The resonance frequency depends on the degree of line com pensation and typically ranges be tween 10 and 45 hz. Therefore the subsynchronous whirl shown in figure 1 is at a whirl frequency ratio of 15th the synchronous, or 0. Yet it may well be that other frequencies interfere with this process and become problematic if not dealt with properly. However, a factor hindering the extensive use of seriescapacitive compensation is the. This is called subsynchronous resonance, which can cause shaft fatigue and possible damage or failure. Design of subsynchronous resonance protection and reduction of torsional interaction in power systems mahdi hedayati department of electrical engineering azad university, gonabad branch gonabad, iran abstractan ssr problem has been noticed and caused repeated triggering of the protection. If resonance frequency is close to a natural frequency. Impacts of subsynchronous and supersynchronous frequency components on synchrophasor measurements hao liu1, tianshu bi1, xiqiang chang2, xiaolong guo2, lu wang1, chuang cao1, qing yan2, jinsong li3 abstract phasor measurement units pmu are playing an. Boukarim, subsynchronous resonance studies and mi tigation methods for series capa citor applications, ieee 2005. Fluxes at these frequencies will induce voltages with corresponding frequencies that will result in.
The effect of wind turbines on subsynchronous resonance. Primer to subsynchronous resonance subsynchronous resonance is the phenomenon where the energy exchange occurs between the mechanical system of turbine generator and network at one or more frequencies below the synchronous frequency. Problem was cured by reducing compensation percentage and installing a torsional relay. Elmarsafawy, use of frequency scan techniques for subsynchronous resonance analysis of. This paper analyses the implications of the ssr and consequential increase of the frequency. The eigenvalue analysis is used to identify frequencies of subsynchronous oscillations as well as the damping of each frequency from state space model of the entire system 1. Diagnostics of subsynchronous vibrations in rotating machinery methodologies to identify potential instability. Analysis of subsynchronous resonance characteristics and. Apr 27, 2015 subsynchronous resonance is an electric power system condition where the electric network exchanges energy with a turbine at one or more of the natural fequencies of the combined system below the synchronous frequency of the system. Addressing subsynchronous resonance nprr562 overview.
Pdf frequency scanning techniques for subsynchronous. Sub synchronous resonance damping in interconnected power. New line shaft bushings were designed that would increase the effective stiffness and damping from the bushings. Pdf on may 4, 2016, hardik parikh and others published frequency scanning techniques for subsynchronous resonance screening analysis find, read and cite all. Subsynchronous resonance accessscience from mcgrawhill. The rotor frequency at this speed is called as subsynchronous frequency. Increase of the current frequency can be initiated by the subsynchronous resonance phenomenon ssr. Forces acting on a rotor the nonsynchronous orbit may or may not be larger than. Resonance in the line may create sub synchronous frequency or super synchronous frequency which leads to fatigue in the turbine generator shaft system. The ngh subsynchronous resonance ssr damping scheme designed to damp subsynchronous currents in the transmission lines and to protect the generating machines from subsynchronous resonance was. The resonance between a seriescapacitorcompensated electric system and the mechanical springmass system of a turbinegenerator at subsynchronous frequencies, that is, at frequencies that are less than the synchronous frequency. Analysis and mitigation of subsynchronous resonance in a.
If the magnitude of the equivalent rotor resistance exceeds the sum of the resistances of the armature and the network, there will be a negative resistance at the subsynchronous frequency, and the subsynchronous current will increase with time. Subsynchronous resonance risk assessment in interconnected. The definition includes any system condition that provides the opportunity for an exchange of energy. A comparison of different frequency scanning methods for study of subsynchronous resonance. The consequence for the reactor coolant pumps is increased flow in primary coolant system.
What is sub synchronous resonance in a power system. Other readers will always be interested in your opinion of the books youve read. Ssr is a resonant condition where the generator system exchanges energy with the connecting electrical system below the subsynchronous frequency. Subsynchronous resonance mitigation for seriescompensated. Sub synchronous resonance ssr is a condition that can exist on a power system where the network has natural frequencies that fall below the fundamental frequency of the generated voltages and produce subsynchronous oscillation of the steam turbine and generator shaft. Comparison of subsynchronous resonance ssr analysis methods. Electric power frequency and nuclear safety subsynchronous. Subsynchronous resonance ssr has gained its name from the fact that the frequencies of interest happen to lie in a region below the synchronous frequency of the network. Whenever the load on an alternator is increased, the rotor speed slightly decreases, this speed is called as subsynchronous speed. Bhavik prajapati, vadodaragujarat,india abstractssr basically an electrical power system condition where electrical network exchange energy with the turbine generator at one or more natural. Damping of torsional oscillations a dissertation submitted to the graduate faculty in partial fulfillment of the requirements for the degree of doctor of philosophy major. Pdf on may 4, 2016, hardik parikh and others published frequency scanning techniques for subsynchronous resonance screening analysis find, read and cite all the research you need on researchgate.
