This book provides a comprehensive practical treatment of the modelling of electrical power systems, and the theory and practice of fault analysis of power systems covering detailed and advanced ...theories as well as modern industry practices.The continuity and quality of electricity delivered safely and economically by today’s and future’s electrical power networks are important for both developed and developing economies. The correct modelling of power system equipment and correct fault analysis of electrical networks are pre-requisite to ensuring safety and they play a critical role in the identification of economic network investments. Environmental and economic factors require engineers to maximise the use of existing assets which in turn require accurate modelling and analysis techniques. The technology described in this book will always be required for the safe and economic design and operation of electrical power systems. The book describes relevant advances in industry such as in the areas of international standards developments, emerging new generation technologies such as wind turbine generators, fault current limiters, multi-phase fault analysis, measurement of equipment parameters, probabilistic short-circuit analysis and electrical interference.*A fully up-to-date guide to the analysis and practical troubleshooting of short-circuit faults in electricity utilities and industrial power systems*Covers generators, transformers, substations, overhead power lines and industrial systems with a focus on best-practice techniques, safety issues, power system planning and economics*North American and British / European standards covered
The knowledge of ground return current in fault occurrence plays a key role in the dimensioning of the earthing grid of substations and of cable sealing end compounds, in the computation of rise of ...earth potential at substation sites and in electromagnetic interference (EMI) on neighbouring parallel metallic conductors (pipes, handrails, etc.). Moreover, the ground return current evaluation is also important in steady-state regime since this stray current can be responsible for EMI and also for alternating current (AC) corrosion. In fault situations and under some assumptions, the ground return current value at a substation site can be computed by means of k-factors. The paper shows that these simplified and approximated approaches have a lot of limitations and only multiconductor analysis can show the ground return current behaviour along the cable (not only the two end values) both in steady-state regime and in short circuit occurrence (e.g., phase-to-ground and phase-to-phase-to-ground). Multiconductor cell analysis (MCA) considers the cable system in its real asymmetry without simplified and approximated hypotheses. The sensitivity of ground return current on circuit parameters (cross-bonding box resistances, substation earthing resistances, soil resistivity) is presented in the paper.
This book provides a comprehensive practical treatment of the modelling of electrical power systems, and the theory and practice of fault analysis of power systems covering detailed and advanced ...theories as well as modern industry practices.
The continuity and quality of electricity delivered safely and economically by today’s and future’s electrical power networks are important for both developed and developing economies. The correct modelling of power system equipment and correct fault analysis of electrical networks are pre-requisite to ensuring safety and they play a critical role in the identification of economic network investments. Environmental and economic factors require engineers to maximise the use of existing assets which in turn require accurate modelling and analysis techniques. The technology described in this book will always be required for the safe and economic design and operation of electrical power systems.
The paper further develops a modeling concept of three-phase, three-legged transformer with tank walls represented as a distributed parameter structure. The circuital models proposed replicate ...accurately all possible zero-sequence impedances and losses of a three-winding transformer. Several model versions are compared to each other and to a conventional topological model with respect to their transient behavior during inrush and short circuit events, and in the presence of geomagnetically induced current (GIC). It was found that in all the cases considered, except that with a large GIC, all the models yield similar results. The reliability of the models is due to the representation of the tank walls behavior in a physical way, allowing one to observe the field distribution over the wall thickness as a function of transformer excitation. The modeled results are in a close agreement with positive and zero sequence data measured on a 25 MVA transformer as well as with inrush current test on a 300 kVA unit.
•The paper deals with the zero sequence impedances in double-circuit overhead lines.•A systematic comparison with IEC 60909-2 formulae has been presented in the paper.•IEC 60909-2 adds zero sequence ...self and mutual impedances between the two circuits.•Zero sequence mutual impedance should not be included in the self impedance.•IEC 60909-2 has errors up to 20% in the phase-to-ground short circuit current.
Positive, negative and zero sequence series impedances (in Ω/km units) are the first step for power flow and short circuit analyses and are also necessary for setting the distance relays. The paper is devoted to the computation of zero sequence series impedance (in Ω/km units) (self and mutual) in double-circuit overhead lines (OHLs) with one or more earth wires. A systematic comparison with matrix approaches demonstrates that IEC 60909-2 formula adds the zero sequence self and the zero sequence mutual impedance between the two circuits. This approximation of having a unique value of zero sequence impedance is misleading and gives great errors when phase-to-ground short circuit occurs along a circuit. It is worth noting that the zero sequence mutual impedance between parallel circuits installed on the same tower may be as high as 50% (or more) of the zero sequence self impedance of a circuit alone. Consequently, zero sequence mutual impedance between the two circuits cannot be neglected or mixed. MCA (Multiconductor Cell Analysis) shows that the simplified IEC approach underestimates heavily (more than 18%, depending upon the spacing between the circuits) the phase-to-ground fault current for a fault occurrence along one circuit of the double circuit.
This paper presents the development of Grid Code requirements for new and renewable forms of generation in Great Britain (GB). After briefly describing the background to the GB Transmission System ...and the volume of renewable generation which is anticipated to connect in the future, the paper discusses the Grid Code and Grid Code change process. In particular, the paper discusses the interfaces with key stakeholders, the technical issues considered in connecting other generation technologies to the Transmission network and the rationale for the final Grid Code requirements. The technical issues discussed include fault ride through, frequency range, frequency response, power/frequency characteristic, reactive range, voltage control and power quality. The paper concludes with the experiences gained in the connection of wind generation projects to the GB Transmission System both before and after the approval of new proposals to the GB Grid Code.
Positive, negative and zero sequence kilometric impedances are the first steps for power flow and short circuit analyses and are also necessary for setting the distance relays. The paper is devoted ...to the computation of zero sequence kilometric impedances (self and mutual) in double-circuit overhead lines (OHLs) with one or more earth wires. A systematic comparison with matricial approaches demonstrates that IEC 60909-2 formula adds the zero sequence self and the zero sequence mutual impedance between the two circuits. This approximation of having a unique value of zero sequence impedance is misleading and gives great errors when phase-to-ground short circuit occurs along a circuit. It is worth noting that the zero sequence mutual impedance between parallel circuits installed on the same tower is not negligible. MCA (Multiconductor Cell Analysis) shows that the simplified IEC approach underestimates heavily (more than 18%, depending upon the spacing between the circuits) the phase-to-ground fault current for a fault occurrence along one circuit of the double-circuit.
The knowledge of ground return current in faulty occurrence plays a key role in the dimensioning of the earthing grid of substations and cable sealing end compounds, in the computation of rise of ...earth potential at substation sites and in electromagnetic interferences (EMIs) on neighbouring parallel metallic conductors (pipes, handrail, etc.). Moreover, the ground return current evaluation is also important in steady-state regime since this stray current can be responsible for EMIs and also for AC corrosion. In faulty situation and under some assumptions, the ground return current value at substation site can be computed by means of k-factors. The paper shows that these simplified and approximated approaches have a lot of limitations and only multiconductor approaches can show the ground return current behaviour along the cable (not only the two end values) both in steady-state regime and in short circuit occurrence (e.g. phase-to-ground and phase-to-phase-to-ground). Multiconductor Cell Analysis (MCA) considers the cable system in its real asymmetry without simplified and approximated hypotheses. The sensitivity of ground return current to circuit parameters (cross-bonding box resistances, substation earthing resistances, soil resistivity) is throughout presented.
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