Hydrogen is becoming an increasingly important energy carrier in sector integration for fuel cell transportation, heat and electricity. Underground salt caverns are one of the most promising ways to store the hydrogen obtained from water electrolysis using power generation from renewable energy sources (RES). At the same time, the production of hydrogen can be used to avoid energy curtailments during times of low electricity demand or low prices. The stored hydrogen can also be used during times of high energy demand for power generation, e.g., with fuel cells, to cover the fluctuations and shortages caused by low RES generation. This article presents an overview of the techniques that were used and proposed for using excess energy from RES for hydrogen production from water and its storage techniques, especially in underground salt caverns, for the aforementioned purpose, and its feasibility. This paper compares and summarizes the competing technologies based on the current state-of-the-art, identifies some of the difficulties in hydrogen production and storage, and discusses which technology is the most promising. The related analysis compares cost and techno-economic feasibility with regard to hydrogen production and storage systems. The paper also identifies the potential, technical challenges and the limitations associated with hydrogen integration into the power grid.

This paper describes the designing of a new external shape for a medium voltage indoor post insulator, which consists of an optimization polynomial. The new external shape provides lower values of electric field strength inside the insulator and in the air. Another innovation is the use of reliable components, i.e. the voltage divider. The new insulator uses a ceramic capacitor with the required capacitance, unlike previous insulators that had problems reaching the appropriate capacitance using cylindrical metal mesh. The insulator model was built with MATLAB software, followed by the calculations of electric fields in EleFAnT software. The differential evolution (DE) algorithm was used as a successful and global optimization algorithm for the optimal design of an insulator's external shape and the position of internal insulator elements.

This paper deals with the Differential Evolution (DE) based method for identification of the heat equation parameters applied for the estimation of a bare overhead conductor`s temperature. The parameters are determined in the optimization process using a dynamic model of the conductor; the measured environmental temperature, solar radiation and wind velocity; the current and temperature measured on the tested overhead conductor; and the DE, which is applied as the optimization tool. The main task of the DE is to minimise the difference between the measured and model-calculated conductor temperatures. The conductor model is relevant and suitable for the prediction of the conductor temperature, as the agreement between measured and model-calculated conductor temperatures is exceptional, where the deviation between mean and maximum measured and model-calculated conductor temperatures is less than 0.03 °C.

This paper presents a thermal model to simulate a thermal behavior of transformers. Heat dissipated is always problem in transformers. Coupled physical and mathematical models would assist in the development of a system that was both accurate and simple. Material properties, the geometry, heat transfer coefficients for each surface are introduced as the input values. For the accurate results of the temperature distributions, the exact values of heat transfer coefficients are required. This paper deals with identification of thermal parameters for FEM-based transformer model. The identification technique is based on stochastic optimization algorithm called Differential evolution (DE). The goal of DE is to identify adequate thermal parameters, in order to achieve best possible agreement between measured and model-calculated values of temperature. The inclusion of identified thermal parameters into the model results in good model's accuracy.

This article provides an overview of the requirements for a grid-oriented integration of hydrogen energy storage (HES) and components into the power grid. Considering the general definition of HES and the possible components, this paper presents future hydrogen demand, electrolysis performance, and storage capacity. These parameters were determined through various overall system studies aiming for climate neutrality by the year 2045. In Germany, the targeted expansion of renewable energy generation capacity necessitates grid expansion to transport electricity from north to south and due to existing grid congestions. Therefore, electrolysis systems could be used to improve the integration of renewable energy systems, by reducing energy curtailment and providing grid services when needed. Currently, however, there are hardly any incentives for a grid-friendly allocation and operation of electrolysis or power-to-gas plants. Two possible locations for hydrogen plants from two current research projects HyCavMobil (Hydrogen Cavern for Mobility) and H₂-ReNoWe (Hydrogen Region of north-western Lower Saxony) are presented as practical examples. Using power grid models, the integration of electrolysis systems at these locations in the current high and extra-high voltage grid is examined. The presented results of load flow calculations assess power line utilization and sensitivity for different case scenarios. Firstly, the results show that power lines in these locations will not be overloaded, which would mean an uncritical operation of the power grid. While the overall grid stability remains unaffected in this case, selecting suitable locations is vital to prevent negative effects on the local grid.

This chapter deals with the influence of the electric field on a Medium Voltage Indoor Post Insulator (MVIPI) with standard and modified external shapes. The goal of this chapter is to show the electric field behavior of the MVIPI with different external shapes and to introduce a numerical model with a favorable distribution of the electric field that relieves the dielectric from stress. The chapter describes an MVIPI with nominal voltage 20 kV AC and shows an existing MVIPI, an MVIPI with a different number of ribs, and an MVIPI with exceptional external shape. The MVIPI’s new external shape does not have the typical shape of the ribs, but a new outline, using the Lagrange polynomial, that will acquire its optimal form through the optimization process. A Differential Evolution optimization algorithm is used for the optimal design of the insulator’s external shape. The value of the Electric Field Strength (EFS) will be minimized within the permissible bounds during the optimization process. The important parameters during the minimization of the objective function are the value of the EFS in the interior and exterior of the insulator. EFS values are shown for every MVIPI example and are compared with the existing MVIPI. The obtained results are analyzed and discussed.