2018, 42(1):1-7. DOI: 10.7500/AEPS20170518001
Abstract:With the construction of ultra-high voltage(UHV)AC/DC interconnected power grid, the advancement of new energy and the deepening of electricity market reform, significant changes have taken place in the operation of power grid in China, which makes higher requirements on the dispatching and control functions. Based on the integrated distribution and concentration deployment scheme of application functions, this paper gives an overview of the new features of the application function, i. e. , global, rapid and accurate, analyzes the technological support to realize such application functions, and points out the urgency of promotion basic work such as power grid model, operation data and management rules.
2019, 43(3):205-215. DOI: 10.7500/AEPS20180508006
Abstract:Direct current (DC) power grid is effective in solving the problems when high penetration of renewable energy is integrated into the power system. However, the construction of the DC power grid will face challenges in the aspects of technology, equipment and standards. Based on the technical characteristics of DC power grid, three typical application scenarios such as high-penetration renewable energy grid connection, offshore wind power grid connection and DC distribution network are analyzed. The latest research progress of key technologies and core equipments of DC power grids is elaborated. The development direction of DC power grid technology is proposed. The key technologies for the development of DC power grids are analyzed. The future development of DC power grid basic theory system, breakthrough in key technologies and core equipment are pointed out. The above research indicates that DC power grid technology will play a greater role in the global interconnected energy network.
2018, 42(6):1-8. DOI: 10.7500/AEPS20170617001
Abstract:The construction of large ultra-high voltage AC/DC hybrid power grid in China has greatly improved the ability to optimize the large-scale allocation of resources, but it also poses new challenges to the power grid dispatch and control system. This paper analyzes the development situation and characteristic variety of power grids, and new demands for power grid dispatch and control technology support. On this basis, the architecture of a dispatch and control system with the characteristics of physical distribution and logical integration is put forward. Also, the core technologies of basic support, model cloud, big data, dispatch and control based on source-grid-load interaction, integrated security risk prevention and control of large power grid, test verification, and system operation & maintenance, are analyzed in detail.
2018, 42(22):2-10. DOI: 10.7500/AEPS20180502008
Abstract:During the development transition period of China's ultra-high voltage(UHV)power grid, the characteristics of power grid continue to change significantly. The traditional defense technologies and measures on security and stability are difficult to adapt, thus the security prevention and control system is needed to improve. The necessity and demand of “system protection” to adapt to construct UHV AC/DC power grid is put forward based on the characteristic-changes of power grid. The design of system protection is proposed, including design ideas, overall composition and specific measures. Then the key technologies of system protection are put forward, and the requirement and framework of panoramic state perception, real-time decision-making and coordinated control as well as precision load control technology are focused on. Finally, the implementation scheme of system protection construction for State Grid Corporation of China is briefly illustrated, which provides a solution for the safe and stable operation control of large-scale UHV AC/DC power grid.
2018, 42(21):10-20. DOI: 10.7500/AEPS20180331006
Abstract:As the link of the energy and electric power system, the effective state evaluation of the power equipment is a powerful guarantee for the stable operation of power system. Based on the existing research results and the perspective of data science, this paper makes an in-depth analysis of the methods in the field of state evaluation of power equipment. Firstly, the paper introduces the new characteristics of state evaluation of power equipment in the context of data science. Then, with the current well-known data science analysis method based on data analysis technology as the starting point, the paper presents the key issues of the state evaluation of power equipment in data preprocessing, calculation and analysis, storage, and visualization. In addition, the paper systematically expounds the specific application, bottleneck and future development of data science in the field of state evaluation of power equipment. Finally, the paper discusses the challenge of data science in the state evaluation of power equipment and anticipates some directions of future research work in this field.
2018, 42(7):2-22. DOI: 10.7500/AEPS20180209010
Abstract:With the increasing demand for the controllability and flexibility of primary equipment in power system and the fast development of power electronic technology, more and more power electronic equipment is applied. In this paper, power electronic primary equipment in power system is collectively called flexible primary equipment. From this point of view, this paper firstly reviews the research progress and engineering applications of flexible primary equipment and their key technologies in flexible AC transmission system, flexible DC transmission system, renewable energy power generation, power energy storage, active distribution system and microgrid. Then the key generic technologies of flexible primary equipment are analyzed, and its development trend is prospected.
