kV Power System Research Articles

Application of artificial neural network for peak load forecasting in 150 kV Semarang power system

Accurate load forecasting is essential for reliable and efficient operation of power systems. Traditional forecasting methods often struggle with capturing complex nonlinear patterns in load data. Artificial neural networks (ANNs) have emerged as a promising alternative due to their ability to learn complex relationships from historical data (Syed et al. in IEEEA 9:54992–55008, 2021. https://doi.org/10.1109/ACCESS.2021.3071654). This study investigates the potential of ANNs for short-term peak load forecasting in a 150 kV power system in Semarang, Indonesia. The study examines the impact of different input variables, including historical peak load, minimum load, population, and energy production, on forecasting accuracy. Several ANN architectures are trained and evaluated using mean absolute percentage error (MAPE) and mean squared error (MSE) metrics as reported by Demuth and De Jesús (neural network design). The results indicate that ANNs can achieve high accuracy in predicting peak load, with MAPE values below 10%. The study also demonstrates the importance of carefully selecting input variables and training parameters for optimal model performance. The findings highlight the potential of ANNs for improving load forecasting accuracy in power systems, contributing to enhanced grid reliability and operational efficiency. The findings of this study contribute to a deeper understanding of the application of ANNs in power system load forecasting. They demonstrate the potential of ANNs to achieve high accuracy and provide valuable insights into the factors influencing model performance. The findings are relevant for power system operators, researchers, and policymakers working to improve grid reliability and efficiency as reported by Prabha Kundur and Malik (Power System Stability and Control, McGraw-Hill Education, New York, 2022. https://www.accessengineeringlibrary.com/content/book/9781260473544).

An easy method for simultaneously enhancing power system voltage and angle stability using STATCOM

The global electricity demand is growing rapidly and is expected to double by 2050. This growth requires significantly expanding the current high-voltage transmission lines, which is a long-term and costly solution. As an alternative, utilities use advanced technologies like Flexible Alternating Current Transmission System (FACTS) devices as a temporary measure, postponing the expansion. However, it is necessary to locate these devices in the network properly to avoid negative outcomes. Traditional methods for FACTS placement focus on voltage profile improvement and power loss reduction, neglecting rotor angle stability. This can lead to oscillatory instability, especially in weak power grids. To address this issue, the paper proposes a simple approach to optimize the placement of shunt FACTS devices in power systems. The method improves both voltage and rotor angle stability without compromising power loss. The proposed approach considers rotor angle stability constraints, which is essential for system stability during transient events. The study was demonstrated on Nigeria’s 50-bus 330 kV power system, with results indicating a 31% improvement in angle stability with an enhanced voltage profile. The method is straightforward, non-iterative, and provides a cost-effective solution for FACTS device placement in power systems.

Analysis of Transient Recovery Voltage of 500 kV Line Considering Current Limiting Reactor

To limit the short-circuit current level, the method of series current, the limiting reactor is used to limit the short-circuit current, and the common access mode of the current limiting reactor is direct access. The series current limiting reactor can effectively limit the short-circuit current in 500kV power system, but after it is connected to the system, it will increase the transient recovery voltage steepness in case of a circuit breaker breaking fault and affect the normal breaking of the circuit breaker. Based on a 500 kV current limiter project, the influence of a lower limit current reactor on the recovery voltage of circuit breaker under different fault conditions is studied by using electromagnetic transient simulation software EMTP. The results show that the transient recovery voltage of the circuit breaker will exceed the standard value after the reactor is connected. When capacitors above 600nF are connected in parallel to the current limiting reactor, the transient recovery voltage could be limited to the standard range.

