Protection scheme for VSC-MTDC based on low-frequency reactive power

2022 ◽  
Vol 204 ◽  
pp. 107703
Author(s):  
Chuanjian Wu ◽  
Dahai Zhang ◽  
Jinghan He
Keyword(s):  
Reactive Power ◽  
Low Frequency ◽  
Protection Scheme

scholarly journals Low-Frequency Signal Sampling Method Implemented in a PLC Controller Dedicated to Applications in the Monitoring of Selected Electrical Devices

Electronics ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 442
Author(s):  
Marcin Jaraczewski ◽  
Ryszard Mielnik ◽  
Tomasz Gębarowski ◽  
Maciej Sułowicz
Keyword(s):  
Power System ◽  
Reactive Power ◽  
Low Frequency ◽  
Sampling Frequency ◽  
Electrical Signal ◽  
Distortion Factor ◽  
Electrical Devices ◽  
Frequency Sampling ◽  
Sampled Signal ◽  
Band Limited

High requirements for power systems, and hence for electrical devices used in industrial processes, make it necessary to ensure adequate power quality. The main parameters of the power system include the rms-values of the current, voltage, and active and reactive power consumed by the loads. In previous articles, the authors investigated the use of low-frequency sampling to measure these parameters of the power system, showing that the method can be easily implemented in simple microcontrollers and PLCs. This article discusses the methods of measuring electrical quantities by devices with low computational efficiency and low sampling frequency up to 1 kHz. It is not obvious that the signal of 50–500 Hz can be processed using the sampling frequency of fs = 47.619 Hz because it defies the Nyquist–Shannon sampling theorem. This theorem states that a reconstruction of a sampled signal is only guaranteed possible for a bandlimit fmax < fs, where fmax is the maximum frequency of a sampled signal. Therefore, theoretically, neither 50 nor 500 Hz can be identified by such a low-frequency sampling. Although, it turns out that if we have a longer period of a stable multi-harmonic signal, which is band-limited (from the bottom and top), it allows us to map this band to the lower frequencies, thus it is possible to use the lower sampling ratio and still get enough precise information of its harmonics and rms value. The use of aliasing for measurement purposes is not often used because it is considered a harmful phenomenon. In our work, it has been used for measurement purposes with good results. The main advantage of this new method is that it achieves a balance between PLC processing power (which is moderate or low) and accuracy in calculating the most important electrical signal indicators such as power, RMS value and sinusoidal-signal distortion factor (e.g., THD). It can be achieved despite an aliasing effect that causes different frequencies to become indistinguishable. The result of the research is a proposal of error reduction in the low-frequency measurement method implemented on compact PLCs. Laboratory tests carried out on a Mitsubishi FX5 compact PLC controller confirmed the correctness of the proposed method of reducing the measurement error.

scholarly journals Stator Inductance Identification Based on Low-Speed Tests for Three-Level NPC Inverter-Fed Induction Motor Drives

Electronics ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 183 ◽  
Author(s):  
Yerganat Khojakhan ◽  
Kyoung-Min Choo ◽  
Chung-Yuen Won
Keyword(s):  
Induction Motor ◽  
Reactive Power ◽  
Low Frequency ◽  
Test Drive ◽  
Identification Process ◽  
Low Speed ◽  
Speed Test ◽  
Simulation And Experiment ◽  
Sinusoidal Current ◽  
Stator Flux

This paper proposes a stator inductance identification process for three-level neutral point clamped (NPC), inverter-fed Induction Motor (IM) drives based on a low-speed test drive. Conventionally, the stator inductance of an IM is identified by methods based on standstill or rotational tests. Since conventional standstill test-based methods have several practical problems when used with three-level inverters because of their nonlinearity, an identification method based on rotational tests is superior in such applications. However, conventional rotational tests cause unintended behavior because of the high speeds used during the test. In the proposed stator inductance identification process, the stator inductance is identified based on a low-speed test drive. In the proposed method, the stator flux is estimated using the instantaneous reactive power of the IM during low-frequency sinusoidal current excitation, and the stator inductance is then identified based upon this. Therefore, the proposed identification process is safer than conventional approaches, as it uses only a low-speed test. The accuracy and reliability of this method are verified by simulation and experiment using three motors with different rated voltage and power.

