**5. Conclusions**

Conclusions resulting from the analysis of the monitored data on the 110 kV – T1 side (power station) as well as the main observations that emerge from the analysis of the electrical measurements performed are:

• there is an unbalance of charge in the three phases of the analyzed electrical circuit;

*Contributing by Monitoring Energy Efficiency to the Development of Optimization Measures… DOI: http://dx.doi.org/10.5772/intechopen.101801*


Under these conditions, the aim is: balanced charging of the three phases, improved power factor compensation, improved flicker level and operation with an improved harmonic regime (electric harmonics).

There is a good classification of the voltage level on phases and between phases, in the normed parameters (framing in the normed limits).

The two proposed performance solutions (in this case):

A. The connection of a STATCOM to the 110 kV bus bars of the user (**Figure 22**) leads to a factor of reduction of the flicker level between 3 and 6 (they multiply). The control block BC receives the information regarding the voltage level at the 110 kV bus bars and determines its maintenance by injection of real-time capacitive reactive power from capacitor C via the appropriate controlled inverter.

**Figure 22.**

*Scheme of a STATCOM (for analyze) [3–7, 12]. a. Scheme of a STATCOM for voltage control at 110 kV bus bars. b. Functioning scheme/diagram of a STATCOM equipment.*

**Figure 23.** *The functioning diagram of a back-to-back FACTS system [15, 16].*

Connecting SVC or STATCOM to the user's 110 kV bus bars, along with using a dedicated 400/110 kV transformer, enables a reduction of practically 1.5 … 2 times (in case of using SVC), and 3 … 6 times (in the case of using STATCOM), of the disturbance level at the 110 kV bars of the Electrical Station [3–7, 12]. In this way, the problems related to the disturbance of the users in the area are completely solved as well [13].

In CIGRE study [12, 14] regarding a STATCOM type FACTS device to improve the flicker level in the case of an ELECTRIC ARC OVEN, it is said that the reduction of the flicker level in a single installation was reduced from an initial factor of Pst95% = 3,75 without STATCOM, to Pst95% = 0.76 with STATCOM in operation, for a short-term probability of 95% [3–7, 12]. This fact indicates that the flicker level has improved about five times with the introduction of the compensator.

B. "Back-to-Back System" - By using this type of system/equipment, the level of flicker indicators on the bar on which it is mounted is eliminated, in the sense that it can be fully controlled [3–7, 12]. This is due to the well-known fact that any type of disturbance is eliminated from the arc furnace to the Power Station by passing through a DC voltage level (**Figure 23**) [15, 16]. Obs. Back-to-back equipment has high-power thyristor electronic devices, which can themselves produce/generate system disturbances, if they are not correctly chosen and calculated with great accuracy.
