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In this paper, a nonlinear robust controller is proposed for the goal of power stabilization in power systems. The here-proposed approach is based on both the use of a properly-chosen sliding surface and the derivation of a disturbance attenuation condition (nonlinear L2-gain). The controller design is then applied to a single-machine-infinite-bus (SMIB) system and some simulation results demonstrate...
This paper proposes a low voltage ride through (LVRT) scheme for the permanent magnet synchronous generator (PMSG) variable speed wind energy conversion system (WECS) at the grid faults to follow the requirements defined by the grid codes. The dc-link voltage is controlled by the machine-side converter instead of the grid-side converter. Taking into consideration the nonlinear relationship between...
In this paper, different control strategies are presented for primary frequency regulation in a diesel-photovoltaic-supercapacitor hybrid power generation system. Firstly, a classical control approach is proposed as a reference. Then, a robust control design based on H∞ control theory is applied to the studied system. Starting from given certain desired performances, Linear Matrix Inequalities (LMI)...
Optimal bidding is considered to be one of the most challenging task for energy producers to bid in a day ahead electricity market. The randomness and uncertain nature associated with the generation of stochastic resources further increase the complexity of the problem. In this paper, an optimal bidding strategy is developed for a Generation Company (GENCO) to participate in a day ahead electricity...
The increasing presence of uncertainties in today's power systems has brought new risks in its daily operation. In addition to the uncertainty of demand and renewable resources, the slow generator's deviation from the system operator's command in real-time dispatch has recently been identified as a new type of uncertainty which may lead to risks of increased stress on AGC as well as market inefficiency...
With the shale gas revolution, coal retirements, environmental regulations, and increasing renewable energy resources, the interdependency of natural gas and electricity has grown significantly. Interdependency challenges, such as mismatched market schedules and disparate market operations, require quantitative modeling in order to garner insights into the effectiveness of various solutions. In this...
As power systems become more reliant on intermittent resources, system operators are faced with the fact that the availability of intermittent resources is beyond human control and largely unpredictable. Due to the lack of compliance from intermittent resources to follow strict dispatch instructions, the dispatch instruction for an intermittent resource is proposed to be a desired dispatch range or...
This paper presents a two-layered framework for managing multi-interval economic dispatch with both transmission and ramping constraints in electric energy systems with a large penetration of variable resources. The proposed model is aimed at ensuring that there is sufficient flexibility in the dispatch to manage large net load ramp events while observing the transmission constraints in the power...
We present an extension of a model predictive control approach for microgrid energy management. We take into account electricity costs, power consumption, generation profiles and power and energy constraints. Uncertainty due to variations in the environment (wind speed), failures and subsequent repairs of the generator, as well as battery lifespan limitations are taken into consideration. Simulation...
In this paper, a computationally efficient set-membership method for robust fault detection of linear systems is proposed. The method computes an interval outerapproximation of the output of the system that is consistent with the model, the bounds on noise and disturbance, and the past measurements. If the output of the system does not belong to this interval, a fault is detected. To compute the output...
The increase in wind generation in an electric power system also increases the uncertainty in supply and can affect how Generating Companies (GenCos) strategize in the electricity market thereby also affecting electricity prices. The study introduces a method for simulating the effects of different wind generation conditions on GenCo market strategy and on electricity market prices. A supply function...
The main problem in integration of renewable power sources to the electricity grid is the uncertainty introduced by the power forecasting process in the optimal scheduling problem, which can considerably increase the generation cost. This problem has been widely analyzed using scenario generation/reduction methodologies. However, the consideration of a reduced number of scenarios can limit the capabilities...
Uncertainty analysis of a very simple sampling phase meter based on four parameter sine wave fitting is presented in this paper. An uncertainty of a sample time and a measured voltage is assigned to every sampled point and a total uncertainty of a phase difference is calculated by means of the Monte Carlo method. Results show the total uncertainty is lower than 0.5 millidegree for selected digitizer...
This paper describes an automated high-accuracy impedance bridge for the comparison of resistors, inductors or capacitors in the range between 1 mΩ and 100 MΩ over a frequency range of 10 Hz to 20 kHz. The bridge consists of a high resolution digitizer and a six-channel digital waveform generator. A solid state multiplexer has been made to switch between the various positions in the bridge and to...
We present the comparison of results from the generation and the measurement of direct currents in the pA range, performed with traceable state-of-the-art methods at highest accuracy. The currents were generated with the capacitor charging method, and measured with the first prototype of a novel picoammeter developed at PTB. The results confirm the agreement between both methods and the linearity...
Effectiveness evaluation of command and control system involves quantitative index as well as qualitative index but none of the conventional evaluation methods such as Analytic Hierarchy Process(AHP) and Fuzzy Comprehensive Method manage to integrate the fuzziness of qualitative index and the randomness of quantitative index. With the application of the cloud model theory, this paper proposes a cloud...
Managing uncertainties becomes a major challenge in power systems with a high penetration of volatile generation and load. On the contrary, the controllability of the transmission system increases due to the evolution of a smart grid and more flexible technologies. In this paper a methodology for analyzing the impact of uncertainties and operational flexibility in the context of different market coupling...
Microgrids have been explored as active cells capable of providing enhanced control schemes towards a more secure, reliable and efficient operation of LV distribution networks or MV networks when aggregated in a multi-microgrid. These structures, within the smart grid concept, rely on a communications infrastructure that introduces uncertainty in the data exchange process. In this paper such uncertainty...
The rapid growth in demand of electricity combined with renewable energy sources (RESs) are presenting serious challenges for the optimal network operation. The future perspective of the dramatic increase in RESs, such as wind and solar energy, may lead to severe problems related to the load dispatch. Other important aspect is the reduction of controllable resources yielding concerns about the reliability...
A self-validated computing (SVC) method, based on affine arithmetic (AA) is proposed in this paper to solve the optimal power flow (OPF) problem for microgrids with renewable sources of variable generation. In the AA-based OPF formulation, all the state and control variables are presented in affine form, to represent the variable load, and wind and solar generation. Hence, the OPF model becomes an...
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