scholarly journals ANALYSIS OF SUBSYNCHRONOUS RESONANCE EFFECT IN SERIES COMPENSATED LINE WITH BOOSTER TRANSFORMER

2013 ◽  
pp. 59-63
Author(s):  
G.V. RAJASEKHAR ◽  
GVSSNS SARMA
Keyword(s):  
Resonance Effect ◽  
Power Networks ◽  
Turbine Generator ◽  
Subsynchronous Resonance ◽  
Three Phase ◽  
Electric Power Networks ◽  
In Series ◽  
Negative Damping ◽  
Series Capacitor Compensation ◽  
Series Capacitor

Series compensation has been successfully employed for many years in electric power networks. Series capacitor compensation has a tendency to act as a negative damping on torsional vibrations of nearby turbine generator units. However, their presence in the system may lead to the Sub-synchronous resonance (SSR) phenomenon especially for the nearby generating plants that have a direct or a near radial connection to series capacitor compensated line. In an attempt to analyze the SSR phenomenon, analysis has been done on Second Benchmark model system using both frequency analysis and eigenvalue techniques with three phase fault for different compensation levels. This analysis has been carried out using Matlab control system toolbox.

Subsynchronous Resonance and Torsional Effects on a Steam Turbine Generator in Transmission Systems With Series Capacitor Compensation

2012 ◽  
Author(s):  
K. R. Mutama ◽  
J. Seeliger ◽  
D. H. Baker ◽  
R. D’Aquila ◽  
B. Fitzgerald ◽  
...  
Keyword(s):  
Steam Turbine ◽  
Operating Conditions ◽  
Torsional Stress ◽  
Turbine Generator ◽  
Transmission Systems ◽  
Torsional Oscillations ◽  
Subsynchronous Resonance ◽  
Modeling Studies ◽  
Series Capacitor ◽  
Series Capacitors

Turbine-generators which connect to transmission systems with series capacitor compensated lines can experience problems with the torsional oscillations of the shaft interacting with the electrical oscillations of the series capacitors and transmission system inductance. This resonant interaction is called Subsynchronous Resonance (SSR) since it involves torsional and electrical oscillations which are below the synchronous operating frequency of the power system. The transmission lines near the Newmont TS Power Plant will soon have series capacitors installed. Modeling studies based on calculated torsional frequencies and estimated torsional damping showed that the turbine-generator could have instabilities of the torsional oscillations under some operating conditions. After the modeling studies were completed, actual tests on the steam turbine generator were conducted to measure the frequency and mechanical damping of the torsional oscillations. Field measurements validated modeling studies and showed the SSR risk may be higher than originally estimated. As a result of these investigations, a torsional stress relay is being installed to protect the unit from subsynchronous torsional effects of the series capacitors. The torsional stress relay will trip the unit if damaging torsional oscillations or torsional instabilities occur.

A New Approach for Investigation of the Turbine Generator Oscillatory Behavior Affecting Power System Quality and Reliability

2004 ◽  
Author(s):  
Rajiv Kumar ◽  
Michael Merkle ◽  
Thomas Leibfried
Keyword(s):  
Power System ◽  
Synchronous Generator ◽  
System Quality ◽  
Turbine Generator ◽  
Generator System ◽  
Rotor Shaft ◽  
Shaft System ◽  
Utility Companies ◽  
Series Capacitor Compensation ◽  
Series Capacitor

