| Abstract: not available |
| Abstract: not available |
| Abstract: This paper describes tests on the relays on a long 500 kV ac line carried out on site using the Real Time Digital Simulator developed by the Manitoba HVDC Research Centre. The purpose of the tests was to examine the relay behaviour when series compensation is inserted in the line in 1993. New settings for the relays have been found which will give adequate cover for all faults although some faults will be entirely dependent on the communication link for short clearance times. |
| Abstract: This paper describes a simulation model which can be used to predict voltages and currents during GIC (Geomagnetically Induced Current) events for the 500 kV line and system in the Manitoba Hydro network. The results from the model are shown to be in close agreement with a recently recorded GIC event. The model is then used to predict waveforms for a possible maximum GIC level combined with different power flows. The effect of this event on the currents going through the harmonic filters and of the distorted waveforms on typical sequence filters is assessed. |
| Abstract: This paper describes a development in relaying hardware and philosophy which has been made possible by DSP's and industrial grade PC's. Details are given of a prototype design capable of being assembled and configured by a Utility. Results of tests on this prototype using the RTDS at the Manitoba HVDC Research Centre are presented. The project is a joint effort between the University of Manitoba and Manitoba Hydro. |
| Abstract: This paper describes the design and performance of a Real Time Digital Simulator (RTDS) for testing relays. The RTDS uses parallel processing architecture to run electromagnetic transient simulations in real time with a time step of the order of 50 microseconds. Relays can be tested in an interactive mode with the output from the relay trip circuit fed back into the simulation to control the appropriate breaker model. Examples are given of tests on distance relays. |
| Abstract: Control of HVDC back-to-back links is normally maintained with separate controllers at each end. This paper proposes a single unified controller for both ends, and assesses its performance. Two new measures of the difficulty of connecting a DC link to a weak AC system are developed, which take into account the link control strategy. Simulation results are used to investigate the performance of the unified controller, and the validity of the proposed measures. |
| Abstract: A fully digital, electromagnetic transients class of power systems simulator capable of continuous real-time operation has been developed at the Manitoba HVDC Research Centre. A detailed model of the Nelson River HVDC System's Bipole 1 controls was prepared for use with the RTDS (Real-Time-Digital-Simulator). Operation of the RTDS using the modelled HVDC controls, as well as using physical controls interfaced to the simulator is presented herein. |
| Abstract: not available |
| Abstract: Adding a dc circuit to an existing ac transmission line or replacing one ac circuit with a dc circuit is one method of significantly increasing the power transfer capability of the transmission line. Coupling at fundamental frequency from the ac circuit to the dc circuit on the same tower interferes with the clearing of dc line faults. Even though dc current in the fault arc can be brought to zero by the controls of the dc transmission systems, fundamental frequency secondary arc current can delay clearing of the fault. The factors which impact the duration of secondary arc are investigated both for balanced and unbalanced conditions on the ac circuit. |
| Abstract: The real time digital simulator (RTDS) developed by the Manitoba HVDC Research Centre is interfaced to a fully analogue HVdc simulator to greatly enhance its capability and performance. This paper describes the principle of the interface and features of the digital simulator. A test system based on an actual HVdc scheme is simulated with the combined real time digital simulator and analogue simulators and compared with the analogue system alone to verify the interface technique. |
| Abstract: not available |
| Abstract: not available |
| Abstract: An alternative and simpler solution is proposed for the direct connection of generators to HVdc converters. The generator exciter windings are connected in series with the output of the HVdc converter and take the place of the conventional smoothing reactor. Existing steady state and time domain simulation programs are modified to represent the behaviour of the series direct connection scheme. It is shown that series excitation extends naturally the power transmission capability and permits fast fault clearances. |
| Abstract: The need for an alternative to the use of electronic analogue simulators for power system simulation using digital computers have been recognized and exploited for quite some time. However, the increasing complexity of the power system with the use of power electronic devices challenges the techniques used to reproduce the physical phenomenon requiring very accurate and reliable representation of the system components and their combined operation as a complete system. Among the many techniques evolved the EMTP and state space formulations have been well accepted by power system engineers. The simplicity and robustness of the EMTP algorithm has gained popularity and is the most popular. On the other hand, the state space formulations are capable of very stable and accurate simulation of nonlinear devices while providing a modular, although is less efficient, approach. For systems involving non-linear components such as HVDC it is found that a hybrid approach results in better overall performance. |
| Abstract: The two alternative methods in current use for the transient simulation of HVdc power systems are Electromagnetic Transient Programs and State Variable Analysis. A hybrid algorithm is described in this paper which combines the two methods selecting their best features. The relative performances of conventional and hybrid algorithms are discussed. Simulation results of typical back-to-back HVdc link show that the hybrid representation provides more stable, accurate and efficient solutions. |
| Abstract: not available |
| Abstract: not available |
| Abstract: When the Nelson River Bipole 1 mercury arc valve group replacement project and planning for the expansion of the Nelson River HVDC system with a third bipole underway, it was decided to pursue a program to develop and validate detailed models of the existing HVDC transmission facilities and their associated ac systems for use in system studies. The first phase of the program concentrated on the development of detailed controls models associated with the Bipole 1 transmission facility. Based on previous experience at Manitoba Hydro with the Electromagnetic Transient DC simulation program (EMTDC), it was decided that model development and validation would use this program. This paper presents the reasons behind the development of detailed models, the methods used in developing models related to Bipole 1, results of validation tests, difficulties encountered during the process, and the overall benefits resulting from the project. An example of applying the models to investigate a low frequency oscillation which has occurred on the dc system in the past is also presented. |
| Abstract: This paper investigates the use of a multilevel GTO thyristor inverter as a static compensator. This design allows the voltage rating of the inverter to be considerably increased without the inherent problems of series connection of the GTO thyristors. Fundamental frequency switching of the inverter produces a staircase type waveform with reduced harmonic generation. The operation and control of the multilevel inverter is discussed in detail. The advantages of such a design over other currently proposed designs is discussed with respect to losses and harmonic generation. |
