scholarly journals Enhanced Efficient EMT-Type Model of the MMCs Based on Arm Equivalence

2020 ◽  
Vol 10 (23) ◽  
pp. 8421
Author(s):  
Xiaodong Li ◽  
Zheng Xu
Keyword(s):  
Power Systems ◽  
Computer Aided Design ◽  
Large Scale ◽  
Type Model ◽  
Computationally Efficient ◽  
Simulation Accuracy ◽  
Electromagnetic Transient ◽  
Hvdc System ◽  
Average Value ◽  
Simulation Speed

The large number of switching elements in modular multilevel converters (MMCs) contribute a tremendous computational burden for electromagnetic transient (EMT) simulation programs. Detailed equivalent models (DEMs) and average value model (AVMs) are currently two major types of accurate and efficient model. However, the DEMs are still computationally inefficient for the simulation scenarios in large-scale MMC based high-voltage direct current (MMC-HVDC) grids, as the models represent all submodule (SMs) switching events, and memorize all individual capacitor voltages. Though the AVMs provide a faster simulation speed by using a single equivalent capacitor on the DC side, they have a relatively low simulation accuracy compared to DEMs, especially under blocked mode. This paper proposes an enhanced computationally efficient model based on arm equivalence (AEM), which can accurately represent the dynamic behaviors in both de-blocked and blocked modes. Compared to the DEMs, the proposed AEM is more efficient, with no loss of accuracy, and the simulation speed is irrespective of the SM number. The accuracy and computational efficiency of the proposed model were validated against the DEM and AVM through several simulation scenarios in a two-terminal MMC-HVDC system on the power systems computer aided design/ electromagnetic transient in DC system (PSCAD/EMTDC) program.

Combined Simulation Based Commutation Failure Analysis in HVDC Systems

2011 ◽  
Vol 383-390 ◽  
pp. 1279-1284
Author(s):  
Wen Bin Ci ◽  
Yu Tian Liu
Keyword(s):  
Power Systems ◽  
Large Scale ◽  
Simulation Method ◽  
Critical Voltage ◽  
Simulation Accuracy ◽  
Electromagnetic Transient ◽  
Simulation Efficiency ◽  
Simulation Based ◽  
Commutation Failure ◽  
Combined Simulation

Commutation failures may lead to serious consequences such as DC blocks. A simulation method of joint using the electromagnetic transient program and the electromechanical transient program is presented to analyze commutation failures. This method is realized in two steps. Firstly, the commutation failure critical voltage under a certain operating condition is determined with PSCAD/EMTDC. Secondly, this critical voltage is used in PSS/E, an electromechanical transient program, to analyze commutation failures of AC-DC systems. Using the proposed method, the effect of AC faults on commutation failures of a practical DC link in China is analyzed. Voltage contours is also utilized to improve the visualization of commutation failures. The combined simulation method, which gives consideration to both the simulation accuracy and the simulation efficiency, is beneficial to better analyze commutation failures of large-scale power systems.

Electromagnetic - Electromechanical Transient Hybrid Simulation of Deyang-Baoji HVDC System Based on ADPSS

2013 ◽  
Vol 805-806 ◽  
pp. 935-940
Author(s):  
Fan Tang ◽  
Guo Liang Su ◽  
Dong Xiang Li ◽  
Yu Hong Wang
Keyword(s):  
Large Scale ◽  
Hybrid Simulation ◽  
Simulation Software ◽  
Transient Simulation ◽  
Power System Simulation ◽  
Electromagnetic Transient ◽  
Hvdc System ◽  
Simulation Speed ◽  
Electromagnetic Transient Simulation ◽  
Scale Grid

three kinds of digital programs used in power system simulation are summarized in this paper. The electromagnetic and electromechanical transient simulation software ADPSS is introduced. Electromagnetic transient simulation, electromechanical transient simulation and electromagnetic-electromechanical transient hybrid simulation are performed respectively on Deyang-Baoji ±500KV HVDC system. The simulation result shows that the electromagnetic-electromechanical transient hybrid simulation has the advantage of electromagnetic transient simulation and electromechanical transient simulation. It can effectively analyze the process of the local electromagnetic transient in large-scale grid. The simulation speed is fast and the result is accurate and reliable.

scholarly journals Design and Dynamic Modelling of PV-Battery Hybrid Systems for Custom Electromagnetic Transient Simulation

Electronics ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 1651 ◽  
Author(s):  
Seok-Il Go ◽  
Joon-Ho Choi
Keyword(s):  
Power Systems ◽  
Hybrid Systems ◽  
Hybrid System ◽  
Computer Aided Design ◽  
Control Method ◽  
Dynamic Modelling ◽  
Transient Simulation ◽  
Electromagnetic Transients ◽  
Electromagnetic Transient ◽  
Electromagnetic Transient Simulation

Battery energy storage systems (BESS) can alleviate the unstable effects of intermittent renewable energy systems, such as solar and wind power systems. In addition, a BESS can level the load of the existing utility grid. The penetration rate of this type of system is expected to increase in the future power grid, i.e., the microgrid. In this paper, a modeling technique is proposed that allows users to customize the photovoltaic (PV) battery hybrid systems. A dynamic power system computer-aided design/electromagnetic transients including DC system (PSCAD/EMTDC) model of a PV battery hybrid system is presented in this paper. Dynamic modeling of PV arrays, BESS, maximum power point tracking (MPPT) algorithms, and bidirectional converters are provided as well. The PV model, battery model, and MPPT control model are designed using a user-defined model (UDM) for custom electromagnetic transient simulation. A control method for stabilizing the output of the PV battery hybrid system is proposed. Finally, a PSCAD/EMTDC simulation is conducted to verify the effectiveness of the operating algorithm.

