Complex Power Grid Research Articles

Fault Location Schemes for Complex Power Grid Based on Multidimensional Information Fusion

Fast and accurate fault location in complex power grid is crucial to ensure the safe operation of power grid. It is inevitable that fault location is not merely in single transmission line but in complex power grid. This article first describes the correlation properties of multidimensional fault characteristics in complex power grid and reveals the relationship between the multidimensional fault characteristics and the fault distance. Then the optimized clustering analysis algorithm is presented to realize rapid and accurate identification of the fault area based on the multidimensional characteristics of measuring points. All the measuring points are divided into four categories: fault area, fault boundary region, fault transition region, and nonfault region. Location zone is constructed by fault region and fault boundary region. Finally, to get fault location results and fault occurrence time, linear equations are established by correlation properties of spatiotemporal information in location zone and solved by the least square method. At the same time, the applicability and reliability of the proposed method are analyzed. The IEEE 30-Bus System and IEEE 57-Bus System are built in PSCAD/EMTDC software. Compared with the existing method, the positioning accuracy of the proposed method is improved by 70.62%. Large number of simulation results show that the proposed method of wide-area fault location has higher accuracy and adaptability.

Анализ возможностей и перспектив применения системы технологического видеонаблюдения на объектах электросетевого комплекса

Анализ возможностей и перспектив применения системы технологического видеонаблюдения на объектах электросетевого комплекса

Large Time Step Electromagnetic Transient Simulation of Large Scale Power System Based on Time Domain Transformation Method

Electromagnetic Transients (EMT) simulation is an effective approach to study the dynamic behavior of complex AC/DC power grids. However, with increasing applications of the electronic equipment and the expansion of power grid, conventional EMT simulation tools are facing significant challenges with regard to simulation speed and scale. In order to improve the performance of EMT simulation, some approaches have been proposed. A time domain transformation methodology [1] has recently been proposed. In this paper, based on the large time step EMT algorithm, an electromagnetic transient simulation program has been developed and is used to study large scale power system dynamic behaviors. The result shows that the new EMT algorithm can not only guarantee the simulation accuracy, but also effectively improve the speed of full electromagnetic transient simulation of large scale complex power grids.

Improved Current Decoupling Method for Robustness Improvement of LCL-type STATCOM Based on Active Disturbance Rejection Control

When theoretically studying the control method of LCL-type static synchronous compensator (STATCOM), we often ignore the influence of complex power grid on the stability and reactive compensation performance of STATCOM. Improving traditional current decoupling method with PI controller (PI decoupling) in synchronous (dq) reference frame, an original current decoupling method with active disturbance rejection controller (ADRC decoupling) is proposed in this paper. First, the influence of internal and external disturbances on STATCOM with PI decoupling method is analyzed. External disturbances include harmonic grid voltage and grid inductance variation. Internal disturbances come from coupled channels between d axis and q axis, and parameter perturbations of LCL filter. Second, the principle of ADRC decoupling method applied to LCL-type STATCOM is analyzed in detail. Taking advantage of ADRC's capability to estimate and compensate for the “total disturbances”, robustness of STATCOM is improved. Comparing with PI decoupling method, ADRC decoupling method can improve the disturbances rejection performance and stability of LCL-type STATCOM. Finally, results from STATCOM simulation model show the effectiveness and superiority of this original method.

Assessment of the effects of climate change on the safety and reliability of the functioning of the electric power complex in Moscow

The article is dedicated to the study of the problem of the influence of climate change on the reliability and safety of the power complex of the Moscow metropolis. The analysis of climatic change in the Moscow region shows the number of dangerous climatic events that have intensified over the past ten years, leading to economic damage. In the paper, the observed manifestations of climate change have been analyzed, isolated and ranked according to the effect on the reliability of the power supply system. The vulnerability of the electric power industry to unfavorable climatic events is considered. The analysis is presented of accident rate, economic damage in some basic elements of the power system.The power supply system of the Moscow energy center is characterized by high reliability and saturation with devices for converting, distributing and transmitting electrical energy. Based on the official statistics of local power outages in the Moscow metropolis, analysis is performed of the intensity of failures of overhead power transmission lines. Correlation analysis of their interrelation with the intensity of occurrence of dangerous climatic events is performed. It is shown that the most intensive effects are not only produced by individual climatic events, but also by some of their combinations: "strong wind" and "ice"; "high humidity" and "a high number of temperature transitions through 0 °C", etc. Based on the dependencies obtained, regularities have been revealed that allow predicting the key parameters of damage from the most frequent unfavorable climatic events, which have become more frequent with climate change. Through the application of regression methods of analysis, the functions of the dependence of the occurrence of wire breaks in high-voltage distribution networks with a voltage up to 110 kV and wire breaks in backbone networks with a voltage over 110 kV on climatic factors are substantiated.An estimation of the total economic damage to the power grid complex in Moscow from the most influential climatic events has been performed. Some low-cost oportunities for adaptation of existing power transmission networks to the change in the Moscow metropolis are considered.