Preliminary Study on the Influence of Wind Power on Low-Frequency Oscillation under Outward Transmitting Thermal Generated Power Bundled with Wind Power Typical Scene

2013 ◽  
Vol 391 ◽  
pp. 271-276
Author(s):  
Peng Li ◽  
Ning Bo Wang ◽  
De Zhi Chen ◽  
Xiao Rong Zhu ◽  
Yun Ting Song
Keyword(s):  
Power Systems ◽  
Power System ◽  
Wind Power ◽  
Wind Farm ◽  
Reactive Power ◽  
Simulation Analysis ◽  
Low Frequency ◽  
Simulation Software ◽  
Frequency Oscillation ◽  
Low Frequency Oscillation

Increasing penetration level of wind power integration has a significant impact on low-frequency oscillations of power systems. Based on PSD-BPA simulation software, time domain simulation analysis and eigenvalue analysis are employed to investigate its effect on power system low-frequency oscillation characteristic in an outward transmitting thermal generated power bundled with wind power illustrative power system. System damping enhances markedly and the risk of low-frequency oscillation reduce when the generation of wind farm increase. In addition, dynamic reactive power compensations apply to wind farm, and the simulation result indicates that it can improve dynamic stability and enhance the system damping.

scholarly journals Modified Voltage Control Law for Low Frequency Railway Power Systems

2017 ◽  
Author(s):  
John Laury ◽  
Lars Abrahamsson ◽  
Math Bollen
Keyword(s):  
Power Systems ◽  
Reactive Power ◽  
Low Frequency ◽  
Voltage Control ◽  
Load Sharing ◽  
Alternative Methods ◽  
Control Law ◽  
Public Power ◽  
Negative Impacts ◽  
Railway Power Systems

In today’s Swedish and Norwegian low frequency railway power system the voltage at a converter is controlled such that its voltage will drop with increased reactive power output. However, for low frequency railways the influence of active power on voltage is larger compared to public power systems and alternative methods are interesting to investigate. This paper presents a modified voltage control law for increased load sharing between converter stations and reduce the risk for converter overload in low frequency railways power systems. The modified voltage control law is derived mathematically and tested with different droops for two case studies. The results confirms the increased load sharing between the converter stations. The results are analysed and discussed; ideas are presented to counteract some of the negative impacts of the modified voltage control law.

scholarly journals Research on improving low frequency oscillation characteristics of wind power system with DFIG-PSS-VI

2021 ◽  
Vol 252 ◽  
pp. 02001
Author(s):  
Ping He ◽  
Mingming Zheng ◽  
Zhao Li ◽  
Qiyuan Fang ◽  
Xiaopeng Wu
Keyword(s):  
Power System ◽  
Wind Power ◽  
Reactive Power ◽  
Low Frequency ◽  
Step Response ◽  
Frequency Oscillation ◽  
Low Frequency Oscillation ◽  
New Energy ◽  
Wind Power System ◽  
Virtual Impedance

The new energy represented by strong random wind power connecting to the power system may make the problem of inter-area low-frequency oscillation more serious. In this paper, a DFIG-PSS controller based on virtual impedance is constructed to solve the low-frequency oscillation problem in the wind power system. The step response of PSS-VI was carried out to test the effect of the controller to verify the advantages of PSS-VI than traditional PSS. The input signal of PSS-VI which is a controller based on PSS installed virtual impedance is the active power of DFIG. The output signal of PSS-VI is added to the reactive power control loop of rotor side controller of DFIG. DFIG-PSS-VI was built in Digsilent/Powerfactory software, and the simulation was carried out on the system of 4 machines and 2 regions. It is verified that PSS-VI can improve the low-frequency oscillation of wind power system.

scholarly journals Protection Scheme using RPI Concept in STATCOM Compensated EHV System

2019 ◽  
Vol 8 (9) ◽  
pp. 2730-2733
Keyword(s):  
Reactive Power ◽  
Phase 1 ◽  
Research Work ◽  
Fault Classification ◽  
Fault Identification ◽  
Test Cases ◽  
Static Synchronous Compensator ◽  
Protection Scheme ◽  
Fault Resistance ◽  
Parameter Scheme

