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最新刊期
卷 44 ， 期 2 ， 2020
- 摘要：Due to the unpredictable factors in the integration of society in the ubiquitous power Internet of Things, the interconnection environment is complex and diverse, the types and number of terminal devices are exploding, and security risks such as network attacks and non-secure data intrusions are always faced. Therefore, the existing security detection and protection technology is no longer fully applicable to current ubiquitous power Internet of Things. The security technology for ubiquitous power Internet of Things is discussed from a new perspective of biological immunology. Firstly, the immune process of the immune system compared to that one the pathogen invades the organism is described. The relationship between bioimmunology and security protection of ubiquitous power Internet of things is expounded. Secondly, the security challenges faced by the perception layer, network layer, platform layer and application layer are analyzed. Based on immunology, the key technologies of antigen recognition, immune response and immune memory are summarized. Finally, the safe immune system for the intelligent linkage of ubiquitous power Internet of Things is devised, and the research areas are prospected.关键词：Ubiquitous Power Internet of Things;cyber-physical-social system;bioimmunology;security defense;network attack3|1|0更新时间：2025-06-16
- 摘要：Automatic optimization and operation of power grid rely on the ubiquitous sensing and complete data support, which are the most basic requirements that must be satisfied in the sensible layer of the ubiquitous power Internet of Things. In the application of power Internet of Things, complete and correct measurement data acquisition is the basis for power quality control. However, in the whole process of data acquisition and transmission, data missing occurs inevitably. Aiming at the above situation, a new method based on low rank matrix completion theory for missing power quality data completion is proposed. This paper first proves that the power quality data have the characteristics of approximate low rank. Based on that, the multi-norm optimization model is designed. The alternating direction method of multipliers is applied to decompose the model into several sub-problems and solve them separately. At the same time, to accelerate the model solution, an optimal selection strategy of adaptive iterative step size is proposed. Effectiveness of the method is verified by high-frequency fault scenarios such as voltage swell, voltage interruption, pulse oscillation and voltage sag. Experimental results show that the method is suitable for power quality data recovery in multiple scenarios, and in the absence of 50% data, the data matrix recovery error is within 3%.关键词：Ubiquitous Power Internet of Things;power quality;missing data;matrix completion;alternating direction method of multipliers（ADMM）4|2|0更新时间：2025-06-16
- 摘要：Distribution Internet of Things (D-IoT) is an important part of ubiquitous power Internet of Things. It is an important measure to improve the efficiency of distribution network operation, optimize the business performance and share development results by creating D-IoT ecosystem. In the future， the D-IoT will face the increasing workload of installation, commissioning, operation and maintenance due to the access of massive low-voltage intelligent terminals. This paper proposes a model system for D-IoT based on the Internet of Things model, IEC 61850 and IEC 61968 standards. Also, the communication protocols of the Internet of Things represented by message queuing telemetry transport （MQTT） protocol and constrained application protocol （CoAP） are applied to standardize the communication between devices and realize efficient transmission of terminal data model. Then, the adaptive access process is discussed from three aspects： the first access of the low-voltage intelligent terminals, the function upgrading and the reason for the withdrawal. Finally, the effectiveness of the proposed method is verified by the experiments and engineering applications.关键词：Ubiquitous Power Internet of Things;distribution Internet of Things;information modeling;Internet of Things protocol;adaptive access3|3|0更新时间：2025-06-16
Ubiquitous Electric Power Internet of Things
- 摘要：Battery energy storage system has many advantages such as short construction period, fast response speed and various application modes. In recent years, it has been continuously expanded in scale and has been more and more widely used with the encouragement of national and local governments. Since Zhenjiang 100 MW energy storage station of China was put into operation in July 2018, it has participated in peak load regulation, frequency modulation, emergency response and other auxiliary services. Based on the structural characteristics of the Zhenjiang 100 MW battery storage station, the operation control strategies of different application modes of the station are studied and analyzed, and the response indices and current operation conditions of the station are tested and analyzed to explore the application value of large-scale energy storage power station on the grid side.关键词：energy storage on grid side;battery energy storage system;control strategy;operation and control3|1|0更新时间：2025-06-16
Special Report
