Normalized Performance Index Research Articles

Thermal and aging performance characteristics of pouch-type lithium-ion battery using heat pipes under nonuniform heating conditions

Lithium-ion (Li-ion) batteries are excellent energy storage technologies for electric vehicles. However, the performance and life cycle of a battery can be degraded by extremely high temperatures under nonuniform heating conditions. This study aims to investigate the performance improvement of a battery thermal management system (BTMS) using heat pipes (HP) under various heat generation conditions. The cooling performances of the BTMS using aluminum plates (AP) and HP were compared by analyzing battery temperature and life cycle while varying the discharge rate (C-rate) from 1C to 5C and the ambient and liquid temperatures from 25 °C to 40 °C. Furthermore, the nonuniform heat ratio, defined as the heat ratio between the tab and bottom of the battery, was introduced to emulate the uneven temperature distribution, ranging from 1 to 3. The average temperature (Tavg) increases of AP and HP decreased by 22.7 % and 32 %, respectively, compared with that using natural convection (NC). HP showed a much lower maximum temperature (Tmax) and temperature difference (ΔT) of the battery than AP, owing to the effective heat transfer using the heat pipe. During cyclic operation, HP maintained stable Tmax and ΔT within 34.3 °C and 4 °C, respectively. As the nonuniform heat ratio increased, Tmax increased significantly, which was more severe in AP than in HP. HP exhibited up to a 41 % higher normalized performance index of Tmax than AP. Additionally, with the nonuniform heat ratio increasing from 1 to 3 at a C-rate of 5C, the ΔT of AP and HP increased by 7.6 °C and 4.4 °C, respectively. Finally, the normalized equivalent full cycles of AP and HP at a nonuniform heat ratio of 3 and a C-rate of 5C decreased by 4.3 % and 1.6 %, respectively, compared to their performance under uniform heat.

Performance investigation and estimation of the 1 kWp photovoltaic array for an isolated hilly area in India

AbstractThis paper presents the assessment of solar resources, investigation of performance, and estimation of normalized performance indices of a 1 kWp Solar PV system in India's climatology of an isolated hilly area. The monthly and yearly mean normalized performance indices are estimated. The annual mean values of the daylight hours, cell temperature, and ambient temperature are 12.7 h/d, 10.89°C, and 1.25°C, respectively. The yearly mean values and corresponding ranges of monthly mean values of capacity factor, performance ratio, array yield, reference yield, final yield, array capture loss and system loss are obtained as 23.60%, 59.82%, 2.83 h/d, 4.63 h/d, 2.69 h/d, 1.8 h/d, 0.14 h/d and (17.56–29.07)%, (47.93–75.55)%, (2.24–3.42) h/d, (2.85–6.1) h/d, (2.13–3.25) h/d, (0.60–2.99) h/d and (0.11–0.17) h/d, respectively. The Levelized Cost of energy is reduced to 85% and 68.22% by using the proposed solar PV/ battery system compared to DG and DG/Battery systems. A saving of 14.8 kl of diesel and the corresponding reduction of emissions of carbon monoxide (244.22 kilograms), unburned hydrocarbons (10.66 kg), particulates (1.48 kg), and nitrogen Oxides (229.42 kg) have also been achieved per year. These findings effectively provide optimal power solution strategies for policymakers in the concerned area.

Performance analysis and evaluation of 10 kWp solar photovoltaic array for remote islands of Andaman and Nicobar

The Andaman and Nicobar island, an union territory of India, is a group of islands located in the Indian Ocean where 93.63% of total power is generated by the diesel generators for which solar photovoltaic (PV) generation system is a viable alternative to meet the load demand of the islands. The proposed paper presents the solar PV resource assessment, performance analysis, and evaluation of normalized performance indices obtained from 10 kWp solar PV array considered at the climatic conditions of five islands of Andaman and Nicobar, mainly Smith, Middle Andaman, Baratang, Car Nicobar and Katchal. The yearly mean normalized performance indices like array yield (Yarr), reference yield (Yref), final yield (Yfin), performance ratio (PR), array capture loss (Lcap), system loss (Lsys) and capacity factor (CF) have been evaluated. The variation of ambient temperature (Tamb) and cell temperature (Tcell) have also been presented. The obtained results show yearly mean capacity factor and performance ratio are in the range of (13.73–14.61)% and (64.70–64.93)%, respectively. The yearly mean array yield, reference yield, final yield, array capture loss and system loss are (3.66–3.90) h/d, (5.08–5.43) h/d, (3.30–3.51) h/d, (1.42–1.53) h/d and (0.37–0.39) h/d, respectively.

Performance indices evaluation and techno economic analysis of photovoltaic power plant for the application of isolated India’s island

The usage of PV technology based electricity generation is much more popular nowadays and is being adopted by many countries as an alternative option for fossil fuel power generations. The present paper focuses on normalized performance indices and techno-economic based feasibility analysis of PV plant in an Indian isolated island, Andaman and Nicobar island where grid supply is not feasible. The estimated normalized indices range obtained for the aforementioned island are 3.0–5.10h/d for array yield, 2.70–4.59h/d for final yield, 1.10–1.95h/d for array capture losses, 0.3–0.51 for system losses and 68.55–80.22% for performance ratio. The island annual global solar radiation is found to be 5.29kWh/m2/day with clearness index lies within 0.42–0.68. The techno-economic analysis is performed by using HOMER simulation software to obtained optimal size by assuming typical seasonal load profile for a single household. The obtained optimal PV configuration contains 2.5kW PV array, 12 numbers of battery and converter size of 2.0kW with cost of energy is found to be $0.398, net present cost of $9637, 224$/year operating cost, 9.3years as battery life, initial capital cost of $6773 and renewable fraction of 1.