Under such circumstances, the shaft will oscillate at this natural frequency. Ferroresonance and subsynchronous resonance can arise in power system circuits when capacitance is connected in series and less commonly when connected in parallel with nonlinear inductive circuits such as transformers and reactors and when the voltage is sufficient to drive the nonlinear inductance to near the knee point of the bh curve. At oscillations the generator will be exposed to frequencies both below subsynchronous and above supersynchronous the nominal frequency. Mar 21, 2011 subsynchronous resonance is a phenomenon in which the resonant frequency of the turbine generator shaft coincides with a natural resonant frequency of the electrical system such that there is a sustained, cyclic exchange of energy between the mechanical shaft and the electrical system. The development of a generalized frequency scan method for analyzing ssr in a singlemachine infinitebus smib power system equipped with fixed series capacitor compensation is presented. This paper investigates a special class of dynamic power system problem, namely subsynchronous resonance ssr resulted from a seriescompensated network connecting doublyfed induction generator dfig based wind farms.
Under a disturbance, series capacitors may excite subsynchronous oscillations, when the electrical resonant frequency of the network is close to natural torsional mode frequency of a turbinegenerator shaft 6. Once the new bushings were installed, the subsynchronous vibration was eliminated. Subsynchronous resonance in doublyfed induction generatorbased wind farms background as wind power is transmitted over long lines, series compensation is often considered as a means of increasing the power transfer capability of an existing transmission line. Mathematical calculations for subsynchronous system modeling subsynchronous resonance in power systems provides indepth guidance toward the parameters, modeling, and analysis of this complex subclass of power systems. Subsynchronous resonance screening study for the pjm.
Analysis and mitigation of subsynchronous resonance in a korean power network with the first tcsc installation minhquan tran 1, minhchau dinh 1, seokju lee 1, jeain lee 1, minwon park 1, chur hee lee 2 and jongsu yoon 2 1 department of electrical engineering, changwon national university, changwon 51140, korea. Series capacitors also have a tendency to amplify the shaft stress during major network transient events. Pdf damping subsynchronous resonance in power systems. Subsynchronous resonance ssr is a condition that can exist in a power system, especially for long. Frequency scanning has been used to study induction generator effects 4. International journal of innovative research in science, engineering and technology. Eigenvalue analysis of ieee fbm for subsynchronous resonance. Subsynchronous oscillations sso and powerworld applications. An abstract of the thesis of connecting repositories.
For plain sleeve fluid film bearings whirl frequencies usually range from 0. This paper conducts an analysis of subsynchronous resonance ssr phenomena in doublyfed induction generator dfigbased wind farms interconnected with series compensated networks. Subsynchronous resonance and factsnovel control strategy for. This paper first provides an overview of subsynchronous resonance ssr and the impact of series compensation on ssr, then other cases are mentioned other than series capacitor where it can also cause severe damages to machines and equipment.
V2 department of eee, valliammai engineering college, srm nagar, kathangulathur 603203, kanchipuram district. Analysing subsynchronous resonance phenomena in the time. New effective method of subsynchronous resonance detection maciej orman, przemyslaw balcerek, michal orkisz abstract the paper presents the novel approach for detection of subsynchronous resonance phenomenon ssr in a series compensated transmission system. Ssr analysis methods features advantages disadvantages eigenvalue analysis. Should the induced subsynchronous torques coincide with one of the shaft natural modes of oscillation, the shaft will oscillate at this natural frequency, sometimes with high amplitude. The development of a generalized frequency scan method for analyzing ssr in a. International journal of innovative research in science, engineering and technology vol. This phenomenon is referred to as subsynchronous resonance ssr. The mechanism of the subsynchronous resonance is well understood. Subsynchronous resonance and factsnovel control strategy. Subsynchronous resonance is a power system condition under which the electrical network interacts with turbinegenerator system at frequencies less than the synchronous frequency 50hz. Natural frequencies and mechanical damping can be calculated in a simplified manner from the individual constants of inertias.
