Analysis Of Hybrid Systems Research Articles

Non-Standard Analysis for Regularization of Geometric-Zeno Behaviour in Hybrid Systems

Geometric-Zeno behaviour is a highly challenging problem in the analysis (including simulation) of hybrid systems. Geometric-Zeno can be defined as an infinite number of discrete mode switches in a finite time interval. Typically, for hybrid models exhibiting geometric-Zeno, the numerical simulation either halts or produces false results, because an infinite number of discrete events occur in a given simulation time-step. In this paper, we provide formal methods for regularization of geometric-Zeno behaviour by using a non-standard analysis. In particular, we provide formal conditions for the existence of geometric-Zeno in hybrid systems, and we propose methods to allow geometric-Zeno executions to be continued beyond geometric-Zeno limit points. The concepts are illustrated with a case study throughout the paper.

Performance analysis of Pico Hydro-Solar Photovoltaic Hybrid System

This paper presents experimental results from the operation of the prototype of Pico Hydro-Solar Photovoltaic Hybrid System. This device includes a pico hydro power with a capacity of 600 VA, a 3x200 WP solar panel, 4x60Ah energy storage, solar charge controller, a 1500 W inverter, and a 15-200 watt variable load. In this experiment, measurements of the current flow and terminal voltage were carried out at the output of photovoltaic, picohydro, battery, and inverter at various different load values, ranging from 15 watts to 200 watts. Measurements are made during the day when the intensity of solar radiation is quite high. The measurement results show that the output voltage on each component is relatively stable at various load values, and the load energy requirements are supplied more by solar photovoltaic components in sunny weather and more by pico-hydro in cloudy weather.

Performance evaluation and thermo-economic analysis of a non-evacuated CPC solar thermal hybrid system: an experimental study

ABSTRACT Hybridisation, using an alternative heat source besides solar power, as a back-up unit can be a promising solution for the deployment of Compound Parabolic Concentrator (CPC) technology in low-temperature (100–150°C) industrial applications. In this research, a new integration of a non-evacuated CPC collector with a back-up system was studied for performance optimisation where a thermo-economic evaluation was carried out to investigate the viability of the proposed model for industrial deployment. In operational assessment, the effects of different operating modes as the manipulation of oil mass flow rate and controlling temperature and their interaction on collector efficiency and thermal behaviour were analysed. Results revealed that the maximum collector efficiency reaches about 72% suggesting improvements compared to the similar works. The hybrid mode operation was also evaluated as accurate and instantaneous proportionally to the weather changes. In addition, thermo-economic assessments identified the optimum adjustment based on the minimum payback period.

A Techno-economic Analysis of Anaerobic Digestion and Gasification Hybrid System: Energy Recovery from Municipal Solid Waste in South Africa

Due to the increased population growth in South Africa, particularly in urban areas, the generation of municipal solid waste has increased and so is the demand of energy. Municipal solid waste can be considered a good candidate for electricity generation in South Africa. This approach does not only have the benefit of recovering electricity from municipal waste, but also contributes to the integrated waste management system. This study aimed to investigate the economic feasibility of hybrid of anaerobic digestion and gasification of municipal waste for electricity generation in South Africa. The research developed a techno-economic model to evaluate the financial profitability of waste-to-energy of gasification, anaerobic digestion and a hybrid system of both waste-to-energy technologies. A spreadsheet was developed to evaluate the financial profitability of waste-to-energy of gasification, anaerobic digestion and hybrid system of both waste-to-energy technologies. The techno-economic model provides cost estimates for the implementation of waste-to-energy technologies in South Africa. This is carried out through a set of financial indicators, namely payback period (PBT), net present value (NPV), profit index (PI), internal rate of return (IRR), levelised cost of electricity (LCOE) and levelised cost of waste (LCOW). Hybrid of gasification and anaerobic digestion manifested positive results across all the financial indicators. The study concluded that a hybrid of anaerobic digestion and gasification waste-to-energy is economically viable. In addition, the hybrid system also provides optimal solution for energy recovery and waste disposal, based on the IRR, LCOE and LCOW values. Sensitivity analysis showed that, energy price and capital expenditure are the major variables affecting the hybrid plant’s investment decision.

