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In the last decade, harmonic analysis of Japanese middle voltage (MV) customer and low voltage (LV) customer has been done, the distribution of the fifth harmonic current can be classified MV customer's single phase load, LV customer's three phase and single phase load named group A and MV three phase load named group B, and the amplitude per load kW has been investigated from sum of each current...
The convex relaxation approaches for power system state estimation (PSSE) offer robust alternatives to the conventional PSSE algorithms, by avoiding local optima and providing guaranteed convergence, critical especially when the states deviate significantly from the nominal conditions. On the other hand, the associated semidefinite programming problem may be computationally demanding. In this work,...
We developed a constrained state estimation method that clarifies the range of the feeder voltage in an unobservable distribution network in which the number of telemetric sensors is smaller than the number of state variables to be estimated. Instead of using pseudo-measurements, whose reliability is affected by unexpected power flow conditions, the method uses constant nominal boundaries as inequality...
This study investigates the impacts of Plug-in Electric Vehicles (PEV) on end-service local distribution feeders. The results show that the PEV charging depresses the feeder voltages significantly and increase the feeder power losses up to 16.7 times. The voltage stress is more profound at the end of the feeder or at the point where many PEV are connected. The most noticeable impact of the PEV is...
A regime shift occurs when a dynamical system's state shifts from a nominal equilibrium to an alternative equilibrium. This concept is often used to describe the collapse of ecological systems, but it also appears in many engineering systems; most notably in the voltage collapse of power systems. This paper uses an information theoretic index known as the Fisher Information (FI) as a real-time statistical...
Travelling wave based line protection has the advantage in fast response speed, however, its performance in practice is still unsatisfactory due to the high frequency limitation characteristic of coupling capacitor voltage transformer (CCVT). This paper presents a directional comparison protection principle based on travelling wave, which utilizes the polarities of high frequency current and low frequency...
Transmission line parameter modeling and PMU measurement calibration are important research topics in power system engineering. State estimation is widely used to estimate voltage with assumption of “accurate” system parameters. Various methods have also been proposed to estimate line parameters based on PMU measurements. However, neither system parameters nor system measurements are reliable enough...
Results from two practical and fast methods to estimate systems' Maximum Loading Point (MLP) using Phasor Measurement Units (PMUs) are used in this paper as initial values for a robust and very efficient method that takes advantage of the geometric characteristics of the maximum loading hyperplane and uses the load flow with step size optimization (LFSSO) technique to estimate the system's proximity...
This paper proposes a Support Vector Machine (SVM) based methodology to classify the loads into various classes based on the load responses, following a disturbance and other information available from the feeder. The classification is performed after a large disturbance, and the model parameters are estimated by using a variable projection based efficient optimization algorithm. For small disturbances...
Continued deployment of renewable and distributed energy resources is fundamentally changing the way that electric distribution systems are controlled and operated; more sophisticated active system control and greater situational awareness are needed. Real-time measurements and distribution system state estimation (DSSE) techniques enable more sophisticated system control and, when combined with visualization...
A hybrid simulation/measurement-based framework for online dynamic security assessment (DSA) is proposed in this work. It combines the strengths and features of simulation-based and measurement-based approaches to develop a tool that integrates the results and provides real-time situational awareness on available operating margins against major stability problems. High performance computing capability...
Monitoring the long term voltage stability of the power grid is necessary to ensure its secure operation. In this paper, a voltage stability index that is linear with the power demand, called the M-index, based only on angles is proposed. The linearity of the M-index can be utilized to estimate the load margin directly. The linearity of the M-index is proved for the two-bus system and a method to...
This study extends previous work on the appropriate definition of reactive power in the presence of harmonic voltages and currents to the three-phase, unbalanced case. As in the single phase case, it is advocated that reactive power be defined in terms of the fundamental components (60/50 Hz) of the current and the phase angle separating them. It is demonstrated that common metering techniques for...
Synchrophasor measurements, as obtained from phasor measurement units (PMUs), of power system frequency, voltages, and currents provide several important capabilities beyond the traditional 4-second substation data used in the energy management systems of control centers. These properties include precise time tagging of the measured data using GPS signals, high sampling rate at 30/50/60 samples per...
Voltage instability may be predicted by the Thevenin equivalent based approach using only local measurements taken at the monitored buses. This paper focuses on reliable estimation of Thevenin parameters from measurements, which are crucial in judging voltage stability. Two parameter estimation methods (least squares and Kalman filter) and a proposed new hybrid method are tested on the NPCC 140-bus...
With the growth of inter-utilities power exchanges and the spread of new and rapid monitoring technologies, the efficient modeling of external networks becomes crucial for a reliable and secure operation. This paper investigates the problem of bad data in interconnected networks when real-time evaluated external equivalents are attached. It is shown that, under this scenario, regular techniques of...
In this paper a hybrid method is proposed to reduce the impact of islanding in the presence of Distributed Generation (DG). The issue of islanding is critical in the distribution system as the non- detection of islanding may lead to the collapse of the system. The islanding is prominent due to the increased penetration levels of DG in the network. In the proposed method, first the placement of DG...
This paper presents a direct power control strategy for a doubly fed induction generator by using an artificial neural network controller with the multilayer perceptron structure. This controller generates the direct- and quadrature-axis rotor voltage signals from both the stator current and voltage that are measured by the Hall sensors. The input variables of the control system are the rotor speed,...
Cyber security provided by robust power systems state estimation methods is evaluated. Tools and estimators developed in robust statistics theory are exploited. The idea consists in considering redundant robust estimation techniques with different robustness properties to improve the overall detection of attacks and synthesizing a decision making process to determine whether an attack is present or...
This paper presents simulation results from a real case study of a medium scale photovoltaic (PV) system integrated into an 11kV distribution network. The investigated system is a semi-rural part of an existing distribution network in Queensland, Australia with planned investments of more than 3MWp PV installation. The studied case is very interesting because of planned high penetration of PV power...
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