Transients following switching in the network and/or the tripping of generating unit auxiliaries can excite oscillatory torques on the turbine-generator-rotor-shaft system. The oscillations can be damped or amplified with time. Damped oscillations affect the power quality and if the oscillations grow with time they may even lead to generating unit outages (and damages) resulting in possible system instabilities. Deregulation of electricity markets has resulted in separation of Utility Companies (responsible for power generation) and Transmission Companies (responsible for power transmission). The decision making is no more under the same umbrella. Companies on both the sides have severe cost reduction focus and each side is tempted to make independent decision favourable to it. The Transmission Companies want to enhance transmission capacity of existing systems by introducing measures like series capacitor compensation. However incorporation of series capacitor compensation may under certain conditions lead to oscillations and also snbsynchronous resonance. Currently, there is an urgent need to establish a systematic methodology to investigate the root cause of such oscillations so that preventive measures can be taken by both the Utility Companies and the Transmission Companies. This paper is a contribution in this direction. In this work, comprehensive dynamic model of synchronous generator system has been developed in software Matlab/Simulink. Generating unit start up and ramp loading to rated load has been simulated to get deeper insight into the oscillatory behaviour of the synchronous generator. Block loading of the turbine generator and sudden load shedding due to auxiliary trip have been investigated in detail. Further, power system network with bus connected parallel generating units and parallel transmission lines, having different series capacitor compensation ratio have been simulated in power system software NETOMAC. Transient conditions have been modelled to investigate the oscillations and the consequent torsional torques and angles between adjacent masses of the rotor shaft system causing fatigue life reduction. This work has very clearly revealed the complex dynamic interrelationship among variables responsible for power system oscillations.

scholarly journals Numerical Analysis of a Spiral Tube Damping Busbar to Suppress VFTO in 1000 kV GIS

2019 ◽  
Vol 9 (23) ◽  
pp. 5076 ◽  
Author(s):  
Reem A. Almenweer ◽  
Yi-Xin Su ◽  
Wu Xixiu
Keyword(s):  
Structural Characteristics ◽  
Electrical Equipment ◽  
Power Networks ◽  
Spiral Tube ◽  
Electric Power Networks ◽  
In Series ◽  
Sf6 Discharge ◽  
Design Characteristics ◽  
Transmission And Distribution ◽  
Transient Overvoltage

Gas insulated substations (GISs) are broadly used for transmission and distribution in electric power networks. Very fast transient overvoltage (VFTO) caused by SF6 discharge during switching operations in a GIS may threaten the insulation of electrical equipment. In this paper, a novel VFTO suppression method with great prospects in engineering, called the spiral tube damping busbar, is proposed. The suppressing mechanism of the new method is analyzed. The structure and the design characteristics of the damping busbar are introduced as well. Moreover, a calculation method for the self-inductance of the damping busbar at high frequency is presented. According to the structural characteristics of the damping busbar, the inductance effect on suppressing VFTO is analyzed. A further improvement in damping VFTO is investigated by designing a spiral litz coil connected in series with the busbar, which increases the damping effect. The simulation results show that the improved damping busbar has a significant suppressing effect on the amplitude and the frequency of VFTO.

scholarly journals Distance Protection of Series Capacitor Compensated Lines: Practical Considerations, Industrial Status and Development

Electricity ◽  
2021 ◽  
Vol 2 (2) ◽  
pp. 168-186
Author(s):  
Md Tanbhir Hoq ◽  
Nathaniel Taylor
Keyword(s):  
Transmission Lines ◽  
Transmission Network ◽  
Distance Protection ◽  
Academic Literature ◽  
System Protection ◽  
The Status ◽  
In Series ◽  
Insight Into ◽  
Series Capacitor ◽  
Current Inversion

The introduction of series capacitors in transmission lines causes problems in terms of reliability and the security of distance protection relays. As distance protection is widely used in the transmission network, the challenge of applying it to series compensated lines has been taken up by utilities and relay manufacturers in various ways. In the field of power system protection, developments are largely driven by relay manufacturers, and are often not published in the academic literature; the status and trend of the relay manufacturer’s development are better found in their product manuals and patent activity. Further insight into specific implementations by transmission utilities can be found from publications in industry-led forums and some academic journals. This article surveys the status and development of distance protection for series compensated lines, with a focus on industrial implementation and practical considerations. Factors that influence the protection of series compensated lines are presented. Implementation examples reported by utilities are summarized as examples of the different situations encountered and the methods used to deal with them. It is observed that many utilities use communication-aided protection in series compensated lines, and distance protection is used with reduced reach. Solutions described in relay manuals are presented to demonstrate the manufacturers’ approaches to problems associated with series capacitor protection. While there are methods to counter voltage inversion, current inversion seems to represent a more serious challenge. A patent overview indicates the trends in this domain to be moving towards time-domain-based faster protection methods.

Sign in / Sign up

Export Citation Format

Share Document