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Electric Power Systems Research

Electric Power Systems Research

Archives Papers: 1,559
Elsevier
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Fault recovery of integrated energy system considering electric-gas coupling characteristic and robust chance-constrained power balance
Yuan Huang; Xinyu Fan; Xiao Xu; Junyong Liu; Lixiong Xu; Zengjie Sun;
Abstracts:After the integrated energy system (IES) encounters extreme disasters, the uncertainty of renewable energy may lead to the imbalance of power supply and demand. This makes the IES fault recovery strategy very complicated. Considering the influence of the electric-gas coupling characteristic of natural gas delay, this paper proposes a fault recovery strategy, including the load recovery and economic efficiency of the operation of the IES. In the recovery stage, a chance-constrained power balance model is employed to solve the power supply and demand imbalance caused by uncertainty. Next, the chance-constrained power balance model is processed via distributionally robust optimization, and it is reformulated into a second-order cone programming (SCOP) problem by dual transformation and conditional value-at-risk approximation. To deal with nonlinear terms, the piecewise linearization method is used to model the load recovery result, renewable energy output, and total operation cost of each period during the fault. Finally, the effectiveness of the proposed strategy is verified by an IES composed of an IEEE 39-node electricity subsystem, a 20-node natural gas subsystem, and a 6-node thermal subsystem.
A wind power forecasting model based on polynomial chaotic expansion and numerical weather prediction
Xiaoling Dong; Delin Wang; Jiayi Lu; Xin He;
Abstracts:Wind farm power prediction plays an important role in power system dispatching, stable operation and maintenance. And the uncertainty of medium and long-term meteorological environment brings uncertainty to the prediction of wind farm power. A statistical method for predicting the medium and long-term power of the wind farm is proposed in this paper, which takes into account the wake effect and the wind speed differences in the vertical wind profile. The uncertainty model of wind farm power is developed by combining numerical weather prediction and generalized Polynomial Chaos Expansion (PCE) method with wind direction and wind speed as uncertainties. And the PCE coefficients are solved using the stochastic response surface method. The mean, standard deviation, and global sensitivity of the wind farm power can be easily calculated and analyzed by using the coefficients. The proposed method is validated from two scales of single moment and continuous time, and the validation shows that the proposed method performs better compared to Monte Carlo simulation, especially in terms of running time. In addition, according to the global sensitivity, the effect of wind speed on output active power is significantly greater than that of wind direction.
Determination strategies of low-voltage ride-through/ zero-voltage ride-through curves in Taiwan grid codes
Nien-Che Yang; Huai-Yuan Yang;
Abstracts:This study proposes a method for establishing the fault ride-through (FRT) criteria, primarily aimed at the low-voltage ride-through (LVRT) and zero-voltage ride-through (ZVRT), in response to the voltage dips. The increased penetration of wind power generation may gradually affect the stability of the power systems. Therefore, the FRT capability of wind turbines is critical; however, a clear and systematic strategy for the FRT curve specifications must be formulated. In this study, the characteristics of the power system of the Taiwan power company (TPC) and existing TPC specifications were considered to determine the suitable FRT criteria. The power system simulator for engineering (PSS/E) software package was used to analyse the TPC power system case data for 2025. A methodology was developed to establish the FRT criteria using a series of PSSE-based simulations, including a short-circuit fault analysis and static and dynamic scenario-based system simulations. The main process was implemented by selecting the observation points based on the voltage dips, developing a transient simulation plan following the TPC regulations, and formulating the FRT curves based on the simulation results.
Fault current constrained impedance-based method for high resistance ground fault location in distribution grid
Wei-Jian Yang; Xiao-Qi Yin; Jun Tao; Hua-Ying Zhang;
Abstracts:Fault locating technology is crucial to the safe operation of a distribution grid. Impedance-based method is quite promising in fault locating due to its low cost and easy implementation. However, this method suffers from low precision when locating high resistance ground fault. This paper proposes a fault current constrained impedance-based fault location method. This method establishes location equations via the assumption that fault resistance consumes zero reactive power. First, this method adds the Thevenin equivalent to the downstream network after the fault. Second, the increment of fault current caused by distributed generations is quantified. These efforts provide an exact estimation of fault current, leading to a higher locating precision when encountering a high resistance ground fault. Simulations based on IEEE-34 node network show that the proposed method outperforms the traditional impedance-based method in precision significantly. Moreover, the proposed method does not need to distinguish fault type in advance, and is compatible to different fault scenarios.
Numerical model of lightning attachment on UHV-AC transmission lines and effects of operating voltage, phase angle, and terrain
Ziwei Ma; Jasronita Jasni; Mohd Zainal Abidin Ab Kadir; Norhafiz Azis;
Abstracts:A numerical model for lightning attachment on UHV-AC double-circuit transmission lines was developed using the leader propagation method (LPM) and the finite element method (FEM). The striking distance (SD) of the ground wire (GW) was calculated based on this model. The effects of operating voltage, phase angle, and terrain on the electric field of the wires were also analyzed. The simulation results revealed that when the phase conductors were energized, upward leaders (ULs) simultaneously occurred on both the GW and the upper-phase conductor. The velocity of the GW UL was faster than that of the upper-phase UL, allowing it to successfully intercept the downward leader (DL) in the air, while the upper-phase UL aborted after propagating 1.8 m under the shielding effect of the GW UL. A new expression of rs=7.2Ip0.87 for calculating the SD on the GW was proposed based on the simulation results. This expression provided reasonable results that fell between those obtained from the electro-geometric models and the analytical model. Additionally, the simulation results demonstrated that extremely high voltage, phase angle, and terrain slope increased the surface electric field of the upper-phase conductor, thereby increasing the risk of shielding failure.
