Rainer Krebs

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.

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.

Vision 2020: Blackout prevention by combined protection and network security assessment

The paper presents the application of software tools to simulate system dynamic behaviour together with the possibility to select critical contingencies of an electrical energy system. The protection system with relay functions, characteristics, settings and communication schemes will be considered. Possible visualization methods are presented which can support the operators to select critical system states - either of the primary or the protection system. Insecure operating conditions can be monitored in the time domain using the full system representation in real time or by calculating the eigenvalues of the system to monitor weakly damped system states and stability margins. Warnings about unselective protected areas can popup for fast information or they can be shown with the corresponding relays in single-line diagrams as a basis for a new protection coordination study. The locations of short circuits with corresponding trip times and unselective trips or no trips can be monitored in two- or three-dimensional diagrams. The optimized settings can be directly transmitted to relays, which are able to receive the adaptive settings.

Vision 2020 — Security of the network operation today and in the future. German experiences

Nowadays the supply of electrical energy from dispersed generation units has an increasing significance. Hence, security related power system operation strategies have to be adapted to face the new situation. In this paper the security of power system operation from the industry and research point of view will be discussed. After presenting an overview about the current situation, the problems will be pointed out. The promising ongoing research topics which have the ability to help the network operators to manage the turn towards a sustainable power system that will allow for exploiting as much regenerative energy as possible by reaching the high standards of security will be described.

New protection concepts for distribution systems with dispersed generation

This paper presents new protection concepts in distribution networks with dispersed energy resources (DER), based on the new standard for a substation automation system (SAS) IEC 61850. The idea and realisation of the new protection concept is implemented in the electronic-learning system for digital protection in the frame of teaching network protection.

Vision 2020 dynamic security assessment in real time environment

In this paper, implementation of power system dynamic security assessment (DSA) into real time simulation environment is described. For this purpose, a powerful simulation system has been used and a flexible security assessment framework developed. The DSA system constructed is user oriented and enables simple evaluation of power system security. The assessment is made in respect to some user defined security constraints considering normal or contingency provoked system operation. For reporting of the results different visualization formats are available. The DSA system is fully automatic and can process any number of study cases without user interaction. It targets high flexibility in power system research and maximum performance at minimum hardware requirements.

Wide area monitoring with synchrophasors German experiences

The stability of electrical transmission networks has been receiving more attention in recent years all over the world. Following several wide-area supply interruptions, so called blackouts, for example in Europe and North America, it is widely accepted that transmission networks have to be improved in terms of both capacity and stability. The quick building of new lines is usually not an option, so measures to enhance the stability of existing networks are of great interest. One well accepted method, increasing the observability of the power system, is the use of phasor measurement data from widely spread positions in the power networks. With a suitable software solution, the information coming from the Phasor Measurement Units (PMUs) helps the control center engineers to gain an awareness of the stability situation throughout the whole network. This aids them in making the right decisions even in critical situations. The application of such a Phasor Data Processing System is presented and discussed.

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.