- 摘要：Industrial and commercial enterprises are the main groups of energy consumption. The objective and accurate evaluation of the value of integrated energy system to industrial and commercial enterprises is the foundation of optimized operation and energy audit. Traditional methods have certain sufficiency in promoting multi-energy complementarity and renewable energy consumption. Thus, a value evaluation method of integrated energy system based on renewable exergy economy is proposed. Taking the management standard for enterprise energy balance as the basis to do the objective and quantitative calculation, considering three indices of product unit consumption, comprehensive energy efficiency and renewable energy utilization, and by using the fuzzy comprehensive evaluation method, the membership function and dynamic weight coefficients of three indices are designed to calculate the comprehensive value score, which is taken as a basis for choosing the optimal operation scheme. The simulation results show that the evaluation method can select a reasonable operation mode according to the energy consumption law of enterprises and effectively promote energy cascade utilization and local consumption of renewable energy, which verifies the effectiveness and rationality of the method.关键词：multi-energy complementarity;green exergy economy;enterprise energy balance;fuzzy comprehensive evaluation;dynamic weight3|2|10更新时间：2025-06-16
- 摘要：With the development of gas turbine and power to gas, the coupling degree of power grid and natural gas network is being deepen, and the mutual influence between them has recieved much attention. In this paper, the shortcomings of current researches on the mutual influence between power grid and natural gas network are overcomed from two aspects: power flow algorithm and sensitivity analysis. Firstly, the unified power flow model of integrated electricity and natural gas system is established. The model simplifies the equation dimension by means of reducing variables, and the model considers the slow time-scale characteristics of natural gas transmission based on the line-pack model. At the same time, in order to avoid the sensitivity of traditional Newton method to the choice of initial state value in the power flow solution of natural gas network, the Newton descent method is proposed to solve the unified power flow model. Furthermore, based on the sensitivity analysis method, with the sensitivity of gas pressure-injected power of electricity-gas coupling node as the key characterisitic quantity, a comprehensive sensitivity index for the analysis of the coupling mechanism of integrated electricity and natural gas system is proposed in order to provide decision-making assistance for the joint operation of the two networks. The analysis of examples verifies the effectiveness of the proposed algorithm. By comprehensively comparing and exploring the interaction characteristics of integrated electricity and natural gas system with the coupling of gas turbine and power to gas, the positive role of line-pack characteristics of the natural gas network in response to system disturbances is verified.关键词：unified power flow;Energy Internet;sensitivity analysis;Newton descent method3|3|0更新时间：2025-06-16
- 摘要：Flexible load scheduling is an important means to optimize load curve, reduce equipment capacity, and promote renewable energy accommodation. Taking transmission delay of heating network and ambiguity about temperature perception into account, a thermal flexible load model is established. Considering three types of electric flexible load including shiftable, transferable and curtailable loads, with the minimum total cost including investment, operation and compensation cost as the objective function, an optimal configuration model of power/thermal energy storage for regional integrated energy system (RIES) is established. Moreover, a simulation program using a commercial software called LINGO is developed to obtain the optimal output of each device and optimal capacity of energy storage. Compared with the scenario where the power/thermal flexible load is not considered， simulation results indicate that the participation of the power/thermal flexible load can optimize the power/thermal load curve, reduce the capacity of the energy storage device, enhance the flexible adjustment capability of RIES, reduce the energy consumption and investment cost of energy storage, and achieve the optimal economic operation of the system.关键词：regional integrated energy system;power/thermal flexible load;energy storage configuration;economic operation3|2|0更新时间：2025-06-16
Cyber Energy Systems
- 摘要：In order to cope with the increasing quality of service （QoS) requirements for demand response services, this paper firstly analyses the characteristics of demand response services and establishes refined traffic models of demand response services. Secondly, by decomposing the communication delay of demand response, the main reasons for the congestion of the demand response communication networks are analyzed. Then, in order to satisfy the quality of service requirements of demand response services, a dynamic scheduling strategy of improved weighted fair queuing based on fuzzy logic is proposed, which considers the dynamic characteristics of load conditions and service burst degree of communication network for demand response services. The simulation results show that the proposed dynamic queue scheduling strategy of demand response can balance the quality of service requirements of different demand response services, reduce the transmission delay of low priority demand response services and improve the jitter performance of transmission delay.关键词：demand response;fuzzy logic;communication scheduling;quality of service (QoS)3|1|0更新时间：2025-06-16
