Johann Jaeger

High-speed fault identification and protection for HVDC line using wavelet technique

This paper describes a new high-speed HVDC line protection using wavelet technique. Based on the representation of the travelling waves through wavelet modulus maxima, the protection criteria for HVDC fine are proposed. Simulations are carried out for testing the criteria. The influences of similar faults are discussed. The protection can detect the HVDC line fault well and identify the HVDC line fault clearly from the similar transients, such as commutation failure and AC single phase fault.

Integration of batteries into a modular multilevel converter

In this paper the challenges of integrating batteries into the Modular Multilevel Converter are described. For this purpose, the technology of this converter topology is briefly introduced. An overview on already available products of battery energy storage systems is given. Based on that, a control concept for a DC-to-DC converter connecting a battery to a module of the Modular Multilevel Converter is presented. This concept contains an additional energy balancing algorithm. Several operating points of the whole system with integrated batteries are simulated. The paper is topped off with measurement results of a started-up hardware setup that is equipped with emulated DC-to-DC converters.

Automated protection security assessment of today's and future power grids

Protection security assessment of power grids becomes an important task in the course of a competitive energy business and a decarbonized power generation. The analysis of past blackouts studied by the North American Electric Reliability Council (NERC) shows that protection relays are involved in about 75% of all major disturbances. One reason for that is the non adequate adaption of the protection systems to the changing network conditions. In particular the relay hidden failures caused relay malfunctions and blackouts, following cascading trippings.

Real-Time Adaption of Dead Time for Single-Phase Autoreclosing

An approach for a real-time adaption of the dead time for autoreclosing on high-voltage lines was proposed. The objective was the optimal adaption of the dead time of a currently running single-phase autoreclosing cycle by calculating the secondary arc current based on measurements. The algorithms for optimization were performed for real-time applications. For this purpose, the fault location plus the load currents of the parallel nonfaulty conductors were measured. The measurement and the calculation of the dead time took place during the fault and the dead-time period. In this way, an optimized dead-time setting with regard to the actual fault location and loading conditions were achieved. This approach results in an online determination of the minimum necessary dead time of a successful reclosing under consideration of the fault location and prevailing loading conditions. Analytical calculations and numerical examples as well as high-voltage field tests verified the results.

An enhanced modulator concept for the Modular Multilevel Converter

This paper deals with an enhanced modulator concept for the Modular Multilevel Converter. Based on an overview on existing concepts including module sorting algorithms and measurement results from a hardware-setup in laboratory, a new concept is developed. Measurement results of the implemented new algorithm for module selection and capacitor energy balancing in various operating points of the converter are presented and analyzed in detail. This elaboration is completed with a classification of the suggested modulator concept compared to established concepts.

Efficiency analysis of data compression of power system transients using wavelet transform

This paper analyzes the wavelet transform application in the data compression of power system transients. It studies the influences on the compression efficiency and quality by different mother wavelets, scale levels and thresholdings. It presents the relation between the compression efficiency and the compression accuracy, and shows how to get the optimal solution. It shows that the wavelet transform leads to a data compression approach with high compression efficiency, high compression accuracy, high compression quality and good denoising effect, so that the wavelet transform can bring remarkable advantages to the fields in which big amounts of data are processed like fault recording and SCADA/EMS/DMS systems.

Innovative strategies for protection security assessment

Protection security assessment of power grids is getting an important task in the course of a decarbonized power generation and a competitive energy business. The analysis of past blackouts studied by the North American Electric Reliability Council (NERC) shows that protection relays are involved in about 75% of all major disturbances. Protection security assessment can be investigated under two different aspects: on the one hand the behavior regarding selectivity, speed and sensitivity and on the other hand the behavior regarding the response on dynamic network phenomena as voltage stability and transient stability. This paper is focused on the protection response on dynamic network phenomena and presents innovative strategies for this investigation aspect. Applicable protection models and the simulation environment based on PSS®NETOMAC will be described. Case studies on real networks show the way of investigation and the achieved improvement of dynamic protection security based on the applied innovative strategies.

Protection coordination — An important task for network security

This paper is dealing with the important task of protection coordination maintaining network security in nationwide power systems under changing network conditions. Existing protection systems have to be analyzed and checked under higher loading and contingency conditions. Adapted protection concepts should be evaluated applied to the network. Nowadays numerical simulation tools like PSS¯SINCAL provide the possibility of a holistic simulation of network and protection behavior. This paper is presenting the results of a protection coordination study based on the proposed method. The collection of protection and network data has been done on the basis of data plausibility algorithms firstly. Numerous different network contingencies were investigated. The software assistance and the visualisation of the enormous amount of output data are described. Generic network and protection configurations leading to maloperation can be clearly found. Further on the possibility of the development of systematic solutions covering the identified practical constraints under the changing network conditions is provided.

Dynamic protection security assessment, a technique for blackout prevention

In most cases of blackouts, protection systems play a significant role. The maloperation of one protection system can lead to a cascade-tripping of many other protection devices, and so a wide-area interruption of the power grid can affect millions of people. Therefore one important task of a transmission system operator (TSO) is to initiate remedial measures to prevent the grid from such interruptions. The TSO has different tools to operate a secure and reliable transmission grid, e.g. state estimator, dynamic security assessment (DSA) tools and so on. The dynamic protection security assessment (DPSA) is another tool to assess the situation in the grid depending on different contingencies. In addition to the transient network models, protection system models are also included for the simulation of stability problems. In contrast to DSA, DPSA assesses the time-dependent behavior of the protection systems and shows their influence on the grid security.

Protection security assessment - An important task for system blackout prevention

Protection security assessment of power grids becomes an important task in the course of a competitive energy business and a decarbonized power generation. The analysis of past blackouts studied by the North American Electric reliability Council (NERC) shows that protection relays are involved in about 75% of all major disturbances. One reason for that is the non adequate adaption of the protection systems to the changing network conditions. In particular the relay hidden failures causes relay malfunctions and blackouts in the past. This paper is presenting a new automated method for blackout prevention. It analyzes and assesses the security of protection systems of networks as a whole. Routinely checks of contingency sequences are carried out and reveal bottlenecks of the protection behavior itself and of the coordination of network and protection. The numerical simulation tool PSS®SINCAL is used providing the possibility of a holistic simulation of network and protection behavior on a fully automated manner. The handling of the big amount of resulting data is done by an intelligent visualization method like a “finger print” analysis.