Optimal allocation of central storage in segmented rural distribution networks considering operational costs and reliability

In this research work a novel approach is established to optimize the capacity of storage devices; owned and operated by aggregator/retailer, which are centrally installed in each load populated segmenting structure of rural distribution network. The objective of this optimization framework is to minimize investment/maintenance and energy purchase costs for the aggregator/retailer while achieving a certain level of network reliability. Genetic algorithm and fmincon optimization methods are used in this work

Impact of electric energy storage scheduling on reliability of distribution system

The development of Electric Energy Storage (EES) integrated with Renewable Energy Resources (RER) has increased use of optimum scheduling strategy in distribution systems. Optimum scheduling of EES can reduce cost of purchased energy by retailers while improve the reliability of customers in distribution system. This paper proposes an optimum scheduling strategy for EES and the evaluation of its impact on reliability of distribution system. Case study shows the impact of the proposed strategy on reliability indices of a distribution system

Impact of PV units in LV feeders on distribution system reliability

Re-supplying loads on outage through cross-connect from adjacent feeders in a distribution system may cause voltage drop and hence require load shedding. However, the surplus PV generated in some of the LV feeders can prevent load shedding, and improve reliability. In order to measure these effects, this paper proposes the application of Direct Load Flow method[1] in reliability evaluation of distribution systems with PV units. As part of this study, seasonal impacts on load consumption together with surplus PV output power injection to higher voltage networks are also considered. New indices are proposed to measure yearly expected energy export, from LV to MV and from MV to higher voltage network

Financially optimized scheduling of electric energy storage in presence of renewable energy resources

The increasing integration of Renewable Energy Resources (RER) and the role of Electric Energy Storage (EES) in distribution systems has created interest in using energy management strategies. EES has become a suitable resource to manage energy consumption and generation in smart grid. Optimize scheduling of EES can also maximize retailer’s profit by introducing energy time-shift opportunities. This paper proposes a new strategy for scheduling EES in order to reduce the impact of electricity market price and load uncertainty on retailers’ profit. The proposed strategy optimizes the cost of purchasing energy with the objective of minimizing surplus energy cost in hedging contract. A case study is provided to demonstrate the impact of the proposed strategy on retailers’ financial benefit

Comparing hemodynamic changes during endoscopic sinus surgery: remifentanil/isofluran versus remifentanil/propofol

"n Normal 0 false false false EN-US X-NONE AR-SA MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:Arial; mso-bidi-theme-font:minor-bidi;} Background: Sinus surgeries are usually associated with bleeding, thus can result in hemodynamic instability. This study investigated the hemodynamic changes induced by remifentanil plus isoflurane administration in comparison with propofol plus remifentanil in patients undergoing sinus surgery."n"nMethods: In this randomized clinical trial study, 96 patients were divided into two groups of isoflurane (1.2 MAC) plus remifentanil (44 patients, group A) and propofol (100 μg/kg/min) plus remifentanil (52 patients, group B). Twenty-two patients in group A and 23 in group B were male. The remifentanil dosage (0.1 μg/kg/min) was equal in both groups and all received 500 ml isotonic solution during the operation too.  Premedications and anesthetic inductions of both groups were similar. The variables included age, BMI, blood loss during surgery, systolic and diastolic blood pressures, pulse rate and mean arterial blood pressure."n"nResults: The mean age, BMI, amount of blood loss, mean systolic (30 minutes before and after the intervention) and diastolic blood pressures (60 minutes before and after the intervention), pulse rate (30 and 60 minutes before and after the intervention), mean arterial blood pressure (60 minutes before and after the intervention) were similar in both groups. The average mean arterial blood pressure, 30 minutes after the intervention (p=0.027) and the mean diastolic blood pressure, 30 minutes after the intervention (p=0.011) in the case group had statistically significant differences with the controls."n"nConclusion: Based on this study, the combination of isoflurane plus remifentanil could better maintain the hemodynamic stability during sinus surgeries

Optimum electricity purchase scheduling for aggregator storage in a reliability framework for rural distribution networks

The inclusion of Renewable Energy Resources (RER) and Electric Energy Storage (EES) can significantly improve the reliability of rural feeder customers with no cross connect switches to alternative supply. In such setups, there can be a financial incentive for aggregators to facilitate bulk storage to deal electricity with energy supplier and customers by using optimal scheduling strategy. Within this context, this paper proposes a framework for network reliability assessment to include bulk storage scheduling strategy in the evaluation. In this technique, seasonal effects on load demand and RER output, electricity market price, islanding provisions and EES state of charge (SOC) are taken into consideration. Finally, a case study is presented to illustrate the application of this approach and to evaluate the results

Storage optimum placement in distribution system including renewable energy resources

The inclusion of bulk Electric Energy Storages (EES) in distribution system offers a number of benefits to utilities to improve reliability and efficiency of the network. However high investment costs of EES installation should be justified for the utilities. Benefits such as system upgrade postponement and cost of energy purchased reduction in the network as well as reliability and efficiency improvement have made utilities persuaded to afford storage investment and maintenance costs. In this regard, optimal sizing and siting of storages has become the focus of the recent researches to provide a tradeoff between investment costs and expected benefits from storages. In this context, this paper proposes a strategy to optimize the size of EESs in the network while minimizing the cost of purchased energy and investment/maintenance cost of the storage. A case study is presented to evaluate this approach and examine the results