Search results for "Frequency control"
showing 10 items of 25 documents
A discrete pulse group control-based series resonant inverter with complete ZCS-assisted inductors for consumer high frequency IH application
2017
This paper presents a pulse density modulated (PDM) voltage source high frequency series load resonant soft switching inverter (SRI) for the HF induction heated fixing roller in the energy saving copy and printing machines. The proposed simple and high efficiency SRI based on PDM control operation can achieve complete zero current soft switching for wide output power regulation ranges. In this work, its transient and steady-state operating principle are described and analyzed on the basis of high frequency PDM. The operating performances as power conversion efficiency, power losses analysis and temperature rising characteristics of this SRI are demonstrated and discussed through experimenta…
Study and design of a controlled oscillator for an embedded system to measure the complex impedance of PEM fuel cell »
2017
We present in this paper the study and the design of a voltage controlled oscillator (VCO) for an embedded system to diagnose the PEM fuel cell. Some problems related to fuel cells used in the electric vehicle field are the management of its efficiency and the lifetime of its membranes. To do this, the diagnosis using measuring the complex impedance is an important phase. It is based on the injection of a perturbation signal at the output of the PEM fuel cell, then we observe its behavior by measuring its impedance. The used measurement method is the electrochemical impedance spectroscopy (EIS) using the load modulation technique, which is implemented in an embedded measurement system based…
Optimal signal selection of wide area damping controller considering time delay in multi-machine power system
2015
This paper presents a validation of selection process for selecting the most effective stabilizing signal to improve damping of inter area oscillations in a multi-machine power system by different signal selection methods. This paper also deals with wide area damping controller scheme compensating time latency of feedback signal in order to damp low frequency inter area oscillations in large power system. Pade approximation to time delay is used with controller synthesis. Eigenvector based coherent machine identification method has been adapted in this research for coherent area identification in multi-machine power system. The selected control signal is tested on the 4 machine 11 bus syste…
Improved primary regulation for minimum energy losses in islanded microgrids
2017
In this paper, an improved primary regulation is proposed for grid forming units supplying islanded microgrids. A minimum losses Optimal Power Flow is run off-line to devise the operating set points composing the primary regulation curve. In this way, after load perturbations, generators can reach an optimized operating point for a given and unique minimum losses energy flows distribution. The idea is to skip the hierarchical control architecture and provide a feasible and optimized operating point. A case study over 24 hours shows the effectiveness of this new approach as well as the improved operation quality of the system.
Influence of the AC voltage frequency on the oscillation trajectory and path length of particles inside a planar–type electric curtain
2015
Abstract Experimental investigations of the average path length of oscillating dust particles inside a planar –type electric curtain (PTEC) are presented as a function of the frequency of the AC voltage. The frequency was adjusted within the range of 10–300 Hz. The oscillation paths of feldspar particles of diameter 40–60 μm inside a small cloud were recorded photographically. The main purpose of this investigation was to study the changes in average path length as a function of the supply voltage frequency. These results can be used to improve the precipitation and separation processes for charged dust particles inside a PTEC.
Frequency dynamics of power systems with temporally distributed disturbances
2021
Abstract The frequency dynamics and stability of power systems is essentially affected by nature and characteristics of the disturbances occurring in the system. Conventionally, frequency transients are examined assuming a single disturbance applied at a given time. However, actual incidents in the power systems can be generally composed of a temporal sequence of events, and thus characterized by multiple power imbalances of different magnitudes and time offsets. The consideration of the effects of the temporal distribution of power imbalances is important for two main reasons: the impact on the frequency dynamics of the system in terms of frequency metrics such as minimum instantaneous fre…
Frequency Dynamics in Fully Non-Synchronous Electrical Grids: A Case Study of an Existing Island
2022
The operation of a power system with 100% converter-interfaced generation poses several questions and challenges regarding various aspects of the design and the control of the system. Existing literature on the integration of renewable energy sources in isolated systems mainly focuses on energy aspects or steady-state issues, and only a few studies examine the dynamic issues of autonomous networks operated with fully non-synchronous generation. A lack of research can be found in particular in the determination of the required amount of grid-forming power, the selection of the number and rated power of the units which should implement the grid-forming controls, and the relative locations of …
A Comparison between RMS and EMT Grid-Forming Implementations in MATLAB/Simscape for Smart Grids Dynamics
2022
The article presents a comparison between phasor RMS and EMT models for grid-forming converters. The specific aspects related to the implementation in Simscape Electrical of MATLAB/Simulink are discussed for both RMS and EMT time-domains. The comparison between the different implementations is performed with the simulation of two widely studied grid-forming schemes, the virtual synchronous machine and the power-synchronization control. The simulation-based comparison examines transient phenomena with different characteristics and time scales, including frequency transients, phase jumps and short-circuit events. Specific indications regarding limitations and suitability of grid-forming model…
A Study of Power-Frequency Dynamics in Isolated Power Networks with 100% Converter-Interfaced Generation
2020
The operation of a system with 100% converter-interfaced generation poses several questions and challenges regarding various aspects of the dynamic characteristics of the system. The effects related to the power-frequency control are among the most relevant issues which need to be investigated. The paper takes into examination the case of an existing isolated power network of a geographical island assuming a completely converter-interfaced generation. The factors playing a fundamental role in the assessment of which sources should be designated to be grid-forming are identified with a small signal model formulation of a generic multiple oscillators system. Simulations and analysis performed…
An original control strategy of storage systems for the frequency stability of autonomous grids with renewable power generation
2021
This work examines the operation of the autonomous power system of a geographical island assuming the integration of significant generation shares from renewable energy sources and the installation of the required storage systems. The frequency stability of the system is investigated considering different operating conditions, in terms of load demand and renewable power generation. The main focus of the work is an original control strategy specifically designed for power converters interfacing storage units to the grid. The proposed strategy is based on an extended frequency droop control, which selects specific droop settings depending on the operating mode—charge or discharge—of the stora…