Peak Load Power Research Articles

SAVING RESOURCES IN THE CONSTRUCTION OF HYDROELECTRIC POWER PLANTS

The article describes run-of-the-river hydroelectric power plants. The authors specify the importance of performing technical and economic calculations in justifying the large-sized units of the water-supplying channel of a run-of-the-river hydroelectric power plant: turbine pits and suction (discharge) pipes. The study shows that the amount of construction work and the total cost of building a hydroelectric power plant depend on the size of these water supply units. The research objective is to analyze the validity of establishing the main dimensions of the suction pipes for modern technical and economic conditions. The researchers use the discounted income method. The calculations are performed for a hydroelectric power plant with an elbow suction pipe. The analysis of how the operating conditions of a hydroelectric power plant influence the savings of construction resources is carried out. The analysis shows that saving construction resources by reducing the length of the suction pipe is justified if the hydroelectric power plamt is designed to work only at peak power loads. For hydroelectric power plants operating at semi-peak or base power loads, the additional construction costs would be appropriate if leading to the decrease in pressure loss and to the increase in electricity generation.

Multi-objective optimization model predictive dispatch precooling and ceiling fans in office buildings under different summer weather conditions

In summer, a ceiling fan has a tremendous potential to cool rooms, resulting in energy saving and a peak load reduction. During the critical peak pricing (CPP) period of the electricity, one method to attain substantial energy cost saving is to turn off the heating, ventilating and air conditioning (HVAC) system, but this may result in overheating. Fortunately, precooling and ceiling fans can be used to reduce the feeling of hot sensation. Therefore, the best control strategy for an HVAC system and ceiling fans is to maximize energy cost saving without much thermal comfort sacrifice. This paper presents a multi-objective optimization model predictive control (MO-MPC) of precooling temperature setpoint and ceiling fan speed. The proposed MO-MPC integrates an optimization engine, Dakota, and a detailed energy simulation tool, EnergyPlus, to determine the optimal control strategies considering the energy cost and thermal comfort simultaneously. A sub-program of substituting EnergyPlus with decision tree regression models for building climate prediction is deployed. If the calculation time is too long to achieve real-time control, this sub-program can be adopted to accelerate the calculation. In this study, the proposed MO-MPC framework is applied to a small and large building in four different cities with different CPPs. For a summer day, compared with the baseline cases of no precooling and no ceiling fan, the optimal strategies for the small building achieve energy cost savings between 10.3% and 33.3% and a peak power load decrease from 44.0% to 51.9%. Without precooling but with a ceiling fan control, on a particular summer day, for the large building case in Shanghai, 7.4% energy saving is achieved. The optimal control of the precooling temperature and ceiling fans result in a 14.4% energy cost saving. By using the decision tree regression models instead of EnergyPlus, the calculation time of the big office reduces from about 10 hours 40 minutes to 24.4 minutes.

A Novel Thermal Energy Storage System in Smart Building Based on Phase Change Material

This paper presents a novel phase change material based thermal energy storage system (PCMTESS) that is suitable for smart building energy management, together with its corresponding thermal-electric combined two-stage dispatching strategy. Benefiting from the phase change materials’ thermal characteristic of absorbing or releasing a significant amount of heat at a constant temperature, this thermal energy storage system is endowed with a high capacity and a relatively stable thermal state during its charge/discharge process. To evaluate the thermal performance of the PCMTESS, which is integrated as a part of building wallboard, a detailed analytic thermodynamic building model is proposed that considers the influence of the forced air convection and the external environments, such as solar radiation. Furthermore, a two-stage electric-thermal combined dispatching scheme is designed to minimize the electricity consumption expenditure and power fluctuation on the premise of maintaining a comfortable indoor temperature. Simulation studies on a smart building indicate that the proposed thermal energy storage system is a feasible and economical solution for solving peak load shaving and power fluctuation.