- 摘要：Load aggregators (LAs) can provide high-quality ancillary service for power system and receive benefits by aggregating distributed user-side resources. However, the uncertainty of user-side response will exert negative effects on both ancillary service quality and economic benefits of LAs. To overcome such a problem, the controllable load resources are considered as virtual energy storage (VES), and combined with narrow sense energy storage (NSES). Then an uncertain response model of generalized energy storage (GES) is established. Furthermore, two control strategies of LAs, namely NSES priority response and VES priority response, are proposed, and the characteristics of both strategies are discussed. Finally, a revenue model of LAs participating in the ancillary service market using the two control strategies is presented, which is verified for the effectiveness using the operation data of PJM electricity market of America. Case studies show that the LAs can get considerable economic benefits by configuring relatively small amount of NSES equipment and adopting the control strategy of VES priority response.关键词：load aggregator;generalized energy storage;control strategy;ancillary service market3|2|0更新时间：2025-06-16
- 摘要：Electric vehicle (EV) has the ability to participate in interaction with power grid as a kind of new distributed energy storage and its most distinct characteristic is its mobility. This paper investigates the characteristics of mobile energy storage and develops the mobile storage model of EV based on the theory of parking generation rate. The mobile behavior of EV is described by taking gridded region as a unit. A synergy vehicle-to-grid (V2G) strategy for mobile energy storage of EV and renewable energy is proposed with the minimum load fluctuation of power gird as its optimization objective, which considers the constraints of power flow, battery performance, owner demands and EV mobility. Finally, case study is conducted in two different scenarios including different mobile characteristics and the scales of EVs. The simulation results show the influence of characteristics of mobility energy storage on the proposed strategy and validates the feasibility of the proposed model and strategy.关键词：electric vehicle;mobile energy storage;parking generation rate;renewable energy;vehicle-to-grid (V2G);dispatching strategy3|1|0更新时间：2025-06-16
- 摘要：Integration of high-proportion residential photovoltaics (PVs) causes serious voltage problems such as voltage violations. Reactive power control of PV inverter and active power control of energy storage system (ESS) are the effective voltage control methods for low-voltage distribution network (LVDN). Aiming at the limited communication conditions of LVDN and the insufficient research on coordination of reactive power of inverter and active power of ESS, a two-stage distributed control strategy based on consensus algorithm for PV inverter and ESS is proposed in this paper. Firstly, through the control effect-cost coefficient to analyze the effect and economy of adjustment for the equipment, a voltage control architecture is proposed in which the reactive power of inverter is first adjusted and then the active power of ESS is adjusted. Then, at the inverter control stage, the utilization ratio of reactive power is used as the consensus variable to ensure that the voltage regulation task is shared according to the inverter capacity. In the ESS control stage, the state of charge (SOC) of ESS is taken as the consensus variable, which not only considers the ESS capacity but also realizes the simultaneous control of ESS power and SOC. The simulation results demonstrate that voltage violations can be effectively mitigated, and voltage control cost can also be reduced. At the same time, the selection range of the control strategy parameters is given.关键词：low-voltage distribution network (LVDN);voltage violation;photovoltaic (PV) inverter;energy storage system (ESS);distributed control;consensus algorithm3|3|0更新时间：2025-06-16
- 摘要：To solve the problem of grid-resource-storage planning of distribution networks with high penetration of distributed generator(DG) clusters and promote the reliability indices of load points, this paper proposes a two-step planning method. The first step is to conduct the multi-objective grid-resource planning of DG clusters considering isolated operation probabilities of clusters. Based on the isolated operation probabilities of clusters obtained in the first step, the energy storage planning in the second step is conducted to guarantee that DG integrated with the clusters could satisfy the isolated operation of clusters. Considering the isolated operation of clusters and the uncertainties of the grid connection during the planning process, the up-stream delivery and the down-stream combination of the reliability index calculation method in the grid-resource planning model are improved. Since the grid-resource collaborative planning model in the first step is a multi-objective problem, augmented ε-constraint method（AUGMECON） is introduced to solve the multi-objective planning model. AUGMECON could provide decision makers with the richer alternatives. Taking the actual distribution network with high penetration of DG in China as an example, it is verified that the proposed grid-resource-storage planning method based on cluster partition can improve the reliability of the system and decrease the power losses and voltage fluctuations.关键词：grid-resource-storage planning;distributed generator cluster;analytical calculation method;reliability assessment;multi-objective planning3|1|0更新时间：2025-06-16
