Analysis of distance protection’s operation in cases of deep saturation of current transformers

There is usually no information about permissible error of current transformers in modes succeed by large relative short-circuit current, at which microprocessor-based protections operate stably. By this reason, it is necessary to use data, defined for analog relays. It leads to value appreciation of a project because it is often essential to reduce current transformers’ error in case of a short circuit fault. Therefore, it is necessary to define the value of current transformers’ error, permitted for impedance relays. Conclusions of fundamental and applied sciences (mathematical analysis, theoretical foundations of electrical engineering, theory of simulation), analytical methods of researching nonlinear circuits and digital signal processing were used. A simulation model was created for setting overall tests of the current trans-former (CT) system. It was a relay protection device that reflected all the important properties of studied objects and allowed an analysis of digital distance protection’s operation at high levels of short-circuit currents. The factors influ-encing over digital distance protection’s operation in case of deep saturation of CTs were revealed, and a certain algorithm for definition of the permissible CT errors was proposed. Stable operation of digital distance protection was observed in case of a fault nearby the place of current transformers’ setting in all theoretically possible combinations of electrical system’s power and length of a protected electric power transmission line. It is valid if electric load choice is carried with account for stable protection’s operation in condition of a fault in the computational point and if voltage swell in secondary wirings is infeasible.

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Power Plant Station Protection System against Voltage Fluctuation

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.793.65 ◽

2015 ◽

Vol 793 ◽

pp. 65-69 ◽

Cited By ~ 2

Author(s):

Abadal Salam T. Hussain ◽

Waleed A. Oraibi ◽

Fadhel A. Jumaa ◽

F. Malek ◽

Syed F. Ahmed ◽

...

Keyword(s):

Power Plant ◽

Power System ◽

Short Circuit ◽

Electrical Power ◽

Circuit Breaker ◽

Digital Signal ◽

Short Circuit Current ◽

Electrical Power System ◽

System Protection ◽

Protective Relay

Electrical Power System protection is required to protectboth the user and the system equipment itself fromany fault, hence electrical power system is not allowed to operate without any protection devices installed. Power System fault is defined as the undesirable condition that occurs in the power system. Some of these undesirable conditions are short circuit, current leakage, ground faultand over-under voltage. With the increasing loads, voltages and short-circuit duty in power plant, over voltage protection has become more important today. Here, the component that had been used is PIC 16F877a microcontroller to control the whole system and especially on the circuit breakers as well as the LCT display unit is used to display the voltage level and type of generator that used to serve the load. Sensors are used to measure both thevoltage and the load. The controlled digital signal from PIC microcontroller is converted by using the digital analog converter to control the whole circuit. Thus a device called protective relay is created to meet this requirement. The protective relay is mostlyoften coupled with circuit breaker in a way that it can isolate the abnormal condition in the system.

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Calculation and Analysis of Three-Phase Transformer Short-Circuit Current

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.986-987.1914 ◽

2014 ◽

Vol 986-987 ◽

pp. 1914-1917

Author(s):

Pei Ming Pan ◽

Huan Lian ◽

Fei Xiang Hui ◽

Wei Pu Tan

Keyword(s):

Short Circuit ◽

Short Circuit Current ◽

Stable Operation ◽

Application Range ◽

Three Phase ◽

Different Types ◽

Calculation Results ◽

Current Calculation ◽

Important Significance ◽

Selection Of

Analysis the important significance of transformer short-circuit current calculation for the stable operation of power system. Lead to three different types of transformer short-circuit current calculation methods, this literature uses a simplified example to compare the characters among three methods. Meanwhile, calculation by using the theory to get a quantitative range of simplified method. The calculation results and theory support each other, finally, summarizing the application range of the three methods, and offering a reference for reasonable selection of short-circuit current methods.

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Review on Short-circuit Current Analysis and Suppression Techniques for MMC-HVDC Transmission Systems

Applied Sciences ◽

10.3390/app10196769 ◽

2020 ◽

Vol 10 (19) ◽

pp. 6769

Author(s):

Boyu Qin ◽

Wansong Liu ◽

Ruowei Zhang ◽

Jialing Liu ◽

Hengyi Li

Keyword(s):

Direct Current ◽

Short Circuit ◽

Short Circuit Current ◽

Power Grids ◽

Stable Operation ◽

Current Analysis ◽

Transmission Systems ◽

Hvdc Transmission ◽

Dc Power ◽

Short Circuit Calculation

The modular multilevel converter (MMC) has been widely adopted in high voltage direct current (HVDC) transmission systems due to its significant advantages. MMC-HVDC is developing towards multi-terminal direct current (MTDC) power grid for reliability enhancement. However, there exist a huge amplitude and a steep rise in fault current due to the low impedances of DC lines and MMCs, which threaten the security and reliability of the DC power grids. It is necessary to restrain the DC short circuit current in order to ensure the safe and stable operation of DC power grids. This paper gives a comprehensive review and evaluation of the proposed DC short-circuit current analysis and suppression techniques used in MMC-based MTDC power girds, in terms of MMC modeling, short circuit calculation, and suppression method. In addition, future trends of countermeasures to short circuit current in MMC-based MTDC power grids are also discussed.

