Nonlinear load modeling for analysis of non-sinusoidal conditions in electrical networks based on measurements of harmonic parameters

Non-sinusoidal conditions in electrical networks need to be calculated for their control and development of technical measures to maintain harmonic parameters according to the requirements of regulatory documents. These calculations are impossible without electrical network and nonlinear load models that adequately reflect them in computational programs. Nonlinear load models have been developed for a long time. Some studies present general modeling principles and models of various nonlinear devices. Others consider some nonlinear devices as equivalent nonlinear loads connected to low and medium voltage networks. A whole host of high-power nonlinear electrical equipment is connected to high voltage networks. Modeling nonlinear loads connected to these networks is a problem. Research of measured parameters of harmonic conditions in electrical networks has shown that they are random values. The probabilistic nature is determined by the network configuration, a range of network components, the number of nonlinear loads, wave and frequency properties of the network, harmonic source phase currents, voltage at terminals of nonlinear electrical equipment, changes in operating conditions and load power, and many other factors. Nonlinear loads can only be modeled based on the measurements of parameters of harmonic conditions due to their unpredictability. The paper presents an overview of existing methods for modeling nonlinear loads, a methodological approach to modeling nonlinear loads based on measured parameters, an algorithm for modeling harmonics of active and reactive currents, a computational program algorithm designed to identify distribution functions of measured current harmonics, and modeling results for current harmonics of railway transformers supplying power to electric locomotives.

Full-color enhanced second harmonic generation using rainbow trapping in ultrathin hyperbolic metamaterials

Metasurfaces have provided a promising approach to enhance the nonlinearity at subwavelength scale, but usually suffer from a narrow bandwidth as imposed by sharp resonant features. Here, we counterintuitively report a broadband, enhanced second-harmonic generation, in nanopatterned hyperbolic metamaterials. The nanopatterning allows the direct access of the mode with large momentum, rendering the rainbow light trapping, i.e. slow light in a broad frequency, and thus enhancing the local field intensity for boosted nonlinear light-matter interactions. For a proof-of-concept demonstration, we fabricated a nanostructured Au/ZnO multilayer, and enhanced second harmonic generation can be observed within the visible wavelength range (400-650 nm). The enhancement factor is over 50 within the wavelength range of 470-650 nm, and a maximum conversion efficiency of 1.13×10−6 is obtained with a pump power of only 8.80 mW. Our results herein offer an effective and robust approach towards the broadband metasurface-based nonlinear devices for various important technologies.

Energy-participation quantization of Josephson circuits

Superconducting microwave circuits incorporating nonlinear devices, such as Josephson junctions, are a leading platform for emerging quantum technologies. Increasing circuit complexity further requires efficient methods for the calculation and optimization of the spectrum, nonlinear interactions, and dissipation in multi-mode distributed quantum circuits. Here we present a method based on the energy-participation ratio (EPR) of a dissipative or nonlinear element in an electromagnetic mode. The EPR, a number between zero and one, quantifies how much of the mode energy is stored in each element. The EPRs obey universal constraints and are calculated from one electromagnetic-eigenmode simulation. They lead directly to the system quantum Hamiltonian and dissipative parameters. The method provides an intuitive and simple-to-use tool to quantize multi-junction circuits. We experimentally tested this method on a variety of Josephson circuits and demonstrated agreement within several percents for nonlinear couplings and modal Hamiltonian parameters, spanning five orders of magnitude in energy, across a dozen samples.