2018, 42(6):106-112. DOI: 10.7500/AEPS20170614011
Abstract:Firstly, a typical topology structure and node classification of flexible DC distribution network(FDCDN)are described. Secondly, a hierarchical coordinated control architecture for FDCDN is proposed. The system-level control adopts elite strategy based non-dominated sorting genetic algorithm with the embedded probabilistic load flow and the converter-level control uses multi-stage DC voltage margin control. The source-load-level control adopts the “quasi-cocktail” source-load response strategy to minimize the terminal power control error. Finally, a simulation model of FDCDN is established on the RTDS&dSPACE combined simulation platform. The effectiveness of the proposed hierarchical coordinated control strategy is proved by simulation.
2018, 42(2):1-10. DOI: 10.7500/AEPS20170625002
Abstract:Power transmission of high voltage, large capacity and long distance, adverse meteorological environment, AC/DC fault coupling propagation, a large number of application of power electronic equipments and other factors have brought new challenges to power system protection and security control. Firstly, the causes and the types of transmission and trans-formation equipment faults, as well as the difference in fault consequences are analyzed in this paper, and the technical system of pro-active protection and control(PPC)of power equipment is proposed. Then, the concepts of security region, dynamic security margin and tolerance time for safety of power transmission and transformation equipment are proposed to describe the safety of equipment as the main features. The technical architecture of pro-active protection and control is further proposed cored on the prediction of security region and security parameters of equipments. Finally, main technical directions of the pro-active protection and control are analyzed in this paper, and feasibility of the corresponding key technology, and prospect of the pro-active protection and control are discussed.
2018, 42(2):84-91. DOI: 10.7500/AEPS20170320005
Abstract:With the rapid development of UHV AC/DC power grid, the connections between power sending-side and receiving-side, AC and DC, and the upper and lower levels of the dispatch center are becoming closer and closer. The risks that local faults spread to the whole power grid are increasing, and the difficulty of dispatching real-time operation control is significantly also increasing. In this context, the paper analyzes the challenges and needs of real-time operation control of UHV AC/DC power grid, and combs out the problems and shortcomings of previous dispatching control system for supporting the operation control of UHV power grid. On this basis, the overall goal, the overall framework and the main modules of the integrated operation monitoring and fault co-processing application of the UHV interconnected power grid application function are proposed. Then, the related key technologies are analyzed and demonstrated, such as the operation status of the UHV power grid with the same monitoring of different dispatch centers, the coordination fault diagnosis of cross-regional power grid, the multi-level fault disposal joint implementation, fault information integration and multi-screen linkage display, “generation-grid-load” optimization coordination, provincial and prefectual power grid load coordination control and so on. Combined with the engineering practice in the relevant dispatch center of the UHV sending side and receiving side, the practical application effect is introduced. Finally, the future development directions and key technologies in the field of dispatching control of UHV power grid are discussed.
2018, 42(3):149-159. DOI: 10.7500/AEPS20170320007
Abstract:The concept of power system high-performance computing mode is illustrated. Following the evolution direction of off-line computation to on-line cooperation, the high-performance computing modes of parallel computation, distributed computation and cloud computation are mainly analyzed to improve the calculation speed and reliability, and provide the computing service. From the aspects of decomposition coordination methods, numerical parallel computing, hard-computing architecture and soft-computing mode, the overview of state estimation, power flow calculation, and online dynamic security analysis(DSA)including the transient stability computation and static safety analysis function are summarized. Three evolution phases to realize on-line computing cooperation roadmap are described, and the key technologies including assignment-mapping mechanism, decomposition-coordination computing service, module service interface and data interaction format are discussed in detail to support the on-line cooperation computation mentioned above. In the end, the on-line cooperation analysis computing scenario and state estimation service mode are designed in the cloud computing environment, which provides a reference for the cloud computing based design and development of dispatching control system.
2019, 43(10):177-191. DOI: 10.7500/AEPS20180814001
Abstract:The adoption rate of electric vehicles(EVs)will considerably increase based on the continuous promotion of EVs and the gradual construction of charging infrastructures. The spatio-temporal distribution prediction of EVs charging load is the basis for the research related to the integration of EVs into the power grid. The key factors of EVs charging load are firstly investigated. Three aspects are considered at the micro level, which are the characteristics of EV, charging facility relevant factors and EV user behavior-related. At the macro level, three main components are addressed in terms of policy, environment and market. Secondly, the paper provides a summary of previous work regarding modeling of spatio-temporal EV charging, where the uncertainties of user behavior are discussed in detail. The application of some new technologies in the current research is presented. Moreover, the research status of EVs participation in discharging potential assessment is delivered. Finally, research gaps that need to be further explored are identified.
