Influence of Renewable Energy Sources on Day Ahead Optimal Power Flow Based on Meteorological Data Forecast Using Machine Learning: A case study of Johor Province

This article investigates a day ahead optimal power flow considering the intermittent nature of renewable energy sources that involved with weather conditions. The article integrates the machine learning into power system operation to predict precisely day ahead meteorological data (wind speed, temperature and solar irradiance) that influence directly on the calculations of generated power of wind turbines and solar photovoltaic generators. Consequently, the power generation schedulers can make appropriate decisions for the next 24 hours. The proposed research uses conventional IEEE -30-bus as a test system running in Johor province that selected as a test location. algorithm designed in Matlab is utilized to accomplish the day ahead optimal power flow. The obtained results show that the true and predicted values of meteorological data are similar significantly and thus, these predicted values demonstrate the feasibility of the presented prediction in performing the day ahead optimal power flow. Economically, the obtained results reveal that the predicted fuel cost considering wind turbines and solar photovoltaic generators is reduced to 645.34 USD/h as compared to 802.28 USD/h of the fuel cost without considering renewable energy sources. Environmentally, CO2 emission is reduced to 340.9 kg/h as compared to 419.37 kg/h of the conventional system. To validate the competency of the whale optimization, the OPF for the conventional system is investigated by other 2 metaheuristic optimization techniques to attain statistical metrics for comparative analysis

Lightning impulse strength of 275 kV and 132 kV tower with composite crossarm

Severe lightning overvoltage is regarded to the multiple flashovers on the overhead lines. Therefore, it signifies the needs of having a robust insulation system, especially to those which highly susceptible to lightning strikes. In order to minimize the impact of lightning, it is necessary to evaluate lightning performance of the tower and its components before implementing any proposed design. Therefore, in this work, a feasibility study was done on proposed 275 kV and 132 kV transmission tower with composite crossarm installed. In order to assess the insulation strength of the tower against the lightning activities, lightning caused events i.e. backflashover and shielding failure were applied onto the tower models by using FEM based software. The CFO of the tower insulation were calculated based on the design provided, whereby it was complementary verified by the voltage and electric field profiles of the simulation. For each case, none had shown a voltage magnitude higher than the voltage supposed to possibly cause 50% chance of flashover

On the behaviour of polymer insulator with deposited moss on the surface against lightning in polluted air condition

Deposited moss on the surface of polymer insulators can be effective on the electrical performance of insulator and network as well. This problem can be sensed especially in the forest areas and tropical countries. In the tropical countries like Malaysia beside of local factors for creation of moss on the surface of insulator, the air pollution plays an important role as well. In this study a 10kV polymer insulator has been chosen an the electrical performance of insulator against lightning was considered through both simulation and experimental works and the results have be discussed accordingly. The results show that the contaminated insulator have different behaviour against lightning and in order to reach a proper insulation level for line, the local factors should be taken into account

Effect of Earthing Enhancing Compound (EEC) on improving tower footing resistance of a 500 kV Tower in a rocky area

This paper presents a comparative analysis of different earthing designs’ performances, with particular interest on the use of earthing enhancing compound (EEC) for a selected earthing design of 500 kV transmission towers in a rocky soil, using the SESCAD tool of the Current distribution, electromagnetic field grounding and soil structure analysis (CDEGS) software. The simulation included the interpretation of soil profile and comparison between designs A, B and C, which are currently used for the 500 kV tower footing resistance (TFR) improvement. Results showed each design had reduced the TFR by 66%, 54.7% and 63.2% for the towers T42, T48 and T50, respectively. In some cases, further improvement of TFR is required, especially in the rocky area where the soil resistivity (SR) value is of more than 500 Ω⋅m. In this case, EEC was used in Design C, encasing both the vertical and horizontal electrodes, and it reduced the TFR further by 16% to 20%. The characteristics of the soil and earthing arrangement design play an important role in achieving a low TFR value, which is directly proportional to the backflashover occurrence and thus to the transmission line performance

Investigation of Insulation Characteristics of GFRP Crossarm Subjected to Lightning Transient

The advancement of material technology has contributed to the variation of high-performance composites with good electrical insulation and mechanical properties. Their usage in electrical applications has grown since then. In Malaysia, the composite made of Glass Fiber Reinforced Polymer (GFRP) has been adopted for crossarm manufacturing and has successfully served 275 kV lines for a few decades. However, the combination of extreme conditions such as lightning transient and tropical climate can impose threats to the material. These issues have become major topics of discussion among the utilities in the Southeast Asian (SEA) region, and also in previous research. In Malaysia, more than 50% of total interruptions were caused by lightning. Limited studies can be found on the composite crossarm, especially on the square tube GFRP filled crossarm used in Malaysia. Therefore, this paper proposes to study the behavior of the particular GFRP crossarm, by means of its insulation characteristics. Experimental and simulation approaches are used. Throughout the study, the GFRP specimen is known to have an average breakdown strength at 7.2 kV/mm. In addition, the CFO voltages of the crossarm at different lengths are presented, whereby the behavior under dry and wet conditions is comparably discussed. At the same time, the polarity effect on the CFO voltages is highlighted. The maximum E-fields at the immediate moment before breakdown are analyzed by adopting the finite element method (FEM). Non-uniform distribution of E-fields is witnessed at different parts of the crossarm structure. Simultaneously, the maximum field localized on the crossarm immediately before the breakdown is also presented

