Load Shift Research Articles

Optimizing design and performance assessment of a community-scale hybrid power system with distributed renewable energy and flexible demand response

Modern urban energy system with renewable energy sources has become an effective solution to enhance energy security and promote carbon neutrality. This paper presents a holistic framework for the optimal design and management of such a flexible hybrid power system at the community scale. This framework integrates the potential assessment of rooftop PV and waste biomass, a general optimization approach with multi-perspective performance evaluation, as well as the impacts analysis of energy policy, demand response, and uncertain economic parameters. The proposed framework was applied to a small neighborhood area in Beijing, China. It was found that 100% utilization of available biomass and rooftop PV would satisfy 73% of local electricity demand with the levelized cost of electricity of 0.1030 $/kWh and the embodied carbon emission of 0.5416 kg/kWh. The flexible shiftable load could lead to lower peak load and less electricity supply cost, and help to match the energy demand with the dispatchable rooftop PV output. However, the economic benefits caused by implementing demand response are more obvious than the environmental benefits. Furthermore, a higher electricity tariff and lower capital cost of PV technology would facilitate the investment in rooftop PV and achieve carbon emission reduction targets.

Potential of Load Shifting in a Parking Garage with Electric Vehicle Chargers, Local Energy Production and Storage

The electrification of the transport sector is of crucial importance for a successful transition to a fossil-free society. However, the electricity grid constitutes a bottleneck. This article provides a case study based on a real-world parking garage with a smart grid infrastructure, called Dansmästaren. The analysis shows how renewable energy sources, energy storage technologies, and smart charging of electric vehicles can smooth out the load curve of the parking garage and relieve the electric grid during peak hours. Dansmästaren is located in Uppsala, Sweden, and equipped with 60 charging points for electric vehicles, a PV system, and a battery storage system. The study utilizes an energy flow model to show the potential of a realistically dimensioned smart energy system, that can benefit the parking facility in itself and the local distribution grid in a city, Uppsala, with grid capacity challenges. The results suggest that the parking garage demand on the local grid can be significantly lowered by smarter control of its relatively small battery energy storage. Moreover, further smart control strategies can decrease demand up to 60% during high load hours while still guaranteeing fully charged vehicles at departure in near future scenarios. The study also shows that peak shaving strategies can lower the maximum peaks by up to 79%. A better understanding of the potential of public infrastructures for electric vehicle charging helps to increase knowledge on how they can contribute to more sustainable cities and a fossil-free society.

Decadal trajectories of land-sea couplings: Nitrogen loads and interception in New England watersheds, discharges to estuaries, and water quality effects

Couplings between coastal watersheds and estuaries were assessed in a series of sites across SE New England. Nitrogen loads to watersheds increased during 1985–1996, but decreased afterwards due to lowered atmospheric deposition. Within-watershed nitrogen interception was high and linked to forest cover. Loads to estuaries also responded to lowered atmospheric inputs. Concentrations of nitrogen compounds were higher in estuaries subject to larger nitrogen loads from land. Estuarine nutrients showed large scatter and decreased from less-saline to saltier reaches. Chlorophyll concentrations were less reliable indicators of coupling to watershed loads. Water quality variables were lagging indicators of changing nitrogen loads, with shifts in concentrations becoming detectable several years after the 1996 shift in total nitrogen loads. Lag delays will be of significance for assessment of the effectiveness of estuarine water quality management.

Small Electric Energy Peak Load Shifting and Valley Filling Device

Small Electric Energy Peak Load Shifting and Valley Filling Device

Centralized optimal management of a smart distribution system considering the importance of load reduction based on prioritizing smart home appliances

AbstractThe distribution system's economic operation is significantly impacted by the management of distributed generation (DG) resources, energy storage (ES), and controllable loads. The paper employs a smart distribution system that incorporates dispatchable and non‐dispatchable DG resources, as well as battery storage, in addition to the demand response (DR) scheme. New modelling was performed in hourly steps to achieve the optimal unit commitment. In smart homes, appliances are prioritized and classified into four types: adjustable, interruptible, shiftable, and uncontrollable loads. Load reduction in smart homes is also considered based on load prioritization and customer participation in the DR scheme to achieve the proposed scheme's objectives. The proposed method considers costs associated with microturbines (MTs), including manufacturing, start‐up, shutdown, and pollution. Additionally, planning is conducted to purchase or sell electricity to the upstream network. The simulation is run on an IEEE 33‐bus system to demonstrate the proposed method's effectiveness. The system is assumed to be capable of operation in both island and grid‐connected modes. The results demonstrate the proposed approach's efficacy in load reduction, operation cost, and execution time.

