1,721,029 research outputs found
Evaluating the benefits of coordinated emerging flexible resources in electricity markets
No full textIncreasing share of variable renewable energy sources (VRESs) with the aim of tackling climate changes impose several techno-economic challenges to power system operation. VRESs reduce the available flexibility by displacing existing flexible units due to their priority in dispatch and simultaneously enhance the need for additional flexibility due to their uncertain nature. In this light, the system is faced with a flexibility gap. One way to cover the created flexibility gap is the incorporation of emerging flexible resources into power systems operation. On this basis, this paper proposes a comprehensive flexible generation portfolio including bulk energy storages (BESs), plug-in electric vehicle parking lots (PEV PLs), and demand response (DR) programs. A stochastic market-based model is proposed to coordinate the interactions among these flexibility providers considering different sets of uncertainty, such as wind power generation and PEV owner's behavior. Finally, various generation mixtures are prioritized based on the system operator's economic, technical, and environmental desires to provide a guideline to opt the most effective generation mixture in the context of flexibility promotion
Evaluating the Operational Flexibility of Generation Mixture with an Innovative Techno-Economic Measure
No full textThis paper aims at providing a novel techno-economic flexibility index to quantify the relative flexibility of different conventional generation technologies. The proposed measure takes into account a comprehensive set of technical flexibility characteristics of generation units including minimum stable generation level, operating range, minimum up/down times and ramp up/down capability. The impact of various technical parameters on the flexibility restriction is determined based on the additional costs imposed to the system operator in order to satisfy that constraint. Afterward, the calculated flexibility index is incorporated into day-ahead market clearing procedure as a new objective function beside operation cost using a multi-objective decision-making approach. Simulation results show that the need of different flexibility levels changes the optimal generation dispatch and results in different operation costs. Furthermore, the impact of two emerging flexible options i.e., bulk energy storages and a typical demand response program in the flexibility contribution of other generation technologies is also investigated. The results reveal that the integration of emerging flexible options frequently changes the flexibility share of conventional units and can provide the required flexibility level at a lower cost
Market transactions of PEV parking lots in the presence of wind generation
No full textGrowing development of renewable energy sources, particularly wind power, has caused great challenges in power system operations need to be carefully investigated. Variability in wind power generation is the main concern regarding wind integration which should be adjusted with a reasonable cost in order to maintain system balance between supply and demand. The continuous augment of Plug-in Electric Vehicles (PEVs) has made them as one promising solution due to their flexibility and low-emission. This paper evaluates the interaction of PEV Parking Lots (PLs) in both energy and reserve markets considering the impact of dispersed and gathered wind generation. To this end, a two-stage stochastic framework is adopted with the aim of modeling the day-ahead network-constrained market clearing. The proposed method considers the uncertainty of wind generation as well as the PEV owner's behavior takes into account the arrival/departure time of PEVs to/from the PL, the initial state of charge (SOC) of PEVs, and their battery capacity using a set of scenarios. Several numerical analyzes are carried out to assess the reserve requirement as a result of dispersed or gathered wind generation. Also, the effectiveness of PEV PLs participation in energy and reserve market on wind integration is examined
Stochastic optimal scheduling of distributed energy resources with renewables considering economic and environmental aspects
No full textA distributed energy resource (DER) system is a multi-input and multi-output energy system consisting of small-scale technologies, which provide electricity and thermal energy close to end-users. In recent years, DER systems have attracted much interest as a promising opportunity with substantial economic and environmental benefits. To reduce energy costs and environmental impact of DER systems, daily operation scheduling is crucial, and presents significant challenges even more under energy demand and supply uncertainty in presence of renewables. The contribution of this paper is to provide a stochastic programming model for the optimal operation scheduling of a DER system with multiple energy devices including renewables, considering economic and environmental aspects. To model uncertain parameters of supply and demand side, 24-h scenarios are generated by using roulette wheel mechanism and Monte Carlo simulation method. A stochastic multi-objective linear programming problem is formulated to find the optimized operation strategies of the DER system to reduce the expected energy costs and CO2emissions, while satisfying the time-varying user demand. By minimizing a weighted sum of the total energy cost and CO2emissions, the problem is solved by using branch-and-cut. Numerical results show that the Pareto frontier provides good trade-off solutions for DER system operators based on economic and environmental priorities. The total daily energy cost and CO2emissions under a stochastic approach result to be lower than those under a deterministic one. Moreover, the operation method provided is found to be efficient in reducing significantly energy costs and CO2emissions of the DER system, as compared with conventional energy supply systems and combined heat and power systems. In addition, a sensitivity analysis is also carried out to investigate the impact of renewables penetration on the economic and environmental performances of the DER system
Investigation of the Impacts of Synchronous Generators' Forced Outage Rates on Reactive Power Market
No full textIn this paper a stochastic reactive power market clearing is presented. In this market, the expected value of the total payment by the independent system operator is minimized by using particle swarm optimization algorithm. By using the developed stochastic reactive power market model, the impacts of synchronous generators' forced outage rates on reactive power market's cost has investigated. Numerical studies have been performed on the IEEE 24-bus Reliability Test System (RTS). The results evidenced that the lower the forced exit rate of the units, the lower the cost paid by the independent operator of the system to settle the reactive power market
Stochastic optimal scheduling of distributed energy resources with renewables considering economic and environmental aspects
No full textA bottom-up approach for demand response aggregators’ participation in electricity markets
No full textThis paper proposes a bottom-up model for demand response (DR) aggregators in electricity markets. This model enables a DR aggregator to consider the technical constraints of customers in developing an optimal trading strategy in the wholesale electricity market. In the bottom level, DR options, called load shifting, load curtailment and load recovery are comprehensively modelled in a stochastic programming approach. Each DR program is mathematically formulated in such a way that practically models the constraints of customers. Further, the proposed model considers the customers’ behaviour in participating in the given DR program through a scenario-based participation factor. On the other hand, the upper level proposes trading the DR outcome in day-ahead and balancing markets with uncertain prices, as well as in forward contracts with a predefined price. The overall bottom-up problem is formulated as a stochastic profit maximization model for the DR aggregator, in which the risk is taken into account using the Conditional Value-at-Risk (CVaR) measure. The feasibility of the given strategy is assessed on a case of the Nordic market
Detection and Analysis of Partial Discharges in Oil-Immersed Power Transformers Using Low-Cost Acoustic Sensors
No full textPartial Discharge (PD) is one of the symptoms of an electrical insulation problem, and its permanence can lead to the complete deterioration of the electrical insulation in high-voltage equipment such as power transformers. The acoustic emission (AE) method is a well-known technique used to detect and localize PD activity inside oil-filled transformers. However, the commercially available monitoring systems based on acoustic sensors still have a high cost. This paper analyses the ability of low-cost piezoelectric sensors to identify PDs within oil-filled power transformers. To this end, two types of low-cost piezoelectric sensors were fully investigated using time-domain, frequency-domain, and time-frequency analysis, separately. Thereafter, the effectiveness of these sensors for PD detection and monitoring was studied. A three-phase distribution transformer filled with oil was examined. PDs were produced inside an oil-immersed transformer by applying a high voltage over two copper electrodes, and the AE sensors were coupled to the housing of the transformer. By extracting typical features from the AE signals, the PD signals were differentiated from on-site noise and interference. The AE signals were analyzed using acoustic signal metrics such as peak value, energy criterion, and other statistical parameters. The obtained results indicated that the used low-cost piezoelectric sensors have the capability of PD monitoring within power transformers
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