Hasil untuk "Distribution or transmission of electric power"

Bikash Patel

William Gouvêa Buratto, Rafael Ninno Muniz, Ademir Nied et al.

Abstract The use of biomass as a renewable energy source for electricity generation has gained attention due to its sustainability and environmental benefits. However, the intermittent electricity demand poses challenges for optimizing electricity generation in thermal systems. Time series forecasting techniques are crucial in addressing these challenges by providing accurate predictions of biomass availability and electricity generation. Here, wavelet transform is applied for denoising, convolutional neural networks (CNN) are used to extract features of the time series, and long short‐term memory (LSTM) is applied to perform the predictions. The result of the mean absolute percentage error equal to 0.0148 shows that the wavelet CNN‐LSTM is a promising machine‐learning methodology for electricity generation forecasting. Additionally, this paper discusses the importance of model evaluation techniques and validation strategies to assess the performance of forecasting models in real‐world applications. The major contribution of this paper is related to improving forecasting using a hybrid method that outperforms other models based on deep learning. Finally, future research directions and potential advancements in time series forecasting for biomass thermal systems are outlined to foster continued innovation in sustainable energy generation.

Rayees Ahmad Thokar, Nikhil Gupta, K. R. Niazi et al.

Abstract Contemporary distribution networks can be seen with diverse dispatchable and non‐dispatchable energy resources. The coordinated scheduling of these dispatchable resources with non‐dispatchable resources can provide several techno‐economic and social benefits. Since battery energy storage systems (BESSs) and microturbine units are capital intensive. A thorough investigation of their coordinated scheduling on a purely economic basis will be an interesting and challenging task while considering dynamic electricity price and uncertainty of renewable power generation and load demand. This paper proposes a new methodology for optimal coordinated scheduling of BESSs and microturbine units considering existing renewable energy resources and dynamic electricity price to maximize daily profit function of the utility. In this study, a recently explored modified African buffalo optimization algorithm is employed. The key attributes of the proposed methodology are comprised of mean price‐based adaptive scheduling embedded within a decision mechanism system to maximize arbitrage benefits. Decision mechanism system keeps a track of system states as a‐priori thus guides the artificial intelligence‐based solution technique for sequential optimization. This may also reduce the computational burden of complex real‐life engineering optimization problems. Further, a novel concept of fictitious charges in coordination with BESS management algorithm is proposed to restrict the counterproductive operational management of BESSs. The application results investigated and compared on a benchmark 33‐bus test distribution system highlights the importance of the proposed methodology.

Binhot P. Nababan, Kevin Marojahan Banjar-Nahor, Musa Partahi Marbun et al.

This study focuses on analyzing switching transients in the upcoming 500 kV Java-Bali Connection (JBC) hybrid OHL and submarine cable project using DIgSILENT PowerFactory software, based on a realistic power system model. Distributed-parameter models with constant parameters of the Bergeron model are utilized. Analysis of the traveling wave effect on the line is conducted, and the integration time step based on the time of the traveling wave is carefully selected. Statistical distributions of energization are produced by varying the circuit configuration and system short-circuit power. It is found that the Switching Withstand Voltage (SWV) during the energization process remain below 1175 kV. The probability distribution is fitted to a normal distribution, with the skewness and kurtosis shown to be skewed to the right and having a lower peak than that of the normal distribution, respectively. When a three-phase short-circuit at the line breaker is induced, the rate of rise of recovery voltage (RRRV) exceeds the IEC standard envelope if only one circuit is operating. In this contribution, switching analysis during no-load energization and de-energization in the planning stage of the mixed OHL-submarine cable is examined.

Zhenzi Song, Xiuli Wang, Tianyang Zhao et al.

