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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...
Modernized grid needs ancillary service as a variety of distributed energy resources are connected. Vehicle-to-grid (V2G) application is one of promising distributed energy resources, which enables to transfer bidirectional power between batteries of plug-in electric vehicle and the grid as well as offer ancillary service to the grid. Benefits of V2G application are voltage and frequency regulation,...
This paper proposes solutions to the problem of voltage sags caused by distributed generators anti-islanding protection. This is a recently identified power-quality (PQ) concern resulting from the increasing penetration of distributed generators into distribution networks. This problem has been previously investigated by the authors and it was revealed that it can seriously affect PQ indices as well...
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 proposes a sliding mode controller for a permanent-magnet synchronous generator wind turbine system to satisfy low voltage ride through requirement. The generator-side converter regulates the DC link voltage instead of grid-side converter. The generator-side controller is designed using the sliding mode control considering the nonlinear relationship between the generator power and the dc-link...
In multi-bus islanded microgrids, the power quality requirements for different areas and buses can be different. This paper proposes a hierarchical control to realize optimal unbalance compensation for satisfying the power quality requirements in different areas. Primary and secondary controllers are applied to realize unbalance compensation for critical bus (CB) and at the same time, to make distributed...
with high penetration of renewable energy in the distribution networks, two challenges are emerging. One is how power grid maintains power quality in condition that the target of investing renewable energy is to gain maximum financial returns. The other is how inverter proactively supports voltage and frequency to sustain network stability. To address this problem, by extending single price curve...
Sustained oscillations observed in power systems can damage equipment, degrade the power quality and increase the risks of cascading blackouts. There are several mechanisms that can give rise to oscillations, each requiring different countermeasure to suppress or eliminate the oscillation. This work develops mathematical framework for analysis of sustained oscillations and identifies statistical signatures...
In this study, we investigate the impact of the dynamic behavior of photovoltaic (PV) power generation systems on short-term voltage stability of the transmission system. First, the impact of the fault ride-through capability of a PV model is studied by setting several recovery speeds of the active current output when the operation of the PV system is interrupted because of a voltage sag. The results...
A distributed secondary voltage controller is designed for droop-controlled microgrids in power distribution networks to improve power quality. Microgrids are typically managed by the droop control mechanism that ensures stability but does not guarantee power quality of voltage magnitude. To solve this power quality problem, the proposed distributed secondary voltage controller maintains a constant...
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...
Transmission line ideal phasing was used to mitigate a distribution voltage imbalance problem. Customers in the common service area of an electrical substation had been reporting power quality problems related to voltage imbalance. Through investigation, an unexpected pattern of seasonal voltage imbalance variation was found to be consistent with transmission network power flow patterns. Linear regression...
This paper presents the implementation of power quality (PQ) analysis platform that can access different venders' PQ meter data being translated to Power Quality Data Interchange Format (PQDIF) files and view the data through a LabVIEW-based graphical user interface. The implemented platform also can manage the retrieved PQ data in a customized database. Performance tests show that the implemented...
This paper presents a novel algorithm, named adaptive morphological lifting wavelet (AMLW). It is the first time to be applied for the detection of power quality disturbances (PQD). AMLW is a nonlinear wavelet transform which is based on morphological operation and the lifting scheme. The adaptability of AMLW lies in that the algorithm can select between two filters, the morphological gradient filter...
In this paper, an approach to evaluate the occurrence of flicker induced by electromechanical oscillations is proposed. This approach employs the extended participation factors (EPF) to statistically quantify the presence of electromechanical modes in the dynamics of the terminal voltage of a distributed synchronous generator. Once the results obtained by the EPF indicate a high probability for the...
Identification of recloser and fuse operations is an important task in a distribution system to help evaluate overcurrent coordination, detect incorrect relay settings, and estimate fault location. The main purpose of this paper is to develop rule-based screening module that can identify the protective device clearing the short-circuit fault. Necessary features that characterize fault clearing devices...
This paper presents a study related to a possible topology of a novelty detector to be applied in Power Systems applications. With the new scenario of Smart Grids a novelty detector should not be focused in the typical PQ disturbances but in any new deviation/variation that may happen in the signal. In this way, the traditional methodology of novelty detection, that is based on a training stage is...
This paper proposes an algorithm for three-phase harmonic state estimation for power distribution networks, by using the Singular Value Decomposition (SVD) technique. As non-linear loads are distributed throughout the network, state estimation-based tools become relevant to assess the impacts of the harmonics on the grid. Moreover, the SVD technique is able to estimate the state with a reduced number...
Virtual Synchronous Generator (VSG) can facilitate friendly integration of distributed generations. However, during voltage sags, traditional VSG control cannot provide reactive power support, or limit the peak current. To solve these problems, a general control strategy of VSG under voltage sags is proposed. First, the topology of VSG and its control scheme are described to formulate the key problem...
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