Search results for "Power Flow"
showing 10 items of 30 documents
A parametric study on unbalanced three phase islanded microgrids with inverter interfaced units
2013
In this paper, the solution of the power flow for unbalanced three phase microgrids systems is proposed. The study aims at the integration of inverter interfaced units using the control law used for primary voltage and frequency regulation, so as to take into account possible small variations of these parameters to account for sudden load changes. The proposed study deals with unbalanced systems which is the typical case of small distribution systems and shows how the power losses term varies as the regulators parameters vary as well, thus showing that these are sensitive parameters that could have an important role in optimal management of such systems.
A model for reactive power tracing by addition of fictitious nodal injections
2012
Abstract This paper proposes an efficient solution to the problem of reactive power flow tracing in electrical transmission networks. For such systems, the tracing techniques used for active power flows cannot be used straightforwardly, due to reactive power variations induced by the line reactances, these variations often being comparable to the powers delivered to the loads. In other words, as is well known, in transmission systems the reactive flows are strongly influenced by the inductive and capacitive effects of the network, making the tracing of power flow and allocation of losses more critical. In this paper, after discussing some methodological aspects, an approach based on the use…
Power tracking with maximum efficiency for wireless charging of E-bikes
2014
Wireless charging techniques, based on Inductive Power Transfer (IPT), are attractive for Electric Vehicles (EV), due to benefits such as convenience and safety. An accurate valuation of the maximum achievable efficiency in an IPT system is extremely unlikely due to the high sensitivity to parasitic elements variations. Therefore, an “on site” procedure of power efficiency characterization is useful to get a precise description of the efficiency curve and obtain the actual maximum efficiency. In this paper, a power tracking algorithm aiming at efficiency maximization is proposed for a Wireless Charging system. The algorithm aims at finding the maximum power transfer efficiency with respect …
Optimal power flow based on glow worm-swarm optimization for three-phase islanded microgrids
2014
This paper presents an application of the Glowworm Swarm Optimization method (GSO) to solve the optimal power flow problem in three-phase islanded microgrids equipped with power electronics dc-ac inverter interfaced distributed generation units. In this system, the power injected by the distributed generation units and the droop control parameters are considered as variables to be adjusted by a superior level control. Two case studies with different optimized parameters have been carried out on a 6-bus test system. The obtained results showed the effectiveness of the proposed approach and overcomes the problem of OPF in islanded microgrids showing loads unbalance.
A multi-agent system reinforcement learning based optimal power flow for islanded microgrids
2016
In this paper, a distributed intelligence algorithm is used to manage the optimal power flow problem in islanded microgrids. The methodology provides a suboptimal solution although the error is limited to a few percent as compared to a centralized approach. The solution algorithm is multi-agent based. According to the method, couples of agents communicate with each other only if the buses where they are located are electrically connected. The overall prizing system required for learning uses a feedback from an approximated model of the network. Based on the latter, a distributed reiforcement learning algorithm is implemented to minimize the joule losses while meeting operational constraints…
A stochastic approach for self-healing capability evaluation in active islanded AC/DC hybrid microgrids
2023
This paper aims to implement a resilience assessment in AC/DC hybrid microgrids using a stochastic simulation approach. Self-healing measures including load shedding, control of distributed generation and flexible devices, like Energy Storage Systems (ESS) and Electrical Vehicles (EVs), are simulated to enable AC/DC hybrid microgrids to supply critical loads in islanded mode, assuming a disconnection of these microgrids from the main AC grid due to a fault. To perform this analysis, a two-stage process is proposed: first, a Monte-Carlo simulation-based stochastic approach is adopted to generate samples to simulate intermittent loads, power generation from Renewable Energy Sources (RESs), an…
A backward sweep method for power flow solution in distribution networks
2010
Abstract A methodology for the analysis of radial or weakly meshed distribution systems supplying voltage dependent loads is here developed. The solution process is iterative and, at each step, loads are simulated by means of impedances. Therefore, at each iteration, it is necessary to solve a network made up only of impedances; for this kind of network, all the voltages and currents can be expressed as linear functions of a single unknown current (in radial systems) or of two unknown currents for each independent mesh (for meshed systems). The methodology has been called “backward” since the unique equation, in case of radial network, and the linear system of equations, in case of meshed n…
Frequency constrained optimal Power Flow based on Glow-worm Swarm Optimization in Islanded Microgrids
2015
This work presents an application of a swarm optimization method to solve the optimal power flow problem taking into account the constraints of frequency and line ampacity in three-phase islanded Microgrids. Each generation unit is equipped with a Power Electronics Interface. In the considered formulation, the droop control parameters are considered as variables to be adjusted by a higher control level, while the frequency is kept in rated bounds. Another typical constraint for OPF formulation, the max ampacity of each line, is also considered. Two case studies with different dimensions and electrical features have been considered and the obtained results show the efficiency of the proposed…
Optimal Power Flow in three-phase islanded microgrids with inverter interfaced units
2015
In this paper, the solution of the Optimal Power Flow (OPF) problem for three phase islanded microgrids is studied, the OPF being one of the core functions of the tertiary regulation level for an AC islanded microgrid with a hierarchical control architecture. The study also aims at evaluating the contextual adjustment of the droop parameters used for primary voltage and frequency regulation of inverter interfaced units. The work proposes a mathematical method for the OPF solution also considering the droop parameters as variables. The output of the OPF provides an iso-frequential operating point for all the generation units and a set of droop parameters for primary regulation. In this way, …
Improved primary regulation for minimum energy losses in islanded microgrids
2017
In this paper, an improved primary regulation is proposed for grid forming units supplying islanded microgrids. A minimum losses Optimal Power Flow is run off-line to devise the operating set points composing the primary regulation curve. In this way, after load perturbations, generators can reach an optimized operating point for a given and unique minimum losses energy flows distribution. The idea is to skip the hierarchical control architecture and provide a feasible and optimized operating point. A case study over 24 hours shows the effectiveness of this new approach as well as the improved operation quality of the system.