Abstract The carbon capture‐transportation‐utilization (C‐CTU) chain strengthens the coupling between terminal energy consumption and renewable energy resources (RES), achieving carbon emission reduction in power generation sectors. However, the dynamic operation of the C‐CTU chain and the uncertainties induced by RES output pose new challenges for the low‐carbon operation. To address above challenges, the nonlinear dynamic operation model of C‐CTU chain is first proposed in this study. It is further incorporated into the day‐ahead operation scheme of the electricity‐carbon integrated system considering the stochastic nature of wind power. This scheme is treated as a two‐stage stochastic integer programming (TS‐SIP) problem with a mixed‐integer nonlinear recourse. By means of the polyhedral envelope‐based linearization method, this recourse is reformulated into its linear counterpart. To further improve the computational performance of classical decomposition algorithms, a novel Benders decomposition framework with hybrid cutting plane strategies is proposed to obtain better feasible solutions within a limited time. Simulations are conducted on two power system test cases with the C‐CTU chain. Numerical results indicate that the engagement of C‐CTU chain promotes the low‐carbon economic operation of the power system. Also, the proposed decomposition algorithm shows a superior solution capability to handle large‐scale TS‐SIP than state‐of‐the‐art commercial solvers.

Zhengjie Luo, Hui Ren, Guoyu Xin et al.

Abstract The aggregation of the remaining battery capacity of electric vehicles (EVs) can be used as distributed energy storage to participate in the microgrid optimisation through vehicle‐to‐grid (V2G) technology. However, the reliability of this service to be delivered is affected by the uncertainty of EVs’ behaviour. The un‐reliable service will bring risks in the operation of microgrid when EVs’ V2G electricity is regarded as an important flexibility resource. This paper, first proposes an analytical method to quantify the reliability of EV aggregation's (EVA's) V2G electricity based on the analysis of historical charging data and compound Poisson process. Based on this model, electric vehicles aggregators can evaluate the V2G bid quantity for any time slot on day t+1 according to the reliability requirements. Secondly, an optimal operation model of microgrid with consideration of V2G's reliability is considered. Finally, a test system with photovoltaics (PVs) and EVA on top of the original IEEE 33‐node system is used to verify the effectiveness of the proposed model. The results show that with the proposed reliability evaluation method of V2G electricity, the optimal operation of the microgrid can be reached with appropriate evaluation of the capability of the EVA.

Mohammad Asadi, Vahid Behnamgol, Ahmad Reza Vali

This paper introduces a novel adaptive second-order sliding mode algorithm for finite-time control of uncertain nonlinear systems. Traditional first-order sliding modes are hindered by chattering and dependence on the upper bound of uncertainty. Although adaptive sliding modes with dynamic gains remove the need for this upper bound, they still suffer from chattering and lack finite-time stability. The proposed algorithm incorporates an additional term in the control law, ensuring a smooth control signal, eliminating chattering, and achieving finite-time stability of the closed-loop system. This method is applied to a thrust vector-based flying object for pitch angle tracking amidst aerodynamic coefficient uncertainties and environmental disturbances. The performance of the proposed thrust vector system is demonstrated through computer simulations, comparing it with two other adaptive first-order and an adaptive super-twisting sliding mode methods. Simulation results show significant improvements in control performance, including reduced chattering and enhanced stability, underscoring the practical effectiveness of the proposed method.

Zhipeng Ma, Ningyi Li, Xingang Chen et al.

Abstract The voltage endurance coefficient n of cross‐linked polyethylene (XLPE) insulation is an important indicator for the analysis of insulation failure mechanism. Accurately obtaining the value of n can provide technical support for the reliability evaluation of cable operation. The constant stress method and the step stress method are used to obtain the values of n, but the test parameters can influence the accuracy of the obtained n values. Two methods for selecting test parameters are proposed. The equivalence between the two methods is established, providing theoretical support for the accurate evaluation of the n value of solid insulation materials by using the step stress method. The accuracy of the evaluation results is verified by analyzing the test data. The test results show that the nstep = 13.04 evaluated by the step stress test with the proposed parameter selection method is consistent with the test result of constant stress nconstant = 12.83.

Xiaolong Li, Guangkuo Zhang, Chen Cao et al.

