Utility Power Supply Research Articles

Study on controllability assessment of a new type of power system based on lagrangian function integrated assessment method

The complex structure and multiple controllability metrics of the new power system require a comprehensive assessment approach. We propose a controllability assessment method based on the Lagrangian function, analyzing key factors that influence controllability. Our index system includes distributed power supply utilization rate, energy storage station charge state, power factor, and voltage offset. Using Lagrange shadow price theory, we construct a guideline layer index system treating bottom indexes as constraints. We formulate an optimization function utilizing the Lagrangian shadow price theory and considering weights calculated from the bottom index’s shadow price. These weights inform primary evaluation. By combining primary evaluation results, weights, and variable coefficients using the percentage system method, we determine comprehensive evaluation results for the new power system’s controllability. Experimental results demonstrate the high reliability of this method’s evaluation indexes, indicating their effectiveness. This research provides valuable insight for the advancement of the new power system. Region 1 had the lowest overall evaluation score of 51.57 and was rated general. The overall score of Region 2 was 77.24, which was considered good. Region 3 received the highest overall score of 86.29 and was rated as excellent.Graphical

A parameter design method of LC filter circuit for closed‐loop dynamic power supply system based on linear power amplifier

AbstractThe linear power amplifier (LPA) suffers from low power supply utilization in the DC power supply mode, leading to reduced output efficiency. This paper constructs an efficient power supply mode based on closed‐loop dynamic power supply system (CLDPSs). The CLDPSs can generate a pair of bipolar dynamic power supplies based on a predetermined signal to provide power to LPA, which can maintain a small voltage drop between the power supply and the output of LPA, thereby improving the power supply utilization of LPA. In addition, the study also focuses on the conflicting relationship between the output ripple and the dynamic performance of the CLDPSs, for which a new parametric design of the LC filter circuit is proposed, aiming to achieve a balance between these two aspects. Finally, a voice coil motor driving platform is constructed for experimental testing. The results demonstrate that the output ripple and dynamic performance of the CLDPSs can be balanced. In comparison to the DC power supply mode, the CLDPSs power supply mode can enhance the efficiency of LPA by 2 times while the driving accuracy of voice coil motor is basically unchanged.

DESIGN AND CONSTRUCTION OF A SMART BLUETOOTH BASED AUTOMATIC TRANSFER SWITCH CHANGEOVER FOR SMALL HOUSEHOLD GENERATORS

The necessity to develop a cost-effective, smooth, and secure method to automate switching between different power sources resulted in this study. The paper proposes the use of an automatic transfer switch, which automatically switches between the utility power supply and a backup generator, to ensure uninterrupted power supply. The study aims to develop a cost-effective and secure system that utilizes an android device for remote control and monitoring of the power-generating unit. By employing Bluetooth technology, the study eliminates the delays and errors associated with manual source switching. The research specifically focuses on creating an automatic transfer switch compatible with 5 KVA key starter power generators and developing an android application for remote control within a 10-meter Bluetooth range. The system uses electromechanical and solid-state relays for the generator's start/stop sequence and power transmission, respectively.

Enhancing geothermal ORC power generation with SOFC: A comprehensive parametric study on thermodynamic performance

Geothermal energy is a promising renewable energy source due to its abundant global reserves. However, most geothermal resources are of low grade, severely restricting their power generation capacity and efficiency. In this study, the geothermal organic Rankine cycle power generation system is combined with a solid oxide fuel cell-gas turbine system to improve the overall power supply and heat utilization efficiency. The heat source and cycle temperature are upgraded using high-temperature solid oxide fuel cell waste gas, and the combined system’s efficiency is further improved through cascade heat utilization. Electrochemical-thermodynamic models are developed for the proposed system, and energy-exergy analysis is carried out. The effects of fuel cell current density, operating temperature and geothermal grade on the combined system’s performance are comprehensively analyzed. Compared to the standalone geothermal system, the energy efficiency and output power of the organic Rankine cycle increase by 8.11% and 7.95% respectively in the baseline case. Under the lowest geothermal temperature condition, the cycle output power is improved by 22.64%. The net power of the combined system can vary from 358 kW to 846 kW by adjusting the fuel cell current density from 1000 A m−2 to 8000 A m−2, demonstrating a flexible power supply capability. The optimal solid oxide fuel cell operating temperature is 1023.15 K, resulting in the highest system overall energy efficiency of 14.85%. The presented work provides essential guidelines for improving geothermal power generation performance and designing applicable combined systems.