Electrical LeaderRank method for node importance evaluation of power grids considering uncertainties of renewable energy

Node importance evaluation of power grids plays an important role in the safe operation and planning of power systems. This paper proposes an electrical LeaderRank (ELR) method to identify the important nodes in complex power grids, considering the renewable energy uncertainties, system topological structure, transmission power flow and the loss of loads caused by cascading failures. The proposed method uses an ELR value function to represent the importance of a system node, which can be derived iteratively from the weighted distribution strategy of its in-linked nodes. Furthermore, the uncertainties of wind and solar energy generation are modelled as interval numbers, and the interval power flow calculation is employed to obtain the interval power in transmission lines, direct adjacent matrix, and finally the interval ELR values. The performance of ELR method has been fully tested and benchmarked on the IEEE 118-bus power system and the Western Liaoning Power Grid of China. Comparative results on four performance criteria have not only demonstrated the validity and superiority of the proposed method, but also confirmed its capability to cope with the node importance evaluation of practical power grids.

Wide-Area Damping Controller Design Based on the Frequency Domain Self-Excitation Method

In this paper, a wide-area DC damping controller design method is proposed to damp the weak interarea oscillation modes. First, the low-order power system control model identification method is proposed based on the frequency domain self-excitation method to obtain the dominant modes and other related information. In what follows, the identified model is transformed into a low-order state space equation. By comparing the geometric metrics of different schemes, the various input signals and installation locations of the controller are selected. Furthermore, the damping controller parameter calculation is realized based on the self-excitation frequency domain identification method, which does not depend on the detailed model of the system. The design process is simple and it is easy to apply in the practical engineering of large-scale complex power grids. The applicability and effectiveness of the proposed controller design method are demonstrated through simulations of a two-area four-generator power system.

Investigation of the Power Grid Accuracy by CMOS Transistor Network using Matlab/ Simulink

The design and analysis of the power distribution and supply system on a chip is a complex issue. The ideal network consists of millions of transistors, which act as energy consumers. This large number makes them complex in terms of design and analysis. Building typical algorithms with logical gates and working automatically is the best way to solve the problem of power grid complexity. In this research, it was proposed to design a new model for consumers on the basis of effective resistance. passive elements were used only in this model and based on the actual resistance and capacity of the logical gates. Consumers and power grids can adopt computational physics methods and consider each group of consumers in each subnet as within total circuits. Emphasis is placed on the interaction between consumers for energy distribution network and energy supply. Using Matlab/ Simulink, accuracy of the system is verified to determine the technical issues related to the operation of the system for power networks.

On Reliability Analysis of Smart Grids under Topology Attacks

Building an efficient, smart, and multifunctional power grid while maintaining high reliability and security is an extremely challenging task, particularly in the ever-evolving cyber threat landscape. The challenge is also compounded by the increasing complexity of power grids in both cyber and physical domains. In this article, we develop a stochastic Petri net based analytical model to assess and analyze the system reliability of smart grids, specifically against topology attacks under system countermeasures (i.e., intrusion detection systems and malfunction recovery techniques). Topology attacks, evolving from false data injection attacks, are growing security threats to smart grids. In our analytical model, we define and consider both conservative and aggressive topology attacks, and two types of unreliable consequences (i.e., system disturbances and failures). The IEEE 14-bus power system is employed as a case study to clearly explain the model construction and parameterization process. The benefit of having this analytical model is the capability to measure the system reliability from both transient and steady-state analysis. Finally, intensive simulation experiments are conducted to demonstrate the feasibility and effectiveness of our proposed model.

Novel complex network model and its application in identifying critical components of power grid

A novel power grid complex network model in order to in-depth characterize the power grid with its complexity is proposed in this paper, based on the power flow transmission network (PFTN). With novel definitions, considering the path, distance and capacity of power transmission comprehensively, the complex network model can comply with the basic electrical law and the physical constraints of power grid. On this basis, an index set for identifying critical buses and branches within the power grid is designed. The index set includes distance and capability degree, hub, distance and capability betweenness, which can fully evaluate the role of nodes or branches in composing the structure and maintaining the system operation of the power grid. Simulations on both IEEE benchmark systems and a provincial power grid in China are conducted using the proposed model, with critical components identification yielding good results. By comparison with existing methods, the effectiveness and superiority of the proposed model are verified.

