7 results about "Sinusoidal modulation" patented technology

This application relates to a Rayleigh scattering noise suppression method and system for a distributed acoustic wave detection system. The method includes: performing optical phase sinusoidal modulation on a high-coherence continuous laser output from a narrow-linewidth laser in an FBG-based distributed acoustic detection system according to a set modulation scheme using an optical phase modulator; the set modulation scheme is Csin(2πf m t), C is the phase modulation amplitude, f m The phase modulation frequency and satisfying f m τ = k, where τ is the time difference between two adjacent reflected light pulses being detected, t is time, and k is an integer. A highly coherent continuous laser beam with sinusoidal phase modulation is passed through an unbalanced interferometer to generate dual light pulses. These dual light pulses are then injected into an FBG array for distributed acoustic wave detection. This achieves low-noise distributed acoustic wave detection and effectively improves the detection performance of FBG-based distributed acoustic wave detection.

This invention discloses a method for identifying broadband voltage fluctuation types in power grids based on multi-feature fusion, relating to the field of voltage fluctuation technology. It addresses the problem of fluctuation type confusion under conditions of multiple disturbances and non-stationary operation. The method involves acquiring three-phase voltage data from voltage transformers and calculating the voltage deviation rate, while simultaneously retrieving the short-time flicker index. A fluctuation identification mechanism is jointly triggered based on these two factors. After triggering, a broadband voltage signal is acquired and modal decomposition is performed. The instantaneous frequencies of each mode are extracted and classified. Historical voltage data is retrieved to construct the voltage envelope trajectory, and the envelope asymmetry is calculated. Disturbances are introduced to different modes to enhance energy, and the modal energy spectra are calculated and fused to form modal modulation feature vectors. A pre-trained support vector machine model is used for classification mapping, achieving accurate identification of sinusoidal modulation, rectangular modulation, and interharmonic modulation voltage fluctuations, thus improving identification accuracy under complex operating conditions.

The application discloses a photovoltaic grid-connected inverter system and a control method based on discontinuous modulation, and relates to the technical field of multilevel inverter control. The method comprises the following steps: obtaining a three-phase sinusoidal modulation wave of a multilevel inverter, constructing a square wave signal and adjusting the amplitude of the square wave signal, and dividing a clamping interval according to the intersection of the square wave and the three-phase sinusoidal modulation wave; based on midpoint balance and resonance suppression, the square wave signal is subjected to compensation voltage superposition; a control threshold for presetting the control midpoint voltage fluctuation range is determined, and the priority of controlling the midpoint voltage and suppressing common-mode resonance is determined; the square wave compensation voltage is adjusted according to the priority; the three-phase sinusoidal modulation wave and the square wave after the compensation voltage adjustment are compared, a DPWM common-mode modulation wave is determined, and a DPWM modulation wave is obtained, and the switching tube is controlled according to the DPWM modulation wave. The application can realize the multi-objective optimization control of midpoint voltage balance, common-mode resonance suppression and reduced switching loss.

The application discloses a single-stage multi-port converter DC side current ripple suppression method and device and a storage medium. The method comprises the following steps: obtaining an initial three-phase sinusoidal modulation wave according to three-phase voltage and current on the AC side of the converter; obtaining a battery current control value according to a DC side photovoltaic voltage and current; obtaining an asymmetric carrier according to the DC side photovoltaic voltage and an energy storage battery voltage; obtaining an actual battery current value according to the initial three-phase sinusoidal modulation wave and the asymmetric carrier, and performing iteration according to the error between the actual value and the control value to obtain a zero sequence component when the error is less than an error tolerance; injecting the zero sequence component into the initial three-phase sinusoidal modulation wave to obtain an improved modulation wave; and intersecting the improved modulation wave with the asymmetric carrier to obtain a converter PWM driving signal. The application realizes DC side current ripple suppression and power distribution between the photovoltaic and the energy storage battery through a zero sequence component injection method, and has the characteristics of remarkable ripple suppression effect and low implementation cost.

The application discloses a flicker measurement method based on feature reduction, and steps of the method comprise the following steps: extracting a power grid flicker envelope D(n) by using an improved Teager energy operator with two-point interval; analyzing and processing the obtained envelope D(n) by using a five-term Rife-Vincent window interpolation FFT method to obtain flicker modulation wave feature parameters: amplitude coefficient m i , frequency f i and initial phase angle θ i ; reducing the obtained feature parameters into a sinusoidal modulation signal, removing the amplitude coefficient m i from 4 / π and combining other parameters to reduce the sinusoidal modulation signal into a rectangular modulation signal; taking (1±10%) of the envelope signal D(n) as a threshold, comparing the number of data points of the reduced signal within the threshold, when the number of data points of one group is greater than N / 4, the greater one is the flicker modulation wave signal, and corresponding flicker parameters are output; if the number of data points of both groups is less than N / 4, no flicker occurs. The application provides a discrimination basis for flicker identification, overcomes the problem that a traditional flicker detection algorithm cannot effectively identify a flicker signal and is limited in use, and improves the detection precision of the flicker.

This invention discloses a zero-sequence component injection DPWM modulation method for driving a dual Y-shift 30° six-phase permanent magnet synchronous motor. The method involves superimposing a sinusoidal modulation wave with a zero-sequence component to form a 60° clamping discontinuous modulation wave. The steps include: S1: Obtaining the six-phase voltage modulation wave and its output current; S2: Taking three-phase windings with a 120° phase difference as one group and three-phase windings with a 30° electrical phase difference from the previous group as another group, obtaining the minimum absolute value of the voltage modulation wave and the maximum absolute value of the corresponding output current in each group; S3: Calculating the injected zero-sequence component in each group; S4: Superimposing the zero-sequence component onto the corresponding voltage modulation wave to obtain a DPWM modulation wave that adaptively clamps the maximum conduction current. This invention determines the optimal clamping region by detecting the inverter output current and reference voltage, reducing system switching losses. The zero-sequence component injection method avoids complex vector calculations, demonstrating significant application value.

This invention discloses a single-stage self-equalizing IIOS converter for distributed photovoltaic MVDC aggregation. The invention comprises N sub-modules, each a three-port structure integrating interleaved parallel Boost units and hybrid full-bridge LLC resonant units. The former implements MPPT (Multi-Level Testing) for the distributed photovoltaic array, while the latter provides isolated voltage boost. Each sub-module's first port connects to an independent photovoltaic array, its second port is connected in parallel to a low-voltage DC bus, and its third port is connected in series to a medium-voltage DC bus. A control method is also provided based on this converter. By employing sinusoidal modulation with consistent primary and secondary drive logic, the hybrid full-bridge LLC resonant unit operates in DC transformer mode, with a constant sinusoidal resonant current. Furthermore, the second ports of each sub-module are directly connected in parallel, thus enabling self-equalizing output voltage among the sub-modules. This invention only requires sampling the output voltage and current of each distributed photovoltaic array to achieve MPPT for each sub-module and self-equalizing output voltage among sub-modules, eliminating the need for sampling the voltage at the third port or additional voltage equalization circuitry.