A 1-mW Class-AB Amplifier With −101 dB THD+N for High-Fidelity 16 $\Omega$ Headphones in 65-nm CMOS

A low-power class-AB amplifier for high-fidelity headphones is presented. The linearity of a class-AB amplifier strongly depends on the loop gain over the audio band and voltage swing. In this paper, a cascode-driven mesh technique limits the number of high-swing nodes in the output stage, thereby preserving the loop gain of the preceding gain stages. A frequency compensation scheme is proposed that extends the unity-gain bandwidth (UGB) and increases the loop gain at 20 kHz. Combining these two techniques, the amplifier achieves −101.4-dB total harmonic distortion plus noise (THD+N) over the full audio band, the lowest ever reported nonlinearity among sub-milliwatt CMOS class-AB amplifiers. The amplifier delivers 51.2-mW peak power to a $16\Omega \|0.33$ -nF load while consuming 0.97 mW of total static power. It has UGB of 12.3 MHz and SNR of 108 dB. These results are consistent when measured over eight test chips. Compared to the recent prior art, the amplifier exhibits >12 dB better linearity and >14-dB dynamic range. This results in 2.5 $\times $ improvement in figure of merit (FOM = Peak Load Power/(Quiescent Power $\times $ THD+N[%])). It occupies 0.16 mm 2 in a standard 65-nm CMOS.

Multi-objective planning for the allocation of PV-BESS integrated open UPQC for peak load shaving of radial distribution networks

Abstract This paper presents a multi-objective planning approach for the optimal allocation of PV-BESS integrated open UPQC (PV-BESS-UPQC-O) for peak load shaving of radial distribution networks. The open UPQC (UPQC-O) is a custom power device which consists of series and shunt inverters. It is designed to provide reactive power compensation and to mitigate some power quality problems. The UPQC-O is integrated with BESS to inject active power to the network during peak hour for peak load shaving. The charging of BESS is to be done using PV panel. A multi-objective optimization problem is formulated, in which maximization of peak load shaving, minimization of cost of placement of PV-BESS-UPQC-O, and minimization of total power loss during peak load demand with the placement of PV-BESS-UPQC-O are the objective functions. The limits on bus voltage magnitude, line current flow, and PV capacity are the constraints of this optimization problem. The Pareto-based multi-objective particle swarm optimization (MOPSO) is used to simultaneously optimize these objectives so as to obtain a set of Pareto-approximation solutions. From this set, a distribution network owner can choose a solution depending upon its desired level of peak load shaving, power loss, and capital expenditure budget.

Experimental Study on the Demand Shifting Effects of PCM Integrated Air-Conditioning Duct

The proportion of electricity used for civil buildings is increasing, which intensifies the imbalance between the demand side and supply side of the grids and leads to a large decrement in grid efficiency and large energy losses. The phase change material (PCM) can be used to store numerous heat or cold for heating, ventilation, and air-conditioning (HVAC) systems for its phase change temperature range suitable for maintaining comfortable building thermal environment. Utilizing PCM for HVAC is an important way to mitigate fluctuations in the power consumption of buildings. This paper proposes a new type of air-conditioning duct combined with PCM. The demand shift effects of the PCM integrated air-conditioning duct is studied through experiments. The PCM material ingredients are designed according to the required phase change temperature range. The feasibility of PCM application in HVAC ducts is verified. The results show that air-conditioning duct combined with PCM can keep the indoor temperature in a comfortable range during the power peak load after shutting down chiller.

Parallel Processing of Probabilistic Models-Based Power Supply Unit Mid-Term Load Forecasting With Apache Spark

Mid-term load forecasting (MTLF) of power supply unit (PSU) is an essential part of refined distribution network planning. By analyzing a large amount of historical data accumulated in electric automation systems, accurate MTLF result can be obtained with the help of big-data and parallel computing technology. In this paper, a dynamic bayes network (DBN)-based MTLF model is proposed to forecast the peak power load of next year of each PSU. In the first stage, we improve the accuracy of MTLF model by using dynamic radius DBSCAN algorithm to determine the optimal state division. In the second stage, to improve the computation efficiency, the calculations of multiple probability matrixes and the modified forward algorithm are implemented on an apache spark-based parallel computing platform. The experiment results indicate that the parallel processing of DBN-based MTLF model has superior performance in accuracy, efficiency, and versatility.

