This study presents a smart energy management system (SEMS) to optimise the operation of the microgrid. The SEMS consists of power forecasting module, energy storage system (ESS) management module and optimisation module. The characteristic of the photovoltaics (PV) output in different weather conditions has been studied and then a 1-day-ahead power forecasting module is presented. As energy storage needs to be optimised across multiple-time steps, considering the influence of energy price structures, their economics are particularly complex. Therefore the ESS module is applied to determine the optimal operation strategies. Accordingly, multiple-time set points of the storage device, and economic performance of ESS are also evaluated. Smart management of ESS, economic load dispatch and operation optimisation of distributed generation (DG) are simplified into a single-object optimisation problem in the SEMS. Finally, a matrix real-coded genetic algorithm (MRC-GA) optimisation module is described to achieve a practical method for load management, including three different operation policies and produces diagrams of the distributed generators and ESS.

Smart energy management system for optimal microgrid economic operation

Online 24-h solar power forecasting based on weather type classification using artificial neural network

Modeling, planning and optimal energy management of combined cooling, heating and power microgrid: A review

This paper presents a methodology for the optimal allocation and economic analysis of energy storage system (ESS) in microgrids (MGs) on the basis of net present value (NPV). As the performance of an MG strongly depends on the allocation and arrangement of its ESS, optimal allocation methods and economic operation strategies of the ESS devices are required for the MG. To optimize the operation strategies and capacities of ESS in MGs, the financial benefit and dynamic models of ESS are discussed. And then, a matrix real-coded genetic algorithm is applied to find maximal NPV, in which each GA chromosome consists of a 2-D real number matrix representing the generation schedule of ESS and distributed generation sources. This paper is to suggest, among those available ESS, the optimal sizes and types of them and their optimal arrangement, such that the total NPV achieved during the system operational lifetime period is maximized. Finally, some computational simulation results are presented to verify the effectiveness of the proposed method.

Optimal Allocation and Economic Analysis of Energy Storage System in Microgrids

In this paper, we study the problem of determining the size of battery storage used in grid-connected photovoltaic (PV) systems In our setting, electricity is generated from PV and is used to supply the demand from loads Excess electricity generated from the PV can be either sold back to the grid or stored in a battery, and electricity must be purchased from the electric grid if the PV generation and battery discharging cannot meet the demand Due to the time-of-use electricity pricing and net metered PV systems, electricity can also be purchased from the grid when the price is low, and be sold back to the grid when the price is high The objective is to minimize the cost associated with net power purchase from the electric grid and the battery capacity loss while at the same time satisfying the load and reducing the peak electricity purchase from the grid Essentially, the objective function depends on the chosen battery size We want to find a unique critical value (denoted as Crefc ) of the battery size such that the total cost remains the same if the battery size is larger than or equal to Crefc, and the cost is strictly larger if the battery size is smaller than Crefc We obtain a criterion for evaluating the economic value of batteries compared to purchasing electricity from the grid, propose lower and upper bounds on Crefc, and introduce an efficient algorithm for calculating its value; these results are validated via simulations

Storage Size Determination for Grid-Connected Photovoltaic Systems

This paper describes the construction and the performance of a distributed power generating system of photovoltaics (PV) using solar energy estimation. Instead of conventional batteries a new storage device, called energy capacitor system (ECaSS), is used for its various advantages. A procedure is described to estimate the PV output power by calculating solar radiation. To calculate the daily insolation, Hottel's equation and Liu-Jordan's equation have been used with some modification. The accuracy of the procedure is verified by comparing the calculated solar radiation with the practically measured one. To apply the procedure even in cloudy/rainy weather, the characteristic of the PV output in different weather conditions has been studied using 1-day-ahead weather forecasts. With an aim to set the optimum amount of buy power, a simulation program has been developed. The system is being operated in optimal economic mode in different weather conditions. The financial benefit and load-leveling capacity of the system have been studied and presented here. It was found that the system provides an excellent economic benefit for nonflat price of electricity and load-leveling facility with a good overall efficiency.