2018, 42(10):163-169. DOI: 10.7500/AEPS20170506002
Abstract:To solve the complexity issue of power terminal communication access under the background of Energy Internet for smart power distribution and utilization(SPDU), an SPDU-terminal communication access architecture with integration of multiple technologies is designed. The paper firstly analyzes the features of power terminal communication access. Then, based on analyzing the shortcomings of existed communication architecture, a three-layer SPDU-terminal communication access architecture is proposed, which features multi-network cooperation and autonomy-selfhealing. Finally, technical implementation is fully depicted and the architecture design is proved to be reasonable through the typical terminal access schemes.
2018, 42(18):1-7. DOI: 10.7500/AEPS20171124001
Abstract:The new challenges facing grid monitoring and control in its own development needs and changes in the external environment are teased out. The new requirements of surveillance control, such as global awareness of the power grid, prevention and control of global risks, unified and coordinated control at multiple levels and flexible adaptation to external environment changes are clarified. In view of the new challenges and new demands, a new mode of global supervision and control of large power grid is proposed, which points out that it needs a wider range of surveillance, more types of surveillance content, more powerful real-time data processing capability, higher data real-time and consistency and other specific content. Based on the concept of “physical distribution and logical unification”, the overall framework of global monitoring is designed, and the key technologies that need to be further studied to realize the new mode are given.
2018, 42(16):155-160. DOI: 10.7500/AEPS20171202001
Abstract:In order to suppress the arc of the single-phase-to-earth fault in neutral point non-effectively grounded system, the operation which switches the fault phase to the earth has been widely used. The prerequisite of this method is to identify fault phase correctly in one cycle. However, the traditional fault phase identification method based on steady process is prone to failure in the case of grounding fault via intermittent arc. This paper analyzes the defects of the conventional methods, establishes the equivalent model of distribution network, and derives the transient time domain expression of the three-phase voltages after the arc extinguishing. The multi-scale wavelet transformation is used to extract the transient high-frequency components of three-phase voltages. A novel method is proposed to identify the fault phase by calculating the amplitude and phase characteristics of the high-frequency components and the conventional methods are combined with this novel method. The simulation results prove the effectiveness of the proposed identification method.
2018, 42(19):184-191. DOI: 10.7500/AEPS20171116010
Abstract:Traveling wave differential protection(TWDP)is constituted by traveling waves and characterized by two features. First, traveling waves is the composite quantities of voltage and current and inherently contains distributed capacitive current. Second, traveling waves are moving electromagnetic field, whereas transmission delay is the in-evitable attribute of movement. Therefore, TWDP is independent of voltage level, distributed capacitive current and line length. TWDP can be developed by transient quantities or steady quantities. The former solution has a fast operation speed, whereas the latter solution has a strong anti-interference capability. TWDP can be applied to AC transmission lines and DC transmission lines. This paper firstly reviews the research status of TWDP technology at home and abroad, and then systematically summarizes traveling wave characteristics. Next, the challenges faced by TWDP technology are analyzed. Finally, this paper analyzes the applications of TWDP on ultra-high voltage(UHV)AC transmission lines, DC transmission lines, and half-wave length AC transmission lines. The prospects of TWDP technology are also presented.
2019, 43(8):77-85. DOI: 10.7500/AEPS20180615002
Abstract:Generalized energy storage system(GESS)includes stationary energy storage system and controllable loads which can store thermal energy, potential energy and electric energy. An optimal model based on bi-level optimization method is proposed to solve the GESS optimal configuration problem of distribution networks with high-penetration renewable energy. According to the proposed method, the external model uses the genetic algorithm to search for the configuration scheme for GESS and the internal model is used to optimize the operation strategy of GESS based on the dynamic programming algorithm. By alternately optimizing the internal and external layers, the capacity of GESS in the distribution network containing renewable energy and controllable loads is optimized. And an IEEE 33-node distribution grid is taken as an example to verify that the proposed method can effectively increase the control resources of the distribution network system through controllable loads, and it can significantly reduce the configuration capacity of stationary energy storage and the operation cost of the system.
