Topic
Frequency response
About: Frequency response is a research topic. Over the lifetime, 25705 publications have been published within this topic receiving 332249 citations.
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TL;DR: In this article, a recursive algorithm is derived to compute the generalized frequency response functions for a large class of non-linear integro-differential equations and applications to Duffing's equation and a modified Van der Pol model are discussed.
Abstract: A recursive algorithm is derived to compute the generalized frequency response functions for a large class of non-linear integro-differential equations. Applications to Duffing's equation and a modified Van der Pol model are discussed.
174 citations
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15 Mar 2000TL;DR: In this article, the frequency-domain channel gains were computed by compiling a set of estimated channel gains as a function of pilot sequences, a setof analytical channel gains variables, and the set of weighting coefficients variables.
Abstract: The invention computes frequency-domain channel gains by compiling a set of estimated channel gains as a function of pilot sequences, a set of analytical channel gains variables, and a set of weighting coefficients variables. A plurality of weighting coefficients are computed as a function of time and frequency correlation functions, a noise correlation matrix, and pilot sequences. A weighting matrix is computed from the weighting coefficients. After receiving a training sequence from at least one transmitter, a received data matrix is computed from the training sequence. The weighting matrix and the received data matrix are used to compute the frequency-domain channel gains. The invention also provides a method for reducing the computational complexity of estimating the time and frequency response of at least one desired signal received by at least one antenna. Also, the time and frequency response of at least one desired signal received by at least one antenna can be both interpolated and predicted with the present invention.
173 citations
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TL;DR: In this paper, a coordinated control scheme was proposed to allow VSC-HVdc link to contribute to the system frequency regulation by adjusting its dc-link voltage. But, due to the decoupling of VSC and signal transmission delay, offshore wind farms may not be able to respond to the onshore grid frequency excursion in time and, consequently, the stability and security of the power system will be put at risk, especially for those with high wind penetration.
Abstract: Modern large wind farms are required to provide frequency regulation service like conventional synchronous generation units. The frequency support capability of modern wind farms has been widely investigated and implemented. Remotely located large offshore wind farms are probably connected to the onshore system grid through voltage-source converter-based–high voltage direct current (VSC-HVdc) transmission systems. Due to the decoupling of VSC-HVdc and signal transmission delay, offshore wind farms may not be able to respond to the onshore grid frequency excursion in time and, consequently, the stability and security of the power system will be put at risk, especially for those with high wind penetration. This paper proposes a coordinated control scheme to allow VSC-HVdc link to contribute to the system frequency regulation by adjusting its dc-link voltage. By means of this approach, the dc capacitors of VSC-HVdc are controlled to absorb or release energy so as to provide frequency support. To further enhance the system frequency response, the frequency support from VSC-HVdc is also finely coordinated with that from offshore wind farm according to the latency of offshore wind farm responding to onshore grid frequency excursion. The control scheme is evaluated for both underfrequency and overfrequency events, and results are presented to demonstrate its effectiveness.
173 citations
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TL;DR: The most significant obstacles to the attainment of quantum-noise limited detection at higher speeds are seen to be the requirement of uniform frequency response from electronic components and the local oscillator laser power requirement, which increases as the square of the bit rate.
Abstract: Recent theoretical work on coherent optical detection systems is reviewed and experimental results in high-speed coherent transmission are summarized. The theoretical advantages and limitations of the various modulation and detection formats are discussed and experimental progress towards the implementation of these systems is reviewed. The most significant obstacles to the attainment of quantum-noise limited detection at higher speeds are seen to be the requirement of uniform frequency response from electronic components and the local oscillator laser power requirement, which increases as the square of the bit rate. To make full use of the single-mode fiber bandwidth, frequency-division multiplexing of many moderate-rate channels is a very promising technique for local systems. For long-distance applications, frequency multiplexing is still possible but is limited by the need for optical amplifiers or wavelength-selective multiplexers. >
171 citations
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TL;DR: In this paper, a variable coefficient combined virtual inertia and primary frequency control strategy for doubly fed induction generators (DFIG) in coordination with diesel generator to participate in wind/photovoltaic/diesel microgrid frequency regulation was proposed.
Abstract: This paper proposes a variable coefficient combined virtual inertia and primary frequency control strategy for doubly fed induction generators (DFIG) in coordination with diesel generator to participate in wind/photovoltaic/diesel microgrid frequency regulation. The frequency response characteristic is analyzed under different wind speeds with corresponding inertia control parameters different. A 10% wind power margin is preserved through overspeed control and pitch angle control to offset the decrease of wind output power after temporary extra power surge, and provide a permanent frequency support for microgrids. The influence of droop control gain setting is also illustrated under different wind velocities. By continuously adjusting the control parameters according to wind speed variation, a variable coefficient method is realized. The method can guarantee an efficient implementation of this strategy in time-varying conditions. Finally, this coordinated control strategy is tested in a storage-independent microgrid with solar, wind, and diesel generators.
171 citations