Network equivalents and practical short-circuit current assessments in large-scale ac power systems

Author(s):  
Nasser D. Tleis
2020 ◽  
Vol 12 (22) ◽  
pp. 9333
Author(s):  
Sangwook Han

This paper proposes a reinforcement learning-based approach that optimises bus and line control methods to solve the problem of short circuit currents in power systems. Expansion of power grids leads to concentrated power output and more lines for large-scale transmission, thereby increasing short circuit currents. The short circuit currents must be managed systematically by controlling the buses and lines such as separating, merging, and moving a bus, line, or transformer. However, there are countless possible control schemes in an actual grid. Moreover, to ensure compliance with power system reliability standards, no bus should exceed breaker capacity nor should lines or transformers be overloaded. For this reason, examining and selecting a plan requires extensive time and effort. To solve these problems, this paper introduces reinforcement learning to optimise control methods. By providing appropriate rewards for each control action, a policy is set, and the optimal control method is obtained through a maximising value method. In addition, a technique is presented that systematically defines the bus and line separation measures, limits the range of measures to those with actual power grid applicability, and reduces the optimisation time while increasing the convergence probability and enabling use in actual power grid operation. In the future, this technique will contribute significantly to establishing power grid operation plans based on short circuit currents.


2013 ◽  
Vol 805-806 ◽  
pp. 756-762
Author(s):  
Bi Qiang Tang ◽  
Li Wen Wang ◽  
Yi Jun Yu ◽  
Fei Shi ◽  
Shu Hai Feng

With the growing scale of power systems in China, short-circuit current levels of power systems have been significantly increasing. Appropriate grid topology adjustment is an effective method for short-circuit current limitation. The specific measures include transmission line outage, transformer outage, etc. In this paper, a practical optimization algorithm of grid topology adjustment is put forward. A weighted comprehensive sensitivity index is adopted to speed up the procedure of adjustment strategy searching. The detailed calculation method of this index for different measure types is presented. And a security & economy assessment is implemented to ensure the feasibility of potential adjustment strategies. Moreover, the framework of an online topology adjustment decision support software based on this optimization algorithm is proposed. The effectiveness of the presented method is demonstrated by the test on a large-scale power system.


Mathematics ◽  
2021 ◽  
Vol 9 (13) ◽  
pp. 1474
Author(s):  
Ruben Tapia-Olvera ◽  
Francisco Beltran-Carbajal ◽  
Antonio Valderrabano-Gonzalez ◽  
Omar Aguilar-Mejia

This proposal is aimed to overcome the problem that arises when diverse regulation devices and controlling strategies are involved in electric power systems regulation design. When new devices are included in electric power system after the topology and regulation goals were defined, a new design stage is generally needed to obtain the desired outputs. Moreover, if the initial design is based on a linearized model around an equilibrium point, the new conditions might degrade the whole performance of the system. Our proposal demonstrates that the power system performance can be guaranteed with one design stage when an adequate adaptive scheme is updating some critic controllers’ gains. For large-scale power systems, this feature is illustrated with the use of time domain simulations, showing the dynamic behavior of the significant variables. The transient response is enhanced in terms of maximum overshoot and settling time. This is demonstrated using the deviation between the behavior of some important variables with StatCom, but without or with PSS. A B-Spline neural networks algorithm is used to define the best controllers’ gains to efficiently attenuate low frequency oscillations when a short circuit event is presented. This strategy avoids the parameters and power system model dependency; only a dataset of typical variable measurements is required to achieve the expected behavior. The inclusion of PSS and StatCom with positive interaction, enhances the dynamic performance of the system while illustrating the ability of the strategy in adding different controllers in only one design stage.


2013 ◽  
Vol 448-453 ◽  
pp. 1732-1737
Author(s):  
Liu Bin ◽  
Hong Wei Cui ◽  
Li Xu ◽  
Kun Wang ◽  
Zhu Zhan ◽  
...  

This paper analyses the characteristics of large-scale offshore wind farm collection network and the impact of the medium voltage collection system optimization,while from the electrical technology point,it proposes the short circuit current of the collection network computational model and algorithms,based on the principle of equivalent circuit.Taking a wind power coolection system planned for a certain offshore wind farm planning for example, the validity of the model and algorithm is verified.


2021 ◽  
Vol 54 (1) ◽  
pp. 147-154
Author(s):  
Issam Griche ◽  
Sabir Messalti ◽  
Kamel Saoudi

The uncertainty of wind power brings great challenges to large-scale wind power integration. The conventional integration of wind power is difficult to adapt the demand of power grid planning and operation. This paper proposes an instantaneous power control strategy for voltage improvement in power networks using wind turbine improving the dynamical response of power systems performances (voltage and transient stability) after fault. In which the proposed control algorithm based on a new advanced control strategy to control the injected wind power into power system. The efficiency of developed control strategy has been tested using IEEE 9 Bus. Simulation results have showed that the proposed method perform better to preserve optimal performances over wide range of disturbances for both considered scenarios studied short circuit and variable loads.


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