Dissolved Gas Analysis Principle-Based Intelligent Approaches to Fault Diagnosis and Decision Making for Large Oil-Immersed Power Transformers: A Survey

Compared with conventional methods of fault diagnosis for power transformers, which have defects such as imperfect encoding and too absolute encoding boundaries, this paper systematically discusses various intelligent approaches applied in fault diagnosis and decision making for large oil-immersed power transformers based on dissolved gas analysis (DGA), including expert system (EPS), artificial neural network (ANN), fuzzy theory, rough sets theory (RST), grey system theory (GST), swarm intelligence (SI) algorithms, data mining technology, machine learning (ML), and other intelligent diagnosis tools, and summarizes existing problems and solutions. From this survey, it is found that a single intelligent approach for fault diagnosis can only reflect operation status of the transformer in one particular aspect, causing various degrees of shortcomings that cannot be resolved effectively. Combined with the current research status in this field, the problems that must be addressed in DGA-based transformer fault diagnosis are identified, and the prospects for future development trends and research directions are outlined. This contribution presents a detailed and systematic survey on various intelligent approaches to faults diagnosing and decisions making of the power transformer, in which their merits and demerits are thoroughly investigated, as well as their improvement schemes and future development trends are proposed. Moreover, this paper concludes that a variety of intelligent algorithms should be combined for mutual complementation to form a hybrid fault diagnosis network, such that avoiding these algorithms falling into a local optimum. Moreover, it is necessary to improve the detection instruments so as to acquire reasonable characteristic gas data samples. The research summary, empirical generalization and analysis of predicament in this paper provide some thoughts and suggestions for the research of complex power grid in the new environment, as well as references and guidance for researchers to choose optimal approach to achieve DGA-based fault diagnosis and decision of the large oil-immersed power transformers in preventive electrical tests.

A Relaxation-Based Network Decomposition Algorithm for Parallel Transient Stability Simulation with Improved Convergence

Transient stability simulation of a large-scale and interconnected electric power system involves solving a large set of differential algebraic equations (DAEs) at every simulation time-step. With the ever-growing size and complexity of power grids, dynamic simulation becomes more time-consuming and computationally difficult using conventional sequential simulation techniques. To cope with this challenge, this paper aims to develop a fully distributed approach intended for implementation on High Performance Computer (HPC) clusters. A novel, relaxation-based domain decomposition algorithm known as Parallel-General-Norton with Multiple-port Equivalent (PGNME) is proposed as the core technique of a two-stage decomposition approach to divide the overall dynamic simulation problem into a set of subproblems that can be solved concurrently to exploit parallelism and scalability. While the convergence property has traditionally been a concern for relaxation-based decomposition, an estimation mechanism based on multiple-port network equivalent is adopted as the preconditioner to enhance the convergence of the proposed algorithm. The proposed algorithm is illustrated using rigorous mathematics and validated both in terms of speed-up and capability. Moreover, a complexity analysis is performed to support the observation that PGNME scales well when the size of the subproblems are sufficiently large.

Recognition and Vulnerability Analysis of Key Nodes in Power Grid Based on Complex Network Centrality

The analysis of blackouts, which can inevitably lead to catastrophic damage to power grids, helps to explore the nature of complex power grids but becomes difficult using conventional methods. This brief studies the vulnerability analysis and recognition of key nodes in power grids from a complex network perspective. Based on the ac power flow model and the network topology weighted with admittance, the cascading failure model is established first. The node electrical centrality is further pointed out, using complex network centrality theory, to identify the key nodes in power grids. To effectively analyze the behavior and verify the correctness of node electrical centrality, the net-ability and vulnerability index are introduced to describe the transfer ability and performance under normal operation and assess the vulnerability of the power system under cascading failures, respectively. Simulation results of IEEE 30-bus and IEEE 57-bus test cases show that the key nodes can be effectively identified with high electrical centrality, the resultant cascading failures that eventually lead to a severe decrease in net-ability, verifying the correctness and effectiveness of the analysis.

Parallel dispatch: a new paradigm of electrical power system dispatch

Modern power systems are evolving into sociotechnical systems with massive complexity, whose real-time operation and dispatch go beyond human capability. Thus, the need for developing and applying new intelligent power system dispatch tools are of great practical significance. In this paper, we introduce the overall business model of power system dispatch, the top level design approach of an intelligent dispatch system, and the parallel intelligent technology with its dispatch applications. We expect that a new dispatch paradigm, namely the parallel dispatch, can be established by incorporating various intelligent technologies, especially the parallel intelligent technology, to enable secure operation of complex power grids, extend system operators U+02BC capabilities, suggest optimal dispatch strategies, and to provide decision-making recommendations according to power system operational goals.

