Hasil untuk "Distribution or transmission of electric power"

Bikash Patel

Ahmed Husham, Innocent Kamwa, Hussein Suprême

Abstract Conventional power systems function under the assumption that loads are uncontrollable, and that the generation control is the primary means of preserving system voltage, frequency, and stability. Thanks to recent advancements of power electronics technology and communication schemes, demand‐side resources are now capable of providing fast frequency regulation. Controllable loads can provide upward/downward reserve during frequency excursions. In this paper, the authors consider collective contribution of large clusters of controllable loads which modulate their aggregate demand power to regulate the primary frequency. Koopman model predictive control is designed to handle local frequency variations caused by various disturbances at each load bus, considering uncertain load models. The efficacy of the proposed method has been validated using the New‐England power system considering two scenarios, namely, load variation, and generation outage.

Jiajia Huan, Yuling He, Kai Sun et al.

Abstract The development of the carbon market is a strategic approach to promoting carbon emission restrictions and the growth of renewable energy. As the development of new hybrid power generation systems (HPGS) integrating wind, solar, and energy storage progresses, a significant challenge arises: how to incorporate the electricity‐carbon market mechanism into the planning of power system capacity. To address this challenge, this article proposes a coupled electricity‐carbon market and wind‐solar‐storage complementary hybrid power generation system model, aiming to maximize energy complementarity benefits and economic efficiency. The model employs a bi‐level optimization method based on the Improved Coati Optimization Algorithm (ICOA) to optimize the system's capacity planning. Simulations reveal that under the coupled electricity‐carbon market scenario, renewable energy capacity increases by 23% over a 5‐year planning period. Additionally, in this scenario, the total cost is 0.042% lower compared to the scenario without coupling. Under the constraint of a 30% renewable energy penetration rate, the capacity development of wind, solar, and storage surpasses thermal power, while demonstrating favourable total cost performance and the comprehensive complementarity index for HPGS. This model offers decision‐making support for optimizing energy resource allocation and improving system reliability and economic viability.

Jian Li, Chaowei Sun, Shuxian Yang et al.

Abstract This paper mainly studies a detection method of dynamic load altering attacks (D‐LAAs) in smart grids. First, communication factors are considered, and a smart grid discrete system model under D‐LAA attack is established. Second, for closed‐loop D‐LAAs, an adaptive fading Kalman filter (AFKF) is designed to estimate the states of smart grids with Gaussian noise in real time, and a Euclidean distance ratio detection algorithm based on AFKF is proposed to detect D‐LAAs. Moreover, the proposed detection algorithm can identify D‐LAAs even in the presence of noise in the measurement data, significantly enhancing the speed of attack detection. Finally, take a smart grid with three generators and six buses as an example. Its feasibility and effectiveness of the Euclidean distance ratio detection algorithm are verified by simulations. The simulations are carried out through the real‐time hardware‐in‐the‐loop simulation platform, which is mainly composed of StarSim and multi‐tasking devices.

Yuan Yan, Yinsong Zhao, Kun Zhao et al.

Abstract Partial discharge (PD) diagnosis is a crucial tool to assess the insulation condition of wind farm cables. Among PD diagnosis techniques, PD localisation is promising as it can provide target maintenance indicators on the insulation weak points of the cables. Accordingly, this paper developed a portable PD detection and location system for wind farm inter‐array cables. The system consists of two non‐invasive and lightweight testing units, which can be conveniently deployed on an energised cable, enabling highly efficient online PD diagnosis of the widely distributed inter‐array cables. The system achieves accurate PD localisation of the energised cable via an improved double‐sided travelling wave method. The method exhibits two superior features: the double‐sided testing units are accurately synchronised via the joint application of Global Position Systems and a pulse‐based interaction process, and a windowed phase difference method is proposed and integrated into the system to robustly estimate the time‐of‐arrival difference in low signal‐to‐noise ratio environment. Validation experiments were conducted on both a 10‐kV cable in the laboratory and a real 35‐kV cable in an on‐shore wind farm.

