A frequency estimation signal generator component arranged to receive an input frequency signal and to generate therefrom a frequency estimation signal. The frequency estimation signal generator component comprises a counter component arranged to sequentially output a sequence of control signal patterns over a plurality of digital control signals under the control of an oscillating signal derived from the received input frequency signal terns. The frequency estimation signal generator further comprises a continuous waveform generator component arranged to receive the plurality of digital control signals and a weighted analogue signal for each of the received digital control signals, and to output a continuous waveform signal comprising a sum of the weighted analogue signals for which the corresponding digital control signals comprise an asserted logical state. The frequency conversion component is arranged to derive the frequency estimation signal from the continuous waveform signal output by the continuous waveform generator component

A frequency estimation signal generator component arranged to receive an input frequency signal and to generate therefrom a frequency estimation signal. The frequency estimation signal generator component comprises a counter component arranged to sequentially output a sequence of control signal patterns over a plurality of digital control signals under the control of an oscillating signal derived from the received input frequency signal terns. The frequency estimation signal generator further comprises a continuous waveform generator component arranged to receive the plurality of digital control signals and a weighted analogue signal for each of the received digital control signals, and to output a continuous waveform signal comprising a sum of the weighted analogue signals for which the corresponding digital control signals comprise an asserted logical state. The frequency conversion component is arranged to derive the frequency estimation signal from the continuous waveform signal output by the continuous waveform generator component

Determining a property of an electrical signal at a node instant at the current instant (INSTC); determining a previous function indicative of a property of the signal at the node at a previous instant; determining an error function in a previous frequency estimation at the node at a previous instant; determining a first current function indicative of the property of the signal at the node at INSTC in accordance with the determined property, the previous function, and the error function; receiving, from another node, a second current function indicative of a property of an electrical signal at the at least one other node at INSTC; combining the first current function and the second current function to produce a current combined function (CCF) indicative of a property of the signal at the node at INSTC; and estimating a current frequency of the signal at the node in accordance with the CCF.

Determining a property of an electrical signal at a node instant at the current instant (INSTC); determining a previous function indicative of a property of the signal at the node at a previous instant; determining an error function in a previous frequency estimation at the node at a previous instant; determining a first current function indicative of the property of the signal at the node at INSTC in accordance with the determined property, the previous function, and the error function; receiving, from another node, a second current function indicative of a property of an electrical signal at the at least one other node at INSTC; combining the first current function and the second current function to produce a current combined function (CCF) indicative of a property of the signal at the node at INSTC; and estimating a current frequency of the signal at the node in accordance with the CCF.

An apparatus and method are provided for detecting a resonant frequency giving rise to an impedance peak in a power delivery network used to provide a supply voltage. The apparatus includes resonant frequency detection circuitry that comprises test frequency control circuitry and a loading circuit. The test frequency control circuitry is arranged to generate control signals to indicate a sequence of test frequencies. A loading circuit is controlled by the control signals and operates from the supply voltage. In particular, in response to each test frequency indicated by the control signals, the loading circuit draws a duty-cycled current load through the power delivery network at that test frequency. Operation of the loading circuit produces a measurable property whose value varies in dependence on the supply voltage, thus enabling the resonant frequency to be determined from a variation in the value of that measurable property.

An apparatus and method are provided for detecting a resonant frequency giving rise to an impedance peak in a power delivery network used to provide a supply voltage. The apparatus includes resonant frequency detection circuitry that comprises test frequency control circuitry and a loading circuit. The test frequency control circuitry is arranged to generate control signals to indicate a sequence of test frequencies. A loading circuit is controlled by the control signals and operates from the supply voltage. In particular, in response to each test frequency indicated by the control signals, the loading circuit draws a duty-cycled current load through the power delivery network at that test frequency. Operation of the loading circuit produces a measurable property whose value varies in dependence on the supply voltage, thus enabling the resonant frequency to be determined from a variation in the value of that measurable property.

A fully distributed island micro-grid attack elasticity control system and method are provided. The method includes following specific steps: collecting basic information of a local AC micro-grid bus of a distributed power generation unit and basic information of a neighbor distributed power generation unit connected through a directed communication topology; predicting, based on a dynamic equation of the distributed power generation unit, a sequence of states thereof within a set period of time, namely, the predicted sequence of states; judging whether a system is under attack according to a comparison result of the predicted sequence of states and a real-time state sampling value of a micro-grid, to obtain a sequence of optimal auxiliary control inputs u.sub.i*; and calculating an optimal angular frequency reference value .sub.i* at the next time point according to the sequence of optimal auxiliary control inputs u.sub.i*.

A fully distributed island micro-grid attack elasticity control system and method are provided. The method includes following specific steps: collecting basic information of a local AC micro-grid bus of a distributed power generation unit and basic information of a neighbor distributed power generation unit connected through a directed communication topology; predicting, based on a dynamic equation of the distributed power generation unit, a sequence of states thereof within a set period of time, namely, the predicted sequence of states; judging whether a system is under attack according to a comparison result of the predicted sequence of states and a real-time state sampling value of a micro-grid, to obtain a sequence of optimal auxiliary control inputs u.sub.i*; and calculating an optimal angular frequency reference value .sub.i* at the next time point according to the sequence of optimal auxiliary control inputs u.sub.i*.

A wireless power transmission system, and a method for controlling wireless power transmission and wireless power reception are provided. According to an aspect, a method for controlling a wireless power transmission may include: detecting a plurality of target devices used to wirelessly receive power; selecting a source resonating unit from among a plurality of source resonating units, based on the amount of power to be transmitted to one or more of the plurality of target devices, a coupling factor associated with one or more of the plurality of target devices, or both; and wirelessly transmitting power to a target device using the selected source resonating unit.

A wireless power transmission system, and a method for controlling wireless power transmission and wireless power reception are provided. According to an aspect, a method for controlling a wireless power transmission may include: detecting a plurality of target devices used to wirelessly receive power; selecting a source resonating unit from among a plurality of source resonating units, based on the amount of power to be transmitted to one or more of the plurality of target devices, a coupling factor associated with one or more of the plurality of target devices, or both; and wirelessly transmitting power to a target device using the selected source resonating unit.