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Improvement of Stable Operation Ability for Large-Scale Wind Power System Based on VSC-HVDC Technology

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.599-601.960 ◽

2014 ◽

Vol 599-601 ◽

pp. 960-963

Author(s):

Cheng Cheng Rao ◽

Hai Yun Wang ◽

Wei Qing Wang

Keyword(s):

Large Scale ◽

Wind Farm ◽

Power Transmission ◽

Short Circuit ◽

Current Control ◽

Stable Operation ◽

Hvdc System ◽

Control Scheme ◽

Wind Power System ◽

Doubly Fed

Rigorous transmission technology is important when large-scale wind farm is connected to the power grid. Hence, a power transmission topological framework based on VSC-HVDC is proposed. The mathematical model is built in the dq synchronous frame, and the related direct current control strategy of VSC converters are designed. The doubly fed induction generator wind farm with VSC-HVDC system are modelled in DIgSILENT/PowerFactory. Ultimately, the conditions of the short-circuit fault at the receiving-end VSC AC bus is simulated. The control scheme is proved to be effective.

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Study on Power Transmission Plan of the Nuclear Power Base in Shandong Peninsula

Volume 2: Smart Grids, Grid Stability, and Offsite and Emergency Power; Advanced and Next Generation Reactors, Fusion Technology; Safety, Security, and Cyber Security; Codes, Standards, Conformity Assessment, Licensing, and Regulatory Issues ◽

10.1115/icone24-60645 ◽

2016 ◽

Author(s):

Chengzhu Yin ◽

Miao Wang

Keyword(s):

Power Plant ◽

Nuclear Power ◽

Large Scale ◽

Power Transmission ◽

Short Circuit ◽

Power Grid ◽

Short Circuit Current ◽

Jiaodong Peninsula ◽

Power Load ◽

Power Base

The nuclear power site resource is very rich in Jiaodong Peninsula of Shandong Province. It is suitable for construction of the large nuclear power base. The transmission scope and direction of Jiaodong Peninsula nuclear power base is analyzed, and optional transmission plans of Plant 1, Plant 2, Plant 3 and Plant 4 are proposed. The transmission plans are recommended based on technical and economic comparison, which provide good references for construction of the large-scale nuclear power base and power grid development planning. Jiaodong Peninsula nuclear power base is planned to be built in the year of 2016–2030, planning capacity of which is 30500MW. The site of nuclear power base is 100∼400km away from the power load center. The nuclear power will use AC transmission and mainly meet the demand of local power load. The early 15500MW gensets will be accessed to the power grid at 500kV, as the following 15000MW gensets will be accessed at 1000kV UHV (Ultra-high voltage) grid. As the accessing of many large-capacity gensets will produce huge impact to the short-circuit current, sectionalized double-bus configuration is recommended in the 500kV main electrical wiring to reduce the short-circuit current of 500kV bus of nuclear power plant. Double bus section cross wire connection is presented to make sure that every two generators on each bus will be connected to different substations on two transmission lines which are set up on different poles and in different paths, to improve the reliability of the power plant. Through analysis and provement, the construction of large nuclear power base must be based on large and stronge power grid, especially the UHV (Ultra-high voltage) AC grid, to meet the demand of huge nuclear power transmission, and to improve the ability of power exchange and ensure the safety of regional power supply. Also, as the nuclear power plant should better be in base-load operation, the construction of large-scale nuclear power base, would make the system load-control demands increase, which leads to more prominent problems. In order to avoid adding additional depth of peaking power operation and reducing the overall economic operation of power system, power grid should have the necessary means to load-control. Namely the construction of peaking units, such as pumped storage units or gas-fired units at about 5000MW. By analyzing and demonstration, large-scale nuclear power base must rely on large-scale power grid, particularly the support of UHV power grid in order to meet the demond of large-scale power transmission and electricity exchange, and also to ensure regional security of electricity supply.