Lateral Misalignment Tolerant Wireless Power Transfer With a Tumbler Mechanism

A transmitting coil with a tumbler structure is presented to improve lateral misalignment tolerance of a wireless power transfer (WPT) system with a planar receiver. The tumbler is made of an acrylic ball and soil. A planar spiral receiving coil wound by Litz wire is centered by Nd–Fe–B magnets. A spherical cap transmitting coil centered also by Nd–Fe–B magnets sticks on the inner surface of the acrylic ball. When lateral misalignment occurs, the transmitting and receiving coils can achieve self-align with the action of magnetic force, and thus the transfer efficiency is improved. A WPT system consisting of two coils with 6 cm outer radii resonated at 107 kHz is studied. A concise theoretical analysis based on circuit model is given first, and then experimental data are reported. The positive correlation between magnetic force and tracking range is given by comparison. Especially, when the transfer distance is 1.5 cm, the WPT system has a 75.5% peak efficiency and a 3.52 W load power at zero lateral misalignment and the tracking range is from 0 to 8.5 cm; In the tracking range the WPT system has a 70.0% average efficiency and the load power maintains over 94.7% of the peak load power. With the increase of transfer distance, the improvements of transfer efficiency and the tracking range both decrease gradually, and the efficiency loss within the tracking range also increases gradually.

Stochastic security-constrained operation of wind and hydrogen energy storage systems integrated with price-based demand response

Because of highly increasing energy consumption, environmental issues and lack of common energy sources, the use of renewable energy sources especially wind power generation technology is increasing with significant growth in the world. But due to the variable nature of these sources, new challenges have been created in the balance between production and consumption of power system. The hydrogen energy storage (HES) system by storing excess wind power through the technology of power to hydrogen (P2H) and delivering it to the electricity network through hydrogen-based gas turbine at the required hours reduces not only wind alternation but can play an important role in balancing power production and consumption. On the other hand, power consumers by participating in demand response (DR) programs can reduce their consumption at peak load or wind power shortage hours, and increase their consumption at low-load or excess wind power hours to reduce wind power spillage and system energy cost. This paper proposes a stochastic security constrained unit commitment (SCUC) with wind energy considering coordinated operation of price-based DR and HES system. Price-based DR has been formulated as a price responsive shiftable demand bidding mechanism. The proposed model has been tested on modified 6-bus and 24-bus systems. The numerical results show the effect of simultaneous consideration of HES system and price-based DR integrated with wind energy on hourly generation scheduling of thermal units. As a result there is some reduction in wind generation power spillage and daily operation cost.

Energy storage allocation in wind integrated distribution networks: An MILP-Based approach

Due to the unpredictable nature of wind energy and non-coincidence between wind units output power and demand peak load, wind units is deemed as an unreliable source of energy. In order to compensate for the short-term fluctuation of wind energy, deployment of energy storage (ES) units in various types have been introduced as a viable solution. This paper develops a stochastic mathematical model for the optimal allocation of ES units in active distribution networks (ADNs) in order to reduce wind power spillage and load curtailment while managing congestion and voltages deviation. Nonlinearities of the original formulation are converted to linear equivalents and the final model lies within the computationally tractable mixed-integer linear programming (MILP) fashion. The IEEE 33-bus 12.66 kV radial distribution test system is utilized to illustrate the effectiveness of the proposed methodology. It was found that the rated power and capacity of ES units are depends on wind units' location and penetration level, in such a way that ES units are allocated near wind units to absorb excessive wind energy as much as possible. Furthermore, the results indicate ES units are useful for other purposes such as voltage management issue even if the wind units are not allocated.