Systematization of industrial technogenic risks at mining enterprises

Research objective is to develop a general approach to systematizing the signs of mining territories, natural and man-made features safety. Research relevance is due to the need to ensure the safety of economic activity in the territory of mining. Methods of research. Subsoil use implies taking into account multiple factors that lead to the risk of decisions implementation. Risk is considered as a potential, numerically estimated probability of the unfavorable events (situations), their consequences in the form of accidents, human casualties, losses, damages, material losses, etc. Risk is a quantitative assessment of the hazards characterizing a situation with uncertain outcome and obligatory manifestation of unfavorable consequences. It is advisable to assess the safety status of any mining enterprise site by a number of indicators that characterize the system’s resilience to negative impacts caused by infrastructural, natural, geological, technological, economic and financial factors. The risk situation caused by statistical processes is associated with accompanying conditions: the presence of uncertainty, the need for an alternative choice, and the possibility of accepted options (alternatives) probabilistic evaluation. Negative phenomena in subsoil use are manifested in the form of deformation of pit walls and dumps, collapse of an individual or a group of pit benches, destruction of transport lines and power supply utilities, rockfall, beneficiation process flow deviations from the designed one, violations of man-made features and the ecological and biological environment, which should be interpreted as man-made disasters of an industrial nature. Results. The classification of risks as a multidimensional category is justified by the factors (causes) of occurrence, the driving force of which generates a negative process and determines its characteristics or individual features. Conclusions. The systematization of various risks based on infrastructural, mining-geological, process flow and environmental factors ensures, at the initial stage of risk formation, the determination of their characteristics and the development of a system of management measures to ensure the sustainable functioning of a mining enterprise.

Optimal Configuration of Hybrid Energy Storage Capacity in a Microgrid Based on Variational Mode Decomposition

The capacity configuration of the energy storage system plays a crucial role in enhancing the reliability of the power supply, power quality, and renewable energy utilization in microgrids. Based on variational mode decomposition (VMD), a capacity optimization configuration model for a hybrid energy storage system (HESS) consisting of batteries and supercapacitors is established to achieve the optimal configuration of energy storage capacity in wind–solar complementary islanded microgrids. Firstly, based on the energy mapping relationship between the frequency domain and time domain, the decomposition mode number K of VMD is determined based on the principle of minimum total mode aliasing energy. Then, considering the smoothing fluctuation characteristics of different energy storage components, the dividing point N of high frequency and low frequency in the unbalanced power between the source and load in the microgrid is selected to allocate charging and discharging power instructions for the battery and supercapacitor. Finally, taking the annual comprehensive cost of the HESS as the objective function, a hybrid energy storage capacity optimization configuration model is established, and the dividing point N is used as the optimization variable to solve the model in order to obtain the optimal configuration results. The case study results show that the proposed method is more economical and feasible than the existing energy storage configuration methods.

Development of Wearable Embedded Hybrid Powered Energy Sources for Mobile Phone Charging System

Mobile phones are an essential part of our day to day living. The increased reliance on mobile phone devices for communication, information sharing, connectivity and entertainment calls for a greater need to keep this device in a functional condition at all times. The epileptic nature of utility power supply, non-accessibility to power in remote locations and affordability of power due to high tariffs calls for a relative option to maintain connectivity of mobile phones. This research proposes to develop wearable embedded powered energy sources for charging mobile phones as a backup for instant and seamless charging of the phone battery once it drains. Our research addresses the inability of mobile phone users to charge their flatten phone batteries conveniently and seamlessly anytime and anywhere they find themselves. The hybrid powered charging system has the ability to harvest dissipated heat within the body of the phone and heat sources from the environment using an energy harvester, alongside the second energy source provided by the solar panel. The energy harvester will serve as a cooling measure to the device to maintain a stable temperature. The entire embedded device not only serves as an alternative power supply but also a protective covering to the mobile phone.