A Cascade BP Neural Network Tuned PID Controller for a High-Voltage Cable-Stripping Robot

A 10 kV distribution network is a crucial piece of infrastructure to guarantee enterprises' and households' access to electricity. Stripping cables is one of many power grid maintenance procedures that are now quickly expanding. However, typical cable-stripping procedures are manual and harmful to workers. Although numerous automated solutions for grid maintenance have been created, none of them focus on cable stripping, and most of them have large dimensions to guarantee multi-functions. In this paper, a new cable-stripping robot for the 10 kV power system is introduced. The design of a live working cable-stripping robot that is appropriate for installing insulating rods is introduced, taking into account the working environment of 10 kV overhead lines and the structural characteristics of overhead cables. The robot is managed by an auxiliary remote control device. A cascade PID control technology based on the back propagation neural network (BPNN) method was developed, as the stripper robot's whole system is nonlinear and the traditional PID controller lacked robustness and adaptability in complex circumstances. To validate the structural feasibility of the cable-stripping robot, as well as the working stability and adaptability of the BPNN-PID controller, a 95 mm2 cable-stripping experiment are carried out. A comparison of the BPNN-PID controller with the traditional PID method revealed that the BPNN-PID controller has a greater capacity for speed tracking and system stability. This robot demonstrated its ability to replace manual stripping procedures and will be used for practical routine power maintenance.

Modeling and Control-Tuning of a Single-Stage MMC-Based BESS

In recent years, the integration of battery energy storage systems (BESSs) with multilevel modular converters (MMCs) has received interest in power system applications. In this work, this configuration is called a MMC-based BESS. The batteries are connected directly to the MMCs on submodules (SMs), called the single-stage approach. Several control strategies have been proposed to guarantee the proper operation of a MMC-based BESS. This system is complex due to the control strategy. Another challenge is in obtaining the controller gains for a MMC-based BESS converter. In this sense, there is a gap in the methodology used to calculate the controller gains. Thus, this work aimed to tune the analytical expressions of a MMC-based BESS by considering the single-stage approach. The methodology is validated through detailed simulation models of 10.9 MVA/5.76 MWh connected to a 13.8 kV power system. Finally, to validate the dynamics of the controllers, the simulation results in the PLECS software for the charging and discharging processes are presented.

Designation of Optimal Location of Phasor Measurement Units by Comparing Different Methods for Türkiye 400 kV Power Systems

Observing a power system in an exceptional manner is rather important for system design. Phasor Measurement Unit (PMU) devices are modern meters installed in the power systems to monitor and control the systems. In this study, Depth First Search Method (DFS), Graph Theoretic Procedure (GTh), Simulated Annealing Method (SA), and Modified Simulated Annealing Method (MSA) were used to determine the optimal PMU layout points. The limitation of the observability of the whole system was also considered in the calculations. The MSA method has been proposed as an alternative solution method for the optimal number of PMUs (OPP). The MSA method has been applied to Türkiye 400 kV Interconnected Power System in which an OPP study has not been applied before. The reliability of the method was tested by comparing the results with that of the IEEE 14-bus testing system. Thus, the number of PMUs for the Türkiye 400 kV Power System and the information on which buses these PMUs should be placed were identified. Among the applied methods, MSA Method yielded the best results. The locations of these devices have also been determined which is introduced as an alternative solution.

Analysis of Power Quality Problems on Nigerian 330 kV Power System Using Statcom with Voltage Sensitivity Index