Charge Transport in Energy Storage and Conversion Devices

Charge transport is one of the most important phenomena, which directly influences the performance of the energy storage and conversation devices. In this work, the authors provide an overview of various rechargeable energy storage battery chemistries and designs, and discuss the charge transport processes related to power capability of the lithium-ion technology. The load distribution by parallel connection of high power batteries or supercapacitor and high-energy cells is discussed and general conclusions are provided. Thus, the reduced peak power load on the high-energy cells are approved by simulation and experiment in passive parallel circuitry of high power and a high energy lithium-ion cells. The definition and advantages of the earlier deduced electrical loss time are explained. It is shown, that at a constant C-rate, defined as the ratio of the applied current and the rated cell capacity in Ah, the electrical loss time has a direct linear correlation to efficiency, and that the electrical loss time allows a direct power capability comparison of various battery cell chemistries and systems. The power capability, specific energy, and energy density of the industry relevant Li-ion battery cells based on electrical loss time approach are summarized and the following conclusions made. Today prismatic cells reach the maximum specific energy of small cylindrical cells, at the same time showing a little bit better power capability, than the investigated high energy cylindrical cells.

Loading Range for the Development of Peak Power in the Close-Grip Bench Press versus the Traditional Bench Press.

The close-grip bench press (CGBP) is a variation of the traditional bench press (TBP) that uses a narrower grip (~95% biacromial distance) and has application for athletes performing explosive arm actions where the hands are positioned close to the torso. Limited research has investigated CGBP peak power. Twenty-six strength-trained individuals completed a one-repetition maximum TBP and CGBP. During two other sessions, subjects completed two repetitions as explosively as possible with loads from 20% to 90% for each exercise, with peak power measured by a linear position transducer. A factorial ANOVA calculated between- and within-exercise differences in peak power. Partial correlations controlling for sex determined relationships between absolute and relative strength and peak power load. Peak power for the TBP occurred at 50% 1RM, and 30% 1RM for the CGBP. There were no significant (p = 0.680) differences between peak power at each load when comparing the TBP and CGBP. For the within-exercise analysis, there were generally no significant differences in TBP and CGBP peak power for the 20–50% 1RM loads. There were no significant relationships between strength and peak power load (p = 0.100–0.587). A peak power loading range of 20–50% 1RM for the TBP and CGBP is suggested for strength-trained individuals.

Electric Vehicle Charging Scheme for a Park-and-Charge System Considering Battery Degradation Costs

This paper studies the electric vehicle (EV) charging scheduling problem of a park-and-charge system with the objective to minimize the EV battery charging degradation cost while satisfying the battery charging characteristic. First, we design the operating model of the system while taking the interests of both customers and parking garage into consideration. Subsequently, a battery degradation cost model is devised to capture the characteristic of battery performance degradation during the charging process. Taking into account the developed battery degradation cost model, EV charging scheduling problem is explored and a cost minimization problem is formulated. To make the problem tractable, we investigate the features of the problem and decompose the problem into two subproblems. A vacant charging resource allocation algorithm and a dynamic power adjustment algorithm are proposed to obtain the optimal solution of cost minimization. Several simulations based on realistic EV charging settings are conducted to evaluate the effectiveness and applicability of the proposed methods in discussed charging scenarios. Simulation results exhibit the superior performance of the proposed algorithms in achieving the most degradation cost reduction and the lowest peak power load compared with other benchmark solutions, which is beneficial for both customers and charging operators.

Internal Loads, but Not External Loads and Fatigue, Are Similar in Young and Middle-Aged Resistance-Trained Males during High Volume Squatting Exercise †

Little is known about the internal and external loads experienced during resistance exercise, or the subsequent fatigue-related response, across different age groups. This study compared the internal (heart rate, OMNI ratings of perceived exertion (RPE), session RPE) and external loads (peak velocity and power and volume load) during high volume squatting exercise (10 × 10 at 60% one-repetition maximum (1RM)) and the fatigue-related response (maximal voluntary contraction (MVC), voluntary activation (VA), resting doublet force, peak power, and blood lactate) in young (n = 9; age 22.3 ± 1.7 years) and middle-aged (n = 9; age 39.9 ± 6.2 years) resistance-trained males. All internal load variables and peak velocity illustrated unclear differences between groups during exercise. Peak power and volume load were likely higher in the young group compared to their middle-aged counterparts. The unclear differences in MVC, VA and blood lactate between groups after exercise were accompanied by very likely greater decrements in resting doublet force and peak power at 20 and 80% 1RM in the middle-aged group compared to the young group. These data indicate that internal load is not different between young and middle-aged resistance-trained males, though certain external load measures and the fatigue response are.

