The requirements on network control systems are growing as secure and economic energy management is becoming ever more important. Planning and implementation of SCADA systems (Supervisor…Descripción completa
Submodule overcurrent caused by DC pole to pole fault in modular multilevel converter HVDC MMC HVDC system is one of the important research objects about its electrical characteristics. In this paper, the fault mechanism before and after the converte
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In this guide, you will learn how to determine the maximum and minimum compensator power in order to compensate reactive power in case of harmonic pollution.
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unit 5 hvdc
A great presentation on Definition and classification of power system stability.
Power System Operation and Control
Wind power is the most reliable and developed renewable energy source. This paper gives a study on power flow control of a grid connected Doubly Fed Induction Generator DFIG wind turbine. Doubly Fed Induction Generator DFIG has widely used for large
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The continuously increasing demand for electric power and the economic access to remote renewable energy sources such as off shore wind power or solar thermal generation in deserts have revived the interest in high voltage direct current HVDC multite
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work on hvdc in arevaFull description
Microgrids are nowadays used to produce electric energy with more efficiency and advantage. However, the use of microgrids presents some challenges. One of the main problems of the microgrids widely used in electrical power systems is the control of
Use of nonlinear loads has been increased in large extent in industries now a days which injects harmonic currents in supply system. These harmonics creates power quality issue. Shunt Active Power Filter SAPF is the popular and efficient solution to
Smoothing Reactor & Reactive power Control o HVDC System
y Prof. Bhim Singh Department of Electrical Engineering Hauz Khas, New DelhiDelhi-110016, -110016, India bsingh@ee.iitd.ac.in,, bsingh@ee.iitd.ac.in
Smoothing reactor is connected before the DC filter and in
It smoothin the DC current
IT also serves as a buffer between the converters and the DC line
including the reduction of ripple in the current
Smoothing Reactor
Smoothing reactor is connected before the DC filter and in
It smoothin the DC current
IT also serves as a buffer between the converters and the DC line
including the reduction of ripple in the current
Functions of Smoothing Reactor
They reduce the incidence of commutation failure in inverters cause y ps n t e vo tage at at t e co converter us
reducing the rate of rise of direct current in the bridge when the dirrect vo di volt ltaage of ano notthe herr ser eriies co conn nnec ecte ted d br briidge co coll llaaps psees
They smooth the ripple in the direct current in order to prevent
The decrease harmonics volta es and currents in the DC Line
Functions of Smoothing Reactor
They limit the crest current in the rectifier due to a short circuit on t e ne
pair operation, due to the discharge of shunt capacitance of the DC line
The last three functions are not relevant for Back-Back HVDC
Inductor value for DC transmission lines - 0.27 H to 1.5 H
Inductor value for Back-to-Back system - 12 mH to 200 mH
Smoothing Reactor
Sizing of the reactor is done not only from the above consideration
Also from the point of view of minimizing the effect of low order
It is necessar to avoid the series resonance of the DC s stem at fundamental frequency and also at the second harmonics
The inductor value must remain constant with variations in the direct current
The smoothing reactor also helps to limit the fault current in the DC line
Smoothing Reactor
It is also necessary to have to small reactor of the order of 5 to 10 , consequences of lightning strokes to the line
The advantage of having the reactor at the ground side is that it allows the converter ground faults to be cleared by converter
The insulation level of the reactor also is reduced for this location of the reactor
Location of Smoothing Reactor
Equivalent Circuit for calculating Ripple
eac ve ower
on ro
Reactive Power Control
The converters in HVDC are line commutated, which implies that the current initiation in the valve can only be delayed with re erence to t e zero cross ng o t e converter us vo tage
This results in LAGGING power factor operation of the converters
Requiring reactive power source connected at the convrter bus for better voltage control
Reactive Power Control
The reactive power source that are used vary from switched ca acitors to static VAR s stems
The operation with weak AC system can be problematic due to voltage instability and dynamic overvoltage
the converter as a static VAR compensator in addition to power conversion
Control strategies
The re ion of o eration of a converter brid e is bounded b the limits on the current and firing angle
The region is bounded by
Minimum α characteristics n mum γ c aracter st cs
Operating Region of Bridge om Pd -Qd p ane
Alternate Reactive power control c aracter st cs
There is need to modif the reactive ower characteristics of the converter station either by – Choice of the reactive power sources – Adjusting the converter control characteristics
The alternate control strategies are . 2. Constant Leading power factor characteristics
