07-08-2012, 01:34 PM
Static Synchronous Series Compensator: A Solid-state Approach to the Series Compensation of Transmission Lines
[attachment=30369]
This paper describes an active approach to series line compensation,
in which a synchronous voltage source (SVS), implemented by a
GTO-based voltage-sourced inverter, is used to provide controllable
series compensation. This compensator, called static synchronous series
compensator (SSSC), is immune to classical network resonances
and it can provide controllable compensating voltage over an identical
capacitive and inductive range, independently of the magnitude of the
line current. Whereas conventional series capacitive compensation at a
given transmission angle increases the transmitted power by a fixed
percentage of that transmitted by the uncompensated line, the SSSC
increases it by a fixed fraction of the maximum power transmittable
by the uncompensated line, as illustrated in Figure 1. The SSSC is also
able to reverse the power flow by injecting a sufficiently large series
reactive compensating voltage, as shown in Figure 2 by the waveforms
obtained from a TNA hardware model.
A Model of Large Load Areas for
Harmonic Studies in Distribution Networks
The paper illustrates the research activity aimed at proposing a
model of complex load areas able to represent with greater accuracy
the rotating part of the load in harmonic studies.
Many studies have been performed by specialists in rotating machinery
in order to characterize more accurately the behavior of induction
motors with an increase in supply frequency. The relevant models
have been shown to accord well with induction motor performances in
respect of both nonsinusoidal supply at high frequencies and during
transients. Even though the above equivalent circuits are suitable for
single-motor representation; they, in fact, do not seem to be directly
utilizable to simulate large groups of motors in system studies such as
harmonic penetration analyses in distribution networks.
Recent works by International Committees on this topic have recognized
the need, as in other power system studies, to model the load
as an aggregate, though evidencing some uncertainties that call for
experimental studies specifically concerned with network distribution
levels.
The parameters that are needed for representing the total rotating
load with a single equivalent motor can no longer directly relate to the
structural characteristics and electrical ratings of individual motors, and
are therefore difficult to evaluate.
[attachment=30369]
This paper describes an active approach to series line compensation,
in which a synchronous voltage source (SVS), implemented by a
GTO-based voltage-sourced inverter, is used to provide controllable
series compensation. This compensator, called static synchronous series
compensator (SSSC), is immune to classical network resonances
and it can provide controllable compensating voltage over an identical
capacitive and inductive range, independently of the magnitude of the
line current. Whereas conventional series capacitive compensation at a
given transmission angle increases the transmitted power by a fixed
percentage of that transmitted by the uncompensated line, the SSSC
increases it by a fixed fraction of the maximum power transmittable
by the uncompensated line, as illustrated in Figure 1. The SSSC is also
able to reverse the power flow by injecting a sufficiently large series
reactive compensating voltage, as shown in Figure 2 by the waveforms
obtained from a TNA hardware model.
A Model of Large Load Areas for
Harmonic Studies in Distribution Networks
The paper illustrates the research activity aimed at proposing a
model of complex load areas able to represent with greater accuracy
the rotating part of the load in harmonic studies.
Many studies have been performed by specialists in rotating machinery
in order to characterize more accurately the behavior of induction
motors with an increase in supply frequency. The relevant models
have been shown to accord well with induction motor performances in
respect of both nonsinusoidal supply at high frequencies and during
transients. Even though the above equivalent circuits are suitable for
single-motor representation; they, in fact, do not seem to be directly
utilizable to simulate large groups of motors in system studies such as
harmonic penetration analyses in distribution networks.
Recent works by International Committees on this topic have recognized
the need, as in other power system studies, to model the load
as an aggregate, though evidencing some uncertainties that call for
experimental studies specifically concerned with network distribution
levels.
The parameters that are needed for representing the total rotating
load with a single equivalent motor can no longer directly relate to the
structural characteristics and electrical ratings of individual motors, and
are therefore difficult to evaluate.