Passivity-based Control of Switched Reluctance-based Wind System Supplying Constant Power Load

This paper presents a passivity-based control (PBC) scheme for the switched reluctance generator (SRG) in small-scale wind energy conversion systems for dc microgrid applications. The main objective is to stabilize the output voltage in case the system supplies constant power loads (CPLs) and operates with maximum power point tracking (MPPT). Stability improvement and dc-link ripple reduction in the presence of CPLs is achieved using system-level modeling of SRG-based dc microgrid through the Euler-Lagrange system (ELS) from the viewpoint of the machine physical structure. Compared with other control methods, the proposed MPPT method based on passivity-based speed controller employs the back electromotive force (EMF) in the generation process as a position-dependent voltage source to overcome the major challenge of SRG complicated uncertain dynamic model. To deal with the time-varying inductance and back EMF of SRG, an adaptation mechanism is incorporated in the proposed adaptive PBC and the control design is constructed by using the Lyapunov theorem where the closed-loop stability is ensured. The effectiveness of the proposed method in avoiding instability effects of SRG and CPL with voltage ripple reduction and precise wind turbine speed tracking is investigated with simulation results and validated with experimental by using a four-phase, 8/6 SRG drive system

A RELIABLE AND EFFICIENT CIRCUITRY FOR PHOTOVOLTAIC ENERGY HARVESTIN FOR POWERING MARINE INSTRUMENTATIONS

This paper presents and demonstrates a simple and reliable electronic circuitry for photovoltaic energy harvesting which best suited for powering marine instrumentations. The main functions of the designed circuitry are: i) tracking the maximum power point of the photovoltaic cells which are subject to continuous movements due to sea waves, ii) power conversion and management of energy storages with a high efficiency; and iii) achieving a high level of reliability for operation of circuit in a harsh marine environment. The proposed circuitry is designed based on an analog controller which implements a sensorless algorithm for maximum power point tracking. The power converter unit includes a simple buck converter with minimum electronic components. Compared with DSP-based digital controllers, the simplicity of the proposed analog controller highly improves reliability of the power conversion unit. The total power consumption of the electronic circuit is in the range of a few milliwatts. This enhances the overall efficiency of power conversion especially in low power (a few watt) applications such as powering of marine and metrological sensors. The circuitry also includes a control unit for battery charging to protect batteries against overcharging. The performance of the designed circuitry is experimentally demonstrated using a test setup for power management unit of an ocean-graphical buoy

Power Electronics for Photovoltaic Energy System of an Oceanographic Buoy

This paper reports on design of power electronics for photovoltaic (PV) energy system of an offshore remote sensing apparatus. Challenges in design of a PV energy system for a marine application are investigated and the design limitations compared to inland PV system are discussed. The designed system includes PV cells as the main source of energy, electric storage (battery), maximum power point tracking (MPPT) and protection circuitries. An MPPT algorithm based on measuring the slope of the PV power-voltage curves is presented which can be implemented with simple analog electronic circuits. The MPPT circuit uses Sepic converter as a core and it also includes a protection unit for maintaining the battery voltage in a safe range. The performance of the proposed MPPT algorithm in presence of measurement noises is verified using a circuit simulation software tool (PSCAD). Simulation results verify that the algorithm appropriately regulates the voltage of PV cells at MPP and it is robust against measurement noises for a signal-to-noise ratio above -2db

Dynamic Model and Control of DFIG Wind Energy Systems Based on Power Transfer Matrix

9 Halama

The Effect of Demand Management Using Optimal Pressure Regulation in WDNs During Normal and Water Scarcity Conditions

Paying attention to the conservation of water resources in order to prevent water crises is one of the most important duties of people in the community, including officials. In this regard, the most effective action is water demand management, for which there are different methods. One of these methods is pressure management in order to demand management, which can be used in normal operating conditions as well as in the event of water scarcity. On the other hand, in critical situations where the available water does not meet the total demand, policies such as intermittent water supply are adopted, which are associated with many problems. Therefore, an alternative method is needed to minimize the disadvantages of intermittent water supply,to meet the objectives of demand management and, at the same time is feasible, efficient, and economical. In this research, a combined simulation and optimization model is created by using EPANET2.2 and MATLAB software. With this model, the effects of adopting a water demand management approach using pressure management on the hydraulics of water distribution networks will be investigated. In this research, optimization is done in two approaches. In each case, a different objective function is defined and a genetic algorithm is used for optimization. The developed model has been analyzed on the WDN of Baharestan city located in Isfahan province. The results show that the model is able to reduce the average network pressure by 8 meters by finding the optimal location and adjusting pressure for pressure-reducing valves under normal conditions. Also, during water scarcity, it is able to distribute the available water among the demand nodes considering equity and justice principles. After imposing an 8% deficit on the network, without applying for a pressure management program, 8 demand nodes experienced a shortage between 15 and 30% and 19 experienced a deficit below 5%. However, after optimizing the pressure, only 3 demand nodes experienced a shortage between 15 and 25% and 6 nodes experienced a shortage of less than 5%