Transmission system is the transportation of electrical energy from generating stations to load centers. However, increase usage of non-linear loads from the consumers has led to electrical Power Quality (PQ) problems which have negative impacts on the operation of the power system especially Nigerian power system. This research analyzed the PQ problem on Nigerian 330 kV power system. Newton-Raphson (NR) iterative method was used to performed load flow analysis on Nigerian 28-bus transmission systems. Then power injection model of the Static Synchronous Compensator (STATCOM) was incorporated to modify the NR mathematical model. The suitable placement for the STATCOM in the system was determined using Voltage Sensitivity Index (VSI) and simulation was done in MATLAB/SIMULINK. The results showed that, the suitable placements of STATCOM controller in the power system were buses 5, 8, 12 and 16. The corresponding STATCOM reactive power, sag voltage and sag duration for buses 5, 8, 12 and 16 were 72.56 MVar, 0.77454 p.u, 0.7336s; 65.35 Mvar, 0.7464 p.u, 0.7419 s; 50.86 Mvar, 0.7615 p.u, 0.6512 s and 53.75 MVar, 0.7442 p.u. 0.5972 s, respectively. Therefore, the results have established the importance of STATCOM with VSI in obtaining suitable solution for PQ problems on electrical power system. Keywords: Transmission System, Electrical Energy, Non-linear Load, Power Quality, Newton-Raphson, STATCOM, Voltage Stability Index. DOI: 10.7176/ISDE/12-6-03 Publication date: October 31 st 2022

Deep-Learning Based Fault Events Analysis in Power Systems

The identification of fault types and their locations is crucial for power system protection/operation when a fault occurs in the lines. In general, this involves a human-in-the-loop analysis to capture the transient voltage and current signals using a common format for transient data exchange for power systems (COMTRADE) file. Then, protection engineers can identify the fault types and the line locations after the incident. This paper proposes intelligent and novel methods of faulty line and location detection based on convolutional neural networks in the power system. The three-phase fault information contained in the COMTRADE file is converted to an image file and extracted adaptively by the proposed CNN, which is trained by a large number of images under various kinds of fault conditions and factors. A 500 kV power system is simulated to generate different types of electromagnetic fault transients. The test results show that the proposed CNN-based analyzer can classify the fault types and locations under various conditions and reduce the fault analysis efforts.

Benchmarking of Single-Stage and Two-Stage Approaches for an MMC-Based BESS

Modular multilevel converter-based battery energy storage systems (MMC-based BESS) can play an important role when applied to power systems, for example, stabilizing and improving power quality. The integration of batteries in an MMC is usually performed in two ways: single-stage (SS) and two-stage (TS) (i.e., with dc/dc converter). Different references discuss the control strategies, sizing methodologies, and the advantages/drawbacks of these approaches. However, a deep comparison of these topologies is still missing in the literature. Thus, benchmarking SS and TS approaches is provided in this work. The battery current spectrum, the battery lifetime, the converter power losses, and the total costs are evaluated for both approaches. In addition, energy oversizing due to rounding is an important figure of merit since batteries account for a large amount of the costs. The case study is evaluated considering commercial battery racks (standard solution) and battery cells (customized solution). For the case studies, different insulated gate bipolar transistor (IGBT) models and states of charge (SOC) ranges are considered. The system under review is a 10.9 MVA/5.76 MWh connected to a 13.8 kV power system. This system aims to perform a time-shift for an industry. In an analysis to optimize the costs of a project that evaluates several variables, the best configuration option is found in the most balanced option. In this sense, when balancing costs in project sizing, power losses, and battery replacement, the optimal design is the SS approach in the customized solution.

A four-step protection strategy to improve stability of high voltage transmission lines

Opportune detection of transient faults and restoration of the faulty phase in the least possible time plays a key role in improving the stability of high voltage transmission lines (HVTLs). This paper presents a novel four-step strategy for the protection of HVTLs so that the stability and reliability of power systems are enhanced. Firstly, the cumulative sum (CUSUM) algorithm is used to quickly detect the transient and determine the faulty phase. In the second step, the settings of the static var compensator (SVC) are changed to reduce the reclosing dead time as much as possible. Afterward, the transient or permanent type of the fault is identified based on the proposed principal component analysis-support vector machine (PCA-SVM) algorithm. In the fourth step, if a transient fault is recognized, the successful single-phase reclosing time is identified by the PCA-SVM and the reclosing command is issued to high voltage circuit breakers (HVCBs). Simulation results obtained by using EMTP-RV and MATLAB for a sample 400 kV power system illustrate that the proposed protection strategy can increase the reliability of the power system via reduction of the dead time, correct detection of transient faults from permanent ones, and accurate detection of the reclosing time.