Margin-Based Framework for Online Contingency Selection in Unbalanced Networks

A framework for performing fast online contingency selection in unbalanced power systems is presented in this paper. Selection methods are typically based on the principle of identifying the effect of contingencies on multiple normalized performance indices and ranking them using the results. Presently used performance indices are highly nonlinear and they are known to mask the effects of single contingencies leading to misclassifications. In this paper, we propose two new methods, one relying on margin-based performance indices and another based on state sensitivity. New performance indices are proposed based on margins of 1) circuit loading, 2) bus voltages, and 3) reactive power. In addition, a state sensitivity method is proposed which estimates a system's post contingency operating state via a single iteration of the quadratized power flow model and provides estimates of post contingency line loading, bus voltages, and reactive power levels. Numerical experiments on a three phase version of the IEEE Reliability Test System show that the proposed performance indices yield more accurate results, at a computational cost comparable to a single power flow iteration. The state sensitivity method is more accurate in identifying critical contingencies but its computational cost is higher. The method has been also demonstrated in the larger PEGASE systems.

Converting reliability constraints by adaptive quantile estimation

The safety factor required to achieve certain reliability turns out to be related to the quantile of the normalized performance index of interest. Quantile functions (quantiles as functions of design parameters) are therefore essential to convert a reliability constraint into the equivalent safety-factor constraint. It is shown in this paper that the estimation of these quantile functions can be achieved by fitting the tail of the normalized performance index. In the cases where the tail varies drastically with the design parameters, a heuristic algorithm is developed to find a series of probability distributions to adaptively fit the tails. Once these probability distributions are obtained, a series of quantile functions can be found to facilitate the conversion of the reliability constraint. Three examples are investigated to verify the proposed approach. Although the theoretical bounds for the approach cannot be proved, the results show that the approach can effectively convert reliability constraints of the three examples into equivalent safety-factor constraints.

Approximation of reliability constraints by estimating quantile functions

A novel approach is proposed to effectively estimate the quantile functions of normalized performance indices of reliability constraints in a reliability-based optimization (RBO) problem. These quantile functions are not only estimated as functions of exceedance probabilities but also as functions of the design variables of the target RBO problem. Once these quantile functions are obtained, all reliability constraints in the target RBO problem can be transformed into non-probabilistic ordinary ones, and the RBO problem can be solved as if it is an ordinary optimization problem. Two numerical examples are investigated to verify the proposed novel approach. The results show that the approach may be capable of finding approximate solutions that are close to the actual solution of the target RBO problem.

Analyzing parallel program performance using normalized performance indices and trace transformation techniques

In this paper we describe how a performance tuning tool-set, AIMS, guides the user towards developing efficient and scalable production-level parallel programs by locating performance improvement opportunities and determining optimization benefits. AIMS's Xisk helps identify potential optimizations by computing various pre-defined normalized performance indices from program traces. Inspection of these index point to specific optimizations that may benefit program performance. After identifying and characterizing performance problems, AIMS's MK can provide quantitative estimates of performance benefits to help the user avoid arduous optimizations that may not lead to expected performance improvements by. MK also helps identify potential pitfalls or benefits of changing any of various system parameters. Based on MK's performance projection, an informed decision regarding the most beneficial program optimizations or upgrades in execution environments can be chosen.

Plant-wide feedback control performance assessment using an expert-system framework

There are many applications where multivariate control schemes are justified from an economic and quality improvement standpoint. Nevertheless, singleinput single-output (SISO) and multi-input single-output (MISO) controllers remain the most commonly used controllers in process applications. This paper reviews SISO control performance assessment and details the development of an expert system that quantifies control loop performance on an on-going basis. The expert system schedules each of a newsprint mill's control loops for analysis, directs the sampling of data, verifies the validity of the data, and quantifies the loop's performance using a normalized performance index.

Plant-Wide Feedback Control Performance Assessment using an Expert System Framework

There are many applications where multivariate control schemes are justified from an economic and quality improvement standpoint. Nevertheless, singleinput single output (SISO) and multi-input single-output (MISO) controllers remain the most commonly used controllers in process applications. This paper reviews SISO control performance assessment and details the development and success of an expert system that quantifies control loop performance on an on-going basis. The expert system schedules each of a newsprint mill's control loops for analysis, directs the sampling of data, verifies the validity of the data, and quantifies the loop's performance using a normalized performance index.

Performance assessment measures for univariate feedback control

AbstractA normalized performance index, η(b), is introduced to characterize the performance of feedback control schemes. η(b) is attractive because it provides a measure of the proximity of control to minimum variance control, which is the optimal feedback control provided that the process can be described by a linear transfer function with additive disturbance. Both time domain and spectral interpretations of this performance index are discussed. A fast, simple, on‐line method for estimating η(b) is given, along with some of the statistical properties of the estimator. Simulation and industrial examples demonstrate the utility of η(b/)