Shiyan Yi, Haichun Liu, Tao Chen et al.

Abstract Numerous studies on short‐term load forecasting (STLF) have used feature extraction methods to increase the model's accuracy by incorporating multidimensional features containing time, weather and distance information. However, less attention has been paid to the input data size and output dimensions in STLF. To address these two issues, an STLF model is proposed based on output dimensions using only load data. First, the load data's long‐term behavior (trend and seasonality) is extracted through the long short‐term memory network (LSTM), followed by convolution to obtain the load data's non‐stationarity. Then, using the self‐attention mechanism (SAM), the crucial input load information is emphasized in the forecasting process. The calculation example shows that the proposed algorithm outperforms LSTM, LSTM‐based SAM, and CNN‐GRU‐based SAM by more than 10% in eight different buildings, demonstrating its suitability for forecasting with only load data. Additionally, compared to earlier research utilizing two well‐known public data sets, the MAPE is optimized by 2.2% and 5%, respectively. Also, the method has good prediction accuracy for a wide variety of time granularities and load aggregation levels, so it can be applied to various load forecasting scenarios and has good reference significance for load forecasting instrumentation.

Mohamed H. Hassan, Salah Kamel, Muhammad Suhail Shaikh et al.

Abstract The Economic and Emission Dispatch (EED) method is widely used to optimize generator output in a power system. The goal is to reduce fuel costs and emissions, including carbon dioxide, sulphur dioxide, and nitrogen oxides, while maintaining power balance and adhering to limit constraints. EED aims to minimize emissions and operating costs while meeting power demands. To solve the multi‐objective EED problem, the supply‐demand optimization (SDO) algorithm is proposed, which employs a price penalty factor approach to convert it into a single‐objective function. The SDO algorithm uses a swarm‐based optimization strategy inspired by supply‐demand mechanisms in economics. The algorithm's performance is evaluated on seven benchmark functions before being used to simulate the EED problem on power systems with varying numbers of units and load demands. Established algorithms like the Grey Wolf Optimizer (GWO), Moth‐Flame Optimization (MFO), Transient Search Optimization (TSO), and Whale Optimization Algorithm (WOA) are compared to the SDO algorithm. The simulations are conducted on power systems with different numbers of units and load demands to optimize power generation output. The numerical analyses demonstrate that the SDO technique is more efficient and produces higher quality solutions than other recent optimization methods.

Rujin Huang, Wenbin Zhang, Junyu Zhu et al.

The accurate voltage measurement of distribution networks is of great significance in power dispatching and fault diagnosis. Voltage sensors based on the spatial electric field effect do not require grounding, which provides the possibility for the distributed measurement of transmission line voltages. However, the divider ratio of suspension grounding voltage sensors is affected by the height between the sensor and the ground, as well as the distance between the sensor and the telegraph pole. In this paper, a self-calibration method based on internal capacitance transformation is proposed to realize the on-line calibration of suspension grounding voltage sensors. The calibration is accomplished by switching different parameters in the conditioning circuit, and the calibration process does not require power failure or known input excitation. In addition, the impact of electric fields in the other two phases of three-phase transmission lines on measurement through simulation research is quantified in this paper. In order to reduce the impact of interference electric fields, an equipotential shielding structure is designed. The circuit topology and probe prototype have been developed and testing has been conducted in laboratory conditions; the experimental results show that the maximum relative error of voltage amplitude is 1.65%, and the phase relative error is 0.94%. The measurement accuracy is not limited by the height to ground or the distance to the telegraph pole. In addition, in the application of an equipotential shielding probe, the maximum deviation of measured voltage is 0.7% with and without interference electric fields.

Vasileios A. Evangelopoulos, Pavlos S. Georgilakis

Biao Li, Can Wan, Fengji Luo et al.