Comparative analysis of different hybrid energy system for sustainable power supply: A case study

Hybrid Power System (HPS) is an energy system with combination of different regenerative energy sources like Solar, Wind, Geo-Thermal, Biomass and several others to achieve energy sustainability. This paper investigates the feasibility of grid connected and stand-alone hybrid energy system to meet electric load requirement of a community or organization, by utilizing the available resources. Potentiality of different energy sources like solar, wind, bio-gas, etc. along with currently used energy sources is studied thoroughly by taking a case study of Kathmandu University central campus, located at Dhulikhel, Nepal. Technical and economic analysis of on-grid and off-grid hybrid system is performed to get optimum model that supply continuous energy to the end user. Furthermore, the possibility of net metering with national utility has been analysed. The main objective of this study is to identify the suitable energy mixed model, that provide the sustainable energy supply to the university, and recommend the possible energy generators to be added for fulfilling the continuously increasing load demand. The load profile of several years of the University is taken into consideration for forecasting the power demand. The findings of the research show that system when adopted to hybrid system can meet up to 55% of the load by renewable resources. Maximum renewable fraction is found to be 0.603 and maximum renewable penetration of 812%.

Critical Clearing Time Sensitivity for Inequality Constrained Systems

With the growth of renewable generation (RG) and the development of associated ride through curves serving as operating limits, during disturbances, on violation of these limits, the power system is at risk of losing large amounts of generation. In order to identify preventive control measures that avoid such scenarios from manifesting, the power system must be modeled as a constrained dynamical system. For such systems, the interplay of feasibility region (man-made limits) and stability region (natural dynamical system response) results in a positively invariant region in state space known as the constrained stability region (CSR). After the occurrence of a disturbance, as it is desirable for the system trajectory to lie within the CSR, critical clearing time (CCT) must be defined with respect to the CSR instead of the stability region as is done traditionally. The sensitivity of CCT to system parameters of constrained systems then becomes beneficial for planning/revising protection settings (which impact feasible region) and/or operation (which impact dynamics). In this paper, we derive the first order CCT sensitivity of generic constrained power systems using the efficient power system trajectory sensitivity computation, pioneered by Hiskens and Pai in [“Trajectory sensitivity analysis of hybrid systems,” IEEE Trans. Circuits Syst. Fundam. Theory Appl., vol. 47, no. 2, pp. 204-220, Feb. 2000]. The results are illustrated for a single-machine infinite-bus (SMIB) system as well as a multi-machine system in order to gain meaningful insight into the dependence between ability to meet constraints, system stability, and changes occurring in power system parameters, such as, mechanical power input and inertia.

Simple Logistic Hybrid System Based on Greedy Stepwise Algorithm for Feature Analysis to Diagnose Parkinson’s Disease According to Gender

The incidence of Parkinson’s disease (PD) is higher in males than in females. This disease can be diagnosed based on gender through the automatic diagnostic system without visiting a specialist physician. For this purpose, the Simple Logistic hybrid system based on the greedy stepwise search algorithm (SLGS) is presented as a novel approach that involves feature analysis to diagnose PD by gender. Six feature groups were extracted from data of 252 subjects and were used to perform this analysis. When the SLGS hybrid system analysis begins, the effective features are first determined by the greedy stepwise search algorithm and diagnosis of PD was made according to the features that were determined using the Simple Logistic classifier. The performance results that were obtained from this system by gender were evaluated using many statistical metrics. The accuracy ratios were 88.71% and 87.15%, with the minimum number of features for males and females, respectively. Additionally, ROC and PRC area values for both genders approached the 0.9 band, showing that the class separation of patients and healthy individuals was nearly perfect. The performance results and perspective of this study were compared with the single published study that used the same data, and the SLGS hybrid system showed higher performance rates than the other study. In addition, the number of the subjects was higher in this study than in other studies and the SLGS system has not been used before in the literature in this field.