Synergetic process between wind power and sewage sludge pyrolysis in a novel renewable-energy microgrid system

AbstractTo relieve the stress of sewage sludge (SS) disposal and effectively increase the use of renewable energy, a novel renewable-energy microgrid system (REMS) was developed, specifically designed to integrate a wind power plant (WPP) with energy storage and the SS pyrolysis process for heat and power generation. Based on a lab-scale pyrolysis experiment and 7-day numerical analysis, we studied the energy-recycling potential of SS and simulated the operational behaviours of REMS. According to the results, the calorific values of the pyrolytic gaseous and liquid products were better than those of the raw material, at 16.19 and 33.53 MJ/kg, respectively. The proposed REMS performed well in power supply and energy utilization with a design performance index of 99.23 when the WPP capacity was 200 MWe and the initial wind-energy curtailment rate was 30%. It indicates that by converting SS into flammable gas, condensable liquid and carbon-rich solid residue, curtailed wind energy could be saved and the synergy between wind power and the SS pyrolysis process enabled the proposed microgrid system to effectively utilize renewable energy and provide reliable on-demand power service. The REMS installed with a 155-MWe WPP achieved the optimal design in system performance, environmental benefit and construction cost under the initial wind-curtailment rate of 34.12%. The design scheme makes REMS capable of satisfying the 15.10-GWh power demand of end users and the 1700-t/day SS disposal need, and the curtailed wind energy could be reduced to zero.

Reactive power compensation using STATCOM in a PV grid connected system with a modified MPPT method

Commonly Static Synchronous Compensators (STATCOMs) are employed extensively as voltage regulators and VAR compensators in transmission networks in power systems. This research proposes the integration of STATCOMs in distribution networks, particularly in PV grid-connected systems that use distributed energy resources to reduce active and reactive power demand from the grid by supplying variable reactive power from an alternative supply which adapts to the load demand. This decreases the dependence on the utility power supply and promotes the integration of STATCOMs with renewables. Complete case studies between the differences in application of a fixed reactive power compensating condenser and STATCOM for dynamic VAR compensation to loads connected at the point of common coupling in a grid connected Photo-Voltaic (PV) system is presented. The scope of this research is to examine the behavior of dynamic loads, such as an induction motor, at steady state operation when the reactive power demand from the supply increases, as well as the effect of this demand variation on the network that supplies such loads. Complete system modeling and analysis for both scenarios, the fixed reactive power compensator and the STATCOM, supplying various load demands, have been developed. The simulation is based on a 100-kW rated PV grid-connected system to simulate behavior and performance of such study. Adaptive Neuro Fuzzy Inference System with Particle Swarm Optimization was used to extract the maximum power point of the PV array proceeded by a sliding mode controller. MATLAB/ Simulink was developed for modelling and analysis. Various load dynamics with varying solar irradiance and increasing reactive power demand of the associated load were simulated to evaluate various challenges and disturbances on the power supply.

Evaluation of electric vehicle penetration impacts on distribution system under responsive load management

Today, with the advancement of technology in the context of the smart grid, consumers' energy consumption pattern can be managed by power distributors under certain conditions. The goal is to benefit both consumers and power supply utilities by implementing techniques that are generally called responsive load management. In this paper, the concept of responsive load is implemented on a standard 26-bus IEEE system network that has 4,000 branches and a maximum of 3,000 electric vehicles. The purpose of the proposed approach is to minimize the cost of customer's energy consumption with consideration their waiting time for electric vehicle (EV) charging. The results are calculated for the 20%, 50% and 80% EV penetration levels through the genetic algorithm. In addition, the impact of satisfaction level on the peak load-to-average load ratio is also evaluated.