Allocation of HV/MV Substations in Iraqi Power Grid Using Delaunay Triangulation

In provincial areas, allocation of the HV/MV substations aims to assign a proper set of numbers and locations of substations to supply loads spatially distributed over a large geographic area with continually emerging towns. This requires identifying the sparse load centers, the existing substations, and the new substations required to cover the potential extension. This paper proposes a method to allocate the main substations to the targeted area based on the lines’ length which are assigned by Delaunay triangulation and geographical coordinates. The proposed configuration is identified by a criterion that is tailored to the Iraqi sub-transmission system in which the standard distances among the substation follow specific patterns. The standard distances that are identified by the proposed methods are represented by the edges of Delaunay triangles. This paper aims to improve the voltage regulation of the distribution grid and avoid problems of overloaded feeders by assigning the proposed locations that reduce the lines’ lengths. The proposed method is verified using simulation tests on Diyala 9-bus system which is a part of the Iraqi 132 kV power system. The results show that the proposed configuration of the substations is reasonably valid and quite close to the real locations of the towns of the system with efficient lengths for the lines.

Constructing protection against single phase-to-earth faults in electricity grids

The neutral of the feeding transformer is grounded through the coil of the arc suppression reactor to reduce the arc current in 6–35 kV power systems during single phase-to-earth faults. The inductance of the reactor is tuned in resonance with the network capacity relative to the ground, for which the reactor is maid variable. The change in the inductance of the reactor is achieved by stepwise regulation of the number of turns of the reactor coils or a smooth change in the air gap in the circuit of its magnetic circuit. Both methods are associated with a mechanical change in the controlled parameter, which is a significant disadvantage of control systems. To improve the quality of regulation, increase the tuning accuracy and faster response, a scheme for thyristor change in the reactive power of the reactor is proposed. According to the method, the reactor inductance remains constant, while the reactor current and its reactive power are regulated, which provides a resonance mode and eliminates the disadvantages inherent in mechanical control.

Analysis of influence of a novel inductive fault current limiter on the circuit breaker in 500 kV power system

A contribution to the engineering application of a proposed 500-kV fault current limiter (FCL) is presented. A new type of FCL composed of a highly coupled split reactor (HCSR) and fast switches is proposed. When the circuit breaker (CB) in series with the FCL in the 500-kV power system interrupts the limited fault current, the rate of rise of the recovery voltage (RRRV) reaches a value much higher than the rated value. Based on a simplified equivalent single-phase circuit, the influence of the new FCL on the interruption procedure of the CB is simulated and discussed. The simulation results show that the high RRRV is caused by high-frequency resonant oscillations between the HCSR and its parasite capacitance. Analysis indicates that when the reactance of the FCL is close to the short circuit reactance of the system, the RRRV will reach the highest value. To solve this issue, we proposed installing a shunt capacitor with the FCL. Simulation results showed that the RRRV under all fault modes could be restrained to below the rated value by introducing a certain shunt capacitor.

Ground Fault Location in 2 × 25 kV High-Speed Train Power Systems by (Auto)Transformers Currents Ratio

High speed trains supply is, nowadays, performed by 2 × 25 kV power systems. If a ground fault occurs, its location and correction are crucial to minimize downtime. One of the methods for locating ground faults in power systems is the impedance method. This was a good solution for 1 × 25 kV railways power systems, as the ratio between reactance and fault distance is linear. However, the use of autotransformers between the catenary, feeder and rails makes this ratio non-linear in 2 × 25 kV configuration. This work presents a novel ground fault location method for 2 × 25 kV power systems. The new method is based on the ratio of the currents of the autotransformers and the substation transformer. The main contribution, compared to previous methods developed, is that this new method is insensitive to the fault current variations produced by the network voltage fluctuations or by the main transformer tap changer position, among others for 2 × 25 kV power systems. The novel approach has been corroborated by numerous experimental tests in the laboratory and computer simulations, with satisfactory results.

