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Time domain reflectometry (TDR) applied to live cables is hampered by the absence of a clear reflection from the far end. Instead, location of partial discharge (PD) can be extracted from small structures in recorded patterns arising from any impedance variation along the signal propagation channel. This paper explores two approaches for a single-sided PD location system. The first method compares...
This paper presents a mathematical model that presents improvements for the gas microturbines (MT) and fuel cells (FC) in the energy management problem of microgrids. In this problem, the objective is to determine a generation policy that minimizes, over a planning horizon, an objective function subject to economical and technical constraints. We propose a detail modeling for MTs and FCs, where the...
This paper presents fundamental concepts associated with the method of Shifted Frequency Analysis (SFA) for modelling electric circuit transients at frequencies close to the fundamental rated power frequency (50Hz or 60Hz). In a Smart Grids scenario, where the inertia of the generating sources is much less than at the transmission system level, electric transients simulation tools like the Electromagnetic...
This paper presents a novel approach to deal with the synchronization of microgrids to the main grid. It is based on the use of a power electronic device derived from the original concept of the SSSC (Static Synchronous Series Compensator). The proposed scheme considers the connection of this device at the point-of-interconnection (POI) of the microgrid to the low voltage side of the substation transformer...
This work presents an alternative strategy to solve hydrothermal systems operation planning by stochastic dynamic programming. Under the presented approach, the hydroelectric plants are grouped into equivalent subsystems of energy and the expected cost functions are modeled by a piecewise linear approximation, by means of the convex hull algorithm. Also, under this methodology, the problem is solved...
The paper comprises a detailed analysis of the error ranges of two commonly proposed load estimation methods for household loads, based on statistics. Firstly, a household load profile model is built taking individual user preference into account. To analyze the error range, it is divided into system error (representing proportion factors) and random error (representing the diversity of stochastic...
This paper describes an algorithm for the identification of rare events with high severities, potentially leading to blackouts in power systems, and the quantification of the risk a given system state holds. Based on the method of probabilistic load flow, probability density functions of the branch loadings under consideration of the forecast uncertainty are determined. From that branch tripping probabilities...
Solution algorithms for the optimal power flow (OPF) problem are well established for traditional electricity networks. However, there is an increasing need for integrating renewable sources and energy storage into electricity networks. These newer devices have physical characteristics that require modification of standard OPF algorithms. In particular, energy storage devices introduce temporal coupling...
In distribution network planning, network loads are modeled with customer class specific load profiles. These profiles use hourly values of expected power and its standard deviation to represent the probability distribution of hourly load for a certain customer class. This paper demonstrates a method for evaluating network impacts of grid connected small scale distributed photovoltaic (PV) generation...
Monte Carlo (MC) sequential simulation is capable of providing system chronological information. It is a very useful tool for power system reliability analysis and planning, especially for systems involving time-dependent sources. In this paper, a new sequential simulation approach is proposed for reliability evaluation of composite power systems. The main idea is to apply Latin Hypercube sampling...
In this paper, a new concept of serving flexible reliability (FR) is introduced in distribution network level. FR is defined as the ability of a grid to continue servicing the high priority customers in contingency states. Customers' priority is recognized based on their value of service reliability. Regarding this matter, the philosophy of designing a hybrid AC-DC microgrid is introduced with the...
It has been suggested that Optimal Transmission Switching (OTS) may reduce generator dispatch costs by as much as 10%, saving millions of dollars annually. However, this conclusion has been deduced primarily from studies using the DC power flow approximation on two power networks derived from the IEEE 118-bus and RTS-96 cases. This paper is a systematic study of the OTS problem. Various OTS formulations...
In this paper a novel impedance determination method for the phase-to-phase loops is described. This approach promises a better accuracy of the reactance calculation of the faulty loops. Thus, better selectivity and security in operation of the distance element applied for the protection of transmission and distribution lines is guaranteed. Moreover, with this new method the separation of the fault...
The paper is concerned with location of arcing faults on power transmission lines. Presented method makes use of artificial neural networks worked out for various fault types. The investigation is focused on the fault cases with accompanying saturation of current transformers, resulting in significant transformation errors. Fault location is based on asynchronous measurements of voltages and currents...
The submitted paper presents a tester designed for testing the protective relays in work conditions close to the real. The device is a simulator operating in real-time of the phenomena taking place in the modeled part of power system. The paper describes the construction (including hardware and software aspects) and operation principle of designed simulator. The MATLAB/Simulink software has been used...
Advanced multifunctional distance protection Intelligent Electronic Devices (IEDs) are complex systems with a multi-level functional hierarchy. Their integration in modern IEC 61850 based substation protection, automation and control systems requires good understanding of their functionality and the IEC 61850 principles of object modeling. The goal of this paper is to present a hierarchical object...
The advent of next generation devices for synchronized phasor measurements (voltage and current values in lines) — PMU — makes it possible to realize linear algorithms of state estimation. The paper suggests the development of the test equation technique for linear state estimation of power system facilities that are monitored on the basis of PMU measurements. New algorithms for the construction of...
This paper introduces a simultaneous state and topology estimation method able to process both conventional (SCADA) and synchrophasor measurements. It is devised to extract from the analog measurements not only estimates for the state variables, but also information concerning the underlying network topology. This can be accomplished by representing selected parts of the electrical network at bus...
Increased penetration of photovoltaic (PV) generation is expected in Japan in the near future; thus a new voltage control scheme is required in order to improve the operation of distribution networks. We propose a new voltage control scheme for distribution networks based on a multi-agent system, in which large voltage fluctuations caused by PV generations are effectively regulated by controlling...
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