**Case 1: Capacitive Series Compensation at line 1-3**

If the dynamic series FACTS Controller (type capacitive)installed at line 1-3 adjusted to deliver a capacitive reactance, it decreases the line's impedance from 10Ω to 4.9919Ω, so that power flows through the lines 1-2, 1-3, and 2-3 will be 250 MW, and 1750 MW, respectively. Fig. 8 illustrates the per cent loading of lines. It is clear that if the series capacitor is adjustable, then other power flow levels may be realized in accordance with the ownership, contract, thermal limitations, transmission losses, and wide range of load and generation schedules. Fig. 8 shows clearly the effect of series capacitive compensation to control the active power flow with another degree of compensation ( 6 *XC* = Ω ).

Fig. 8. Load flow solution with consideration of dynamic compensators: Case1

Fig. 9. Load flow solution with consideration of dynamic compensators: Case1

Understanding Power Quality Based FACTS

**2.3 Basic types of FACTS controllers** 

• Combined series-shunt Controllers

Controller only supplies or consumes variable reactive.

impedance, variable source, or a combinaison of these.

*Voltage Control* 

**c. Hybrid Controllers (Combined series-shunt)** 

*Bus i Bus J* 

*Vr*

flow and hence represents injection of current into the line (Mahdad, 2010).

and total power losses.

**a. Series Controllers** 

Fig. 12. Series Controller **b. Shunt Controllers** 

Fig. 13. Shunt Controller

Gyugyi L, 1999) : • Series Controllers • Shunt Controllers

Using Interactive Educational GUI Matlab Package 215

As we can see from simulation results depicted in different Figures; the location of series FACTS devices affect significtly the perfermances of power system in term of lines loading

In general, FACTS Controllers can be classified into three categories (Hingorani, NG., and

In Fig. 12 the series controllers could be variable impedance, such as capacitor, reactor, etc., in principle; all series controllers inject voltage in series with the line. Even variable impedance multiplied by the current flow through it, represents an injected series voltage in the line. As long as the voltage is in phase quadrature with the line current, the series

In Fig. 13 as in the case of series Controllers, the shunt controllers may be variable

+Q -Q

In principle, all shunt controllers inject current into the system at the point of connection. Even a variable of shunt impedance connected to the line voltage causes a variable current

This could be a combination of separate shunt and series compensators, which are controlled in coordinated manner, or a unified power flow with series and shunt elements.

P *Power flow control* 

*Bus i Bus J* 

#### **Case 2: Inductive Series Compensation at line 2-3**

If the dynamic series FACTS Controller (type inductive) installed at line 2-3 adjusted dynamically to deliver an inductive reactance, it increase the line's impedance from 5 Ω to 12.1Ω, so that power flows through the lines 1-2, 1-3, and 2-3 will be 248.22 MW, 1751.78 MW and 1248.22 MW, respectively.

Fig. 10. Load flow solution with consideration of dynamic compensators: Case2

Fig. 11. Load flow solution with consideration of dynamic compensators: Case2

It is clear from Fig. 9 and Fig. 10, that if the series inductance is adjustable, then other power flow levels may be realized in accordance with the ownership, contract, thermal limitations, transmission losses, and wide range of load and generation schedules.

As we can see from simulation results depicted in different Figures; the location of series FACTS devices affect significtly the perfermances of power system in term of lines loading and total power losses.