A microgrid formation-based restoration model for resilient distribution systems using distributed energy resources and demand response programs

In recent years, resilience enhancement of electricity distribution systems has attracted much attention due to the significant rise in high-impact rare (HR) natural event outages. The performance of the post-event restoration after an HR event is an effective measure for a resilient distribution network. In this paper, a multi-objective restoration model is presented for improving the resilience of an electricity distribution network. In the first objective function, the load shedding in the restoration process is minimized. As the second objective function, the restoration cost is minimized which contradicts the first objective function. Microgrid (MG) formation, distributed energy resources (DERs), and demand response (DR) programs are employed to create the necessary flexibility in distribution network restoration. In the proposed model, DERs include fossil-fueled generators, renewable wind-based and PV units, and energy storage system while demand response programs include transferable, curtailable, and shiftable loads. The proposed multi-objective model is solved using ɛ-constraint method and the optimal solution is selected using the fuzzy satisfying method. Finally, the proposed model was successfully examined on 37-bus and 118-bus distribution networks. Numerical results verified the efficacy of the proposed method as well.

Power System Impacts of Electric Vehicle Charging Strategies

This article explores the potential impacts of integrating electric vehicles (EVs) and variable renewable energy (VRE) on power system operation. EVs and VRE are integrated in a production cost model with a 5 min time resolution and multiple planning horizons to deduce the effects of variable generation and EV charging on system operating costs, EV charging costs, dispatch stacks, reserves and VRE curtailment. EV penetration scenarios of the light-duty vehicle fleet of 10%, 20%, and 30% are considered in the RTS-GMLC test system, and VRE penetration is 34% of annual energy consumption. The impacts of EVs are investigated during the annual peak in the summer and during the four weeks of the year in which high VRE and low loads lead to overgeneration. Uncoordinated and coordinated EV charging scenarios are considered. In the uncoordinated scenario, charging is undertaken at the convenience of the EV owners, modeled using data from the Idaho National Laboratory’s EV Project. Coordinated charging uses an “aggregator” model, wherein EV charging is scheduled to minimize operating costs while meeting the daily charging requirements subject to EV availability and charging constraints. The results show that at each EV penetration level, the uncoordinated charging costs were higher than the coordinated charging costs. During a high-VRE, low-load week, with uncoordinated EV charging at 30% penetration (3% energy penetration), the peak load increased by as much as 27%. Using coordinated charging, the EV load shifts to hours with low prices, coincident with either low load, high VRE, or both. Furthermore, coordinated charging substantially reduces the curtailment of PV by as much as nine times during the low-load seasons, and the curtailment of wind generation by more than half during the summer peak season, compared to the scenarios with no EVs and uncoordinated EV charging. Using a production cost model with multiple planning cycles, load and VRE forecasts, and a “look ahead” period during scheduling and dispatching units was crucial in creating and utilizing the flexibility of coordinated EV charging.

Effect of the Indentation Load on the Raman Spectra of the InP Crystal.

Nanoindentations and the Raman spectroscopy measurements were carried out on the (001) surface of undoped and S-doped InP crystal. The samples were indented with the maximum load ranging from 15 mN to 100 mN. The phase transition B3→B1 was not confirmed by spectroscopic experiments, indicating a plastic deformation mechanism governed by dislocations activity. Increasing the maximum indentation load shifts and the longitudinal and transverse optical Raman bands to lower frequencies reveals a reduction in the elastic energy stored in the plastic zone right below the indentation imprint. Mechanical experiments have shown that a shift in Raman bands occurs alongside the indentation size effect. Indeed, the hardness of undoped and S-doped InP crystal decreases as a function of the maximum indentation load.