Life Cycle Sustainability Assessment of Wastewater Systems under Applying Water Demand Management Policies

Sustainability assessment of urban water and wastewater infrastructures, especially when it comes to managing existing systems, is of paramount importance. Hence, this study presents a comprehensive approach to investigate the sustainability of a real wastewater system under different water demand management policies (WDMPs) in the operation and maintenance stage. In this regard, life cycle sustainability assessment (LCSA) is used through its three main pillars, which are (1) environment, (2) economy, and (3) society. Accordingly, (1) Environmental assessment is conducted using life cycle assessment (LCA) considering a thorough inventory dataset; (2) The economic assessment results are analyzed by the life cycle cost (LCC) method; and (3) Social life cycle assessment (SLCA) is conducted using the analytic hierarchy process (AHP) method, in which three main stakeholders “public and local community”, “workers and employees”, and “treated wastewater and sludge consumers” are considered. Finally, to prioritize scenarios, the results of LCA, LCC, and SLCA for every scenario are aggregated to account for the sustainability score using the AHP. The results of applying the proposed method to a real case study show that scenarios leading to less reduction in wastewater production are more sustainable options as they represent better performance regarding economic and social aspects. The proposed framework provides a better insight into the integrated sustainability analysis of urban water infrastructures. In addition, it can be used as a guideline for exploring the effects of WDMPs on wastewater systems in different study areas

Life Cycle Sustainability Assessment of Wastewater Systems under Applying Water Demand Management Policies

Sustainability assessment of urban water and wastewater infrastructures, especially when it comes to managing existing systems, is of paramount importance. Hence, this study presents a comprehensive approach to investigate the sustainability of a real wastewater system under different water demand management policies (WDMPs) in the operation and maintenance stage. In this regard, life cycle sustainability assessment (LCSA) is used through its three main pillars, which are (1) environment, (2) economy, and (3) society. Accordingly, (1) Environmental assessment is conducted using life cycle assessment (LCA) considering a thorough inventory dataset; (2) The economic assessment results are analyzed by the life cycle cost (LCC) method; and (3) Social life cycle assessment (SLCA) is conducted using the analytic hierarchy process (AHP) method, in which three main stakeholders “public and local community”, “workers and employees”, and “treated wastewater and sludge consumers” are considered. Finally, to prioritize scenarios, the results of LCA, LCC, and SLCA for every scenario are aggregated to account for the sustainability score using the AHP. The results of applying the proposed method to a real case study show that scenarios leading to less reduction in wastewater production are more sustainable options as they represent better performance regarding economic and social aspects. The proposed framework provides a better insight into the integrated sustainability analysis of urban water infrastructures. In addition, it can be used as a guideline for exploring the effects of WDMPs on wastewater systems in different study areas

Vacuum-Packaged Piezoelectric Energy Harvester for Powering Smart Grid Monitoring Devices

This paper presents an analytical method for the design and power optimization of vacuum-packaged piezoelectric energy harvesters. It is shown that the maximum power point of a vacuum-packaged energy harvester is different from the conventional one which occurs when the electrical damping ratio equals to its mechanical counter-part. Also, it is shown that the captured power by a vacuum-packaged energy harvester is highly sensitive to the vibration frequency due to very low-mechanical damping ratio, e.g., up to 50% power drops corresponding to 2% deviations in the frequency. The analysis and design are performed in the context of an ac-line magnetic field energy harvester in which the line frequency is also fixed and this energy harvester is useful for developing the self-powered wireless monitoring devices. Furthermore, the vacuum-packaged devices are inherently robust against dust storm and icing phenomenon, which occur for overhead power lines. The proposed analytical method is established based on simplified assumptions and then an accurate method is developed for the analysis of vacuum-packaged devices. Obtained theoretical results are verified in the laboratory through a prototype of the vacuum-packaged piezoelectric device, which captures up to 90 mu W from a 10-A line current