2019, 43(6):70-76. DOI: 10.7500/AEPS20180201004
Abstract:The wind/photovoltaic/storage microgrid(MG)is an effective solution which achieves complementary advantages and efficient use of distributed sources. However, many factors affect the economics with various influences. The criticality of economic factors is quantified and analyzed in the wind/photovoltaic/storage MG. Based on the analysis of operation mode, the economic model of MG planning is built. The model is aimed at optimal annual net profit considering the operation characteristics of micro-sources, the power balance between the MG and the utility grid as well as the reliability constraints. Also, the evaluation indices of economic operation are established. On this basis, economic factors in both planning and operation aspects are quantified by calculating the influence coefficients. A practical MG in Yunnan Province is used as case study. The analysis results show that rational allocation of energy storage can improve the economics of MG planning, and the key economic factors of wind/photovoltaic/storage MG include the equivalent life cycles of energy storage, the unit investment cost of wind generators and the discount rate on the planning level, and the energy supplied, unit electricity price as well as unit environmental benefit of wind power and photovoltaic generation on the operation level.
2018, 42(23):148-154. DOI: 10.7500/AEPS20171110008
Abstract:The fault indicator or its function block can detect the fault presence and remotely transmit fault detection signals to the feeder automation(FA)system for locating the faulty section of a feeder. This paper uses the logical node of fault passage indicator in IEC 61580-90-6 to build the IEC 61850 based models for distributed FA system. The logical nodes about distributed fault location, fault isolation and service restoration functions are structured, respectively. The system configuration language(SCL)in IEC 61850 is extended to describe the primary topology and function deployments of distribution networks. The communication service mappings from IEC 61850 to specific protocols are presented according to the application requirements in FA system. Finally, the system exchange process is designed to realize the data flow configuration between substation automation system and FA system. The case study shows that the presented IEC 61850 based models can support distributed FA functions and promote the interoperability between distribution terminal devices.
2019, 43(1):176-185. DOI: 10.7500/AEPS20180216001
Abstract:A concentrating solar power plant can use a new type of solar power generation equipment to carry out the conversion of “solar-heat-electricity” and could maintain stable electric power output, which provides an effective way to enhance the capability of accommodating solar power output. A concentrating solar power plant is proposed to support the system operation in a combined heat and power(CHP)microgrid, in which a wind power station, an electrical energy storage device, and an electric heater are equipped. Then, retail electricity prices and retail heating prices in the microgrid are utilized as signals to induce users to participate in the demand response program. The demand price elasticity matrix is employed to model the response of the participated electrical loads and thermal loads in the demand response program. Considering the uncertainties of wind power and solar power outputs, a fuzzy chance constrained programming model is established with an objective of maximizing the operational benefit of the microgrid. Then, the model is simplified, and a mixed integer linear programming model is attained and solved by the well-developed commercial solver CPLEX. Finally, a sample microgrid system is used for demonstrating the presented model and method for a typical winter day and a typical summer day.
2019, 43(2):105-111. DOI: 10.7500/AEPS20180213002
Abstract:Several existing problems in current power control of renewable energy are analyzed and the functional design and strategy of the intelligent control system for grid-connected power of renewable energy is introduced. The online sensitivity calculation method of the renewable energy station is proposed. Firstly, equivalent device in the state estimation system is confirmed according to grid-connected network of renewable energy power station. Based on real-time operation mode of the grid, the sensitivity of the equivalent device is calculated and then converted into the sensitivity of renewable energy station. The station/unit participating in the section control and the quantity of adjusted power is determined, and the problem of wind-coal coordinating control under the complex network structure is solved. When the renewable energy participates in peak regulation by tracking the negative spare capacity considering the regulation rate of thermal power unit and the area control error, the executed instructions would be adjusted in time once an exception occurs to ensure that automatic generation control(AGC)assessment indicators could meet the requirements. According to the power generation capacity, installed capacity and grid receiving space of the integrated renewable energy power station, the control sequence is determined and updated dynamically. The strategy can realize resource priority and fairness control among renewable energy stations and ensure the maximized consumption of renewable energy power. The operation result in Shanxi power grid shows that the intelligent control system can guarantee effectiveness of ensuring safe and stable operation of power grids, improving new energy consumption and promoting fair dispatch of new energy power stations.