- 摘要：Distributed generators with high permeability cause voltage quality problems such as voltage deviation and fluctuation, and increase network loss as well. Aiming at this problem and taking configuration of energy storage as a solution, the optimal allocation strategy of energy storage location and capacity of distribution network is put forward combined with the power four-quadrant output control strategy of the battery energy storage system, which aims at improving the economic benefit and voltage quality of the distribution network. Specifically, an economic operation model for distribution network with the goal of minimizing the sum of purchase cost, network loss cost and investment cost is constructed. The time scale is set as 15 min for rolling calculation, and the lowest total cost in a typical day is used to choose the siting and sizing of storage. Meanwhile, the migration and fluctuation range of each node voltage is constrained, and the mixed integer second-order cone mathematical programming is used to optimize the solution. The simulation results of IEEE 33-bus distribution network demonstrate the feasibility and efficiency of the proposed optimal configuration method.关键词：distribution network;voltage quality;economic benefit;battery energy storage system;power four-quadrant output;siting and sizing4|2|0更新时间：2025-06-16
- 摘要：In distribution network state estimation, measurement devices are limited and network observability is not achieved unless pseudo measurements are used. Considering the measurement errors and the deviations between the pseudo measurements and the actual values, the (pseudo-) measurements have uncertainties in distribution network state estimation, which will affect the performance of state estimation. The global sensitivity analysis method of the distribution network state estimation is proposed, to identify the critical (pseudo-) measurement uncertainties and their locations, which have an impact on the accuracy of state estimation. Based on the sparse polynomial chaos expansion, the global sensitivity indices are calculated to improve the computational efficiency of the global sensitivity analysis. And the metering placement method based on the importance ranking of uncertain parameters is provided. The proposed approach is tested on the IEEE 33-bus distribution system. Compared with the common methods, the accuracy and efficiency of the proposed method are verified. This method overcomes the shortcomings of the traditional state estimation sensitivity analysis. It evaluates the influence of the correlation of (pseudo-) measurement uncertainties on state estimation. The metering placement method based on the global sensitivity analysis is able to significantly improve the accuracy of distribution network state estimation.关键词：distribution network;state estimation;uncertainty;global sensitivity analysis;sparse polynomial chaos expansion;measurement configuration3|4|0更新时间：2025-06-16
- 摘要：When an extreme disaster causes a blackout, multiple power sources could be coordinated with energy storage to restore critical loads, which is able to enhance the resilience of distribution network. Firstly, the role of multiple coordinated sources for service restoration in enhancing the resilience of distribution network is introduced. Secondly, the multi-period load restoration problem is formulated and relaxed as a mixed integer second-order cone program, with the goal of maximizing the weighted power supply time of the load and minimizing the total power loss. The load state, output power and commissioning state of power lines in each period are taken as optimized variables, and finite energy constraints, operational constraints and topological constraints are considered. The proposed model could be efficiently solved by commercial solvers and then the optimal recovery strategy is obtained. Finally,based on standard cases of the modified IEEE 13-bus and IEEE 123-bus test distribution systems, the simulation results show that the proposed method is effective and superior.关键词：distribution network;distributed generator;power supply restoration;resilience;optimal decision-making3|1|0更新时间：2025-06-16
- 摘要：The output power of high-penetration wind power and photovoltaic generation in microgrid is random and fluctuating. Meanwhile, the load power in microgrid is stochastic and varying,which easily causes frequency fluctuations in the microgrid. Moreover, the operation mode change of the microgrid will cause in variations in both network equivalent parameters and operation parameters. Consequently, aiming at frequency fluctuations and parameter perturbation of controlled objects in AC/DC hybrid microgrid, this paper proposes a frequency control method for the AC/DC hybrid microgrid based on H∞ mixed sensitivity, which can control and stabilize the AC-region frequency. Firstly, the
- 摘要：With the gradual application of unified power flow controller (UPFC) as new generation components of flexible AC transmission systems in transmission lines, it is necessary to study the protection principle of the line with UPFC in deep. By analyzing the transient influence of UPFC on fault line, it is concluded that the series side of UPFC has a serious attenuation effect on the high frequency components, and the reliability of single-end transient protection is reduced. The analysis of the fault transient characteristics of busbar-connected outgoing lines shows that there is a significant difference in the current spectrum distribution between the fault side line and the non-fault side lines for the same busbar. By using the wavelet energy entropy to extract the transient information of each outgoing line of the busbar, a directional pilot protection scheme for the line with UPFC is proposed. The simulation results show that the scheme can accurately identify the internal faults, external faults and bus faults. The scheme also has good sensitivity and reliability under fault conditions such as different transition resistances and fault inception angles.关键词：fault transient component;unified power flow controller (UPFC);busbar outgoing line;transmission line protection;wavelet energy entropy3|2|0更新时间：2025-06-16