Determination of Optimal Phase Measurement Unit Settlements In the Turkey 400 kV Power System

Güç sistemlerinde gerilim ve açı kararsızlığı gibi olumsuz nedenlerden dolayı güç sisteminin hızlı bir şekilde gözlenebilmesi ve kontrol edilmesi gerekmektedir. Fazör Ölçüm Birimi (FÖB) teknolojisi bu gereksinimi karşılayan oldukça yeni bir teknolojidir. Güç sisteminin tamamen gözlemlenmesi, sistemin planlanması, sistemin herhangi bir kararsızlık durumuna gelmeden gerekli önlemler alınarak kararlılığı ve güvenirliği sağlanması için, güç sistemine kaç adet FÖB yerleştirilmesi gerektiğini ve FÖB’lerin hangi baralara yerleştirilmesinin uygun olacağı analiz edilmesi büyük önem taşımaktadır. Güç sisteminde kullanılan FÖB’lerin maliyetleri yüksek olduğu için, güç sistemindeki baralara optimum şekilde yerleştirilmesi önemlidir. Sistemi tamamen gözlenebilir kılan en az sayıda FÖB’lerin belirlenmesi için farklı metotlar kullanılmaktadır. Önerilen metotların amacı, güç sistemi veri yollarındaki toplam FÖB sayısını minimize etmek ve böylece FÖB'lerin kurulum maliyetini en aza indirmektir. Bu çalışmada, optimal çözüm için benzetimler Matlab kod kullanarak ve Matlab kod yazılımı üzerinde çalışan PSAT Toolbox ara yüzü ile gerçekleştirilmiştir. Uygulamada Derinlik Arama Metodu, Graf Teorisi Metodu, Yinelemeli N-1 Güvenlik metotları kullanılarak gerçekleştirilmiştir. Bu metotlar Türkiye 400 KV’luk güç sistemi üzerinde uygulanmıştır. Bu çalışma sonucunda güç sisteminde herhangi bir kararsızlık durumuna gelmeden gerekli önlemler alınarak kararlılığı ve güvenirliği sağlana bilmesi için en az sayıda FÖB kullanılarak güç sistemindeki hangi baralara yerleştirilmesinin uygun olacağı belirlenmiştir. Elde edilen simülasyon sonucunda hem maliyeti azaltmak hem de güç sisteminin tamamının gözlenmesinin sağlamak için optimum sayıda FÖB’leri hangi baralara yerleştirilmesi gerektiği bulunmuştur.

Improvement of voltage profile for large scale power system using soft computing approach

In modern power system operation and planning, reactive power is an important part of power system operation to supply electrical load such as an electric motor. However, the reactive current that flows from the generator to load demand can cause voltage drop and active power loss. Hence, it is essential to install a compensating device such as a shunt capacitor close to the load bus to reduce the total power loss of the transmission line and improve the voltage stability of the system. This paper presents the application of a genetic algorithm (GA), particle swarm optimization (PSO), and artificial bee colony (ABC)) to obtain the optimal size of the shunt capacitor where those capacitors are located on the critical bus. To examine the efficacy of the proposed algorithm, Java-Madura-Bali (JAMALI) 500kV power system grid is used as the test system. From the simulation results, the use of PSO and ABC algorithms to obtain the sizing of the capacitor’s capacity can reduce the power loss of around 15.873 MW. Moreover, a different result is showed by the GA approach where the power loss in the JAMALI 500kV power grid can be compressed only up to 15.54 MW or 11.38% from the power system operation without a shunt capacitor. The three soft computing techniques could also maintain the voltage profile within 1.05 p.u and 0.95 p.u.

