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This paper proposes a novel DC-side controller for grid-connected voltage source converters during asymmetrical faults. The controller is based on a modified second order generalized integrator (SOGI). The main objective is to mitigate the second order harmonic voltage oscillation on DC link as well as the positive sequence third-order harmonic current injection into the AC grid, due to negative sequence...
This paper proposes a scalable algorithm to identify and analyze bifurcation points of a large power system model of dynamic voltage instability. Different types of bifurcations are analyzed, such as: saddle-node (fold), Hopf, singularity-induced, and limit-induced bifurcations. The interval bisection based algorithm is proposed for determination of the steady-state equilibrium point. The proposed...
This paper aims to contribute to the development of methods for alleviating overloads in the transmission system. Among the several possible alternatives to achieve this goal, branch (transmission lines and transformers) switching will be the focus in this work. Even though this possibility is well-known, a very interesting branch switching method was proposed recently in the literature to identify...
This paper compares the performance of different droop-based control techniques in an islanded microgrid that operates solely on electronically interfaced distributed energy resources (DERs). Specifically, the following techniques are compared: conventional droop-based control including a full pulse width modulating (PWM)-based voltage source converter (VSC) with power, voltage and current controls;...
Characteristics of the current emission for new developed devices are changing resulting in lower low order harmonics and an increase in high order harmonics. For the low voltage network this results in an increase in high order harmonic voltages, violating more often the limits for the harmonic voltages at the 15th and 21th order harmonic. To improve this situation harmonic current could be reduced,...
The paper presents an alternative approach to voltage stability boundaries evaluation. The proposed method is direct, but has advantages over conventional direct methods. It is based on optimization technique and allows to evaluate the distance to power system voltage stability boundary. The paper demonstrates the concept of the approach based on simple power system models. Also implementation of...
The renewable sources' influence regarding the distribution network expansion planning is tackled. Two cases are involved into discussion: with and without renewable sources. The obtained expansion solutions are analyzed for each case and a final one is proposed. Thus, network reconfiguration is used and technical losses minimization. The power flow is computed using conventional methods, but the...
Power-to-Gas can contribute with valuable balancing power and seasonal storage capacity to future power systems. In Portugal, forecasts for 2020 show significant excess of renewable energy generation that can be transformed by power-to-gas technology and fed into the natural gas infrastructure. This work suggests an innovative approach to assess future power-togas integration potentials at the national...
This paper introduces a multi-objective optimization based Model Predictive Control (MPC) strategy for damping inter-area oscillations in power systems. The previous MPC control strategies presented in the power system literature have been based on single-objective optimization, but this paper extends the approach to multi-objective optimization. The controller is designed using a linear discrete...
This paper aims at assessing the power system reliability by estimating loss of load (LOL) index using mutual information based Bayesian approach. Reliability analysis is a key component in the design, analysis and tuning of complex structure like electrical power system. Consideration is given to rare events while constructing the Bayesian network, which provides reliable estimates of probability...
Smart Meters (SMs) are undergoing an increasing deployment all over the world and have been introduced to several regions. The SMs generally have remotely accessible breakers which offer remote switching functionalities to the Distribution System Operators (DSOs). The DSOs have the possibility of using this unique functionality of SMs for various future applications, e.g., switching some loads during...
The Fault Ride Through (FRT) capability of renewable energy sources (RES) for providing support to the power grid under several disturbances allows us to consider them not only as passive elements in the power system network, but also as ancillary services for the mitigation of evolving contingencies. In this paper, an investigation of the FRT operation of RES according to current grid regulations...
This paper presents a control method based on dynamic model of three-level neutral-point-clamped (NPC) voltage source converter (VSC) for integration of renewable energy sources (RESs) into the power grid. The proposed control method can provide continuous injection of active power besides the compensation of all reactive power and harmonic current components of loads through integration of RESs into...
The power-to-gas (PtG) technology is an energy storage option for variation management in power systems with high penetration of variable electricity generation. This paper investigates the effects of PtG units on the economic dispatch of power systems for the case of Denmark. The paper proposes a multi-period scheduling model for PtG based on a dc optimal power flow framework. The model has been...
Wind energy is clean, affordable, efficient and effectively infinite. Therefore, it is the biggest player in energy transition arena and penetration of it in power systems is increasing. The high penetration of wind farms (WFs) causes problems because wind itself is variable and uncertain. Moreover, it results in complicated effects on power flows and voltages. Grid operators are supposed to develop...
In recent years, the penetration of renewable resources in electrical power systems has increased. These renewable resources add more complexities to power system operations, due to their intermittent nature. As a result, operators must acquire additional reserves in order to maintain reliability. However, one persistent challenge is to determine the optimal location and quantity of reserves; this...
The level of harmonic currents emitted by nonlinear household devices depends on many factors. Beside the general circuit topology, e.g. presence or absence of power factor correction (PFC) circuit the emission depends significantly on the distortion of the supply voltage. The paper discusses typical voltage distortions in public low voltage grids and proposes parameters for their quantification....
In this paper a procedure for estimating the inertial frequency response of a power system with high wind energy penetration is presented, and the influence of the wind power fluctuations on the variability of the inertial response is analyzed. The procedure is based on the accuracy of the disturbance start-time detection and the frequency's rate of change. An algorithm for estimating the disturbance...
Demand response based on real time pricing introduces a new feedback loop between consumers' behavior and short term electricity markets. This feedback raises some concerns due to its potential destabilizing impact on electricity markets. Any analysis of this impact requires electricity market model. In this paper, several market models used for this purpose in the literature are analyzed and it is...
World wide the wind power plants are located far away from the existing interconnection substations to the power system. Therefore, compensation methods are considered for the reactance of long distance cable connection. High voltage DC transmission cables for wind power plants interconnection to the grid can also be considered and used. In the present paper, the problems raised by AC cables, from...
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