TMTDyn: A Matlab package for modeling and control of hybrid rigid–continuum robots based on discretized lumped systems and reduced-order models

A reliable, accurate, and yet simple dynamic model is important to analyzing, designing, and controlling hybrid rigid–continuum robots. Such models should be fast, as simple as possible, and user-friendly to be widely accepted by the ever-growing robotics research community. In this study, we introduce two new modeling methods for continuum manipulators: a general reduced-order model (ROM) and a discretized model with absolute states and Euler–Bernoulli beam segments (EBA). In addition, a new formulation is presented for a recently introduced discretized model based on Euler–Bernoulli beam segments and relative states (EBR). We implement these models in a Matlab software package, named TMTDyn, to develop a modeling tool for hybrid rigid–continuum systems. The package features a new high-level language (HLL) text-based interface, a CAD-file import module, automatic formation of the system equation of motion (EOM) for different modeling and control tasks, implementing Matlab C-mex functionality for improved performance, and modules for static and linear modal analysis of a hybrid system. The underlying theory and software package are validated for modeling experimental results for (i) dynamics of a continuum appendage, and (ii) general deformation of a fabric sleeve worn by a rigid link pendulum. A comparison shows higher simulation accuracy (8–14% normalized error) and numerical robustness of the ROM model for a system with a small number of states, and computational efficiency of the EBA model with near real-time performances that makes it suitable for large systems. The challenges and necessary modules to further automate the design and analysis of hybrid systems with a large number of states are briefly discussed.

Advanced exergoeconomic analysis of solar-biomass hybrid systems for multi-energy generation

In this study, advanced exergoeconomic analysis of solar-biomass hybrid energy systems for the northern part of Cameroon is conducted. Three concentrating solar power (CSP) technologies, parabolic trough collector (PTC), linear Fresnel reflector (LFR) and solar tower (ST), hybridised with biomass-fired (BF) technology are investigated. It is found that exergy destruction from the solar field alone is responsible for the most of the whole exergy destructions (86.3% for PTC-BF, 92.2% for ST-BF and 85.4% for LFR-BF). The results show that LFR-BF hybrid system is the best cost-efficient system while ST-BF hybrid system is the worst cost-efficient system considering initial investment, avoidable-endogenous exergy destruction, cost associated with avoidable-endogenous exergy destruction and total cost required for the optimisation.

Advanced exergoeconomic analysis of solar-biomass hybrid systems for multi-energy generation

Advanced exergoeconomic analysis of solar-biomass hybrid systems for multi-energy generation

Techno-Economic Analysis of Standalone Solar Photovoltaic-Wind-Biogas Hybrid Renewable Energy System for Community Energy Requirement

Integrated renewable energy system (IRES) is integration of different energy sources to provide uninterrupted and viable solution for electrification especially for areas not connected to main grid due to difficult terrain and economic reasons. IRES has many advantages like non-depleting, non-polluting nature, better load matching and better renewable energy utilization. In the present study, mathematical modelling, size optimization and techno-economic analysis of standalone IRES have been carried out. Hybrid system is modelled to have maximum contribution from wind and solar energy with minimum net present cost (NPC) of system to meet electric load demand of CRC building, IIT Madras, India (13.01°N and 80.24°E). The results show that most feasible system configuration consists of 12 kW Photovoltaics, 3 kW wind turbine and 15 kW biogas generator with NPC and cost of energy equal to $ 117,098 and $ 0.09/kWh respectively. The IRES generates 71,826 kWh of energy to meet AC load of 64,396 kWh per year. The capacity factor and percentage contribution of PV, wind turbine and biogas generator are 17.8%, 6.57%, 39.1% and 26%, 2.4%, 71.6% respectively. The paper also presents sensitivity analysis of hybrid system with variation in capital cost of different components.