- 摘要：In order to improve the enthusiasm of the power pipelines entering into urban underground utility tunnels, it is of great significance to formulate a fair and reasonable cost sharing method. The cost sharing model for the power pipelines entering into utility tunnels is established by using the deviation minimization method considering interest balancing of plural subjects. The entrance expense and daily maintenance expense are allocated to pipeline companies by the proposed model. The occupied space, the direct buried cost, the direct buried operation and maintenance cost of each pipeline are taken as the proportion factors. The satisfaction degree to the cost sharing results of all pipeline companies is taken as the group satisfaction factor in the cost sharing model. The interest of power companies and the other pipeline companies is balanced with the cost sharing willingness of each pipeline company and the evaluation results of the independent third party. Finally, the effectiveness and practicability of the proposed method are verified by the case study results of the utility tunnels in a city.关键词：power pipelines entering into utility tunnels;plural subjects;interest balancing;cost sharing;proportion factor;group satisfaction3|1|0更新时间：2025-06-16
- 摘要：To solve the problem that traditional point-to-point prediction method is not applicable to the load with large fluctuation and uncertainty, this paper implements a prediction interval method based on improved evaluation index to improve existing forecasting evaluation index from two aspects of interval width and cumulative error, which enhances the reasonableness of prediction results. On this basis, weighing the characteristics and importance of each evaluation index for the influence on prediction results, the comprehensive evaluation index for interval prediction is established, and the interval prediction model is constructed by using neural network. Aiming at the optimization of the comprehensive evaluation index, the particle swarm optimization algorithm is used to train and optimize the structure parameters, so as to achieve ideal effect of interval prediction for fluctuating load. The historical load data with strong uncertainty is used to validate the proposed method. Comparing with the traditional point-to-point and interval forecasting methods, the results and analysis of the improved interval prediction verifies the effectiveness and superiority of the method.关键词：fluctuation load;interval prediction;boundary estimation;neural network;particle swarm optimization algorithm3|1|0更新时间：2025-06-16
Basic Research
- 摘要：This paper shows that power-heat decoupling transformation of combined heat and power (CHP) plant is the essence of configuring short-term heat sources for CHP units. From the view of configuring compensation heat sources, applicable scenarios, feasible operation region, heating cost and heating capacity of four compensation strategies are analyzed, including heating storage, electric boiler, bypass compensation and low-pressure cylinder cut-off . The operation flexibility evaluation model of transformed CHP plant is established. Examples are given to analyze the flexibility improvement effects of the four strategies in different scenarios when they are used alone or in combination.关键词：combined heat and power plant;power-heat decoupling;operation flexibility improvement;renewable energy accommodation3|1|0更新时间：2025-06-16
- 摘要：An ultra-short-term wind power forecasting method combining multiple clustering algorithm and hierarchical clustering algorithm is proposed. To deal with the dynamic condition of training samples and identify the samples that are similar to the characteristics of the period to be predicted, the historical power series and historical meteorological series are clustered separately. The clustering index of the power series consists of Euclidean distance and covariance, and the layer-by-layer method is used for meteorological series clustering. Two clustering results are combined into multiple sample subsets. Multiple neural network forecasting models based on particle swarm optimization and back propagation (PSO-BP) are established by using the method of classification modeling and feature matching. And the model with the most similar characteristics to the predicted period are used. The proposed forecasting approach has been applied in actual wind generation data tracking in Qinghai province of China. The simulation results show that it can improve the forecasting accuracy of ultra-short-term wind power.关键词：ultra-short-term wind power forecasting;multiple clustering;covariance;neural network model;classification modeling;feature matching3|1|0更新时间：2025-06-16
