ann based svc switching at distribution level for minimal injected harmonics

ANN Based SVC Switching ANN Based SVC Switching at Distribution Level for at Distribution Level for

Minimal Injected HarmonicsMinimal Injected Harmonics

Presented By

A.Yateesh Kumar Yadav

AURORA’S RESEARCH AND TECHNOLOGICAL INSTITUTE

DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING

The Indian power distribution systems are facing a variety of problems due to non-linear loads in the last decade. In addition to poor voltage profile, the power factor and harmonics of the system are the major concerns of the utility.

To improve voltage stability and power system stability in long transmission line reactive power need to be compensated.

A Static Var Compensator generally consists of a Thyristor Controlled Reactor (TCR) & a Thyristor Switched Capacitor (TSC) and compensates loads through generation or absorption of reactive power.

The ANN controller is used to control the SVC so that it balances the reactive power drawn by the supply, minimize the reactive power drawn from the supply and minimize the harmonics injected into the system in an acceptable time.

In this shunt type compensation are used because generally voltage is maintained constant and current is variable .

Thus series, series-series & series-shunt connections are not used for compensations due to variable voltage.

For shunt type compensation the techniques used for minimal injecting harmonics are

1) SVC

2) STATCOM

3) DSTATCOM

In transmission line, 99% SVC or STATCOM are used where as 1% DSTATCOM are used.

1) STATIC VAR COMPENSATOR

The Static Var Compensator (SVC) is a shunt type FACTS device which is used to improve the power quality for the purpose of voltage and reactive power control. SVC is connected as Thyristor Controlled Reactor- Fixed Capacitor (TCR-FC). The SVC is an automated impedance matching device, designed to bring the system closer to unity power factor .The current in the reactor is varied by the method of firing delay angle control method.

2) ARTIFICIAL NEURAL NETWORK

ANN is a controller which is used to solve non-linear problem caused due to harmonics. The function of ANN is to process the information. ANN choose the optimum combination of firing angles of TCR for controlling SVCs on-line.

Dr Cleve Moler, Chief scientist at MathWorks, originally wrote Matlab, to provide easy access to matrix software.

Stands for MATrix LABoratory.

Matlab is a high-performance language for technical computing.

SIMULINK is a Matlab toolbox designed for the dynamic simulation of linear and nonlinear systems as well as continuous and discrete-time systems.

Use the Library Browser to browse and search Simulink block libraries for blocks to use in your models. 

Neural network toolbox in MATLAB 7.0 version was used for training and simulating ANNs.

Advantages

1) Unlimited data transfer.

2) Higher efficiency within compensating techniques.

Disadvantages

1) It is very costly.

2) Working process is complex.

These type of techniques can be used in

1) Transmission Line

2) Sub-Stations

3) Micro-Grid

This type of control techniques are used for minimization of harmonics but present this are not used in India due to cost point of view.

The proposed ANN based approach can be effectively used to reduce and balance the reactive power drawn from the source

under unbalanced loadings while keeping the harmonic injection into the power system low. The case study proves that

the percentage THD under optimized condition is much less than the percentage THD under unity power factor condition. The computational time required was found to be satisfactory

for the system considered. The scheme can be effectively used at distribution level where the load harmonics is not a major problem. The performance of various controllers is then

compared based on non linear simulation results. Among these the performance of the proposed controller is found to be better

and damp out the system oscillations at faster rate. Digital computer simulations were performed using

MATLAB/SIMULINK software.