A reverberator based on a room response modal analysis is adapted to produce distortion, pitch and time manipulation effects, as well as gated and iterated reverberation. An example modal reverberator is a parallel collection of resonant filters, with resonance frequencies and dampings tuned to the modal frequencies and decay times of the space or object being simulated. In one example, the resonant filters are implemented as cascades of heterodyning, smoothing, and modulation steps, forming a type of analysis/synthesis architecture. By applying memoryless nonlinearities to the modulating sinusoids, distortion effects are produced, including distortion without intermodulation products. By using different frequencies for the heterodyning and associated modulation operations, pitch manipulation effects are generated, including pitch shifting and spectral inversion. By resampling the smoothing filter output, the signal time axis is stretched without introducing pitch changes.

Analysis of smart meter and/or similar data based on frequency content is disclosed. In various embodiments, for each of a plurality of resource consumption nodes a time series data including for each of a series of observation times a corresponding resource consumption data associated with that observation time is received. At least a portion of the time series data, for each of at least a subset of the plurality of resource consumption nodes, is transformed into a frequency domain. A feature set based at least in part on the resource consumption data as transformed into the frequency domain is used to detect that resource consumption data associated with a particular resource consumption node is anomalous.

Analysis of smart meter and/or similar data based on frequency content is disclosed. In various embodiments, for each of a plurality of resource consumption nodes a time series data including for each of a series of observation times a corresponding resource consumption data associated with that observation time is received. At least a portion of the time series data, for each of at least a subset of the plurality of resource consumption nodes, is transformed into a frequency domain. A feature set based at least in part on the resource consumption data as transformed into the frequency domain is used to detect that resource consumption data associated with a particular resource consumption node is anomalous.

Systems and methods relate a device for monitoring or tracking clock frequency. The device can include a first circuit configured to receive a reference clock signal and provide a first signal in response to a first number of cycles of the reference clock signal, and a second circuit configured to receive a sample clock signal and provide a second signal in response to the first signal. The second signal is indicative of a second number of cycles of the sample clock signal occurring during the first number of cycles of the reference clock signal. The device can also include a third circuit configured to determine a ratio of a first frequency of the reference clock signal to a second frequency of the sample signal using the second signal.

An islanding operation detection device for a distributed power supply comprising an inverter connected to a commercial system power supply comprises: a commercial system frequency measurement circuitry; a reactive power injection amount calculation circuitry to calculate an amount of reactive power injection; a feedback signal generation circuitry; a reactive current control circuitry to feedback-control an output current command value to the inverter; an output current control circuitry to update the reactive current command value when a phase angle of the commercial system voltage is in the range of 90N so as to control an output current value of the inverter to follow the output current command value; and an islanding operation detection circuitry to detect whether or not the distributed power supply is in islanding mode, based on a commercial system frequency when the reactive power corresponding to the calculated amount of reactive power injection is injected.

A method and device for determining the location-dependent pulse responses in signal transmission from a transmitter in a transmission volume to a receiver in a reception volume, wherein either the transmitter or the receiver is a device fixed in a predetermined location and the other is a movable device includes: continuously emitting a band-limited signal by the transmitter; continuously capturing the signal and recording the signal with time indexing by the receiver; moving the movable device during the emission and capturing of the signal along a trajectory within the transmission or reception volume while continuously capturing the location coordinates of the movable device and recording the location coordinates with time indexing; and numerically solving a linear system of equations, the unknowns of which system of equations represent the pulse responses at discrete sampling points in the transmission or reception volume associated with the movable device.

A method and system are provided. The method includes collecting, from a plurality of phasor measurement units, a plurality of synchronized phasor measurements from different portions of a power system. The method further includes estimating, by a controller, oscillation modes of the plurality of synchronized phasor measurements. Each estimated oscillation mode specifies, for each of the plurality of synchronized phasor measurements, two or more of an amplitude, a phase, a frequency, and damping coefficients. The method also includes performing, by the controller, a modal analysis of the oscillation modes of the plurality of synchronized phasor measurements to identify critical modes based on critical mode identifying criteria. The method additionally includes constructing, by the controller based on the critical modes, a power system oscillation dampening control signal for controlling a grid-scale storage portion of the power system to dampen one or more oscillations of the power system at any given time.

A method and system are provided. The method includes collecting, from a plurality of phasor measurement units, a plurality of synchronized phasor measurements from different portions of a power system. The method further includes estimating, by a controller, oscillation modes of the plurality of synchronized phasor measurements. Each estimated oscillation mode specifies, for each of the plurality of synchronized phasor measurements, two or more of an amplitude, a phase, a frequency, and damping coefficients. The method also includes performing, by the controller, a modal analysis of the oscillation modes of the plurality of synchronized phasor measurements to identify critical modes based on critical mode identifying criteria. The method additionally includes constructing, by the controller based on the critical modes, a power system oscillation dampening control signal for controlling a grid-scale storage portion of the power system to dampen one or more oscillations of the power system at any given time.

A circuit for detecting a knee of waveform is disclosed in the present invention. The circuit detects the knee and a total oscillation time of a voltage waveform as a load switch of load circuit is turned off. In the circuit, a filter filters the voltage waveform to transmit a reference voltage to a first and a second comparator. When the first and the second comparator determine that the voltage waveform achieves a sum of the reference voltage and a set voltage, the first and the second comparator transmit a first and a second signal to a knee detection module. When the knee detection module receives the first signal rather than the second signal in an oscillation time, or receives the second signal rather than the first signal in the oscillation time, the knee detection module records the knee and trigger a time recorder computes the total oscillation time.

An electrical measuring system of a six-port circuit includes a delay line and a arithmetic unit. In a first operating mode, an electrical signal can be on the one hand transmitted directly to a first input terminal and on the other hand via the delay line to a second input terminal of the six-port circuit. In an embodiment, the measuring system is configured such that, in the second operating mode, it does not supply a signal to the first input terminal of the six-port circuit and it supplies a reference signal to the second input terminal of the six-port circuit.