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This paper provides 240 V ac air conditioning load data collected during summer peak heat load in Austin, TX. Air conditioning load profiles are studied in high, one-minute data resolution over the course of a typical, representative work-week where both electrical power and power factor are displayed. While THDv is 3.35%, TDDI is more concerning at 11.17% due to odd harmonics out to the 9th order...
In this paper, the outlier issues in harmonic source location using parameter identification method are introduced and discussed. The theoretical models and outlier issues in parameter identification method are firstly introduced. Zero-crossing criteria of denominators in parameter solving processes are then obtained through theoretical derivations. Finally, the applicability of equivalent impedance...
With the increasing use of non-linear loads, the harmonic problems have become of great concerns. One of the solutions to harmonics is the application of shunt active power filters (APFs). The APF reference compensation strategy proposed in this paper adopts the backpropagation neural network (BPNN) to train the control algorithm and calculate the reference compensation current under steady state...
This paper proposes a new approach to estimate the non-constant nonlinear frequency of a power system electro-mechanical oscillation mode by deriving an approximate, analytic expression about the oscillation amplitude-frequency dependency. The approach uses the Harmonic Balance Method (HBM) together with one of three representative function approximation techniques, i.e. Taylor Expansion (TE), Chebyshev...
This paper presents a method to estimate the loads on a distribution feeder in real-time with limited real-time customer load data from AMI. The method consists of two modules: a load clustering module and a load modeling module. Load clustering helps to identify customer loads with similar profiles thereby helping to determine the subset of customers that need to be monitored in real-time. The load...
High-frequency harmonics produced by modern switched mode power supplies have attracted attention in research community recently. To clarify if these harmonics are indeed a potential power quality concern, a research work has been conducted to understand the propagation characteristics of the harmonics. Through field measurements and computer simulations, the research found that the high-frequency...
This paper presents an analytical method to realize even order harmonic elimination in flux-switching permanent magnet machines. The proposed method enables the calculation of total offset angle of flux linkages, taking into account an offset angle of stator slot and rotor poles. The 6-slot, 12-slot, and dual structure flux-switching permanent magnet machines are analyzed using the proposed method...
It becomes necessary to utilize electromagnetic/ electromechanical hybrid simulator to modern large HVAC and DC power system, where multiple HVDC links feed into concentrated load areas. In this paper, a practical real-time hybrid simulator is proposed. The simulator makes RTDS and external transient program running on a computer link together effectively and smoothly. The entire interface schemes...
The operating region of modular multilevel converter (MMC) is limited by the maximum allowable voltage ripple of cells, which is associated with the arm energy variation. Injecting the controlled second-order harmonic component into the circulating current can reduce energy variation of arm and thus extend the operating region of MMC. Care must be taken, however that the second-order circulating current...
A general condition is derived for the reduction of stator vibrations in multiphase switched-reluctance motors (SRMs) through current regulation in a low-torque and low-speed region. By exploring a wider space of solutions than had previously been examined, optimized solutions are found which simultaneously minimize acoustic noise and vibration and also minimize qualities such as copper loss, peak...
The voltage source converters (VSC) are the key power interfaces between the individual ac grids and dc grids in the hybrid power system. When the ac grid is unbalanced, the grid currents are distorted and the harmonic is induced. Meanwhile, the oscillations in the active and reactive power are also increased,which may damage these interfaces. In order to ensure the safety of the converters and the...
This paper focuses on the modeling of integrated ac-dc backup and generation power systems, which has received increasing attention due to the emergence of microgrids and distributed generations. The conventional shifted-frequency analysis (SFA) type dynamic phasors (DPs) assume a bandpass spectrum of power system signals, and thus are only suitable to model system components wherein the 60Hz fundamental...
This article presents three dynamic linear state space models of Modular Multilevel Converter (MMC) which are suitable for small-signal dynamic studies and controller design. The three models differ by the number of states (two, six and ten) and therefore are suitable for different applications based on the required accuracy. The 2nd and 6th order models ignore dynamics of the second harmonics and...
The paper develops a mathematical model for a modular multilevel converter (MMC) using extended-frequency dynamic phasors. The developed model is capable of capturing both the low- and high-frequency dynamic behavior of the converter depending on the requirements of the study to be performed. The paper shows the mathematical development of the model, its validation against a fully detailed electromagnetic...
This paper shows the modeling process of a DFIG machine with slot harmonics, its back-to-back voltage sourced converter (VSC), their control and the connection to a HVDC station. These models are mutually connected and their harmonic interaction is analyzed. Special attention is given to the slot harmonics of the DFIG machine due to their dependence on the machine speed and the possibility that they...
Application of long EHV XLPE underground cables has divers effects on the transient behavior of transmission grids, mainly due to their large capacitive shunt impedance. Low-order resonance frequencies are one of the features of long c ables that deserve special attention. This paper investigates the resonance behavior of partial cable-based EHV networks by simulating a 380 kV double-circuit mixed...
Traditional monitoring systems for transmission and distribution (T&D) networks are only installed in substations, so there is no real-time and accurate power information available for on-site power quality monitoring and equipment maintenance. This issue increases the fault risk in T&D networks, and degrades the reliability and quality of power supply. Moreover, it is often difficult and...
Classification of power quality (PQ) disturbances has become an important issue due to the increasing of disturbing loads in electric power system and sensitivity to these disturbances. However, there are still some challenges in this issue such as lack of adequate training data to match disturbances with their corresponding types, especially for some multiple disturbances. In this paper, a new semi-supervised...
This paper demonstrates the capability of a hybrid simulation tool that can perform islanding detection studies in distribution networks with photovoltaic (PV) generation systems. The hybrid tool is constructed by interfacing an electromagnetic transient (EMT) tool with the Open Distribution System Simulator (OpenDSS) which is a phasor analysis tool developed by the Electric Power Systems Institute...
With the growing permeability of parallel inverters in the grid, resonance problem has frequently appeared in new energy systems and seriously affected the power quality around the world. Besides, resonance analysis is attracting more and more attention recently. Therefore, resonance problem of the clustered grid-connected photovoltaic (PV) system is urgent to be studied. To solve this problem, this...
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