Novel Distributed Power Generating System of PV-ECaSS Using Solar Energy Estimation

In this paper, the development and the performance of a viable distributed grid-connected power generation system of Photovoltaic-Energy Capacitor System (PV-ECS) considering solar energy estimation have been described. Instead of conventional battery Electric Double Layer Capacitors (EDLC) are used as storage device and Photovoltaic (PV) panel to generate power from solar energy. The system can generate power by PV, store energy when the demand of load is low and finally supply the stored energy to load during the period of peak demand. To realize the load leveling function properly the system will also buy power from grid line when load demand is high. Since, the power taken from grid line depends on the PV output power, a procedure has been suggested to estimate the PV output power by calculating solar radiation. In order to set the optimum value of the buy power, a simulation program has also been developed. Performance of the system has been studied for different load patterns in different weather conditions by using the estimated PV output power with the help of the simulation program.

Development of an Advanced Grid-Connected PV-ECS System Considering Solar Energy Estimation

This paper represents the most effective automatic power factor improvement by using static capacitors which will be controlled by a Microcontroller with very low cost although many existing systems are present which are expensive and difficult to manufacture. In this study, many small rating capacitors are connected in parallel and a reference power factor is set as standard value into the microcontroller IC. Suitable number of static capacitors is automatically connected according to the instruction of the microcontroller to improve the power factor close to unity. Some tricks such as using resistors instead of potential transformer and using one of the most low cost microcontroller IC (ATmega8) which also reduce programming complexity that make it most economical system than any other controlling system.

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Automatic Power Factor Improvement By Using Microcontroller

Implementing texturization process on the monocrystalline silicon substrate reduces reflection and enhances light absorption of the substrate. Thus texturization is one of the key elements to increase the efficiency of solar cell. Considering as-cut monocrystalline silicon wafer as base substrate, in this work different concentrations of Na2CO3 and NaHCO3 solution, KOH–IPA (isopropyl alcohol) solution and tetramethylammonium hydroxide solution with different time intervals have been investigated for texturization process. Furthermore, saw damage removal process was conducted with 10% NaOH solution, 20 wt% KOH–13.33 wt% IPA solution and HF/nitric/acetic acid solution. The surface morphology of saw damage, saw damage removed surface and textured wafer were observed using optical microscope and field emission scanning electron microscopy. Texturization causes pyramidal micro structures on the surface of (100) oriented monocrystalline silicon wafer. The height of the pyramid on the silicon surface varies from 1.5 to 3.2 µm and the inclined planes of the pyramids are acute angle. Contact angle value indicates that the textured wafer’s surface fall in between near-hydrophobic to hydrophobic range. With respect to base material absolute reflectance 1.049–0.75% within 250–800 nm wavelength region, 0.1–0.026% has been achieved within the same wavelength region when textured with 0.76 wt% KOH–4 wt% IPA solution for 20 min. Furthermore, an alternative route of using 1 wt% Na2CO3–0.2 wt% NaHCO3 solution for 50 min has been exploited in the texturization process.

Texturization of as-cut p-type monocrystalline silicon wafer using different wet chemical solutions

In this work, a small grid-connected distributed generation system with load leveling function has been developed using PV panel and ECS. The system can produce power by PV panel, store energy from grid line and PV panel when the load demand is low, and finally supply the stored energy to load during the peak demand. To level the daily load properly, it is necessary to know how much power the PV panel will generate tomorrow. Hence a procedure has also been devised to estimate the output power of PV panel by calculating solar radiation. The accuracy of the calculated soar radiation and PV output power has been verified by practically measured data. Everyday we have to declare, how much power will be taken from the grid line tomorrow, for proper functioning of the system. With an aim to set the optimum value of grid power, to level the load properly and to use 100% output power of PV panel, a simulation program has also been developed. Finally the performance of our system has been studied for several days in different weather conditions, using the estimated output of the PV panel and the simulation program.

Md. Habibur Rahman

Papers

Novel Distributed Power Generating System of PV-ECaSS Using Solar Energy Estimation

Development of an Advanced Grid-Connected PV-ECS System Considering Solar Energy Estimation

Automatic Power Factor Improvement By Using Microcontroller

Texturization of as-cut p-type monocrystalline silicon wafer using different wet chemical solutions

A grid-connected PV-ECS system with load leveling function taking into account solar energy estimation