Performance Research on Hybrid System Using MATLAB Simulink

This paper proposes the performance analysis of hybrid system using MATLAB simulation. In the present era, the increasing energy demand due to increase in the large number of loads depress the electrical grid system to fulfil the energy demand of each and every customer. It is impossible for the grid system to do so, therefore to get rid off from these issues a renewable energy-based hybrid system is developed that fulfils the energy demand in most efficient way without undergoing in the process of load shedding. The system is design in the MATLAB Simulink and the result obtained is compared to improve the efficiency of the system.

Moment analysis of stochastic hybrid systems using semidefinite programming

This paper proposes a method based on semidefinite programming for estimating moments of stochastic hybrid systems (SHSs). The class of SHSs considered herein consists of a finite number of discrete states and a continuous state whose dynamics as well as the reset maps and transition intensities are polynomial in the continuous state. For these SHSs, the dynamics of moments evolve according to a system of linear ordinary differential equations. However, it is generally not possible to exactly solve the system since time evolution of a specific moment may depend upon moments of order higher than it. Our methodology recasts an SHS with multiple discrete modes to a single-mode SHS with algebraic constraints. We then find lower and upper bounds on a moment of interest via a semidefinite program that includes linear constraints obtained from moment dynamics and those arising from the recasting process, along with semidefinite constraints coming from the non-negativity of moment matrices. We illustrate the methodology via an example of SHS.

Counterexample Guided Abstraction Refinement for Polyhedral Probabilistic Hybrid Systems

We consider the problem of safety analysis of probabilistic hybrid systems, which capture discrete, continuous and probabilistic behaviors. We present a novel counterexample guided abstraction refinement (CEGAR) algorithm for a subclass of probabilistic hybrid systems, called polyhedral probabilistic hybrid systems (PHS), where the continuous dynamics is specified using a polyhedral set within which the derivatives of the continuous executions lie. Developing a CEGAR algorithm for PHS is complex owing to the branching behavior due to the probabilistic transitions, and the infinite state space due to the real-valued variables. We present a practical algorithm by choosing a succinct representation for counterexamples, an efficient validation algorithm and a constructive method for refinement that ensures progress towards the elimination of a spurious abstract counterexample. The technical details for refinement are non-trivial since there are no clear disjoint sets for separation. We have implemented our algorithm in a Python toolbox called Procegar; our experimental analysis demonstrates the benefits of our method in terms of successful verification results, as well as bug finding.

Numerical analysis and performance investigation of new hybrid system integrating concentrated solar flat plate collector with a thermoelectric generator system

Advanced solar thermal devices with a high performance/cost ratio is a major concern nowadays. In this paper, we investigate the energetic efficiency of a new concept based on a direct coupling of a solar water heater with a thermoelectric module, in order to exploit the maximum of the solar spectrum, produce heat and electricity at the same time and improve the normal solar collector efficiency. An unsteady-state mathematical model of the system is presented in details to describe the system behavior. Using state-of-the-art thermal transfer calculations, the differential equations of the global system were established and solved numerically. The system model is solved using MATLAB program, while the finite difference method is based. Our major finding shows that the new hybrid system significantly improves the storage process by controlling the flow rate according to the concentration ratio variation. This flow rate attains a capacity of 1200.453 L/day, for 0.92 × 1.9 × 0.05 m3 a collector tilted at 30° under 20 suns, and produces a significant additional electrical energy about 10.41 Watts, which is very promising for future thermal/electrical applications.

