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A detailed model of grid-connected doubly-fed induction generator (DFIG) suitable for fault analysis is presented. 5th order model of wound rotor induction machine together with a two-mass model of the mechanical drive-train is employed to investigate transient voltage stability of integrated wind turbine. Converter system is represented in such a way to contain adequate model of the rotor- and stator-side...
This paper presents an idea and a role of multi- energy companies in the Polish energy markets. Authors present key aspects of development of Polish electricity market and rules of a co-operation in this area between communal and distribution entities. Paper includes also a description of the first M-E and M- I companies (M-ECO, M-ICO) operating in Poland. A profile and a role of these companies in...
This paper presents a master control unit (MCU). The main idea of the MCU is to reduce the impact of wind energy on the system. Therefore, a power schedule to reduce the fluctuating impact on the system is developed. The power schedule is developed in accordance to the German industries. The power schedule uses less energy the wind offers which makes it possible to reduce the stochastic nature of...
Phase comparison protection has been traditionally applied using a fixed ratio of sequence quantities to modulate the power line carrier at either end of the line. This paper examines a practical method to control this ratio adaptively in order to provide better coverage for high resistance earth faults. The paper also looks at techniques to compensate for phase errors introduced by charging current...
The design of the protection system becomes fundamental to guarantee the adequate operation of the electric system under fault conditions, as it makes possible to isolate only faulted devices without affecting to the other ones. Electric fuses are protection devices broadly used in distribution networks, being designed to interrupt the current by means of the melting of one of their components when...
The paper deals with transients attendant on filter-compensating capacitive units (FCU) switching-off. The transients disturbs the converter operating mode, breaks the valves commutation, which may caused a converter turn-off. Such processes are caused the saturation of the voltage transformers, used for control of the converter, at FCU switching-off. The problem can be solved by the use of voltage...
In power system operation, maintaining power flow solvability is important. In the recent deregulated environment, uncertainty has become more prevalent in power systems because of diverse power transactions and benefit-based operational schemes. Thus, in the present and future power industry, there may be more unsolvable cases than there were in the past integrated power industry. This paper presents...
In the last years electric systems, all around the world, experienced voltage stability problems, basically related to their exploitation, near to the limits, caused by market opportunities and progressive growth of loads with low power factor (air-conditioning, electronic devices, etc.). In this paper it is investigated the problem of modeling some specific components of the electric power system,...
Richness of modern power systems with high- performance rapid devices of automatic control, in particular, excitation controllers with power system stabilizers, and also more and more wide use of self-acting counter-emergency control operating on the vapor turbines has provided an opportunity of the complete use of transmission lines' capacity on conditions of aperiodic and a transient stability and...
This paper deals with a new method for eigenvalue region prediction of critical stability modes of power systems based on decision trees. The critical stability modes result from inter-area oscillations in large-scale interconnected power systems. The existing methods for eigenvalue computation are time-consuming and require the entire system model that includes an extensive number of states. However,...
Searching for the optimal radial configuration of large distribution systems is a problem leading to combinatorial explosion of the number of configurations to analyze. Several deterministic and heuristic methods have been applied in order to endeavor near-optimal solutions. However, no method can ensure that the optimal solution is found in a finite time, so that developing and testing new heuristics...
An all current directional algorithm based on wave propagation is presented. It can be applied to point out to the faulty feeder in radial network with ramifications, no matter how the neutral is grounded. The algorithm is explained on constant parameter EMTP cable model and tested on frequency dependent L.Marti cable model with sheaths grounded on both sides.
This paper provides an extended comparison between the use of customer class-based and area-based load profiling to assess the total revenues and the load deviations resulting from the consumption of the electricity users in a system partitioned into several territorial areas. Within each area, it is assumed that part of the users is subject to permanent metering, whereas for other partially-metered...
A combined wavelet analysis - Kalman filtering approach is presented in this paper for the automatic detection and analysis of voltage dips in power systems. Wavelet analysis is used to process the voltage waveform for detection and better estimation of the time-related parameters of a voltage dip in voltage supply, while Kalman filtering is used for the estimation of voltage magnitude and phase angle...
This paper presents and analyses a new method for the detection of the point of collapse and a new index for the definition of the distance of the voltage collapse point. This paper demonstrates that a point of a Newton-Raphson power flow becomes singular when the full sum of the partial derivate of the reactive power equations in relation to the voltage level is approximately constant. Numerical...
This paper introduces a method for forecasting energy prices using artificial intelligence methods such as neural networks and fuzzy logic and a combination of the two. The forecasted price is then used to design an optimal bidding strategy for a generator according to his/her degree of risk aversion. A typical thermal plant is assumed to be located in the Ontario electricity system to apply this...
This paper presents a mu robust controller to improve small signal stability of an AC/DC power system. It is shown that the suggested controller can improve the system stability despite severe disturbances while considering the uncertainties of the power system dynamics. The simulation results verify the capability of the suggested method and designed controller.
Greece, as member of the European Union follows the European policies regarding compliance with the Kyoto Protocol, as expressed by the draft directive of 2001 on "A framework for greenhouse gas emissions trading within the European Community". Accordingly, it is proposed that 38% of the CO2 emissions in EU should be included in the quota system by 2010, with a penalty of 50 euro/tn of CO...
A major problem with wind power is that it is intermittent. Even if it were predictable, the problem of matching generation to demand is difficult. Storage is sometimes advocated, but this tends to be very expensive. The paper examines the main conventional solutions to the intermittency problem - provision of extra reserve generation to compensate for unexpected wind power lulls, and increased interconnection...
There are over 8400 MW of installed wind power in the Spanish Electrical System. This amount of installed power, compared with a load peak around 43700 MW, has a big impact on system operation. Some particularities of the Spanish Peninsular Power system, a satellite of the UCTE interconnected network, with weak interconnection ties with the rest of Europe, suggest that this integration should be analysed...
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