- 摘要：The high-penetration integration of volatile wind power degrades the damping characteristic and the primary frequency regulation performance of the power system, which restricts the further improvement of the wind power penetration. This study improves the frequency regulation capability of the high-penetration wind power system while maintaining the dynamic stability level of the system, which is of great importance to increase the wind power penetration limit. Firstly, the paper puts forward a solution to the wind power penetration limit with constraints of damping ratio and frequency deviation. Then, based on the opposite effects of inertial parameters of thermal power units on the damping characteristic and the primary frequency regulation performance of the system, a coordinated optimization method for the inertial parameters of thermal power units is proposed, which considers the damping ratio and dynamic frequency response capability of the system. The simulation results prove that the calculation results of the proposed solution to the wind power penetration limit are of high reference value. After the introduction of the coordinated optimization strategy, the dynamic stability characteristic and the primary frequency regulation characteristic of the system are improved effectively. The optimization effect has a strong applicability and the wind power penetration of the power system has also been improved.关键词：high-penetration wind power system;wind power generation;penetration limit;damping characteristic;primary frequency regulation;inertia time constant3|2|0更新时间：2025-06-16
- 摘要：Conventional harmonic responsibility determination methods have shortages such as the inability to achieve long-time scale dynamic responsibility determination, the need for special measurement, the inability to utilize the data of existing monitoring systems, and the inability to determine the harmonic responsibilities of users on the same feeder. Thus, this paper proposes a determination method of user harmonic responsibility based on correlation analysis of monitoring data. Firstly, the monitoring data are collected, including the harmonic voltage data from the power quality monitoring system and the average active power data of each user from the power information collection system. By the canonical correlation coefficients based on these data, the harmonic responsibility at the point of common coupling (PCC) is divided into the background harmonic responsibility and the harmonic responsibility of concerned users. Secondly, the dynamic distortion correlation coefficients of harmonic voltage and active power of each user are calculated, which are used to reflect the relationship between user power consumption behavior and harmonic voltage distortion at PCC. Finally, the long-time scale index for harmonic responsibility determination is developed with consideration of the relationship and user power consumption capacity. The validity and practicability of the proposed method are verified by the data in the actual monitoring system, and the long-time scale dynamic harmonic responsibility determination of each user on the feeder can be realized based on the existing monitoring data.关键词：harmonic responsibility determination;long-time scale;monitoring data;correlation relationship;dynamic distortion correlation coefficient3|1|0更新时间：2025-06-16
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Analysis and Evaluation of Voltage Sag Severity Based on Data Mining and Improved Grey Target Theory
摘要：Aiming at the problem of voltage sag severity evaluation, a data mining and analysis method based on mutual information and improved grey target theory is proposed. The index of sag distance and cross influence domain is proposed, and the framework of severity evaluation is established considering various characteristic attributes of voltage sag. A mutual information network model is constructed for data mining of voltage sag, and a voltage sag knowledge base is built by using connection weight to extract rules to preliminarily analyze the severity level of voltage sag in the whole grid, which avoids the problem of conflict rules caused by traditional support and confidence based data mining methods. An improved method for calculating the target centricity is proposed. Combining with the sag severity level of the whole grid obtained from data mining, a conditional search model of voltage sag severity is established to evaluate the sag severity of substation, which solves the problem of multiple matching results and improves the accuracy of voltage sag evaluation. The feasibility of the proposed method is verified by an example analysis.关键词：voltage sag;mutual information;grey target theory;severity evaluation;data mining3|3|0更新时间：2025-06-16 - 摘要：The traditional active power filter (APF) using inverter technology needs to use electrolytic capacitor bank for energy storage, which has the disadvantages of large size, high price and low reliability. To solve this problem, this paper focuses on the single-phase AC/AC-type APF without DC energy storage unit. The principle of reactive power and harmonic comprehensive compensation based on even-order harmonic modulation (EHM) technology is introduced. The Fourier series method and data fitting method are used to obtain the relationship of frequency and quantity between each even-order modulation term in the duty cycle and odd-order components in the compensation current. A decoupling modulation strategy is proposed for the coupling control of even-order modulation wave, which improves the compensation accuracy and stability of the system. A single-phase comprehensive compensation scheme is designed, and the simulation and experimental results verify the correctness of the theoretical analysis and the feasibility of the proposed strategy.关键词：active power filter (APF);direct AC/AC conversion technique;even-order harmonic modulation (EHM);decoupling modulation3|1|0更新时间：2025-06-16