Abstract The market‐driven demand side management of distribution networks suffers from the challenge of operational security issues. This paper proposes a distribution locational marginal price (DLMP) based bi‐level transactive control model for distribution networks to manage demand side resources of nodal agents, ensuring both the network security and the agents' optimal decision. The proposed model consists of a DLMP‐pricing model at the upper level and DLMP‐based demand response (D‐DR) models at the lower level, integrating the DLMP‐pricing of the distribution network and the decision‐making of agents. The DLMP‐pricing model is constructed as the dual form of a linearized optimal power flow problem to determine DLMP related to the decision of all agents. The D‐DR model enables each nodal agent to minimize its own expenditure under the DLMP, which is established as a linear programming problem. The bi‐level model is converted into single‐level programming through replacing the D‐DR models by Karush‐Kuhn‐Tucker conditions, in which the bi‐linear items of the complementary slackness are further linearized by introducing integer variables. Consequently, the intractable bi‐level transactive control model is equivalently reconstructed as a single‐level mixed‐integer linear programming problem that can be conveniently solved. Comprehensive numerical studies validate the effectiveness of the proposed model.

Renke Huang, Wei Gao, Rui Fan et al.

Abstract Inter‐area oscillation is a serious problem that threatens a power system. Appropriate damping control of the inter‐area oscillation would ensure the grid stability and maintain the tie‐line power transfer capability. In this paper, a novel reinforcement learning (RL) based power oscillation damping (POD) controller is proposed that uses Thyristor Controlled Series Compensators (TCSC) to damp inter‐area oscillations. By leveraging the unbiased gradient direction estimation of the natural evolution strategy (NES), the power flows on the tie‐lines were successfully regulated and inter‐area oscillations were damped through dynamically modulating the inserted reactance of the TCSC. Furthermore, parallel computation techniques were adopted to speed up the training process of the NES. The proposed RL‐based POD controller has been tested on both two‐area four‐machine system and North American MinniWECC system. Extensive studies have demonstrated the excellent performance of the proposed RL‐based TCSC POD controller in damping inter‐area oscillations.

Adolfo Blengini Neto, Maria Beatriz Barbosa, Lia Moreira Mota et al.

Modern electric power systems consist of large-scale, highly complex interconnected systems projected to match the intense demand growth for electrical energy. This involves the decision of generation, transmission, and distribution of resources at different time horizons. They also face challenges in incorporating new forms of generation, distributed generations, which are located close to consumer centers, and new loads such as electric vehicles. Traditionally, the nonlinear Newton–Raphson optimization method is used to support operational decisions in such systems, known as Optimal Power Flow (OPF). Although OPF is one of the most practically important and well-researched sub-fields of constrained nonlinear optimization and has a rich history of research, it faces the convergence difficulties associated with all problems represented using non-linear power flow constraints. The proposal is to present an approach in a software component in cloud Application Programming Interface (API) format, with alternative modeling of the electrical optimization problem as a non-linear objective function and representing electric network constraints modeled through both current and voltage Kirchhoff linear equations. This representation overcomes the non-linearity of the OPF problem considering Distributed Energy Resources (DER). The robustness, scalability, and availability of the method are tested on the IEEE-34 bus system with several modifications to accommodate the DER testing under conditions and in radial or meshed distribution systems under different load scenarios.

Kiarash Gharani Khajeh, Davood Solatialkaran, Firuz Zare et al.

Abstract The grid‐tied inverters are the most vital components in renewable energy‐based power systems. Hence, maintaining the power quality of a grid‐tied inverter output within the standard range is an ongoing challenge in the power system. The appeared individual harmonics at inverter output current caused by grid voltage harmonics depend on the inverter output equivalent admittance. This consists of a combination of admittance seen from the point of common coupling and the phase‐locked loop path. Therefore, the precise calculation of the aforementioned admittance is an inevitable requirement to design a harmonic mitigation strategy. By adding a virtual admittance to the system through modifications in the inverter control loop, the output equivalent admittance can be removed. For this purpose, in this paper, a novel full‐feedforward harmonic suppression scheme is proposed which can effectively eliminate individual harmonics injected from the grid. Consequently, the individual output current harmonics of the inverter will be effectively suppressed. Simulation and experimental results have been carried out for a typical single‐phase grid‐tied inverter to verify the efficiency of the proposed scheme against emitted harmonics from the grid.