Influence of road profiles and truck braking on the dynamic load transfer to the pavement

ABSTRACT During the braking manoeuvre of a vehicle on a pavement, the mechanics associated with load transfer is complex due to the presence of slip, load shift between the front and rear axles, and development of longitudinal forces. The road profiles, braking intensity, truck mass, and speed during braking play a critical role here. This investigation reports an attempt to collect such data. A unique Hardware-in-Loop set-up was integrated with vehicle dynamics software, TruckMaker, to perform a realistic braking manoeuvre. Three truck loadings were chosen from the axle load survey conducted in the field (unladen, laden, and overloaded). Three ISO road profiles (A, B, C) generated using the power spectral density approach, three initial speeds (30, 50, and 80 km/h), and three braking intensities (Partial (10%), Partial (45%), and Complete (100%)) were chosen for the simulation. In total 81 simulations were performed considering all the above-said factors. From the analysis of wheel slip values, it was identified that the wheels of unladen trucks lock during complete braking, irrespective of the speeds and road profiles. The complete braking manoeuvre for all vehicle types showed more load shift from the rear axle to the front axle compared to partial braking manoeuvres. Also, the unladen trucks were found to transfer more percentage (>50%) of their rear axle load to the front axle during braking. The maximum longitudinal force developed at the tyre-pavement interface was found to be independent of the loading conditions during complete braking.

Building flexibility revenue in modeled future bulk power systems with varying levels of renewable energy

The buildings sector can provide important demand-side flexibility for the integration of renewable energy. With the changing power system and rapid advancement in building energy control technology, technology providers and demand response aggregators need to know what potential revenues could be obtained by providing grid services. We dispatch a normalized and parameterized model of building load shifting against marginal service prices from grid investment and operational models to produce a database of the capacity, energy, and ancillary service revenues (gross value of providing bulk power system services) for a marginal kilowatt-hour (kWh) of shiftable load. The database is geographically disaggregated, hourly, and parameterized so that flexibility value can be estimated for a wide range of building technologies. The database covers the contiguous United States under three 2030 grid scenarios. Given the high degree of uncertainty in such grid projections, the results are perhaps best interpreted in terms of regional climate and grid mixes and are thus potentially applicable in non-U.S. contexts. Upon analyzing the results, we find the monthly mean gross value of building load shifting is 0–38 cents/kWh-day and the daily gross value of shifting the highest-value hour each day can be up to 620 cents/kWh-day. The different revenues obtained by aggregating results in different ways, as well as observed regional and seasonal differences, suggest different building technologies and grid environments might call for demand response program designs and business models.

Reflecting on Plastic Surgery Training During Early COVID-19 Pandemic: Resident Exposure and Telemedicine.

Coronavirus disease 2019 (COVID-19) pandemic has been an unprecedented public health crisis. As hospitals took measures to increase their capacity to manage COVID-19 patients, plastic surgeons have also had to modify their routine to continue serving their vital role within the hospital environment. In an effort to reduce exposure to COVID-19 and conserve hospital resources, many plastic surgery programs drastically modified call schedules, restructured inpatient teams, triaged operative cases, and expanded telemedicine encounters. Plastic surgery programs focused on craniofacial procedures were impacted by precautionary preventative protocol and shifts in case load made to protect both the healthcare teams and the patients. At academic centers, plastic surgery trainees of all domains felt the impact of these changes. Recognizing the implications on future craniofacial surgical practice, the pandemic has made, the goal of the authors' study is to measure initial impacts of COVID-19 on plastic surgery trainees using a nationwide survey. The authors' results present the first quantitative analysis of plastic surgery trainees' exposure to COVID-19, deployment to other medical specialties, usage of personal protective equipment, and implementation of telemedicine during the pandemic. While healthcare systems have greatly adapted to pandemic complications and can anticipate vaccination, resurgence of COVID-19 cases linked to the delta variant heightens the authors' urgency in understanding the early pandemic, and its lasting impacts on healthcare. In the months following pandemic onset, telemedicine has become a mainstay in healthcare, trainees have adapted and become integrated in patient care in novel ways, and visits unable to transition to telemedical settings received substantial attention to ensure patient and provider safety. An institutional review board-approved anonymous, multiple-choice and short-answer, Qualtrics survey regarding plastic surgery resident experiences with COVID-19 exposure. It was sent to all US plastic surgery program directors and program coordinators on April 23, 2020 with the request to distribute the survey to their residents. Residents were given the option to participate in a raffle for a $50 gift card. Outcomes measured included demographics, exposure to COVID-19, availability of resources, and adjustments to residency training practices. Sixty-nine plastic surgery residents throughout all years of training from 18 states responded. Gender, year of training, and location did not significantly impact these reports.Sixteen percent of residents reported covering a COVID-19 team. Twelve percent reported covering a shift not within their scope of practice. From these reports, residents mostly worked in the intensive care unit (50%) and the emergency department (29%).Half of the residents believe they were exposed to high-risk patients. This was reported in a variety of settings: the emergency department for plastic surgery consults (34%), caring for plastic surgery inpatients (16%), performing trauma reconstruction surgery (16%), cancer reconstruction surgery (12%), elective surgery (6%), and intraoperative consults (6%).Seventy-two percent of residents reported adequate access to personal protective equipment. Equipment type varied by patient exposure. When attending to a non-COVID-19 inpatient, most residents used a standard mask (62%) rather than an N95 mask (21%). N95 masks were generally used in patients with unknown COVID-19 status. Residents reported using eye and face shields when attending to non-COVID-19 ICU patients (17%), patients with unknown COVID-19 status (27%), and in the operating room (34%).Forty percent of residents implemented telemedicine to see patients for new consults, follow-up visits, postop checks, and wound checks. Eighty-five percent of residents report that they would continue to incorporate telemedicine in the future. Most significant reported barrier to using telemedicine is the limited ability to perform a physical examination (33%) followed by limited patient access to telemedicine (21%). Other challenges included poor ease of use for patients or providers, billing questions, and lack of interpersonal connection with patients. This study, to the best of the authors' knowledge, is the first to quantitatively investigate how plastic surgery residents have been affected by the widespread impacts of the COVID-19 pandemic. It reports resident exposure to COVID-19 and their associated concerns, resident access to and perceived adequacy of personal protective equipment, as well as changes to clinical practice.