Research on wind power grid-connected operation and dispatching strategies of Liaoning power grid

As a kind of clean energy, wind power has gained rapid development in recent years. Liaoning Province has abundant wind resources and the total installed capacity of wind power is in the forefront. With the large-scale wind power grid-connected operation, the contradiction between wind power utilization and peak load regulation of power grid has been more prominent. To this point, starting with the power structure and power grid installation situation of Liaoning power grid, the distribution and the space-time output characteristics of wind farm, the prediction accuracy, the curtailment and the off-grid situation of wind power are analyzed. Based on the deep analysis of the seasonal characteristics of power network load, the composition and distribution of main load are presented. Aiming at the problem between the acceptance of wind power and power grid adjustment, the scheduling strategies are given, including unit maintenance scheduling, spinning reserve, energy storage equipment settings by the analysis of the operation characteristics and the response time of thermal power units and hydroelectric units, which can meet the demand of wind power acceptance and provide a solution to improve the level of power grid dispatching.

Peak Power Load and Energy Costs Using the Example of the Startup and Idling of a Grinding Machine

Countries worldwide are experiencing changes in their electricity generating portfolio, from base load sources – coal or nuclear – to more sustainable but more volatile and intermittent sources – wind or photovoltaics. Industrial, high wattage consumers with machines that have frequent short-term peak power loads can cause grid failure when a demand peak coincides with an available power lull. These demand peaks are fulfilled by fossil-fuel-based peaking power plants. To avoid additional energy and cost expenditures of peaking power plants and reduce the lifecycle impact of production, peak demand needs to be mitigated. A procedure is proposed to reduce the peak loads of a grinding machine by controlling machine parameters. First, spindle energy and power data is measured while varying ramp up time to evaluate peak load and energy consumption trade-offs. Then, a model is developed with three different objectives: minimize energy, peak power, or cost.

An Experimental Fuzzy Inference System for Global Grid Electricity Peak Power Load Forecasting Third Core Module of First Console on G2P3S

Our World gives several symptoms of climate change. Devastating draughts increase (negative for World (-)), global mean temperature increase (-), lightning strikes increase (-), sea ice cover melt (-), tree mortality increase (-), and forest degradation increase (-) have been observed for decades. They are all negative measures for continuity of life. Diversity of species has been decreasing, so that life on Earth is dying. Only responsible specie for this situation is humankind. This study presents a small footstep to prevent this situation. Modeling of a 100% renewable power grid on World (Global Grid) is eminent. Annual peak power load (Gigawatt: GW, Kilowatt: kW) (peak demand or load) forecasting in power demand side is crucial for global grid modeling. This study presents an experimental fuzzy inference system for the third core module (100 years’ power demand forecasting) of the first console (long term prediction) of Global Grid Peak Power Prediction System (G2P3S). The inputs (world population, global annual temperature anomalies °C) and the output (annual peak power load demand of Global Grid in GW) are modeled with seven triangular fuzzy input membership functions and seven constant output membership functions. The constant Sugeno-Type fuzzy inference system is used in the current experimental model. The maximum absolute percentage error (MAP) is calculated as 45%, and the mean absolute percentage error (MAPE) is found as 39% in this experimental study. The MAP and MAPE of the first core module model (Type 1) were 0,46 and 0,36. The MAP and MAPE of the second core module model (Interval Type 2) were 0,46 and 0,36. As a result, this study is a good start for the third core module of the first console on Global Grid Peak Power Prediction System research, development, demonstration, & deployment (RD3) project. This experimental study also warns humankind in this subject. Hopefully, the most polluting societies on our World such as China, United States, India, Russia, Japan, Germany, South Korea, and Canada take urgent actions to start to build the foundations of 100% renewable power global grid by organizing a global grid consortium.