Nga Nguyen, Dilip Pandit, Riley Quigley et al.

Due to their many advantages, renewable energy resources (RERs) are proliferating rapidly to satisfy a significant portion of the global energy demand. It is predicted that the importance of RER generation will continue to increase in the future of the energy industry. In spite of all their known benefits, the integration of RERs poses several challenges to system stability and reliability. Low inertia characteristics and the intermittent output of RERs introduces additional variation into an already variable grid frequency. System regulation capability and reliability are reduced as RERs gradually replace conventional generators. This paper reviews the challenges associated with RER integration on system frequency response and how these challenges affect system reliability. Advanced methods for mitigating challenges associated with increasing RER integration, while ensuring system security, are discussed, and the necessary mathematical background is provided in concise form. A model is developed for determining the maximum level of RER penetration based on stability constraints. Emerging methods to advance the integration of RERs are discussed.

Xiaobin Cao, Haiman Wang, Manxiang Wang et al.

Abstract The design of a grounding system is influenced by the soil conductivity. The cost of a ground grid in areas with different soil resistivities varies from tens to hundreds of times to achieve the same ground resistance. Existing studies have found that the electrical performance of soil changes suddenly with the change in water contents. However, it can only be assumed macroscopically that this change is caused by the connectivity of water distribution. Neither this assumption can be confirmed nor any critical conditions can be defined. This paper presents a mathematical study of soil conductivity from a microscopic point of view, known as the micro‐element statistical method. The method uses scientific statistical analysis to study the apparent conductivity of water elements in soil and is used to conclude that the apparent conductivity at the micro level is exponentially distributed. Based on the relationship between the mean of apparent conductivity distribution and water contents, the critical condition of soil resistivity mutation is defined, and the mechanism of soil resistivity change is explained. The method presented in this work can be used to study the influence of temperature, ion type concentration, solid particle type and pore structure on soil conductivity by changing the corresponding conditions and material type.

Mahendran MV, Vijayan V

Abstract It is distinguished that there should be a balance between power generation and load demand, thereby maintaining the frequency and tie‐line power of the multi‐source multi‐area interconnected power system (MS‐MA‐IPS) in a determined limit to safeguard the entire system from failure. Hence, load frequency control (LFC) by adjusting the megawatt output of generators is applied, which has been considered as the most recent research work in this field. Under these circumstances, this paper intends to construct a dual‐mode‐switch‐controller‐based LFC in a multi‐area power system, which obviously considers the impact of incremental control action along with the system dynamic constraints such as capacitive energy storage, generation rate constraint, and governor with dead band. In order to achieve this effect, in this research work, the operations of the proposed controller of the MS‐MA‐IPS are based on the dual‐mode switch, and here, switching is carried out with respect to a threshold value ξ. Based on switching, the control varies between proportional–integral (PI) control and model‐predictive control. Moreover, in order to make the performance elegant, the proportional gain of the PI controller Kpg and the threshold of the switch ξ are optimally tuned by introducing a novel optimisation algorithm referred to as particle updated dragonfly algorithm, which is the conceptual hybridisation of the traditional dragonfly algorithm and particle swarm optimisation. Finally, the performance of the proposed model is evaluated by varying the control parameters such as Cg, TCD, Tr, and Trb to minimize the undesired deviations in power flows between control areas.

Boyu Qin, Ruowei Zhang, Hengyi Li et al.

