Johann Jäger

Advanced Coordination Method for Overcurrent Protection Relays Using Nonstandard Tripping Characteristics

This paper describes an advanced coordination method for an optimized protection time grading based on a new nonstandard tripping characteristic for overcurrent protection relays. The intention is the highest possible reduction of tripping times for a selective fault clearing in distribution networks protected by overcurrent relays without communication links. The new nonstandard tripping characteristic will be described from its basic idea to its constraints of the optimization problem. The optimization is solved by the method of Lagrange generalized with the Karush-Kuhn-Tucker conditions and is aimed at selective fault tripping with shorter tripping times as standard characteristics and conventional coordination methods. Overcurrent relay coordination becomes a mathematical optimization task. A comparison with the standard characteristics and conventional coordination methods shows a notable advancement regarding their average and maximum tripping times which can be achieved using this new method.

Transient shunt reactor dimensioning for bulk power transmission systems during normal and faulty network conditions

This paper presents an analysis of a 500 kV bulk power transmission system and the dimensioning of proper shunt reactors to be applied under steady state and transient aspects in particular. Therefore, the behavior of single-pole auto-reclosing under line-to-ground fault conditions is analyzed. Hence is described the necessity and influence of factors such as phase and neutral reactors, capacitive and inductive couplings on the extinction of secondary arc. Those are investigated in order to justify the feasibility of single-pole auto-reclosing. A practical example of the system is developed with respect to an investigation of the impact of neutral reactors. The considerations have been firstly done analytically and verified subsequently based on transient simulations using ATP/EMTP.

Enhancement of the reliability of extra and ultra high voltage transmission systems

Single-pole auto-reclosing is an approved method to enhance the reliability in transmission systems. But with increasing system voltage, the maximum line length, for which a common single-pole auto-reclosing is successful, decreases. Therefore this paper will show how single-pole auto-reclosing can also be applied in extra and ultra high voltage transmission systems, by extending the system with high-speed grounding switches or with four-legged shunt reactor schemes. The operation mode of both will be illustrated.

Preventive methods against blackouts based on protection security assessment in future grids

The paper presents a new automated method for assessing the security of protection systems concerning selectivity and speed to reduce the risk of unnecessary disturbances and blackouts. The invented algorithms are capable to handle complex structures. Hence, the system behavior of a protection system and network is analyzed and assessed as a whole and it has not to be reduced to its single components or devices. The simulation tool is used as an engine to provide the possibility of a holistic simulation of networks together with the protection. The system-method can be divided into two main approaches: Fault pattern analysis (FPA) and economic impact assessment (EIA). The FPA calculates running faults through the whole grid for diverse scenarios of load flows. Economic aspects of nonselective protection systems are also be introduced and presented by the EIA method. It benefits from the fact that protection devices violating dependability or security will lead to additional outage. This outage is calculated and evaluated by the differences of simulated outage and unavoidable outage. The large amount of resulting data is stored in a central database. Intelligent filtering and data preparation allow a holistic assessment and visualization of complete networks of different architecture. Routinely checks of contingency sequences with the presented methods will reveal bottlenecks of the protection behavior itself and of the coordination of network and protection.

Protection security assessment using automated analysis

Protection security assessment of power grids becomes an important task in the course of a competitive energy business and distributed power generation based on renewable resources. 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 unintended supply interruptions in the past.

Avoiding cascading protection tripping in transmission systems and assessment of quality and security of the protection system

This paper describes typical developments of blackouts from simple cause to cascading outages. The involvement of the protection system at the beginning and during the enlargement of the incident to the blackout will be shown. Measures to avoid cascading protection tripping will be presented. A new method will be proposed to assess the quality and security of protection systems which can be applied online and offline for systems with up to some ten thousand relays.

Adaptive Protection Co-ordination Methods Concerning a Dedicated Operation of Large IPP Units Connected to the Transmission Grid

This paper presents advanced protection coordination methods to be applied for the integration of IPP units to the transmission grid. A typical system configuration of an IPP unit installation is considered. The protection system is also assumed to be commonly which is based on the distance protection principle. The changing network conditions and their impacts on the protection system caused by the IPP are described. Thus the topics of co-ordination of different characteristics, teleprotection schemes, distance grading and relay loadability are investigated and methods for covering their adverse impacts are given. It can be seen that only modern relay technology is not leading to a proper protection system. Only well co-ordinated and adapted protection relays will result in a system of high reliability of the IPP in-feed and in an economic benefit for the IPP investors finally.

Transient behaviour of high-impedance protection applications using for networks with distributed generation

The presented paper is dealing with protection principles which are preferable applied to networks with distributed generation (DG). A basic physical explanation of the high-impedance protection principle in relation to the low-impedance principle will be given considering the transient behaviour in particular. It can be shown that special requirements on the protection co-ordination for networks with DG can be covered by the high-impedance protection principle. Measurement results of a high current lab confirm the favourable behaviour of the high-impedance protection principle. It was also possible to investigate the transient behaviour of the high-impedance principle under extreme conditions like CT remanence effects. A close correlation between digital simulation and measurement results of the transient behaviour could be achieved during the investigations.

Anwendung der Dualen Planungsmethodik

Im Folgenden werden Vorgehensweise und Ergebnisse der Dualen Planungsmethodik am Beispiel der Netzanbindung von Windkraftanlagen (WKA) im Modelllandkreis, auch unter Einbeziehung vorhandener und zukunftiger Photovoltaikanlagen, dargelegt.

Veranlassung, Problemstellung und Notwendigkeit

Die Netze der elektrischen Energieversorgung erfahren einen stetig wachsenden Zubau an Regenerativen Energieeinspeiseanlagen (REA). Die Forschungs‐ und Entwicklungsanstrengungen auf dem Gebiet der REA und deren netzkompatible Anbindung haben seither ebenfalls zugenommen. Im Zuge dessen hat das Bayerische Staatsministerium fur Umwelt und Verbraucherschutz das Forschungsprojekt „Neue Methoden der elektrischen Netzplanung zur nachhaltigen Anbindung von Windkraftanlagen im Binnenland“ initiiert. Die Ergebnisse dieses Projektes bilden die Grundlagen des vorliegenden Buches. Die dabei erarbeiteten Methoden der Netzplanung wurden auf das Versorgungnetz eines bayerischen Landkreises angewandt, in dem ein massiver Zubau an REA in den letzten Jahren zu verzeichnen war. Die Nutzung der Windkraft und der Photovoltaik haben daran den grosten Anteil. Aus Grunden der Ubersichtlichkeit und Vertraulichkeit wurden alle Netzdaten und topographischen Gegebenheiten in eine aquivalente Modellregion uberfuhrt.