Influencing factors of the high-quality economic development in China based on LASSO model

This paper constructs an index system for high-quality economic development in China from four dimensions: economic system, social system, environment system, and power system. The LASSO method was presented as screen indicators, then we use the panel fixed effect model to investigate the specific impact of key factors on high-quality economic development. The results indicate that: (1) Innovation-driven, infrastructure construction, green technology development, power supply, and efficient utilization of electrical equipment are the most important influencing factors to promote high-quality economic development. (2) Increasing financial expenditures for pollution prevention and control and strengthening the application of green technology will help to adjust the economic structure. (3) Building a complete green energy system will be an essential part of high-quality economic development. On this basis, heterogeneity analysis is carried out according to regional economic differences and power supply and demand positioning. These findings have great significance in high-quality economic development of China.

Improvement of the transmission and sub-transmission overhead lines lightning performance using line arresters – Experience in Brazil

Lightning has been reported as the major cause of non-scheduled outages that occur in Brazilian’s power system, being responsible for approximately 50 – 70% of the outages verified in overhead lines with rated voltages up to 230 kV and creating many issues for power supply utilities and consumers. In agreement with the information of the National Institute for Space Researche (INPE) Brazil is the country with the largest incidence of lightning activities in the world, with about 50 - 70 million lightning outages a year somewhere in the country. With this considerable amount of lightning caused distubances, the resulting damages caused to the electric power systems are high such that the costs of losses and repairs exceed an annual value of 350 million dollars. This fact has been taken up by several power supply utilities and industrial consumers and caused them to invest in partnership with universities and research centers in the development of theoretical studies and the promotion of improvements along the critical sections of their overhead lines with poor lightning performance, thereby increasing their reliability. In many cases line arresters have been considered as the most effective method to improve the lightning performance. In Brazil, the first application of line arresters was in the middle of the nineties and from this time on more than 3,000 units of gapless line arresters were installed on overhead lines from 34.5 kV up to 230 kV. The analysis and evaluation of overhead lines lightning performance before and after the line arresters installation have shown a good effectiveness, with average indexes for the improvement higher than 70%. Good field experience and the proven results obtained in the the overhead lines lightning performance after the line arresters installation have been encouraging more and more Brazilian power supply utilities and industrial consumers to develop studies to evaluate the line arresters application along their overhead lines presenting poorer lightning performance. This paper presents information about the experience of the Brazilian power supply utilities as well as industrial consumers in the application of line arresters to improve the overhead lines lightning performance. Procedures used to optimize the characteristics of the line arresters, quantity and location along the critical sections of the lines; field experience as well as the lightning performance of the lines before and after the line arresters application are presented and discussed.

A new intelligent approach for size optimization of a renewable energy based grid connected hybrid energy system

AbstractAdopting hybrid power systems to provide access to clean, reliable, and inexpensive energy is necessary for countries like India to accomplish their goals of sustainable development. This work proposes an optimization approach for sizing a grid‐connected hybrid renewable energy system (HRES) that includes photovoltaic, biomass, biogas, and a battery. In this research, a recently developed Aquila optimization algorithm is utilized to evaluate the optimal size of HRES for a cluster of villages near Sarai Jairam, Agra district, Uttar Pradesh, India using the MATLAB software package. The goal of this optimization approach is to reduce the net present cost for HRES while satisfying the operational constraints, including the reliability of the power supply and maximum utilization of the photovoltaic, biomass, and biogas complementary properties. Initially, three HRES configurations in the off‐grid mode were optimized using the suggested Aquila optimization technique. To confirm the findings, the optimization results for the same models of off‐grid HRES were obtained using the harmony search (HS) and particle swarm optimization (PSO) algorithms. The same algorithms were also used to optimize the grid‐connected SPV/biomass/biogas with the battery model of HRES. Finally, the outcomes from the off‐grid models presented above were compared to the grid‐linked model. The grid‐connected configuration which is obtained by the Aquila optimization approach provides an optimal solution with the least net present cos t (NPC) and minimum cost of energy (COE) when compared with HS and PSO. The optimal grid‐connected HRES includes 235 kW of PV, a 10 kW biogas generator, a 64 kW biomass generator, and a 50.40 kWh battery bank. The overall net present cost and the COE are found to be $547 670 and $0.0768/kWh, respectively.