The Behavior of Polyurethane Foam-Filled Glass-Fiber-Reinforced Polymer Crossarm Subjected to Lightning Transient Voltage

The demand for composite materials in high-voltage electrical insulation is escalating over the last decades. In the power system, the composite glass-fiber-reinforced polymer has been used as an alternative to wood and steel crossarm structures due to its superior properties. As a composite, the material is susceptible to multi-aging factors, one of which is the electrical stress caused by continuous and temporary overvoltage. In order to achieve a better insulation performance and higher life expectancy, the distribution of the stresses should firstly be studied and understood. This paper focuses on the simulation work to better understand the stress distribution of the polyurethane foam-filled glass-fiber-reinforced polymer crossarm due to the lightning transient injection. A finite-element-based simulation was carried out to investigate the behavior of the electric field and voltage distribution across the sample using an Ansys Maxwell 3D. Electrical stresses at both outer and inner surfaces of the crossarm during the peak of lightning were analyzed. Analyses on the electric field and potential distribution were performed at different parts of the crossarm and correlated to the physical characteristics and common discharge location observed during the experiment. The results of the electric field on the crossarm indicate that both the outer and internal parts of the crossarm were prone to high field stress

The behavior of polyurethane foam-filled glass-fiber-reinforced polymer crossarm subjected to lightning transient voltage

The demand for composite materials in high-voltage electrical insulation is escalating over the last decades. In the power system, the composite glass-fiber-reinforced polymer has been used as an alternative to wood and steel crossarm structures due to its superior properties. As a composite, the material is susceptible to multi-aging factors, one of which is the electrical stress caused by continuous and temporary overvoltage. In order to achieve a better insulation performance and higher life expectancy, the distribution of the stresses should firstly be studied and understood. This paper focuses on the simulation work to better understand the stress distribution of the polyurethane foam-filled glass-fiber-reinforced polymer crossarm due to the lightning transient injection. A finite-element-based simulation was carried out to investigate the behavior of the electric field and voltage distribution across the sample using an Ansys Maxwell 3D. Electrical stresses at both outer and inner surfaces of the crossarm during the peak of lightning were analyzed. Analyses on the electric field and potential distribution were performed at different parts of the crossarm and correlated to the physical characteristics and common discharge location observed during the experiment. The results of the electric field on the crossarm indicate that both the outer and internal parts of the crossarm were prone to high field stress

The Advancement of Solid-State Transformer Technology and Its Operation and Control with Power Grids: A Review

Solid-state transformer (SST) technology is one of the developing technologies that will be widely used in the future to integrate low-voltage and high-voltage networks with control circuitries and power electronics converters, facilitating renewables integration in smart grid applications. SST technology has crucial key advantageous features, including compact size and weight, low cost, and ease of connection in offshore applications. However, SST technology exhibits a few concerns, such as implementation, protection, economic, and communication compatibility, that need to be addressed. This paper aims to review SST technology with its advanced control schemes and provide future directions for research and development, applications, and prospects. In line with this, highly cited SST technology papers are examined to derive and summarize concerning issues related to its operation and control with further research development of power grids. Moreover, this review discusses the assessment and state-of-the-art technology of SSTs in different applications, focusing on configurations, control circuitry, and their drawbacks and benefits. Numerous issues and challenges of SST technology are explored to identify the existing knowledge gaps and potential future recommendations. All these critical analyses, information, and evaluations would benefit power engineers and researchers in developing and implementing advanced intelligent SST technologies for sustainable energy management in future power systems

Impact of lightning on tower footing design of 500 kV transmission line

This study evaluates several tower earthing designs for improving 500 kV transmission line’s lightning performance and ensure its continuous operation. The study includes the assessment of the soil profile and a comparison of the findings obtained using the default and new earthing arrangement, both of which are intended to improve the tower footing resistance (TFR-during steady-state) and tower footing impedance (TFI-during lightning). Assessment of the TFR and TFI has been performed before and after the earthing design improvement. In addition, the impacts of these TFR and TFI, which are also defined as low and high-frequency earthing, respectively, relying on a specification of TFR and soil resistivity (SR) ranges at different locations have also been taken into consideration. The study was performed with the help of the SESCAD tool of Current Distribution Electromagnetic Field Grounding and Soil Structure Analysis program (CDEGS), as well as the PSCAD/EMTDC software, which was used for low and high frequency earthing, accordingly. Upon the completion of the investigation, the findings revealed that the modification to the earthing arrangement had a beneficial effect on lowering the TFR by 84.29 % and 88.34 % for Towers T41 and T42, respectively. While for TFI, the results revealed a significant decrease below the TFR during high frequency operation, which was attributed to soil ionization process that occur due to lightning. This was proved by the fact that the values were significantly below the TFR. All these enhancements are now being explored and evaluated across all of Malaysia’s 500 kV networks, where lightning is regarded to be the primary risk factor for power outages