System dynamics of oxyfuel power plants with liquid oxygen energy storage

Traditional energy storage systems have a common feature: the generating of secondary energy (e.g. electricity) and regenerating of stored energy (e.g. gravitational potential, and mechanical energy) are separate rather than deeply integrated. Such systems have to tolerate the energy loss caused by the second conversion from primary energy to secondary energy. This paper is concerned with the system dynamics of oxyfuel power plants with liquid oxygen energy storage, which integrates the generation of secondary energy (electricity) and regeneration of stored energy into one process and therefore avoids the energy loss caused by the independent process of regeneration of stored energy. The liquid oxygen storage and the power load of the air separation unit are self-adaptively controlled based on current-day power demand, day-ahead electricity price and real-time oxygen storage information. Such an oxyfuel power plant cannot only bid in the day-ahead market with base load power but also has potential to provide peak load power through reducing the load of the air separation unit in peak time. By introducing reasoning rules with fuzzy control, the oxygen storage system has potential to be further extended by integrating renewable energy resources into the system to create a cryogenic energy storage hub.

Radiative detached divertor with acceptable separatrix Zeff

The feasibility study is performed for the radiative detached divertor (RDD) concept, which characterizes a variety of detached plasmas with impurity amounts providing the highest levels of divertor radiation without X-point MARFE (XPM), based on a set of restrictive criteria for the leading plasma parameters (LPPs) including, e.g., tolerable peak power loads below 1 MW/m2, low separatrix densities, allowable impurity concentrations, and acceptable Zeff values for a DIII-D like tokamak. For this, extensive simulations with the 2-D edge plasma transport code were done scanning the deuterium and impurity inventories practically for all impurity elements from beryllium to neon and the analysis of LPP variations in these scans is presented. It is shown that, for a given D inventory, the total radiation fraction with an increase in the impurity inventory reaches a flat top level, frad = 0.85 ± 0.01, whereas the higher frad corresponds to XPM. This critical fraction is the same for all elements and values of the D inventory. Successful RDD solutions with a flat top radiation meeting all ad hoc LPP criteria are found for some elements. Boron and nitrogen are shown to be the most promising elements for seeding, since they are capable of providing alone the successful RDD at the lowest concentrations. Several important effects on impurity radiation are considered including: cross-field impurity transport in regions with strong temperature gradients, multi-species thermal force, charge-exchange of impurity ions with D atoms originating from recombination, impurity entrainment by parallel flows, flows caused by inner/outer divertor asymmetries, and Mach ∼ 1 flows reached inside radiation-ionization fronts. The impurity radiation profiles of various elements are analyzed suggesting three patterns differing in the radiation front position with respect to the D ionization source. The modeled relocation of D from the pedestal into divertor regions; an enhanced pedestal enrichment for impurities with high first ionization potential; and RDD capability of confining inside the divertors the large D inventories as neutral atoms, are considered as effects of increasing impurity inventory. The responses of a flat-top RDD to the input parameters variation are studied. For instance, dependencies of LPPs on the input power increase, which express the sharp and even bifurcation transitions between two distinct branches corresponding to the detached and attached divertors, are discussed.

Using air source heat pump air heater(ASHP-AH) for rural space heating and power peak load shifting

In order to mitigate the severe atmospheric pollution caused by the gas emission of scattered coal consumption during winter in the Beijing-Tianjin-Tangshan area, a winter space heating scheme based on the use of an air source heat pump is proposed. This scheme offers clean heating in rural areas by enhancing the efficiency of electric peak adjustment through peak shifting. The paper firstly introduces how to use air source heat pumps to replace heating stoves for rural residential heating, then explains how to use this heating method to adjust power peak load. Finally, computation analysis and experimental verification was carried out to show the effects on the power grid in the Beijing-Tianjin-Hebei area and on farmer households if all the 6 million farmer households in the Beijing-Tianjin-Hebei Region were to use this heating method.