Optimal Location and Sizing of Reactive Power Compensation Devices for Voltage Stability Improvement of Radial Power Systems

With the advancement in technology, the electricity demand is increasing day by day. Power supply utilities are facing the problem to expand their network owing to the problems like availability of land in urban areas and Right of Way (ROW). Due to these problems, many of the existing lines are operating nearer to their thermal stability limit. Maintaining the voltage within the limits will be a challenging task for the utilities. Increased loading of the lines is making the power system to the verge of voltage stability. Many indices are proposed in the literature for predicting the voltage stability of the system. In this paper, L-Index is used for voltage stability analysis of the radial distribution system. L-Index sensitivity method is used to the locate and size the reactive power compensation devices. The effectiveness of L-Index sensitivity method on the larger power system like IEEE-33 bus system is presented in this paper and simulation studies are performed using MATLAB/SIMULINK.

DESIGN ANALYSIS OF AN AUTOMATIC PHASE SELECTOR

Power instability in Nigeria caused by overbearing demand of power by consumers and lack of proper maintenance of the power system devices among others has brought about the need for alternative power sources such as generators, solar, typical inverters and other alternative supplies which requires one form of switching or the other to achieve phase selection during power failure. This paper gives a design analysis of an automatic phase selector linking available power supplies, that is; switching between a three-phase public utility supply, as a result of total power outage in the public supply to an alternative secondary supply (in this case a Generator and an Inverter system) and back when power is restored. The design adopts the use of a microcontroller-based system interconnected with other hardware components for proper isolation, switching and visualization of switching conditions. The system design is divided into two major part: the hardware which consists of the power supply, sensing circuit, controller or control logic circuit, display and the power electronics switching unit and the software instruction code on the microcontroller unit. The design analysis was first carried out accompanied with computer simulation on a software tool (Proteus 8 Professional, version 8.4) to carry out performance evaluation of the sub-circuits, thereafter, a practical implementation of the design was carried out and tested with the utility power supply using five (5) switches, three of which represents the three-phase primary supply and the other two represents the secondary supply.

Free Switching Control Strategy for Multi-Operation Modes of Multi-Port Energy Router in Distribution Area

For the distribution area with a high penetration rate of new energy, the traditional power supply system has some problems, such as a single form of power supply and low utilization of new energy. Because the multi-port energy router can realize the interconnection and complementation of multiple energy forms, it has become the key piece of equipment in the hybrid AC/DC distribution area. Nevertheless, restricted by the existing control strategy, the performance of the energy router in complex operation mode switching and coordinated control still needs to be further improved. To address this issue, the free switching control strategy is proposed in this paper. Firstly, the topology and model of the multi-port energy router are designed and established. Secondly, the operation mode of the system is analyzed, and the control strategy of each port is designed. Then, a reference power calculation method suitable for multi-mode operation is derived. Based on this, the control strategy does not need to be changed when operation modes are switched. Furthermore, the extended state observer is introduced to track and compensate for the new energy disturbance, which can improve the power quality of the system. Finally, the simulation and experimental results show that the proposed control strategy of the multi-port energy router can realize flexible and controllable power transmission among various modules in the distribution area and the free switching of multi-operation modes without changing the control strategy.

Research on energy control of low voltage PV storage microgrid

Abstract Renewable energy sources cannot guarantee long-term and stable output supply when they are given energy consumption at the load end. At the same time, traditional solar and utility power supply systems cannot guarantee the priority of using solar energy to generate electricity, which has certain limitations. In this regard, an energy control strategy for achieving smooth and no backflow switching and prioritizing the use of clean energy solar energy under a joint power supply system of a solar power grid and a municipal power grid is proposed, which is used for a conventional combined power supply system of a contactor switching circuit. A topology of low voltage power grid is proposed, which effectively reduces the impact on the solar power grid and the municipal power grid during the system switching process combined control mode for controlling the current phase and repetitive control at the output end of the solar power grid in the combined power supply mode, and adding a feedforward control method for the grid voltage is adopted to ensure that the solar grid and the municipal power prioritize the use of clean energy solar energy and, at the same time, ensure the maximum utilization of solar energy. This paper chose the combined power supply system with the solar power grid and the municipal power grid as the object of this research. The topology structure and controlling strategy of the power supply system were comprehensively and deeply researched, and on this basis, the combined power supply system prototype was designed on the foundation of DSP28335 and CPLD. Moreover, hardware parameters are designed in the system, and an energy management optimization algorithm based on the system is developed on the corresponding experimental platform. The experimental results show that the proposed energy control strategy can effectively reduce the impact on the solar power grid and the municipal power grid during the system switching process, ensure that the solar power grid and the municipal power grid have no backflow combined power supply and give priority to the use of clean energy solar energy.

