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The circuit parameters involving stray load loss and harmonic torques of high speed induction motors fed by inverters are determined by both finite element method and experiments, respectively. In the finite element method, the parameters are directly determined from the electromagnetic field distribution of the motors under load conditions. On the other hand, in the experiment, the parameters are...
Decentralized methods for computing optimal real and reactive power setpoints for residential photovoltaic (PV) inverters are developed in this paper. It is known that conventional PV inverter controllers, which are designed to extract maximum power at unity power factor, cannot address secondary performance objectives such as voltage regulation and network loss minimization. Optimal power flow techniques...
Grid integration of distributed energy resources (DERs) is increasing rapidly. Furthermore, smart grid technologies are making the grid more bi-directional providing opportunities to consumers to supply power back to the grid. Energy storage technologies like battery and ultracapacitor (UCAP) can be integrated through grid tied-inverters to support variable DERs such as solar and wind. In these cases,...
This paper provides recommendations for volt-VAr and voltage ride-through needs from distributed energy resources (DERs) to contain fault induced delayed voltage recoveries (FIDVRs) events and help stabilize the grid. FIDVR events can potentially cause chain reactions and destabilize the grid. Additionally, it will provide typical residential air conditioner (RAC) unit performance during voltage transients...
Large-scale integration of distributed generations (DGs) may degrade the stability of the power distribution system. This paper proposes a control method to improve the system stability of grid-connected inverter-based distributed generation (DG) systems. The proposed method is to add a stabilizer inside the inverter interface controller of a DG unit to supply auxiliary current reference signal for...
The voltage surge due to fast switching insulated gate bipolar transistor (IGBT) and resonance can introduce voltage surge and distort the inverter output voltage/current waveforms. This may cause premature failure to sensitive loads and introduce harmonics in the grid voltage/current waveforms. This paper investigates the impacts of voltage surge and resonance on power electronic converter-fed grid-connected...
A study was performed to determine the impact of single-phase photovoltaic (PV) generation on distribution laterals at high penetration levels. The study addresses concerns about the impact on load balance, fault current balance, power quality and islanding conditions. Methods and tools used for this study, which are appropriate for general analysis of PV on single-phase laterals, are discussed. Guidelines...
In the near future, transmission grids will include an increasing share of directly connected voltage source converters. These systems should be able to support the utility grid autonomously. The present paper reviews the most popular approaches to address the challenge of proper load sharing amongst multiple parallel inverters applied to the utility grid case. Originally developed for Microgrid or...
Currently, the standards used to calculate the short circuit (SC) current ignore the contribution of DC systems to the SC current when short-circuit faults occur in an AC systems. With the rapid development of High Voltage Direct Current systems (HVDC), it has become important to determine whether the contribution of the HVDC system can be ignored when calculating the SC current. This study investigates...
Solar is the fastest growing source of renewable electricity in the U.S. The anticipated PV proliferation brings integration challenges on system volt/var performance at the utility scale. One of the greatest challenges is to maintain desirable feeder voltages in utility distribution networks. The intermittent PV generation causes more frequent operation of volt/var control (VVC) devices to alleviate...
Rooftop Solar Photovoltaic (PV) systems installations have been increasing in the Low voltage distribution networks due to decreased cost and government incentives (e.g. feed-in-tariff). The high penetration of these PV systems can inject harmonics into the network causing problems to sensitive loads and controllers of loads. Due to the solar irradiation dependency, the power generation is variable...
New winding configurations for mutually coupled salient pole switched reluctance machines (MCSRMs) have been proposed that enables the application of three-phase standard inverters for variable speed drives. The proposed topologies comprise phase windings carrying balanced three phase currents from standard inverters along with DC excitation coils in the stator slots. Both concentrated and distributed...
The traveling wave protection performance of traditional DC transmission line can be influenced by fault conditions, so this paper proposes a traveling wave based directional pilot protection method. Analysis shows, for an internal DC line fault, that the forward traveling wave is less than the backward traveling wave at two ends of the proposed line within a short time of post-fault; but in the case...
Using the characteristic difference of transient energy, a transient energy based directional unit protection is proposed. Assuming the positive direction of current is from DC busbar to DC line, for an internal line fault, the detected transient energies on both ends of the line are all negative, which denote the positive direction fault. When an external fault occurs, the transient energy on one...
Proportionate sharing of load changes in a microgrid without communication among the generators is a difficult problem. In this paper an exact power sharing algorithm is developed that uses an optimization-based technique to minimize the exchange of state information among the generators. To demonstrate the application of the developed framework we present simulation results for a system constructed...
Line-commutated thyristor-controlled rectifiers are extensively used in industrial applications, where controllable dc voltage is required. The simulation software developments trend is towards proposing new packages for power electronics components that are computationally more efficient and still accurate. One of the most widely-used modeling techniques is known as parametric average value modeling...
In this paper, an I–V tracer which operates autonomously, with no need to be disconnected from its load, will be discussed. The current state of I–V tracers commercially available will be discussed and motivation will be provided for the online autonomous I–V tracer. Design of such an I–V tracer using the single-ended primary inductance converter (SEPIC) will be discussed, and simulation results of...
This paper presents an online clustering modeling method for large-scale photovoltaic (PV) power plants. The proposed method utilizes the defined feature distance of inverter control parameters as the clustering index to derive the equivalent PV plant model. Based on the offline parameter database and the online matching method, the feature distance weighted by online parameter sensitivity is obtained...
This paper presents a battery-based storage (BBS) for wind generator (WG) system. The BBS is composed by an Asymmetric Cascaded H-Bridge Multilevel Inverter (ACMI) with staircase modulation. The proposed structure is connected in parallel to the whole WG system. Such connection plus the use of the ACMI allow a reduction in the power losses, compared to the commonly found storages connected where the...
Reactive power compensation is used by utilities to ensure customer voltages are within pre-defined tolerances and reduce system resistive losses. While much attention has been paid to model-based control algorithms for reactive power support and Volt Var Optimization (VVO), these strategies typically require relatively large communications capabilities and accurate models. In this work, a non-model-based...
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