Behavioral Modeling of Memristor-Based Rectifier Bridge

In electrical engineering, radio engineering, robotics, computing, control systems, etc., a lot of nonlinear devices are synthesized on the basis of a nanoelement named memristor that possesses a number of useful properties, such as passivity, nonlinearity, high variability of parameters, nonvolatility, compactness. The efficiency of this electric element has led to the emergence of many memristor technologies based on different physical principles and, as a result, to the occurrence of different mathematical models describing these principles. A general approach to the modeling of memristive devices is represented. The essence is to construct a behavioral model that approximates nonlinear mapping of the input signal set into the output signal set. The polynomials of split signals, which are adaptive to the class of input signals, are used. This adaptation leads to the model’s simplification important in practice. Multi-dimensional polynomials of split signals are built for the rectifier bridge at harmonic input signals. The modeling error is estimated in the mean-square norm. It is shown that the accuracy of the modeling is increased in the case of using the piecewise polynomial with split signals.

Simulation of a Nonlinear Frequency Multiplier using the FDTD Technique

Nonlinear circuits are a key component in RF transceivers. Efficiency and power requirements for 5G communication are creating new challenges in simulation and modeling of nonlinear devices. An application of the finite-difference time-domain (FDTD) method to nonlinear circuits comprising diodes is demonstrated. A frequency multiplier is constructed from a diode and a low-pass filter. The diode is simulated in the context of this circuit to demonstrate the formation of harmonics.

Supercontinuum generation in dispersion engineered AlGaAs-on-insulator waveguides

The effect of engineering the dispersion of AlGaAs-on-insulator (AlGaAs-OI) waveguides on supercontinuum generation is investigated at telecom wavelengths. The pronounced effect the waveguide width has on the nonlinear dynamics governing the supercontinua is systematically analyzed and the coherence of the spectra verified with numerical simulations. Using dispersion engineered AlGaAs-OI waveguides, broadband supercontinua were readily obtained for pulse energies of $$\sim \text {3 pJ}$$ ∼ 3 pJ and a device length of only 3 mm. The results presented here, further understanding of the design and fabrication of this novel platform and describe the soliton and dispersive wave dynamics responsible for supercontinuum generation. This study showcases the potential of AlGaAs-OI for exploring fundamental physics and realizing highly efficient, compact, nonlinear devices.

Selection of Features Based on Electric Power Quantities for Non-Intrusive Load Monitoring

Non-intrusive load monitoring (NILM) is a process of determining the operating states and the energy consumption of single electric devices using a single energy meter providing aggregate load measurements. Due to the large spread of power electronic-based and nonlinear devices connected to the network, the time signals of both voltage and current are typically non-sinusoidal. The effectiveness of a NILM algorithm strongly depends on determining a set of discriminative features. In this paper, voltage and current signals were combined to define, according to the definitions provided in Standard IEEE 1459, different power quantities, that can be used to distinguish different types of appliance. Multi-layer perceptron (MLP) classifiers were trained to solve the appliance detection problem as a multi-class event classification problem, varying the electric features in input. This allowed to select an optimal set of features guarantying good classification performance in identifying typical electric loads.

Nonlinear detour phase holography

Nonlinear photonic crystals are capable of highly-efficient nonlinear wavefront manipulation, providing a promising platform for compact and large-scale integrated nonlinear devices. However, the current nonlinear encoding methods for nonlinear photonic...

Solar Cells, Thermophotovoltaics, and Nonlinear Devices Based on Quantum Wells

This chapter describes the basic principles behind the solar-cell operation using both an empirical picture and fundamental thermodynamic relationships. It considers how semiconductor materials are selected for use in solar cells and why materials with different gaps need to be stacked to improve the conversion efficiency. It also discusses advanced solar-cell concepts such as quantum-well, intermediate-band, and hot-carrier solar cells. Thermophotovoltaic devices that are similar to solar cells, but designed for emission peaks at much lower effective temperatures than the surface of the sun (and narrower gaps), are also discussed, and multistage thermophotovoltaic devices are described in detail. The chapter concludes by presenting the basic nonlinear physics of intersubband transitions in quantum wells, and how to take advantage of these physical principles for second-harmonic generation and difference-frequency mixing. The important application of generating THz emission from mid-IR quantum cascade lasers using difference-frequency mixing is emphasized.