THE IMPACT OF STATCOM ON DISTANCE RELAY

Under The Esteemed Guidance Of

Presented by:  

DISTANCE PROTECTION

It is used for the protection of transmission or sub-transmission lines . It includes a no of distance relays of same or different type.

Types of Distance Relays

Impedance relay measures line impedance b/w fault point and relay location.

Reactance Relay measures reactnce of transmission line.

MHO Relay measures component of admittance

What is FACTS ?

Benefits of FACTS

•Increase the system security•Provide greater flexibility•Increase the loading capability•Reduce reactive power flow & loop flowFACT Devices

Used for power flow control,load sharing and voltage regulation of system oscillations .some of are,

STATCOM ,SSG ,SSSC ,TCVR ,TCVL ,UPFC

STATCOM

IT IS OPERATED AS A SHUNT-COMPENSATED STATIC VAR COMPENSATOR WHOSE CAPACITIVE/INDUCTIVE OUTPUT CURRENT CAN BE CONTROLLED INDEPENDENT OF AC SYSTEM VOLTAGE.

•It is based on a voltage /current sourced converter.•It acts as active filter to absorb system.•Statcom has strong on fluence on load flow control & voltage control over other devices.

STATCOM MODEL

•This tool is used to model the 138kV parallel transmission system with 48-pulse STATCOM installed in the mid-point of one transmission line.

•It is installed in the middle of the second transmission line.

•The positive & negative sequence line impedances are 0.195+j3.3425Ω/km

•The zero sequence transmission line impedance is 2.638+11.27jΩ.

48-pulse voltage inverter

It consists of four 3-phase, 3-level GTO inverters and four phase-shifting transformers.

APPARENT IMPEDANCE CALCULATION

•The relay is installed on the right side of Bus S.•When a single phase to ground fault occurs at the right side of STATCOM and the distance is n*L from the relay point, the positive, negative and zero sequence networks of the system during the fault are

Mho characteristic with a positive sequence voltage polarization is used as zone one distance relay to cover 80% of the transmission line.

SIMULATION RESULT

To study the coverage of the mho characteristic, faults at different positions have been studied, and the apparent resistance and reactance for different fault locations are

phase to phase fault

STATCOM on the right side

simulation results

•During a fault, the apparent impedance will increase if the STATCOM supplies reactive power to the system, the apparent impedance will decrease and vice-versa.

•Influence ratio will increase with an increasein location of the fault.

•During a phase to phase fault, the apparent reactance increases but the apparent resistance may decrease

•The position of distance relay has a big impact on the relay performance.

CONCLUSION

The simulation results show clearly the impact of STATCOM on distance relay performance.

Work is underway in extending the study for other types of system and fault conditions such as the effect of the location of STATCOM on distance relay

THANK Q