PHIL Test Bench for Online-Identification Methods of Complex Power Grid

Power generation is shifting towards renewable and distributed energy production due to increased awareness of climate change and the recent advancements in renewable technologies. Distributed energy generation typically consists of wind and solar power plants, virtually all of which are connected to power grid by an inverter. As a consequence, the stability issues generated by the active power electronic devices are continuously increasing. The increased requirements for the functionality of the grid-connected inverters require a sophisticated test bench for experimentation. Power hardware-in-the-loop methods allow combining of the simulations to actual hardware, and thus, enable running experiments on real devices in time-varying conditions. This paper presents the use of a power hardware-in-the-loop test bench for stability studies of grid-connected systems. Experimental MIMO measurements based on pseudo-random sequences injected with a three-phase grid-connected inverter are presented and used to demonstrate the effectiveness of the proposed method.

Keeping the Lights On Across the Continent

Operators need new visualizations to help them monitor increasingly complex power grids at wider geographical scopes. We developed a work domain analysis of power grid operations from interviews, focus groups, and observations. The work domain analysis helped determine information requirements for a wide-area monitoring design concept that follows ecological interface design principles. We validated the design concept in a usability evaluation, achieving an above-benchmark System Usability Scale score of 77 out of 90. This work domain analysis and ecological interface design process will equally apply to the design of other power grid monitoring displays.

Voltage Control Strategies for Solid Oxide Fuel Cell Energy System Connected to Complex Power Grids Using Dynamic State Estimation and STATCOM

In this paper, a novel Dynamic State Estimation–current feedback with STATCOM control scheme is proposed for the mitigation of voltage fluctuation of Solid Oxide Fuel Cell (SOFC) power station connected to the complex power grids during electrical faults. The proposed control scheme is compared to two existing control strategies and shows its superiority in alleviating voltage flickers and deviations as well as protecting the internal membranes of the fuel cells. Since SOFC internal dynamic states are able to closely reflect the transience and dynamic behavior of SOFC, using them in controller designs can generate better regulations of the state-related internal voltage of SOFC than other methods. STATCOM is also utilized in this study to mitigate the voltage oscillations induced by unavoidable voltage fluctuations during electrical faults. The power system with proposed control strategy is proven to be stable through linear analysis. The acquisition of the useful internal dynamic states is realized using unscented Kalman filter algorithm based state estimator. The success of incorporating estimated states into the development of control strategies is conducive to the designs and implementations of new control schemes for power systems and also the applications of interdisciplinary control theories.

Research and Application on the Power Grid Environmental Risk Communication Strategy

Grid environment is complex and changeable modern intelligent power grid construction in a problem that cannot be ignored. In order to ensure safe and reliable operation of the grid, at the same time ensure that mutual coordination of grid environment and social environment, natural environment. This article introduce the risk communication strategies to achieve the various requirements of different interest groups to achieve common acceptable level of risk, so as to achieve the goal that the maximum benefit from the collective interests and at the same time maximize their own interests. So on the one hand can realize residents and enterprises with high quality of electric energy. On the other hand, it can realize the sustainable development of ecological environment in regional range.

동적 토픽분석을 활용한 스마트그리드 연구동향 분석

The power grid has been changed to a smart grid system to satisfy the growing need for power grid complexity, demand, reliability, security, and efficiency with a combination of existing power and ICT technology. This study analyzes the research trends in smart grid technology in the period since the introduction of the smart grid system and compares it with industrial trends to grasp the progress and characteristics of Smart Grid technology and look for ways to innovate the technology. To do this, we analyze the research trends using dynamic topic modeling, which is capable of time-series research topic analysis. Next, we compare the results of research trends with industrial trends analyzed by Gartner’s experts to demonstrate that smart grid research is evolving to the level of industrialization. The results of this study are quantitative analysis through data mining, and it is expected that it will be used in many fields such as companies that want to participate in industry and government agencies that need to establish policies by showing more objective analysis results.

Cascading failure forecast of complex power grids: A review

Cascading failure forecast of complex power grids is the premise of revealing the propagation mechanism of power system blackouts, keeping cascading failures from wantonly spreading and developing early preventive strategies against cascading failures. This paper summarizes the existing cascading failure forecast methods, and introduces the application of pattern search method, model method and risk evaluation method to cascading failure forecast of power grids in detail. Finally, the paper proposes the future research direction of cascading failure forecast of complex grids according to the present research.