Economic-environmental operation of an unbalanced microgrid including energy storage systems via semidefinite relaxation

This paper proposes a mathematical optimization approach based on semidefinite programing (SDP) for optimal operation of an unbalanced microgrid (MG) equipped with renewable energy resources (RERs) as well as energy storage systems (ESSs) including compressed air energy storage (CAES) and electric vehicles (EVs). The SDP converts nonlinear and non-convex models proposed for day-ahead optimal operation into a convex approximation, which is easily implemented by commercial software. An optimization problem is formulated such that it minimizes the costs related to operation and environmental effects limited to several technical limitations. It is clear that there is an intrinsic deviation between predicted and actual uncertainty variables in MG. This paper presents a stochastic optimal operation model based on Information Gap Decision Theory (IGDT) with risk averse strategy to overcome this information gap and to help Microgrid Operator (MGO). As demand response programs (DRPs), the shiftable load and time of use (ToU) are considered for enhancing the flexibility of MG. Employing the presented model in the 21-bus test system shows that CAES and EVs, as novel ESSs, have good capability to reduce the costs pertaining to operation and emissions in the day-ahead optimal operation.

Lowest Tariff Load Shifting Demand Side Management Technique in Smart Grid Environment

Electrical energy is playing an important role in our day-to-day life. The burden on utility is increasing continuously due to huge utilization of electrical energy thereby utilities are suffering from peak shortage. The concept of demand side management can be applied to relieve the utilities from suffering peak load burden. In this paper, a Lowest Tariff Load Shifting (LTLS) approach of DSM is suggested to flatten the load curve as desired by the utilities. Residential and commercial loads are considered for validation of proposed algorithm. The use of DSM techniques can delay the expansion of power system for short duration such as few months or years. This paper produces a flatten load curve by applying LTLS technique of DSM and results demonstrates cost saving and peak load reduction in residential as well as commercial area.