Hybrid electromechanical-electromagnetic simulation to SVC controller based on ADPSS platform

2014 ◽  
Vol 25 (4) ◽  
pp. 112-122 ◽  
Author(s):  
Lin Xu ◽  
Yong-Hong Tang ◽  
Wei Pu ◽  
Yang Han
Keyword(s):  
Power Systems ◽  
Large Scale ◽  
Power Grid ◽  
Dynamic Performance ◽  
Electromagnetic Simulation ◽  
Hybrid Power Systems ◽  
Transient Model ◽  
Electromagnetic Transient ◽  
Time Simulation ◽  
And Control

To test the dynamic performance and damping features of a static var compensator (SVC) controller accurately in large-scale interconnected AC/DC hybrid power systems, it is of vital significance to build the detailed electromagnetic transient model. However, it is unrealistic and time-consuming to build the detailed models of all the devices in the actual large-scale power grid. Utilizing the hybrid simulation function in the advanced digital power system simulator (ADPSS) and by dividing the large-scale power grid into the electromagnetic transient sub-grids and electromechanical sub-grids, the computation speed of real-time simulation is remarkably enhanced by the parallel computational capabilities of digital simulator. The SVC controller and the nearby substation are modelled in the electromagnetic transient sub-grid, and the residue sub-networks are modelled in the electromechanical sub-grid. This paper focuses on the mechanism of the hybrid electromechanical and electromagnetic simulation, the detailed modelling and the ADPSS-based digital closed-loop test methodologies of the SVC controller. Eventually, the validity and effectiveness of the modelling and control methods are confirmed by the experimental results.

scholarly journals Simulation and Characteristics Analysis of Multiple Wind Generators in Large-Scale Wind Farms Based on Simplified Model

Electronics ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 1994
Author(s):  
Jing Wang ◽  
Guopeng Zhao
Keyword(s):  
Large Scale ◽  
Wind Farms ◽  
Simulation Models ◽  
Generator System ◽  
Transient Model ◽  
Electromagnetic Transient ◽  
Wind Generator ◽  
Wind Generators ◽  
Simulation Speed ◽  
Output Characteristics

In the view of the high complexity and a large amount of data of the electromagnetic transient model for the single wind generator, it is difficult to realize the multi-unit simulation modeling of large-scale wind farms by power system simulation software. In this paper, the simplified models of single direct drive and doubly-fed wind generator system are proposed, respectively. In order to study the output characteristics of the wind generator system, the components with small inertia constant in the electromagnetic transient model are neglected, and the shafting model, the converter model, and the control loops are simplified and reduced, respectively. Based on the study of the single electromagnetic transient model of wind generators, the simplified simulation models are built by the PSCAD (Power Systems Computer Aided Design) simulation platform, which are carried out under the conditions of constant wind speed, step wind speed, and fault. The output characteristics of the simplified models under different working conditions are compared in detail models. The simulation results show that, within the allowable calculation accuracy range, the dynamic response curves of the single simplified model and the electromagnetic transient model are consistent. The simulation speed can be significantly improved, the time consumption can be reduced, and the simulation speed can be increased more obviously when the number of simulation models increases. Therefore, it can be applied to the simulation research of multi-wind generators in large-scale wind farms.

Cloud-Based Multimedia Content Protection System

2020 ◽  
pp. 164-169
Author(s):  
B. Aparna ◽  
S. Madhavi ◽  
G. Mounika ◽  
P. Avinash ◽  
S. Chakravarthi
Keyword(s):  
Large Scale ◽  
Protection System ◽  
Multimedia Content ◽  
Computationally Efficient ◽  
Content Protection ◽  
Protection Systems ◽  
Multimedia Content Protection ◽  
High Scalability ◽  
Cloud Infrastructures ◽  
Rapid Deployment

We propose a new design for large-scale multimedia content protection systems. Our design leverages cloud infrastructures to provide cost efficiency, rapid deployment, scalability, and elasticity to accommodate varying workloads. The proposed system can be used to protect different multimedia content types, including videos, images, audio clips, songs, and music clips. The system can be deployed on private and/or public clouds. Our system has two novel components: (i) method to create signatures of videos, and (ii) distributed matching engine for multimedia objects. The signature method creates robust and representative signatures of videos that capture the depth signals in these videos and it is computationally efficient to compute and compare as well as it requires small storage. The distributed matching engine achieves high scalability and it is designed to support different multimedia objects. We implemented the proposed system and deployed it on two clouds: Amazon cloud and our private cloud. Our experiments with more than 11,000 videos and 1 million images show the high accuracy and scalability of the proposed system. In addition, we compared our system to the protection system used by YouTube and our results show that the YouTube protection system fails to detect most copies of videos, while our system detects more than 98% of them.

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