scholarly journals A Topology Analysis-Based MMC-HVDC Grid Transmission Capacity Calculation Method

Symmetry ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 822
Author(s):  
Xiao Yu ◽  
Bing Zhao ◽  
Shanshan Wang ◽  
Tiezhu Wang ◽  
Lu Zhang
Keyword(s):  
Calculation Method ◽  
Transmission Capacity ◽  
Affecting Factors ◽  
Multilevel Converter ◽  
Topology Analysis ◽  
High Voltage Direct Current ◽  
Operation Modes ◽  
Capacity Calculation ◽  
Power Limits ◽  
Power Dispatching

Modular multilevel converter-based high voltage direct current (MMC-HVDC) has a broad application prospect in renewable energy transmission. With the development of converter capacity, the transmission capacity calculation for MMC-HVDC grids becomes important for power dispatching. The existing method depends on manual work and is suitable for a simple grid. However, as the grid structure and operation modes become more and more complex, it becomes difficult to calculate the transmission capacity of different operation modes for an MMC-HVDC grid. This paper analyzed and simplified affecting factors and basic topologies. On this basis, a topology-based MMC-HVDC grid transmission capacity calculation method is proposed. First, an MMC-HVDC grid is divided into sending end grid, transmission section lines, and receiving end grid. Then the power limits of these three parts are calculated. Finally, the transmission capacity is determined by analyzing the connection mode of these three parts. This method can be adapted to any kind of MMC-HVDC grid and can be easily programmed.

scholarly journals A Calculation Method of Available Transmission Capacity for Medium and Long-term Electricity Trading

2021 ◽  
Vol 256 ◽  
pp. 02037
Author(s):  
Fei Shi ◽  
Shuhai Feng ◽  
Hengfeng Zheng ◽  
Liwen Wang ◽  
Xu Wu
Keyword(s):  
Numerical Simulation ◽  
Calculation Method ◽  
Probabilistic Method ◽  
Transmission Capacity ◽  
Transmission Channels ◽  
Electricity Trading ◽  
Simulation Results ◽  
Power Dispatching ◽  
Transaction Security

In view of the fact that China’s power dispatching agencies and trading centers are relatively independent, but the medium and long-term power transactions need physical execution, which leads to higher requirements for transaction security boundary, this paper proposes a calculation method of available transmission capacity for medium and long-term power transactions, which calculates the available transmission capacity of transmission channels through probabilistic method to improve the enforceability of transaction results. Numerical simulation results also verify the effectiveness of the algorithm.

scholarly journals Simulation Model to Analyze the Consequences of DC Faults in MMC-Based HVDC Stations

Electricity ◽  
2021 ◽  
Vol 2 (2) ◽  
pp. 124-142
Author(s):  
Davin Guedon ◽  
Philippe Ladoux ◽  
Sébastien Sanchez ◽  
Sébastien Cornet
Keyword(s):  
Power Transmission ◽  
Renewable Energy Sources ◽  
Energy Sources ◽  
Modular Multilevel Converter ◽  
Multilevel Converter ◽  
Circuit Breakers ◽  
High Voltage Direct Current ◽  
Proposed Model ◽  
Proper Design ◽  
Reliability And Availability

The global development of high-voltage direct-current (HVDC) systems in fields such as renewable energy sources, interconnection of asynchronous grids or power transmission over great distances, is unquestionably important. Though widely used, the modular multilevel converter with half-bridge cells is sensitive to DC pole-to-pole faults and the time-response of the protections is critical. Reliability and availability are paramount: circuit-breakers must minimize the effects of any fault on the converter, while ensuring rapid restart. This paper focuses on the modelling aspects to analyse the behaviour of HVDC stations during DC pole-to-pole faults, using either AC or DC circuit-breakers, with different parameters. The proposed model can represent the main issues met by the converter cells during DC faults, such as semiconductor overcurrents and overvoltages, allowing a proper design of the cells.

Calculation method of winding eddy‐current losses for high‐voltage direct current converter transformers

2016 ◽  
Vol 10 (6) ◽  
pp. 488-497 ◽  
Author(s):  
Yaqing Liu ◽  
Dandan Zhang ◽  
Zhenbiao Li ◽  
Qinqing Huang ◽  
Bin Li ◽  
...  
Keyword(s):  
High Voltage ◽  
Direct Current ◽  
Eddy Current ◽  
Calculation Method ◽  
Eddy Current Losses ◽  
High Voltage Direct Current ◽  
Current Converter

scholarly journals Single Pole-to-Ground Fault Analysis of MMC-HVDC Transmission Lines Based on Capacitive Fuzzy Identification Algorithm

Energies ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 319
Author(s):  
Hongchun Shu ◽  
Na An ◽  
Bo Yang ◽  
Yue Dai ◽  
Yu Guo
Keyword(s):  
Transmission Lines ◽  
Fault Analysis ◽  
Identification Algorithm ◽  
Discharge Process ◽  
Multilevel Converter ◽  
Fuzzy Identification ◽  
Hvdc Transmission ◽  
High Voltage Direct Current ◽  
Ground Fault ◽  
Hvdc Transmission Lines

The probability of a single pole-to-ground fault in high voltage direct current (HVDC) transmission lines is relatively high. For the modular multilevel converter HVDC (MMC-HVDC) systems, when a single pole-to-ground fault occurs, the fault current is small, and it is difficult to identify the fault quickly. Through a detailed analysis of the characteristics of the single pole-to-ground fault of the MMC-HVDC transmission line, it is found that the single pole-to-ground fault has obvious capacitance-related characteristics, and the transient process after the single pole-to-ground fault is the discharge process of the distributed capacitance of the line. However, other faults do not have such obvious capacitance-related characteristics. Based on such feature, this paper proposes a novel capacitive fuzzy identification method to identify the single pole-to-ground fault. This algorithm can effectively identify both the fault of single pole-to-ground and the fault pole, which can contribute to the large database of the future smart grid.

scholarly journals Study on Flexural Bearing Capacity Calculation Method of Enclosure Pile with Partial Excision in Deep Foundation Pit

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Mingfeng Lei ◽  
Linghui Liu ◽  
Yuexiang Lin ◽  
Jin Li
Keyword(s):  
Flexural Strength ◽  
Bearing Capacity ◽  
Calculation Method ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Theoretical Derivation ◽  
Deep Foundation Pit ◽  
Practical Engineering ◽  
Capacity Calculation ◽  
Partial Excision

During deep foundation pit construction, the structural clearance intrusion, which is caused by the complex formation conditions and the inefficient drilling equipment, is usually detected due to the vertical deviation of piles. To meet construction requirements, pile parts intruding into the structural clearance are supposed to be excised. However, the sectional flexural strength of the pile is bound to decrease with partial excision, which would reduce the bearing capacity of the enclosing structure during construction. In this paper, a theoretical derivation of the normal sectional flexural strength of the partially excised circular pile is proposed. The derivation adopts the assumption of the plane section and steel ring equivalence and can be solved by the bisection method. Furthermore, the calculation method is applied to the pile evaluation of a practical engineering; also, the method is verified by the numerical method. The application results show that the excision of rebar and pile’s sectional area will cause a rapid linear decline in the sectional flexural strength. After excising 18 cm radial thickness of the circular pile (ϕ800 mm) and 6 longitudinal rebars, the sectional flexural strength of the pile decreases to 58% from the origin, which cannot meet the support requirement. The analysis indicates that pile reinforcements must be carried out to maintain the construction safety.

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