- 摘要：With the continuous expansion of power grid, it is of great practical value to rapidly form the node impedance matrix of large-scale power grid. In order to accelerate the generation of impedance matrix, a graphic processing unit （GPU）-based parallel branch addition method is designed based on collaborative central processing unit （CPU） and GPU computation architecture. In addition, by analyzing the relationship between the topology structure of power grid and the chain branch, an optimized algorithm of node numbering is designed based on the minimum loop of the graph theory. The minimum loop of the substation level is extracted from the connections of plants/substations, and the topological sort is used to determine the order of group additions. The order of substation additions is determined based on the group, and then node numbering order is optimized. The experimental results show that, comparing with the serial computing method, the proposed method has a significant improvement in computation efficiency. In the calculation of large power grid, the speedup ratio could get tens of times, and the speedup ratio of additional chain branches could reach hundreds of times.关键词：node impedance matrix;branch addition method;node numbering;graphic processing unit （GPU）;topological sort3|1|0更新时间：2025-06-16
Application Research
- 摘要：The probability distribution and the corresponding causes of frequency in different years， in interconnected mode and isolated mode, are analyzed based on massive measurements in an actual regional power grid. In the interconnected mode, the probability distribution changes from band distribution with shape edges to bimodal distribution. The reason is that the standard deviation of the system power imbalance is increasing, resulting in a large frequency fluctuation, and the primary frequency regulation frequently acts to form the bimodal distribution. In the isolated mode, the probability distribution exhibits an obvious bimodal distribution. The reason is that the decrease of grid scale leads to severer frequency fluctuation and frequent action of primary frequency regulation. The key work for improving frequency regulation of power grid is to strengthen ultra-short-term prediction and intraday planning balance and reduce system power imbalance.关键词：power system frequency;probability distribution;bimodal distribution;primary frequency regulation;frequency fluctuation3|3|0更新时间：2025-06-16
- 摘要：In the ultra-high voltage direct current (UHVDC) projects which is based on the structure of dual 12-pulses valve groups in series, the following actions may lead to the metallic-bypass branch operation: the manual and auto sequence control of switching equipment in DC yard, the protective blocking of one pole, the online protective quitting of valve groups. This paper describes the forming process of the metallic-bypass branch operation and proposes the corresponding countermeasures. The prevention should be taken as the major principle in dealing with metallic bypass branch operation, and the isolation methods should be taken as the supplementary measures，such as the pole isolation and the failure protection of neutral bus switch. The countermeasures described in this paper have been applied in the ±800 kV UHVDC project from northwest Yunnan to Guangdong in China Southern Grid. The on-site test and simulation test show the problem of metallic-bypass branch operation in dual 12-pulses valve groups in series has been effectively solved.关键词：valve groups in series;DC transmission;metallic bypass;protective block3|2|0更新时间：2025-06-16
Engineering Application
- 摘要：In power system off-line and real-time electromagnetic transient simulation, the ideal switch model is often used for typical controllable power electronics devices represented by insulated gate bipolar transistor (IGBT). With the increasing applications of IGBTs in AC/DC converters and DC circuit breakers, the operation status of IGBT can affect the dynamics of system transients which can increase the voltage current pressure of devices in serious cases. This may cause damage to the device and consequently threat the safe and reliable operation of the converter and the complete system. Electromagnetic transient simulation based on ideal switch model cannot accurately simulate the characteristics of the device and the pressure， which it is subjected to in the transient process. The study of the inter-dynamics among the system circuit, individual devices, and the corresponding control system requires IGBT modeling schemes with higher accuracy for electromagnetic transient simulation. In recent years, detailed modeling schemes of multiple IGBT and decoupling methods are proposed and applied in off-line and real-time simulation. Due to the rapid development of high-performance computing platform, relatively detailed models can be applied to the simulations of AC/DC power system with a large amount of IGBT devices. The modeling schemes are classified and the function, the modeling complexity, and the accuracy of various IGBT models are analyzed. The system solution schemes, parallel computing schemes and the simulation platforms in detail are also described. Moreover, typical applications of IGBT detailed modeling schemes are introduced. The difficulties and limitations in areas of IGBT modeling schemes, system solution methods, parallel computing schemes and applications are analyzed, and the corresponding research suggestions are proposed as well.关键词：electromagnetic transient simulation;power system;insulated gate bipolar transistor (IGBT);device model;modular multi-level converter (MMC)3|1|0更新时间：2025-06-16
Review
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