This article reports the results from the implementation and testing of a Wide-Area Power Oscillation Damper (WAPOD) controlling a 180 Mvar TCR Static Var Compensator (SVC) installed in the Hasle ...substation of Norwegian 420 kV transmission grid. The WAPOD uses voltage phase angle signals from two distant locations in the Norwegian grid as inputs to the damping controller. The damping controller modulates the voltage reference set point used by the SVC's voltage controller, thereby creating a damping effect. The WAPOD is an extension to the existing Power Oscillation Damping (POD) controller that uses local measurements. A switch-over logic allows for the use of no damping control, local damping control or wide-area control. Field tests were performed during November 2011, and involved the disconnection and re-connection of a 420 kV transmission line. The performance of the WAPOD is compared to that of state-of-the-art local Phasor POD, and when no damping control is enabled. The testing results show that the WAPOD performed satisfactorily and according to the design expectations. These results show that the potential flexibility of the WAPOD to choose, among the different PMU signals, those that have the good observability of inter-area modes can be an advantage to the use of local feedback signals for damping control, as it is current practice today. Further testing of this WAPOD with other PMU signals from locations with stronger observability will be helpful to illustrate the advantage of this flexibility.
This article presents a software development toolkit for Wide Area Monitoring Systems. By using this development toolkit, a researcher is able to manipulate synchrophasor data in the LabView ...environment, which enables fast software prototyping and testing. This toolkit makes full scale testing in real-time easier for researchers, liberating them of complex and time consuming synchrophasor data handling. The toolkit exploits the IEEE C37.118.2-2011 protocol making it independent of any specific equipment and their manufacturers. An application of the development kit is demonstrated in a laboratory environment with a specially designed experimental setup composed of a real-time digital simulator and four phasor measurement units (PMUs).
Spectral analysis applied to synchrophasor data can provide valuable information about lightly damped low-frequency modes in power systems. This paper demonstrates application of two non-parametric ...spectral estimators focusing on mode frequency estimation. The first one is the well-known Welch spectral estimator whereas the application of Multitaper method is proposed here. In addition, the paper discusses mode estimator tuning procedures and the estimators' performances in the presence of "forced" oscillations. The validity of the proposed application of the non-parametric estimators and tuning procedures is verified through both simulated data and PMU data originating from the high-voltage grid of the Nordic power system. Special attention is given to the analysis of the behaviour of different low frequency modes present in the Nordic grid, including that of forced oscillations.
This article provides an overview of a monitoring application, its testing and validation process. The application was developed for the detection of sub-synchronous oscillations in power systems, ...utilizing real-time measurements from phasor measurement units (PMUs). It uses two algorithms simultaneously to both detect the frequency at which the oscillatory event occurs and the level of energy in the oscillations. The application has been developed and tested in the framework of SmarTS Lab, an environment capable of hardware-in-the-loop (HIL) simulation. The necessary components of the real-time chain of data acquisition are presented in this paper, as well as testing and validation results, to demonstrate the accuracy of the monitoring tool and the feasibility of fast prototyping for real-time PMU measurements based applications using the SmarTS Lab environment.
This article analyzes the impact of forced power system oscillations on mode damping estimation. Parametric (Yule-Walker) and non-parametric (Welch) methods for mode estimation are tested in the ...presence of forced power system oscillations. For mode damping estimation based on non-parametric methods, an application of Half Power Point method is proposed. Performances of the mode estimators are evaluated using both simulated and real synchrophasor data from the Nordic Grid. The presence of forced oscillations poses difficulties to mode damping estimators, these difficulties are identified, illustrated and explained herein.
For power networks such as the Nordic Grid, that have operation constraints limits imposed by the existence of low-damped electromechanical oscillations, the estimation of electromechanical mode ...properties is of crucial importance for providing power system control room operators with adequate indicators of the stress of their network. This article addresses the practical application of different spectral analysis techniques that can be used for the estimation of electromechanical mode properties using data emerging from real synchronized phasor measurement units (PMUs) located at both the low-voltage distribution and high-voltage transmission networks of the Nordic grid. Emphasis is made on providing systematic approaches to deal with imperfect data found in practice so that accurate estimates can be computed.
This paper presents a software implementation of a real-time power system mode estimator application which uses ambient synchrophasor data. The software is built using Statnett's Synchrophasor ...Software Development Kit (SDK) as a platform for fast prototyping of real-time synchrophasor applications. The SDK extracts synchrophasor data received in the IEEE C.37.118 protocol and provides them as LabVIEW signals. These signals are preprocessed and mode frequencies and damping ratios are calculated by Yule-Walker's method. The implemented LabVIEW software employs state machine logics which enables modifications and upgrades to the algorithm.
Smart grids have attracted significant attention lately, and one can even speak of a hype. However, much of the attention is paid to the distribution side and consumer interaction. Nevertheless, also ...at the transmission level important improvements can be achieved through farsighted and careful intelligent grid design and implementation. This paper identifies different research areas and their respective boundary interactions in order to enable a practical "Smart Grid" implementation in the European power system. Emphasis is placed on three essential aspects of the Smart Transmission Grid. First, the necessary evolution of synchrophasor measurement technology is discussed, as well as the limitations towards and its full integration into power system operation and control. An important aspect to achieve this full integration is the necessity to test and integrate any proposed solution in an open and transparent environment. Secondly, the IT, data and communications paradigm is critically discussed. And lastly, the key questions that are open to the transmission system operators are discussed, specifically regarding the coordination within the pan-European power system and its security. Going beyond the purely academic point-of-view, this paper specifically aims to bring a realistic approach towards research for the transmission network.
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