An 80-Year-Old Man With Hematochezia and Hyperkalemia

Question: An 80-year-old man with a history of colon cancer with previous resection and a primary anastomosis as well as chronic kidney disease presented to the emergency room with a presyncopal episode. On arrival, he was hypotensive, with a hemoglobin of 9.9 g/dL, blood urea nitrogen of 45 mg/dL, and creatinine of 1.9 mg/dL with a serum potassium of 6.0 mmol/L. The patient’s hyperkalemia was attributed to chronic kidney disease and was managed medically. After treatment for hyperkalemia, on the same day of admission, the patient developed bright red bleeding per rectum. The patient underwent colonoscopy on day 2 of admission, which showed internal hemorrhoids, as well as a dusky appearing mass at the rectosigmoid junction, 13 cm from the anal verge measuring 5 cm in length (Figure A). Biopsies of the mass were obtained, and histologic analysis of the biopsies is shown (Figure B). What is the etiology of these endoscopic and histologic findings? See the Gastroenterology web site (www.gastrojournal.org) for more information on submitting your favorite image to Clinical Challenges and Images in GI. Histology showed colonic mucosa with ischemic injury, ulceration, acute inflammatory exudates, absence of neoplastic cells, and the presence of sodium polystyrene sulfonate (SPS) crystals (highlighted in the rectangle in Figure B). Immunohistochemical stain for cytomegalovirus was negative (not shown). Upon review of the patient’s medications, 1 dose of SPS (Kayexalate) had been given on the first day of admission before the development of hematochezia. Owing to a suspected sampling error, the patient underwent repeat colonoscopy 5 days after the index endoscopy which showed notable regression of the previously seen pseudotumor (Figure C); biopsies of the remnant lesion showed persistent ischemic type injury with acute inflammatory exudates and SPS crystals (indicated by the blue arrow in Figure D). SPS is a potassium-binding resin used to treat acute hyperkalemia. SPS has been associated with gastrointestinal complications, including ischemic colitis, bleeding, and perforation.1Bui M. Chou S.Y. Faubert P. et al.Resin-induced colonic pseudotumor: rare complication from chronic use of potassium binders in a hemodialysis patient.Case Rep Nephrol. 2016; 20163692086PubMed Google Scholar Ischemic colitis with associated pseudotumor formation is a rare adverse event that can mimic a malignant process, and present as hematochezia or as a radiographically apparent colonic mass.1Bui M. Chou S.Y. Faubert P. et al.Resin-induced colonic pseudotumor: rare complication from chronic use of potassium binders in a hemodialysis patient.Case Rep Nephrol. 2016; 20163692086PubMed Google Scholar These pseudotumors are non-neoplastic, inflammatory, and necrotic lesions that have been reported to occur in the esophagus, colon, and in extraintestinal areas.2Chatila A.T. Bilal M. Merwat S. Kayexalate-induced colonic pseudotumor.Clin Gastroenterol Hepatol. 2019; 17: e73Abstract Full Text Full Text PDF PubMed Scopus (4) Google Scholar,3Goh L.H. Wong J. Chng T.W. et al.Extra-intestinal sodium polystyrene sulfonate crystal-induced inflammatory pseudotumour in an asymptomatic haemodialysis patient.Int Urol Nephrol. 2021; 53: 1265-1266Crossref PubMed Scopus (1) Google Scholar Although the mechanism is unknown, it is proposed that SPS causes a shift in the osmotic load and, therefore, vascular redirection and then ulceration or ischemia.2Chatila A.T. Bilal M. Merwat S. Kayexalate-induced colonic pseudotumor.Clin Gastroenterol Hepatol. 2019; 17: e73Abstract Full Text Full Text PDF PubMed Scopus (4) Google Scholar The characteristic pathologic finding includes a fish scale pattern seen on hematoxylin and eosin staining representing SPS crystals. SPS-induced pseudotumor formation does not seem to be dose dependent; investigators have reported the development of SPS-induced ischemic pseudotumor after a wide range of doses, ranging from merely 2 doses to scheduled administration up to 1 year.1Bui M. Chou S.Y. Faubert P. et al.Resin-induced colonic pseudotumor: rare complication from chronic use of potassium binders in a hemodialysis patient.Case Rep Nephrol. 2016; 20163692086PubMed Google Scholar, 2Chatila A.T. Bilal M. Merwat S. Kayexalate-induced colonic pseudotumor.Clin Gastroenterol Hepatol. 2019; 17: e73Abstract Full Text Full Text PDF PubMed Scopus (4) Google Scholar, 3Goh L.H. Wong J. Chng T.W. et al.Extra-intestinal sodium polystyrene sulfonate crystal-induced inflammatory pseudotumour in an asymptomatic haemodialysis patient.Int Urol Nephrol. 2021; 53: 1265-1266Crossref PubMed Scopus (1) Google Scholar Recognition of this entity is therefore important irrespective of the SPS dose and duration to avoid unnecessary interventions.1Bui M. Chou S.Y. Faubert P. et al.Resin-induced colonic pseudotumor: rare complication from chronic use of potassium binders in a hemodialysis patient.Case Rep Nephrol. 2016; 20163692086PubMed Google Scholar SPS-induced ischemic pseudotumor regresses with discontinuation of the drug. This case highlights the potential for mistaking SPS-induced pseudotumor formation for malignancy. In addition, in the absence of a dose response, a single dose of SPS can lead to the development of ischemic pseudotumor.