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Research on Short-Circuit Current of Wind Power System and its Impact on Relay Protection

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1070-1072.258 ◽

2014 ◽

Vol 1070-1072 ◽

pp. 258-263

Author(s):

Hua Bo Shi ◽

Zhi Chen ◽

Gan Li ◽

Bo Zhou

Keyword(s):

Power System ◽

Wind Power ◽

Short Circuit ◽

Relay Protection ◽

Short Circuit Current ◽

Green Energy ◽

Stable Operation ◽

Technical Problems ◽

Wind Power System ◽

The Impact

Wind energy is clean and renewable energy with rich resources. As one of the most promising green energy, wind power has become an important part of the electricity supply. But there are still many technical problems to be solved related to wind power generation and integration, because it may have significant impact on safe and stable operation of the power grid. Therefore, the doubly-fed wind generator and direct-driven permanent-magnet wind power generator are studied. Their models are built in PSCAD/EMTDC for electromagnetic transient simulation, in order to study the characteristics of their short circuit fault current, as well as the impact on the relay protection of the wind power system. The research outcomes provide a reference and basis to wind power failure characteristics research.

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Thermal Stability of Overhead Power Transmission Lines Under Growing Short-Circuit Current Levels

Power Technology and Engineering ◽

10.1007/s10749-018-0960-y ◽

2018 ◽

Vol 52 (3) ◽

pp. 361-365

Author(s):

O. Yu. Gusev ◽

A. P. Dolin

Keyword(s):

Thermal Stability ◽

Transmission Lines ◽

Power Transmission ◽

Short Circuit ◽

Short Circuit Current ◽

Power Transmission Lines ◽

Overhead Power Transmission Lines ◽

Thermal Stability Of

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Reducing Short Circuit Level in 400 kV Iraqi Grid System by Using FACTS Device

Iraqi Journal of Computer Communication Control and System Engineering ◽

10.33103/uot.ijccce.19.2.10 ◽

2019 ◽

pp. 90-99

Keyword(s):

Power Systems ◽

Transmission Lines ◽

Power Transmission ◽

Short Circuit ◽

Electrical Power ◽

Short Circuit Current ◽

Power Grids ◽

Power Transmission Lines ◽

Power Stations ◽

Flexible Alternating Current Transmission

Electrical power systems are different in their sizes because of their amount of generation power stations, substations, transmission lines and loads. Therefore, these factors may impact on short circuit levels values. Capacity of power stations and dummy transmission lines in Extra high voltage grid (400kV) of the Iraqi Electrical power grids cause high short circuit levels values such that exceed both rating of the peak and breaking capacity of switchgear equipment's. Reduction of short-circuit levels by using Fast-acting Flexible Alternating Current Transmission Systems (FACTS) types devices in power grids maintain the operation of power grids with acceptable value of short circuit levels for their electrical equipment's and preventing cascading event outages which may lead to blackouts. This paper mainly studies strategies on how to add Short Circuit Current Limiter (SCCL) device by determining its number, value and location of connection in power grids by programing with (PSS™E version 30.3 Package Program). IEEE 25-bus system is used for testing the adding series SCCL at power transmission lines method procedure. The results of adding series SCCL with power transmission lines give significant reducing short circuit levels for the stations have highest short circuit levels in order to prevent the blackouts of overall power grid.

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Multi-Walled Carbon Nanotube-Assisted Encapsulation Approach for Stable Perovskite Solar Cells

Molecules ◽

10.3390/molecules26165060 ◽

2021 ◽

Vol 26 (16) ◽

pp. 5060

Author(s):

Jin-Myung Choi ◽

Hiroki Suko ◽

Kyusun Kim ◽

Jiye Han ◽

Sangsu Lee ◽

...

Keyword(s):

Solar Cells ◽

Carbon Nanotube ◽

High Performance ◽

Short Circuit ◽

Perovskite Solar Cells ◽

Short Circuit Current ◽

Open Circuit ◽

Stable Operation ◽

Cover Glass ◽

Multi Walled Carbon Nanotube

Perovskite solar cells (PSCs) are regarded as the next-generation thin-film energy harvester, owing to their high performance. However, there is a lack of studies on their encapsulation technology, which is critical for resolving their shortcomings, such as their degradation by oxygen and moisture. It is determined that the moisture intrusion and the heat trapped within the encapsulating cover glass of PSCs influenced the operating stability of the devices. Therefore, we improved the moisture and oxygen barrier ability and heat releasing capability in the passivation of PSCs by adding multi-walled carbon nanotubes to the epoxy resin used for encapsulation. The 0.5 wt% of carbon nanotube-added resin-based encapsulated PSCs exhibited a more stable operation with a ca. 30% efficiency decrease compared to the ca. 63% decrease in the reference devices over one week under continuous operation. Specifically, the short-circuit current density and the fill factor, which are affected by moisture and oxygen-driven degradation, as well as the open-circuit voltage, which is affected by thermal damage, were higher for the multi-walled carbon nanotube-added encapsulated devices than the control devices, after the stability test.

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