Abstract Herein, the surface charge characteristics of a tri‐post insulator in a ± 500 kV direct current gas‐insulated transmission lines (DC‐GIL) filled with SF6 are thoroughly studied. The influences of volume and surface conductivity of the insulator on the surface charge and consequent electric field distribution are discussed. An improved method is introduced to obtain the distribution of surface charge with considerable accuracy and efficiency for the calculation. It is found that with increasing the volume conductivity, the dominative conduction mechanism changes from surface conduction to bulk conduction, while the inverse variation appears with increasing the surface conductivity. During the variation of electric conductivity, obvious effect of surface charge accumulation is found on the electric field distribution involving the variation of peak electric field strength and its location. Besides, high charge density usually appears along with low peak field strength during this variation. It can be concluded that the surface charge accumulation should be paid special attention when analysing the insulation characteristics of tri‐post insulators. The variation of volume and surface electric conductivity should be thoroughly considered.

Peng Li, Lei Jiang, Chunyan Zhang et al.

Abstract Development and utilization of renewable energy is an effective way to deal with global warming. In this context, integrated electricity–heat–gas energy system (IEHGES) provides a new way for the efficient use of renewable energy. Existing IEHGES planning methods focus on the improvement of cost and energy efficiency, while not designing a capacity configuration scheme for high renewable energy penetration scenarios. Here, a coordinated planning method for IEHGES considering renewable energy consumption is proposed. Firstly, electricity/gas/heat storage, electric boiler and power to gas are co‐configured to realize heat‐electricity decoupling operation of combined heat and power, providing flexible and controllable electricity supply for the system. Then, coordinated planning method of IEHGES is proposed which takes into account the coordination of multi‐energy and the coordination between optimal planning and optimal operation. The spare capacity factors are included in the planning and cost of environmental penalty and renewable energy generation subsidy are included in operation cost. In view of the uncertainties, complementary characteristics between electricity, gas and heat supply systems in IEHGES are combined with k‐means to obtain optimal schemes of coordinated planning. Finally, the correctness and validity of the proposed method are verified by three indexes in a case study.

Naoto Yorino, Shinya Sekizaki, Kota Adachi et al.

Abstract This paper summarizes our recent work on Grid‐Forming Inverter (GFM) application to power systems. We have developed a novel design of GFM, a single‐phase synchronous inverter (SSI) for the conventional 100/200V distribution network based on the concept of “non‐interference core (NIC) dynamic model.” This paper first explains the design concept of NIC‐SSI and a simulation model of SSI for power system analysis. Then the stabilization effect is investigated, where the installation of SSI on the single‐phase consumer side is assumed as a new concept. The improvement of frequency and transient stability are evaluated. The SSI model is verified by comparing the developed root mean square (RMS) simulation, hardware‐in‐the‐loop (HIL) simulation, and the experiment using SSI hardware. The simulation results show that the SSI has the considerable ability of grid stabilization. Singlephase micro‐grid (SMG) operations using SSIs are also presented. The effectiveness of SMG operations is shown based on laboratory experiments.

L. Hu, D. Ottinger, S. Bogle et al.

<p>Sulfur hexafluoride (SF<span class="inline-formula">₆</span>) is the most potent greenhouse gas (GHG), and its atmospheric abundance, albeit small, has been increasing rapidly. Although SF<span class="inline-formula">₆</span> is used to assess atmospheric transport modeling and its emissions influence the climate for millennia, SF<span class="inline-formula">₆</span> emission magnitudes and distributions have substantial uncertainties. In this study, we used NOAA's ground-based and airborne measurements of SF<span class="inline-formula">₆</span> to estimate SF<span class="inline-formula">₆</span> emissions from the United States between 2007 and 2018. Our results suggest a substantial decline of US SF<span class="inline-formula">₆</span> emissions, a trend also reported in the US Environmental Protection Agency's (EPA) national inventory submitted under the United Nations Framework Convention on Climate Change (UNFCCC), implying that US mitigation efforts have had some success. However, the magnitudes of annual emissions derived from atmospheric observations are 40 %–250 % higher than the EPA's national inventory and substantially lower than the Emissions Database for Global Atmospheric Research (EDGAR) inventory. The regional discrepancies between the atmosphere-based estimate and EPA's inventory suggest that emissions from electric power transmission and distribution (ETD) facilities and an SF<span class="inline-formula">₆</span> production plant that did not or does not report to the EPA may be underestimated in the national inventory. Furthermore, the atmosphere-based estimates show higher emissions of SF<span class="inline-formula">₆</span> in winter than in summer. These enhanced wintertime emissions may result from increased maintenance of ETD equipment in southern states and increased leakage through aging brittle seals in ETD in northern states during winter. The results of this study demonstrate the success of past US SF<span class="inline-formula">₆</span> emission mitigations and suggest that substantial additional emission reductions might be achieved through efforts to minimize emissions during servicing or through improving sealing materials in ETD.</p>