This research work present a protection scheme for fault detection and fault classification in EHV with static synchronous compensator (STATCOM) using Regulated Power index (RPI) concept. RPI per phase is defined as the ratio of the sum of sending end apparent power and receiving end apparent power to the apparent power at receiving end for that phase [1]. STATCOM is used for reactive power compensation and regulates the system voltage by absorbing and generating reactive power. As per the requirement of system parameter scheme is developed for the detection of fault, identification of faulty phase and tripping the faulty phase. This scheme will be validated by considering various fault test cases considering severe fault conditions with very low resistance, high fault resistance conditions and internal faults with static synchronous compensator (STATCOM) at sending end on the MATLAB model of transmission system at 220 KV level.

scholarly journals An Optimal Load Disaggregation Method Based on Power Consumption Pattern for Low Sampling Data

2019 ◽  
Vol 11 (1) ◽  
pp. 251 ◽  
Author(s):  
Huijuan Wang ◽  
Wenrong Yang ◽  
Tingyu Chen ◽  
Qingxin Yang
Keyword(s):  
Power Consumption ◽  
Optimization Model ◽  
Smart Grids ◽  
Large Scale ◽  
Reactive Power ◽  
Low Frequency ◽  
Performance Comparison ◽  
Consumption Pattern ◽  
Frequency Data ◽  
Load Disaggregation

In recent years, Smart Grids have been developing globally. Since smart meters only acquire low-frequency data, non-intrusive load monitoring technology using the signature extracted from high-frequency data needs an additional measurement device to be installed, so it is not suitable for promotion to the smart grid environment. However, methods using low-frequency features are poorly-suited when several appliances are switched on at the same time, or devices with similar power values are used. In response to these problems, this paper proposes a load disaggregation method based on the power consumption patterns of appliances, combining an improved mathematical optimization model and optimized bird swarm algorithm (OBSA) for load disaggregation. Experiments show that the method can effectively identify the operating states of appliances, and deal with situations in which multiple instruments have similar power characteristics or are simultaneously switching. The performance comparison proves that the improved model is more efficient than the traditional active and reactive power (PQ) optimization model in load disaggregation performance and computation time, and also verifies the robustness of the proposed method and the convergence of OBSA. As an inexpensive method without extra measurement hardware installed, the process is suitable for large-scale applications in smart grids.

Loss Of Excitation (LOE) Protection of Synchronous Generator

2017 ◽  
Vol 8 (1) ◽  
pp. 230 ◽  
Author(s):  
Hui Hwang Goh ◽  
Sy yi Sim ◽  
Mohd. Nasri Abd Samat ◽  
Ahmad Mahmoud Mohamed ◽  
Chin Wan Ling ◽  
...  
Keyword(s):  
Reactive Power ◽  
Harmful Effect ◽  
Synchronous Generator ◽  
Synchronous Generators ◽  
Financial Cost ◽  
New Techniques ◽  
Power Generator ◽  
Grid Systems ◽  
Protection Scheme ◽  
Power Swing

<p>Synchronous generators require certain protection against loss of excitation because it can lead to harmful effect to a generator and main grid. Systems of powers are evolving with applications of new techniques to increase reliability and security, at the meantime techniques upgradation is being existed to save financial cost of a different component of power system, which affect protection ways this report discuss the way of loss of excitation protection scheme for an increase in a synchronous generator. It is obvious that when direct axis synchronous reactance has a high value, the coordination among loss of excitation protection and excitation control is not effective. This lead to restricting absorption capability of the reactive power generator. This report also reviews the suitable philosophy for setting the limiters of excitation and discusses its effect on loss of excitation protection and system performance. A protection scheme is developed to allow for utilization of machine capability and power swing blocking is developed to increase the reliability when power swing is stable.</p><p><em> </em></p>

scholarly journals Effect of Reactive Power Characteristic of Offshore Wind Power Plant on Low-Frequency Stability

2020 ◽  
Vol 35 (2) ◽  
pp. 837-853 ◽  
Author(s):  
Weihua Zhou ◽  
Yanbo Wang ◽  
Raymundo E. Torres-Olguin ◽  
Zhe Chen
Keyword(s):  
Power Plant ◽  
Wind Power ◽  
Reactive Power ◽  
Low Frequency ◽  
Frequency Stability ◽  
Offshore Wind ◽  
Wind Power Plant ◽  
Power Characteristic ◽  
Offshore Wind Power
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