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STATCOM – Working Principle, Design and Application

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What is SATACOM? STATCOM or Static Synchronous Compensator is a power electronic device using force commutated devices like IGBT, GTO etc. to control the reactive power flow through a power network and thereby increasing the stability of power network. STATCOM is a shunt device i.e. it is connected in shunt with the line. A Static Synchronous Compensator (STATCOM) is also known as a Static Synchronous Condenser (STATCON). It is a member of the Flexible AC Transmission System (FACTS) family of devices. The terms Synchronous in STATCOM mean that it can either absorb or generate reactive power in synchronization with the demand to stabilize the voltage of the power network. Working Principle of STATCOM: To understand the working principle of STATCOM, we will first have a look at the reactive power transfer equation. Let us consider two sources V1 and V2 are connected through an impedance Z = Ra + jX as shown in figure below. In the above reactive power ...
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Difference between Snubber Circuit and Crowbar Circuit

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As we know, both Snubber Circuit and Crowbar Circuit is used for protection against Overvoltage using Thyristor but they way they protect the Thyristor has some difference. Crowbar Circuit: Power supplies are normally reliable, but if they fail then they can cause significant damage to the circuitry they supply. To protect against this it is possible to add a simple SCR overvoltage crowbar protection circuit. Crowbar protection is a fail-safe protection mechanism which short circuits the output of a power supply under failure conditions such as over voltage. Here Fail-Safe means, in case of failure the system will go to safe condition. Crowbar protection can also refer to a circuit which has its sole purpose to cause a fuse to blow by subjecting it to high current. Figure below shows a typical Crowbar Circuit. Above Crowbar Circuit uses an 8V supply and has its overvoltage protection set at 9.1V but this overvoltage setting can be adjusted by changing to the zene...
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Single Line to Ground Fault Analysis

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In earlier posts we discussed, Concept of Symmetrical Components and  Calculation of Symmetrical Components . It is recommended to go through these topics before analyzing Single Line to Ground Fault. You must read,  Concept of Symmetrical Components  and  Calculation of Symmetrical Components Let us consider a three phase system with earthed neutral as shown below. Let us assume that a ground fault takes place in A phase (In many industries and numerical relays, normally the phases are said as A, B and C instead of R, Y and B, though they represent the same thing i.e. A phase means R phase, B means Y phase and C means B phase). E a , E b and E c are the Generator terminal voltage per phase. Bold letters here represent vector form.  Because of ground fault in A phase, the voltage at the point of fault will become zero and current through the other phases i.e. B and C phases will become zero. Therefore we can write as V a = 0 I b = 0 I c = 0 Therefore, from...
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