, wherein the electrical device is a generator of a wind turbine or a power grid. ### Claim 11 (depends on 10) A wind turbine comprising: a frequency converter as set forth in claim 10.