Mohammad Kazem Salehi, Mohammad Rastegar

Abstract Residential buildings may use energy storage, flexible loads, and renewable energy sources to reduce energy consumption and increase demand side flexibility. The flexibility of a single building can be coordinated with other facilities in a transactive energy (TE) market to reduce energy costs. In addition, cloud energy storage (CES) has been proposed to provide storage services for residential buildings with more economic benefits than individual energy storage units in recent years. Although the TE market and CES implementation have received much attention in previous works, a suitable structure for CES participation in TE market has not been addressed. Furthermore, previous studies ignored all or some sources of uncertainties in the TE decision making process. This paper presents a stochastic optimization model in a transactive energy framework based on a distributed optimization algorithm for peer‐to‐peer energy trading using the alternating direction method of multipliers in the presence of CES. This paper considers the uncertainties of the inflexible load demand, renewable energy generations, and market prices using an artificial neural network‐based scenario generation and reduction methodology. Numerical results show improvements toward addressing the challenges of the uncertainties while maximizing the CES's owner revenue and minimizing the customers’ costs in the proposed model.

Hamed Shadabi, Innocent Kamwa

Abstract This paper studies the hybrid energy storage system to provide frequency support for the interconnected AC grid through MTDC systems interfacing renewable resources. A hybrid energy storage structure was created using a supercapacitor (SC) and battery storage systems (BESs). To coordinate the sharing of power between SC and BESS, an improved droop controller based on virtual inductance, capacitance, and resistance gain (VICRC) is suggested. Meanwhile, the droop controller's steady‐state deviation of the DC link voltage is immediately suppressed. The SC will be in charge of compensating the high‐frequency demand, whereas the BESS will be in charge of compensating the low‐frequency power demand, thanks to a decentralized energy management process. In addition, the suggested method aids in the rehabilitation of the SC's SOC. Finally, the simulation results with detailed models of the wind farms and AC–DC grid converters are performed on IEEE tests systems in Simulink/SPS and the results extensively discussed to evaluate the proposed structure.

Miren T. Bedialauneta, Elvira Fernandez, Igor Albizu et al.

Abstract Low‐sag conductors are characterised by their ability to operate above the “knee‐point temperature” (KPT). Sag‐tension performance must be calculated while designing a new overhead line. The ampacity limit of the conductor is influenced by the sag and the temperature of the conductor. The maximum sag must be limited to a certain value to ensure a safe clearance between the conductor and ground. In this study, a gap‐type conductor in operation was monitored to evaluate the actual KPT. The KPT in low‐sag conductors is a crucial factor since it affects the sag of the conductor, which must be limited for safety reasons. The KPT was detected based on the change in the coefficient of thermal expansion value of the conductor. To perform this detection, the conductor tension and temperature were monitored. This study proposes a procedure to estimate the coefficient of thermal expansion (CTE) value. The results showed a gradual displacement in CTE. This procedure was used to perform measurements in a pilot line.