Performance Analysis of Hybrid Power System Along With Conventional Energy Sources for Sustainable Development in Rural Areas

The energy demand within the world has improved for a few reasons because of technical advancements, increasing enterprises, and increasing commercial energy consumption. Sufficient energy models will support the accurate use of renewable resources like solar, wind, biomass, biogas, and the fuel cell is a portion of the advantages used. Hybrid energy systems of these advantages will contribute viably to sustainable development and electrification in rural areas that do not access power grids. This study reviews the performance analysis of hybrid system along with conventional resources for sustainable development in remote areas. This paper also reviews the recent trends in energy usage from available renewable energy sources in addition to examine an expansive review of the performance analysis of different hybrid energy technologies in rural areas. It is also discussed the relative investigation of hybrid energy systems along with conventional energy sources particularly suited to the small and isolated areas supported by the literature. In continuation of this, the paper also discusses the future energy sources

Dynamical stability analysis of MDOF real-time hybrid system

Abstract Real-time hybrid simulation is an advanced testing methodology to evaluate structural responses under realistic operating conditions. Typically, the real-time hybrid system uses actuation and control system to apply load and motion boundary conditions on the experimental substructure. The inherent system dynamics present phase lags, in addition to the communication delays, that both cause negative damping in the real-time hybrid system. In this study, the dynamic equation of motion is derived for a generalized multiple-degree-of-freedom hybrid system. The negative damping effect is quantified, which depends not only on the actuator motion control performance, but also more importantly on the partition between the numerical and experimental substructures (i.e. how the stiffness and mass are assumed in both substructures). It is demonstrated the worst-case hybrid substructure partition may have very narrow stability margin in its tolerance of any system delay. The proposed equation of motion gains system level understanding of any arbitrary hybrid substructure partition; thus allow both frequency domain system analysis and time domain evaluation. The benchmark problem is studied to validate the proposed equation of motion compared with the virtual testing method, both approaches show excellent correlation. These pre-testing assessments could establish quantitative predictive measures about the system stability limit and performance criteria. Thus they are very important in the early design stage of a feasible real-time hybrid implementation, help reduce the risks of unintended physical testing responses.

Sensitivity Analysis for Hybrid Systems and Systems With Memory

We present an adjoint sensitivity method for hybrid discrete—continuous systems, extending previously published forward sensitivity methods (FSA). We treat ordinary differential equations (ODEs) and differential-algebraic equations (DAEs) of index up to two (Hessenberg) and provide sufficient solvability conditions for consistent initialization and state transfer at mode switching points, for both the sensitivity and adjoint systems. Furthermore, we extend the analysis to so-called hybrid systems with memory where the dynamics of any given mode depend explicitly on the states at the last mode transition point. We present and discuss several numerical examples, including a computational mechanics problem based on the so-called exponential model (EM) constitutive material law for steel reinforcement under cyclic loading.

Analysis of Wind Diesel Hybrid System by Homer Software

Analysis of Wind Diesel Hybrid System by Homer Software

Stability analysis and output-feedback synthesis of hybrid systems affected by piecewise constant parameters via dynamic resetting scalings

We develop novel criteria for robust stability of a class of hybrid systems that are affected by piecewise constant uncertain parameters with dwell-time constraints. These criteria result from clock-dependent Lyapunov arguments that are based on several new robust stability conditions for continuous-time linear time-invariant systems which are affected by parametric passive uncertainties and do not admit any discrete dynamics. In contrast to other approaches, our stability analysis results rely on separation techniques from robust control involving dynamic resetting scalings. Moreover, these techniques are expected to pave the way for covering much more general uncertainties within the framework of integral quadratic constraints. Building upon the new insights on robust stability, we are able to propose an output-feedback gain-scheduling design methodology similarly to our recently obtained synthesis result involving dynamic resetting D-scalings. Most of the obtained conditions are expressed as infinite-dimensional (differential) linear matrix inequalities which can be numerically solved by using relaxation methods based on, e.g., linear splines or matrix sum-of-squares. We apply our results to obtain novel stability criteria and to design distributed controllers for networked systems over undirected switching topologies. Finally, the approach is illustrated with several numerical examples.