The phenomenon is called subsynchronous resonance ssr, and it affects turbinegenerators at subsynchronous frequencies that are specific to torsional oscillation modes of individual units. Subsynchronous resonance is an electric power system condition where the electric network exchanges energy with a turbine generator at one or more of the natural frequencies of the combined system below the synchronous frequency of the system. Subsynchronous resonance is a phenomenon in which the resonant frequency of the turbine generator shaft coincides with a natural resonant frequency of the electrical system such that there is a sustained, cyclic exchange of energy between the mechanical shaft and the electrical system. A disturbance near a series capacitor excites current or voltage components at the electrical natural frequency. Boukarim, subsynchronous resonance studies and mi tigation methods for. Emphasizing field testing to determine the data required, this book facilitates thorough and efficient oscillation and damping modeling using eigenvalues of a systems linear. System configuration the system considered in the present work is the ieee second benchmark model 5 with additional. Subsynchronous vibrations in a centrifugal pump are usually associated with fluid film radial bearings in either the pump or its driver.
In the turbomachinery industry there are several different terms that can be used to refer to the same thing. Analysis of subsynchronous resonance in power systems k. Subsynchronous resonancessr has gained its name from the fact that the frequencies of interest happen to lie in a region below the synchronous frequency of the network. An excitation of this frequency would have a corresponding rotor shaft excitation frequency which is the system frequency 60 hz in this case minus the network resonance frequency. Damping of subsynchronous resonance in an series compensated system using pscad naresh babu. The eigenvalues can be used to determine system damping as well as resonant frequency.
The subsynchronous resonance ssr is an important problem in the power system. If the frequency corresponds to an undamped natural frequency of a generator shaft, the electrical power system may interact with the shaft and cause subsynchronous resonance. Pdf a comparison of different frequency scanning methods. This section presents the basic concept and major classifications of ssr. Taking the vietnamese vungang thermal plants as an example, a shaft failure of vungang i. Eigenvalue analysis of ieee fbm for subsynchronous resonance studies rushabhkumar d. The parameters of excitation system significantly affect the lowfrequency oscillation damping. This paper analyses the implications of the ssr and consequential increase of the frequency on the nuclear power plant safety. New effective method of subsynchronous resonance detection. The operation mode selector block has only one task for setting a manual. Hzbased onintherotor and lead tothe torque amplication. Subsynchronous resonance is an electric power system condition where the electric network exchanges energy with a turbine at one or more of the natural fequencies of the combined system below the synchronous frequency of the system.
It can cause shaft fatigue and possible damage or failure of the generator involved. The phenomenon is called subsynchronous resonance ssr, and it affects turbinegenerators at subsynchronous frequencies that are specific to torsional. Evaluating and correcting subsynchronous vibration in. The inherent natural frequencies for mode 0, 1, 2 and 3 are 1. Subsynchronous resonances studies digital asset management. Since the frequency of voltage flicker modulation with low frequency range corresponds to the em torque frequency, the em torque frequency is subsynchronous. Since the earth whirls in the same rotational direction as its synchronous rotation, the subsynchronous orbit is considered to be forward whirling. Design of subsynchronous resonance protection and reduction. Abstractthis paper focus on eigenvalue analysis of ieee first benchmark model.
Subsynchronous resonance ssr is a condition that can exist in a power. Analysis of subsynchronous resonance in power systems. International journal of innovative research in science. In this research paper, an experimental set up which demonstrates generation, transmission and distribution with low power rated machine is experimented. Analysing subsynchronous resonance phenomena in the timea.
Impacts of subsynchronous and supersynchronous frequency. Subsynchronous resonance file exchange matlab central. It is seen that all the unstable torsional modes of various frequencies are stabilised effectively. Analysis of subsynchronous resonance effect in series compensated line with booster transformer international journal of electrical and electronics engineering ijeee, issn print. A summary of several major analysis methods is shown in table1. The subsynchronous resonance ssr is an important problem in the power system, and especially the series compensated transmission lines may cause ssr in the turbine generators, such that it leads to the electrical instability at subsynchronous frequencies and potential turbinegenerator shaft failures.
A simplified system for subsynchronous resonance studies. The frequency of nonsynchronous vibration is often referred to in terms of its whirl frequency ratio. This method overcomes shortcomings present in the traditional frequency scan technique which is widely used in power system analysis. A novel twodegreeoffreedom 2dof control strategy combined with a damping control loop is designed and analyzed for enhancing the system. Study of subsynchronous resonance and analysis of ssr ranjit m. Analysis of subsynchronous resonance in power systems abstract approved. Whether youve loved the book or not, if you give your honest and detailed thoughts then people will find new books that are right for them. Electrical engineering by kim touy khu in charge of major work approved iowa state university ames, iowa 1977. Bhavik prajapati, vadodaragujarat,india abstractssr basically an electrical power system condition where electrical network exchange energy. Eigenvalue analysis of ieee fbm for subsynchronous. Three aspects of subsynchronous resonance ssr related problems in power systems are addressed in this dissertation which aims at contributing to a better. Subsynchronous resonance in doublyfed induction generator.
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