Model Predictive Control of the Input Current and Output Voltage of a Matrix Converter as a Ground Power Unit for Airplane Servicing

This paper deals with the design, control, and implementation of a three-phase ac–ac mobile utility power supply using a matrix converter for airplane servicing applications. Using a matrix converter as a compact direct ac-to-ac converter can provide savings in terms of the size and cost of a mobile power supply compared to common back-to-back converters. Furthermore, using the proposed direct matrix converter eliminates the need for bulky electrolytic capacitors and increases the system’s reliability and lifetime. A finite control set model predictive control is used to generate a high-quality 115 V/400 Hz output voltage and a low-harmonic-distortion source current with a unity input power factor for various load conditions, including balanced, unbalanced, linear, and nonlinear loads. The predictive strategy is used to control the output voltage and source current for each possible switching state in order to simultaneously track the references. To achieve a further reduction in the system’s size and cost, an active damping strategy is used to compensate for the instability caused by the input filter in contrast to the passive method. Experimental tests were conducted on a prototype matrix converter to validate the performance of the proposed control strategy.

Multiple AI based Controlling Techniques for Power Filter Output Quality Improvement

The excessive of power electronics devices in distribution system has evolved the problem of power quality. This work represents the effective solution of shunt active power filter for eliminating the harmonics to maintain the quality of utility power supply. In the proposed scheme shunt active filter acts as a voltage source and eliminates harmonics by injecting equal but opposite harmonics components at the point of common coupling. Simulation of shunt active filter based on instantaneous reactive has been achieved in the MATLAB/SIMULINK environment. The controllers are being designed with the objective of reducing the THD% in voltage and current available at the nonlinear load terminal of the system. The controller incorporated optimization algorithms based on the artificial intelligence techniques as well. The comparative analysis of the effectiveness and efficiency of the controllers in improving the quality factors has been carried out. The distortion level in the output voltage waveforms in both the cases being fed to the load when compared, it is found that proposed hybrid structure of control for the filter is more effective in reducing the distortion as compared to standard PQ theory based architecture. The study concluded that the total harmonic distortion in the voltage output waveform being fed to the load using only PQ theory based online learning algorithm is found to be 1.59 % while in case of the output voltage at the load terminal from the power filter using proposed hybrid algorithm comprising of NN learning with CSA optimizing control and PQ_RLS algorithm for THD reduction the THD% level is 0.43 %.

Research on Load Forecasting of Charging Station Based on XGBoost and LSTM Model

At this stage, due to the increasing use of electric vehicles, the position of electric vehicle load scheduling in grid power scheduling is becoming more and more important. Effective electric vehicle power dispatching can balance the peak-valley difference of power dispatching, increase the power supply utilization rate of power grid dispatching, and reduce the power supply pressure of line transformer. The load forecast can describe the user’s electricity consumption habits in the next period of time, and can provide important data basis for power dispatching. This paper summarizes the research status of electric vehicle charging load, analyzes traditional charging load research methods, propose a charging load forecasting method combining XGBoost(Extreme Gradient Boosting) and LSTM (Long Short Term Memory Network), And use the data of a charging station in Jiangsu to verify the calculation example. The proposed method is based on the prediction results of the XGBoost model for feature engineering, extracting data features using phase space reconstruction techniques and statistical methods. In addition, training the LSTM model for load prediction. Based on the charging record data of domestic charging stations, this paper applies the artificial intelligence method to the charging load forecast of domestic charging stations for the first time. The charging station load forecasting method studied in this paper can support the regional load forecasting research of electric vehicles with high permeability, and further optimize power dispatching.