A comprehensive and modular set of appliance operation MILP models for demand response optimization

Demand response programs are essential to enable accommodating larger shares of variable power generation based on renewable sources, the deployment of which is imperative for decarbonizing the economy and mitigating global warming. Consumers/prosumers are increasingly exposed to and may benefit from time-differentiated energy prices aimed to induce changes in regular consumption patterns. These changes are also beneficial for retailers and grid operators in face of the variability of wholesale market prices, renewable energy availability and grid conditions. The optimization models to be implemented in autonomous home energy management systems require a rigorous modeling of appliance operation to generate effective load scheduling solutions, respecting their physical operation principles and use patterns in everyday life. A balance should be sought between the detail level of optimization models and the computational requirements to generate usable solutions having in mind their implementation in low-cost processors. This paper presents a comprehensive and modular set of mixed-integer linear programming models aimed at enabling their seamless incorporation in home energy management systems, allowing for the integrated optimization of all energy resources (exchanges with the grid, load management, electric vehicle and stationary battery, local microgeneration). Detailed energy consumption optimization models for shiftable, interruptible and thermostatic loads are presented, also including the power cost component and ways of dealing with user's discomfort. The modular models are presented in a building block manner enhancing the flexibility of their utilization in overall models with different objective functions encompassing the economic and comfort dimensions. Computational results are presented for a case study using actual data, which considers a time-of-use tariff with six periods. In addition to comparing with a plain tariff scheme, different consumer profiles are simulated to assess the impact of comfort requirements on cost. These results show that whenever consumers have the flexibility to change their consumption patterns, they are able to lower the net electricity bill by having an energy management system endowed with the models herein proposed to make optimized decisions on their behalf.

Optimal scheduling of a hybrid AC/DC multi-energy microgrid considering uncertainties and Stackelberg game-based integrated demand response

The emergence of solid-state transformers (SSTs) enriches the system structure and operation mode of the multi-energy microgrid (MEMG). This paper depicts a novel hybrid AC/DC MEMG structure based on a three-stage SST, and proposes a two-level optimal scheduling model considering generation and load uncertainties, as well as Stackelberg game-based integrated demand response. In the upper level model for the energy hub operator (EHO), the pricing strategy and equipment dispatch are optimized to maximize profit, and the two-stage adaptive robust optimization and reserve allocation are used to address the uncertainties of renewable generation and loads, respectively. In the lower level model for the demand response aggregator (DRA), the response strategy of different loads, including shiftable, adjustable and replaceable loads, is optimized for surplus maximization. To solve the proposed scheduling model, the two-level optimization problem is transformed to a single-level min–max-min problem according to Karush-Kuhn-Tucker conditions, then it is divided into two subproblems and solved by the column-and-constraint generation algorithm and CPLEX solver. Furthermore, a case study is carried out to validate the effectiveness of the proposed model, and it shows that the total benefit of EHO and DRA can be improved by 5.75% due to the demand response strategy.

Impact of implementing a price-based demand response program on the system reliability in security-constrained unit commitment problem coupled with wind farms in the presence of contingencies

Large scale penetration of highly intermittent wind energy sources has caused new challenges to the reliable operation of power systems. To address these challenges, demand response program is considered as an efficient solution to manage shift-able loads. In this paper, the impact of demand response on power system reliability has been evaluated by developing a two-stage stochastic security constraint unit commitment that considers both the wind volatility and line outages at the same time. The allocation of ramping products and spinning reserves to cover these uncertainties has also been modeled. wind curtailment and load shedding are considered as alternative strategies, and an optimal exchange between them and the use of spinning reserves and flexible ramping products has been modeled in the objective function. To assess the system reliability, the expected load not served (ELNS) index was evaluated in different cases. The proposed scheme as a mixed-integer linear programming problem was solved by a scenario-based two-stage stochastic programming method. The IEEE test systems 6-bus, modified 24-bus, and 118-bus were examined numerically. The results show that the simultaneous consideration of demand response and flexible ramping product coordinated with wind energy has adequate flexibility to reduce the reliability index and system operational cost.