Abstract Low voltage ride through (LVRT) requires wind generation systems (WGS) to maintain continuous operation and provide reactive power support under grid voltage dips. This paper proposes a novel disturbance attenuation control (DAC) approach based on state‐dependent Riccati equation (SDRE) technique to enhance the LVRT capability of doubly fed induction generator‐based (DFIG‐based) WGS. The DAC problems are formulated with the control objectives for rotor side converter and grid side converter, and the weighing matrices are designed with fully studied principles to balance the control effect and cost. The SDRE technique is adopted to solve the DAC problems, and an alternative feasible state dependent coefficient construction algorithm is applied to improve computational efficiency. An active Crowbar circuit with overcurrent limiting mechanism is applied to ensure the rotor current and DC link voltage within the secure zone. Comparisons with conventional PI controller, exact linearization controller and coordinated control strategy are performed, the results demonstrate the proposed DAC approach has a better transient performance and enhances the LVRT capability of DFIG‐based WGS.

Jay Pearson, Torrey Wagner, Justin Delorit et al.

Remote and contingency operations, including military and disaster-relief activities, often require the use of temporary facilities powered by inefficient diesel generators that are expensive to operate and maintain. Site planners can reduce operating costs by increasing shelter insulation and augmenting generators with photovoltaic-battery hybrid energy systems, but they must select the optimal design configuration based on the region's climate to meet the power demand at the lowest cost. To assist planners, this paper proposes an innovative, climate-optimized, hybrid energy system selection model capable of selecting the facility insulation type, solar array size, and battery backup system to minimize the annual operating cost. To demonstrate the model's capability in various climates, model performance was evaluated for applications in southwest Asia and the Caribbean. For a facility in Southwest Asia, the model reduced fuel consumption by 93% and saved $271 thousand compared to operating a diesel generator. The simulated facility in the Caribbean resulted in more significant savings, decreasing fuel consumption by 92% and saving $291 thousand. This capability is expected to support planners of remote sites in their ongoing effort to minimize fuel supply requirements and annual operating costs of temporary facilities.

Zhanlong Zhang, Jing Zou, Yihua Dan et al.

The grounding electrode buried in soil is prone to corrosion affected by soil and leakage current. The surface of corroded grounding electrodes is wrapped with corrosion product, which affects the normal current dissipation process and weakens the grounding performance. The accurate analysis of the grounding performance with corrosion layer can lay a solid theoretical basis for the safety of the power system. In this study, the corrosion layer is regarded as a layer of conductive medium between the electrode and soil. The leakage current along the electrode and the charge on the interface are analysed by coupling point matching method with boundary element method. Finally, the leakage current, grounding resistance, ground potential rise (GPR) and the step voltage of the two typical electrodes with corrosion layer are investigated. The results show that the corrosion layer causes the reduction of the leakage current at the end of the electrode and the enhancement of the leakage current in the middle location. Furthermore, the corrosion layer causes the increase of the grounding resistance and GPR, and the decrease of the step voltage. In addition, the influence of the reduced radius on the grounding performance is much smaller than that of the corrosion layer.

Florin Capitanescu

Many utilities are still reluctant in adopting optimal power flow (OPF) tools for decision‐making in operation. This paper scrutinizes this issue from the perspective of whether all control actions proposed by an OPF are truly effective to an operator. To this end, the paper focuses on suppressing ineffective control actions in OPF problems. This goal is aligned with the meaning of optimization in practice, that is improvement of operation performance of slightly noisy or imperfectly known real world models. The paper proposes a conceptually different new approach, which computes automatically the number of effective control actions that do not worsen the ideal model OPF objective by more than an operator‐specified tolerance. The proposed approach relies on a three‐step methodology that solves different OPF problems, in which smooth continuous approximation functions are used to convert the benchmark mixed integer nonlinear programming (MINLP) problems into nonlinear programming (NLP) problems. The proposed approach is compared with two other alternatives for the OPF problem of thermal congestion management using three test systems of 60, 118, and 2746 buses, respectively. The results show that, among the competing approaches, the solutions of the proposed continuous approximation lead to the best trade‐off between sub‐optimality and computation speed.