Diagnostics analysis of partial discharge events of the power cables at various voltage levels using ramping behavior analysis method
Sambeet Mishra; Praveen Prakash Singh; Ivar Kiitam; Muhammad Shafiq; Ivo Palu; Chiara Bordin;
Keywords:Internal partial discharge;High voltage engineering;Power cable;Uncertainty quantification;Trends and patterns;Diagnostics methods
Abstracts:Partial discharge events can occur in high-voltage cables. It can be caused by defects in the cable insulation, contamination, or a combination of both. Partial discharge in cables can lead to insulation failure and cable failure. This investigation aims to identify the trends and patterns in the internal partial discharge (PD) occurrences in the power cables when exposed to different voltage levels - 6.4, 7.4, 9.4, and 11.3 kV. For pattern extraction, a well-established method, ramping behavior analysis, is implemented to extract and classify PD occurrences into sets of significant and stationary events. In this investigation, significant events correspond to an absolute peak (the discharge pulse) and subsequent oscillations from the measurement sensor. The stationary events represent a collection of noise that is recorded during the measurement. These noise signals are essentially small variations within a pre-determined threshold range. Furthermore, a comparative analysis is performed for each voltage level and for the voltage levels. This investigation brings new knowledge on how internal partial discharge pulses occur at various voltage stress levels. Specifically, the emerging patterns and trends of internal partial discharge events. The results indicate that there is a positive correlation between the number of PD events and the increase in stress levels. Furthermore, negative PD peaks are more frequent at lower stress levels.
Modeling market trading strategies of the intermediary entity for microgrids: A reinforcement learning-based approach
Sanaz Ghanbari; Salah Bahramara; Hêmin Golpîra;
Abstracts:Participation of a large number of microgrids (MGs) in the energy markets faces several challenges. To address these challenges, MGs can be aggregated by an Intermediary entity (IE). In this paper, a new decision-making framework is proposed to solve the energy management problem of multiple MGs and their participation in the energy market through the IE. This framework has three main functions. First, energy price forecasting is conducted using the long short-term memory (LSTM) recurrent neural networks method. Then, the power exchange of the MGs with the main grid is optimized by solving their energy management problem. In this stage, the integrated power exchanges of the MGs with the grid are determined based on the predicted prices. In the final function, the Monte Carlo reinforcement learning technique is employed to optimize real-time pricing decisions and identify potential obstacles that may affect proposed bid prices. This approach addresses energy management challenges and enables profitable energy trading in multiple MGs within energy markets, with confirmation supported by simulation results. The results show a maximum increment of 4.55% in the profit of the IE when purchasing energy and a 3.79% maximum increment when selling energy in the real-time market compared to day-ahead decisions, respectively.
Visually impaired recognition of a fully loaded high and medium voltages electrical network for layout formation and fault monitoring
Arnaout Mohamad; Koubayssi Ali; Badreddine Fatima; Kawssan Mohammad; Kafal Moussa; Rammal Rabih;
Abstracts:Faults in power systems are inevitable. These faults can cause undesirable outages that interrupt people's life, block factories’ production chain, and may even in worse case scenarios contribute to killing hospitalized patients. To minimize such catastrophes, many techniques were developed for the purpose of instantaneous monitoring and repairing of power systems. However, due to the increasing complexity of transmission line networks, enhancements to the fault location techniques became a necessity to align with the new challenges. This paper presents a technique designed to diagnose faults in a power network under test; it starts by a comparison between two commonly used Fault Location Algorithms: impedance and travelling wave-based methods. The latter have shown numerous advantages when compared to impedance-based methods that led us to the adoption of a travelling-wave variant Time Domain Reflectometry (TDR). TDR was incorporated with the graph theory and an optimization algorithm (Particle swarm optimization (PSO) in order to acquire the fault data rapidly, accurately, and with the least possible complexity.
A new method for fault location in special parallel lines called “stitched lines”
Milad Gil; Mohammad Mehdi Mobashsher; Ali Akbar Abdoos;
Abstracts:Today, a special kind of parallel double-circuit line, designated "stitched lines," is employed in various transmission and sub-distribution networks in some countries, like Iran. In this type of unusual line, two circuits are connected at the beginning and end of the route and enter the high-voltage substations by a single line. Since on these lines there is no access to the current of each circuit separately, their protection, especially fault location, has faced a major challenge. Therefore, this article establishes a new method based on symmetrical components (positive sequence) to determine the location of the faults in the stitched lines. To scrutinize the performance of the proposed approach, comprehensive simulations have been run in the PSCAD/EMTDC software under a variety of different situations. The suggested method's accuracy has been established for a variety of fault locations and resistances. It has also been determined how the suggested approach performs when subjected to noise, current transformer saturation, arcing faults, transposition type, source impedance variation, and load changes. The obtained results show that the proposed approach is accurate under different scenarios, making it an excellent choice for practical applications.
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