Triceps surae strength balancing as a management option for early-stage knee osteoarthritis: A patient case

BackgroundKnee osteoarthritis is a progressive disease that may require management for years before knee arthroplasty can be considered. Previously reported musculoskeletal models suggest that rebalancing the strength of the triceps surae muscles can reduce the joint loads. MethodsA single patient diagnosed with mild/moderate medial left knee osteoarthritis was treated with botulinum toxin injections in the gastrocnemius muscle of the calf, based on the hypothesis that this would rebalance the triceps surae load distribution and reduce tibiofemoral joint loads. Tests were performed before and 4 weeks after injection to record functional clinical scores and to obtain lower limb joint kinematic and kinetic data of walking, which were subsequently analyzed with a musculoskeletal simulation model. FindingsThe patient experienced a clinically relevant improvement in self-reported pain levels in activities-of-daily-living, stair climbing, 6 minutes' treadmill test, range-of-motion, and in the functional knee questionnaire, KOOS. No improvement was seen when performing lunges. The musculoskeletal simulations showed the expected shift in loads between the muscles, reduced knee loads, and improvement of the load symmetry between the legs. InterpretationThe case corroborates the hypothesis, and this suggests further tests by randomized controlled trials. If confirmed, this simple and reversible medical intervention can improve the management of early-stage knee osteoarthritis.

Voltage instability curtailment and quality improvement with phasor measurement unit in power system

PurposeThe earlier methods are more resilient to improvements such as load shift and path change. This results in problems such as a voltage drop and a high reactive flux. In addition, due to the delay, congestion or interruption of the transmission, the system cannot receive all phasor measurement unit (PMU) measurements at the relevant time as well as the presence of noise in the received data.Design/methodology/approachWith the development of wide area measurement system technologies, it seems to be possible to track voltage stability online via time-stamped PMUs. As the voltage instability causes a voltage decomposition, voltage instability is one of the most important problems when monitoring the power supply.FindingsThis harmonic distortion significantly decreases the data quality in the grid. As a result, instability ascertainment based on PMU has been suggested as a method for detecting voltage instability in power systems monitored with PMU. In addition, a technique called instability amendment via load dropping has been proposed to keep the device from collapsing due to voltage failure.Originality/valueTo improve the power output, the power prominence melioration technique was developed. This proposed system has been implemented in MATLAB Simulink and compared with the recent researches.

A two-stage framework for demand-side management and energy savings of various buildings in multi smart grid using robust optimization algorithms

Advances in technology and population growth are two factors responsible for increasing electricity consumption, which directly increases the production of electrical energy. Also, due to environmental, technical and economic constraints, it is challenging to meet the demand at certain hours, such as peak hours. Therefore, it is necessary to manage the network consumption to modify the peak load and complete the power system constraints. One way to achieve this goal is to use a demand response program. The best infrastructure for running these types of programs is the smart grid (SG). This paper first considers many shiftable loads of different kinds in the SG, including residential, commercial, and industrial microgrids. The load shift method is, then, modeled as a multi-objective optimization problem to manage the shiftable load consumption of the SG. The main goals of this problem include reducing the cost of customer bills, the peak load, losses and improving network voltage. Simulations are performed by two methods of Simplex and Improved Grey Wolf Optimization (IGWO). The Simplex method is implemented with the CPLEX solver in General Algebraic Modelling System (GAMS) software and the IGWO algorithm is implemented in MATLAB software. Then, the effect of implementing the proposed program with both methods is examined and compared. For example, in terms of reducing the peak load, the CPLEX method could reduce the peak in the residential, commercial, and industrial microgrids by 6.7%, 1%, and 16% more than IGWO, respectively. CPLEX also can reduce the production costs of residential, commercial, and industrial microgrids by more than 3.5, 2.2, and 3.9% compared to IGWO. In general, the CPLEX solver provides better results than the IGWO in many cases.