| Abstract: not available |
| Abstract: A project was undertaken to test the validity of the electromagnetic transients simulation of dc links using digital computer programs. The Nelson River dc transmission system of both Bipoles One and Two were modeled on the computer using Manitoba Hydro's EMTDC program. The well known Electromagnetic Transients Program EMTP was also used for small reduced system models. Results from actual system tests were used to compare with the computer simulation of the same test. Comparisons are also made between EMTDC and EMTP as simulation tools for studying dc transmission. Computer simulation of dc links is presented as a valid option to the use of real time hard wired simulators. |
| Abstract: This paper establishes the validity of digital simulation of transients in HVDC-ac power systems. For the digital simulation BPA's EMTP was used. Manitoba Hydro's Nelson River HVDC system comprimising two HVDC bipoles, Bipole 1: 1668 MW and Bipole 2: 1000MW was used for digital simulation test cases. The simulation results were compared with the field tests conducted by Manitoba Hydro. The paper presents a new technique of initialization for digital computer simulation. Direct comparison of the computed results with field tests establishes clearly the validity of simulation. Comparison of the results of this paper with those of Reference [1], shows that both EMTP and EMTDC programs can be used for accurate digital simulation. EMTDC is a new program and it is found to be very efficient and economical for digital simulation. |
| Abstract: There is often a temptation to model the reactive power loads on a synchronous machine as an equivalent lumped capacitor or reactor for the purposes of transient simulations. Significant errors can result from such an approach, especially in the simulation of fast rotor transients in machines connected to HVdc systems. This paper attempts to show where such simplified representations are allowed, and where they are not. The results indicate that a long and unloaded transmission line may be represented by an equivalent capacitor, but that other loads such as HVdc filters may not. Certain other modelling aspects such as breaker opening are also discussed. |
| Abstract: Sometimes, a synchronous machine experiences a sudden increase in capacitive loading, due for example to a load rejection by the blocking of an hvdc rectifier, or to the tripping of the synchronous machines when connected to a predominantly capacitive load. This sudden increase in capacitive loading can initiate oscillations in the stator circuit, which are reflected as sudden oscillations in the machine's field current. In machines with solid state exciters without reverse current capability, severe oscillations may momentarily try to reduce the field current to zero, and result in excessive field overvoltages. It is these overvoltages, that this paper attempts to study, through detailed simulations and also through demonstration on a laboratory setup. The situation discussed here relates to such phenomena occurring on machines connected to hvdc rectifier stations, although similar situations could also exist in other systems. |
| Abstract: not available |
