No abstract

No abstract

This paper is concerned with the application of damping torque technique to examine the efficacy of various control signals for reactive power modulation of a midpoint located Static Var System (SVS) in enhancing the power transfer capability of long transmission lines. A new auxiliary signal designated Computed Internal Frequency (CIF) is proposed which synthesizes internal voltage frequency of the remote generator from electrical measurements at the SVS bus. It is demonstrated that this signal is far superior than other conventional auxiliary control signals in that it al.lows full utilization of the network transmission capacity. The damping torque results are correlated with those obtained from eigenvalue analysis.

No abstract

Controller design of a STATCOM-based voltage compensator requires a valid analytical model of the system. If phasor algebra is used for modeling, it is difflcult to accurately describe the STAT-COM behaviour during compensation of subcycle transients in t h e PCC voltage. In this paper, a small-signal model of the system, with a distribution line, is derived. Predictions based on frequency-domain analysis are made, which are validated by experimental results. This model, therefore, can be used for controller design where subcycle voltage transients are to be compensated. It is shown that the voltage controller, so designed, can accomplish voltage sag mitigation. A discussion on the design of dc bus voltage controllerand experimental results showing its performanceis also included.

No abstract

No abstract

The development of power semiconductors, specially IGBT's has led to the small power HVDC transmission based on Voltage Source Comerten (VSCs). The VSC based HVDC transmission system mainly consists of two converter stations connected by a de cable. This paper presents the modelling and control design of VSC based H M C which uses tweIve pulse three level converter topology. The reactive current injected by individual VSCs can be maintained constant or controlled to regulate converter bus voltage constant. While one VSC regulates the de bus voltage the other controls the power Bow in the dc link. Each VSC can have up to 4 controllers depending on the operating mode. The controller structure adapted for power controlIer is of PID type and all other controllers are of PI type. Each operating mode requires proper tuning of controller gains in order to achieve satisfactory system performance. This paper discusses a systematic approach for parameter optimization in selecting eontroller gains of VSC based HVDC. The analysis of VSC based HVDC is carried using both D-Q model (negkting harmonics in the output voltages of VSC) and three phase detailed model of VSC using switching functions. While the eigenvalue analysis and controller design is based on the D-Q model, the transient simulation considers botb models. The analysis considers different operating modes of the converters.