Transient events are short-lived bursts of energy in a system resulting from a sudden change of the state. They can be caused by faults, switching events or sudden changes in generation and load. Given the need to expand HV cable grids and to interconnect national grids to increase grid flexibility, the effects of such transients need to be understood in order to maintain the security of power supply and power quality. This book presents an overview of formulas to model transients in cable systems based on complete solutions of Maxwell's equations. It presents solutions to particularly model important high frequency phenomena. The impedance and admittance at a very low frequency for HVDC systems are investigated. In addition, the modeling methods of underground cables created in the Electromagnetic Transients Program (EMTP) are described. Moreover, the wave propagation characteristics of overhead lines and underground cables, and steady-state and transient behaviour of three-phase cables are further investigated in this book. Finally, transients in large interconnected HV cable networks in Denmark and the Netherlands are presented as case studies. Electromagnetic Transients in Large HV Cable Networks enables researchers, HV system manufacturers and grid operators to model, simulate and analyse transient phenomena in large HV cable systems and to create solutions to counter and mitigate them.
Inspec keywords: power cables; optimisation; optical design techniques; EMTP; underground cables; finite difference time-domain analysis; wave propagation; nanophotonics; laser modes; ring lasers; method of moments
Other keywords: underground cables; nanophotonics; optical design techniques; wave propagation; finite difference time-domain analysis; large HV cable networks; electromagnetic transients; laser modes; ring lasers; method of moments; optimisation
Subjects: Power cables; Optimisation techniques; General electrical engineering topics; Nanophotonic devices and technology; General and management topics; Lasers; Power engineering computing; Other numerical methods; Optimisation techniques; Other numerical methods
Provides a brief summary of each of the following chapters, covering; impedance and shunt admittance; modeling of cables; wave propagation characteristics of overhead and underground cables; steady-state and transient characteristics on three-phase cables; transients in the interconnected EHV cable network in Denmark and steady-state and transient behaviour of hybrid overhead line-underground cable networks in the Netherlands.
This paper is about the evaluation of series impedance and shunt admittance of underground cable. Underground cables are used extensively for the transmission and distribution of electric power. The Characteristic Impedance of a Transmission line is defined as the square root of ratio of series impedance per unit length per phase and shunt admittance per unit length per phase. If z and y are series impedance and shunt admittance of line. The transmission line of both short and medium-length use approximated lumped-parameter model. The earth-return cable is the internal potential coefficient of matrix.
This chapter describes the modeling of cables by the well-known electromagnetic transient (EMT) simulation techniques which are widely used and implemented into various EMT-type simulation tools. The modeling methods based on numerical electromagnetic analysis (NEA) approaches such as finite-difference time-domain (FDTD) and method of moments (MoM) are also discussed. The EMT-type simulation tools are very powerful to analyse phenomena in a large and complex network provided that the phenomena are associated with transverse electromagnetic (TEM) mode of propagation. On the contrary, the NEA approach can deal with TEM and non-TEM mode phenomena, as it solves Maxwell's equation directly. However, it is computationally heavy, and infeasible to deal with a large network.
In this chapter, the wave propagation characteristics and external electromagnetic field components calculated based on extended and classical transmission line (TL) approaches on overhead and underground cables are investigated and analyzed. Considering a typical three-phase underground cable, the lateral and total external electromagnetic fields components at the various field observation points using the two phases and single-phase energizations are investigated and analyzed.
The charging and discharging characteristics of underground cables are explained and investigated. Simulations of electromagnetic transients on an RTE 225 kV cable system are thoroughly investigated and studied. The chapter also deals with transient simulations on homogeneous and crossbonded cables using extended and classical TL approaches. The influences of the extended TL approach on different mode energizations are also investigated and made clear. The authors also consider very-fast transients (VFTs) in gas-insulated substations (GISs). Field test results of VFTs are summarized, considering electromagnetic disturbances in GIS control circuits. Also, numerical instabilities are observed in VFT simulation results by using existing EMT-type simulation tools.
This chapter studied temporary overvoltages and slow-front overvoltages on the Kyndbyværket-Asnæsværket cable line in Denmark. The series resonance overvoltage caused by the cable energization was studied. The most severe switching scenarios were first identified. The simulations were performed with the most severe assumptions of the Kyndbyværket 132 kV network and the Asnæsværket 132 kV network. The parallel resonance caused by transformer inrush currents was studied as the most severe scenario. Severe overvoltages were observed with the most severe scenarios, but they were within withstand voltages of related equipment. The overvoltage caused by the system islanding was discussed. The statistical distributions of a ground fault and fault clearing overvoltages of the Kyndbyværket-Asnæsværket line were then investigated. The maximum overvoltage found in the analysis was 1.37 pu, which was much lower than SIWV 1050 kV (3.2 pu). Effects of dummy source impedances were not significant. The sequential switching may be applied to the Kyndbyværket-Asnæsværket line as a countermeasure of the zero-missing phenomenon. The sequential switching does not affect the severity of the overvoltages.
This chapter addresses the most important technical issues related to the operation of power systems composed of both overhead lines (OHLs) and cables (hybrid OHL-cable systems). The research is conducted for a hypothetical 80 km double-circuit connection in the future Dutch 380 kV grid, called the Spaak project. For this purpose, accurate steady-state and EMT models of the entire Dutch transmission grid are used to ensure the maximum simulation accuracy.
This book presents an overview of formulas to model transients in cable systems based on complete solutions of Maxwell's equations. It presents solutions to particularly model important high frequency phenomena. The impedance and admittance at a very low frequency for HVDC systems are investigated. In addition, the modeling methods of underground cables created in the Electromagnetic Transients Program (EMTP) are described. Moreover, the wave propagation characteristics of overhead lines and underground cables, and steady-state and transient behaviour of three-phase cables are further investigated in this book. Finally, transients in large interconnected HV cable networks in Denmark and the Netherlands are presented as case studies.