Zezhong Wang, Yuan Si, Lianguang Liu

Abstract When studying the harm of geomagnetic storms to the power system, the focus is often placed on the influence of transformers reactive power loss (GIC‐Q) caused by geomagnetic induced current (GIC) on voltage fluctuation. GIC‐Q, as a reactive load, can cause power flow changes, and the small disturbance stability is affected by the power flow distribution before disturbance, so GIC‐Q connects geomagnetic storms with small disturbance stability. In this study, the probability distribution function of induced geoelectric fields is established, and the sample data is obtained by sampling. Combined with the GIC benchmark network model, multiple sets of GIC‐Q in each substation are calculated and added to the system one by one to study the influence of geomagnetic storms on the oscillation characteristic parameters and establish the risk index of small disturbance instability. The result shows that the risk index value of oscillation instability in the occurrence of geomagnetic storms increases both in the AC system and the AC/DC hybrid system, but the increased range of risk value of local oscillation instability decreases with the addition of DC systems. The research results can provide a reference for evaluating the influence of geomagnetic storms on the stable operation of power systems.

Mohsen Tavakoli Allahabadi, Saeid Hasheminejad

Luis Gutierrez‐Lagos, Kyriacos Petrou, Luis Fernando Ochoa

Abstract Distributed energy resources (DER), such as, photovoltaic systems and batteries, are becoming common among households. Although the main objective is reducing electricity imports (bills), they could also provide system‐level services via an aggregator. However, the more DER provide services, the more important is ensuring that the corresponding operation does not result in network issues. To help DER aggregators understand the implications of network constraints, an AC optimal power flow‐based methodology is proposed to quantify the effects that three‐phase low voltage (LV) and medium voltage (MV) network constraints can have on the volume of services that can be provided for a given horizon, and the potential benefits from using DER reactive power capabilities. Using a convex multi‐period formulation that avoids binary variables for batteries and incorporates voltage‐dependent load models, the methodology maximizes DER exports (services) for service‐related periods and household self‐consumption for other periods (reducing bills). Different service periods are assessed to explore the extent of services throughout the day. Results using a realistic UK MV‐LV network with 2400+ households, show that aggregator services can be highly overestimated when neglecting MV‐LV network constraints, are influenced by voltage‐demand load characteristics, and that exploiting DER reactive power capabilities can significantly unlock further services.

Shruti Nema, Sincy George

Abstract In view of the growing load demand in developing countries, overloading in existing transmission lines is a major concern. In addition to the voltage drop due to overloading, the proliferation of non‐linear loads in recent years distort the shape of sinusoidal voltage. Stable transmission of power through a transmission line under such condition is a challenge. In the presence of harmonics, control of transmittable power using static synchronous series compensator needs additional efforts, where increased power demand can be fulfilled by taking into consideration various other parameters. If an attempt is made to increase transmittable power through a transmission line using SSSC, power loss, the magnitude of voltage and its shape deteriorate in the presence of non‐linear loads. Thus, the trade‐off between transmittable power, transmission loss and voltage quality is tackled by optimal control of the compensator. In this study, a novel optimal control of SSSC is proposed with the objective of minimising transmission loss by maintaining the voltage within the limits while enhancing the transmittable power under non‐sinusoidal conditions. A two‐machine model of power system with 400 kV transmission line with parameters as per standards issued by the Central Electricity Authority is considered for validation of the algorithm using MATLAB platform and results are presented.

Mrutyunjaya Mangaraj

Abstract The motivation of this paper is to introduce a new Hebbian least mean square control algorithm for two level self‐supported voltage source converter based distributed static compensator. The Hebbian least mean square controller is employed on the various aspects such as, weight updating, direct and quadrature unit voltage template, active and reactive part of reference supply currents and switching signal generation. Firstly, a set up equations using Hebbian least mean square are premeditated to compute both active and reactive weight updating. Secondly, DC and AC proportional integral controller outputs are involved with the updating weight to generate the reference supply current. The error signal obtained from both reference and actual source current is processed through the hysteresis current controller for the gate signal firing. The MATLAB/Simulink results as well as experimental results prove that the proposed algorithm is competent to afford the better voltage regulation, voltage balancing, source current harmonic reduction and power factor correction. Finally, performance obtained from the proposed controller reveals the applicability for various loading condition in the distribution grid.