Root cause analysis for shunt reactor failure in 500 kV power system

Error has been long recognized as ubiquitous to the practice of electrical engineering for failure analysis, however, the correct methodology for decision science is necessary, especially with more statistical data analysis, in this research a new methodology proposal for update the international standard IEC 60076, by using the root cause analysis, with traditional methods, principal components analysis, data mining and causal map, it is possible to eliminate the error, in this analysis an update for the standards have been discovered, they need to improve to avoid critical failures in the power system, for the shunt reactors. This research explores the failure mode and root cause analysis of shunt reactors in high voltage through examination of the design and implementation in Latin American. The case study has been evaluated for a shunt reactor in the 500 kV power system, and a discussion is considered for 279 shunt reactors, they were located in Latin America, finally the principal component analysis, cluster and causal mapping for the strategy correction is done. In this research, a real case study has discovered with twelve failures modes and fourteen activities to avoid the design and construction mistakes, they should be considered to improve the international standards in the design of this important equipment for the power system. Furthermore, if in the analysis, the shunt reactor is full loading, all the fatigue fractures occur for a vibration in the shunt reactor with a partial discharge in the bushing connection and the spring closure of the equipotential devices. It results in a larger investigation with the new proposal, it is the root cause of one of the most critical points. These results indicated that re-evaluating shunt reactor design to ensure an optimal behavior with the components for this equipment in a full load stage.

Controlled Switching of Series Compensated Transmission Lines: Challenges and Solutions

A new controlled switching method for purely series compensated transmission lines is proposed here. The main idea is based on the estimation of trapped charges using a recursive digital filter for correction of the secondary voltage of the capacitive voltage transformer. Several operating conditions of series capacitor banks are taken into account to define the controlled switching strategy for transmission line reclosing. It is also shown that one can take advantage of the existing techniques for uncompensated and shunt compensated lines. The challenges and potentialities of the proposed method are highlighted through alternative transient program (ATP) of a 500-kV power system where switching transient overvoltages are limited to 1.85 p.u.

Power flow analysis of a 5-bus 10 kV power system with high temperature superconducting cable

High temperature superconducting (HTS) power cable provides a promising solution for the challenges the power grids confront. As most of the existing HTS cable projects operated the cable in an isolated system, we have little knowledge about the power flow of the system when HTS cable integrated, which is essential for planning, operation, and protection of a power system containing HTS cable. In the paper, we build a 10 kV 5-bus power system with one HTS cable line and the same line with normal cable is as the benchmark. We solve the model and analyse the power flow of the system under normal operation, line disconnection, source power off, and load growing conditions. The results show that HTS cable tends to undertake more transmission energy and makes the connected buses more robust in terms of voltage drop. As HTS cable’s behaviour is different, it is necessary to readjust the settings and configurations of the secondary side apparatus of power system.

Improving Angle Stability by Switching Shunt Reactors in Mixed Overhead Cable Lines. An Italian 400 kV Case Study

Stringent environmental constraints make the construction of new transmission overhead lines more and more difficult. Alternatively, today it is possible to use cable lines for high (HV) and extra-high (EHV) voltage systems. The configuration of the so-called mixed lines can create some problems in the operation of the electrical system, both during steady-state and transient conditions. In particular, the system stability is one of the main concerns when analyzing the dynamic response of power systems. In this paper, the study of angular stability of a system containing a mixed line is presented: a specific control logic applied to the shunt reactors of the mixed line is proposed as improvement of the overall system stability. The proposed switching logic is first discussed from a theoretical point of view and validated with two different testing systems. Then, the existing overhead-cable lines connecting Sicily to the rest of continental Europe 400 kV power system are taken as case study for the application of the proposed switching strategy. Several simulations are performed in the power system analysis software NEPLAN360: the results show the fundamental role of the timing of the control actions applied on the shunt reactors in helping the system to keep the stability. The proposed control proves to be an effective support to the system subjected to critical contingencies, contributing decisively to avoid the angular separation between areas and therefore to preserve the stability of the system.