**2. Causes of outages and blackouts in Libya**

Since the 2011 uprising, the Libyan power grid has suffered from several operating and infrastructure problems. Most of the maintenance projects have stopped due to security and political problems of the country. Among the most prominent of these problems are; the repeated attacks on GECOL's assets and on workers, stealing of electrical equipment such as copper wires, transformers, and electrical transmission towers. Which caused the GECOL to be unable to perform some of the necessary periodic maintenance for most of the power plants. These problems resulted in a decline in the performance of the electricity network and a severe deficiency in the production capacity of the generating stations, long outages, and blackouts in most areas in the country [6].

### **2.1 A brief overview of power plants in Libya**

The GECOL owns about 26 electric power plants. These power plants contain 85 generating units of different ages, sizes, and operating technology. These units are mostly concentrated on the sea in the North [6]. The official installed capacity by the GECOL until 2017 is 10.238 GW, while the energy available to consumers only 5.53 GW until the date of this study, which represents 52% of the total capacity of the GECOL. Besides, 19 units of the GECOL units are must be discontinued due to the end of their useful life and the futility of their continued operation [6]. In short that, there is a deficit in the power production of the GECOL at a rate of approximately 25% of the average production, compared to the maximum value of the energy demand, which is 7.5 GW [7].

#### **2.2 Overview of control department in GECOL**

The control infrastructure in the GECOL consists of several levels. At the top of the system, is the National Control Center (NCC), as shown in **Figure 1**. Its mission

**Figure 1.** *Distribution control system of GECOL precedence DCC's in yellow [6].*

is to supervise, coordinate and control the power plants. The main transmission network is 400 KV, whereas 220 KV is the subnet that linking between Egypt in the east and Tunisia in the west [6].

Libya's control system is divided into two parts: the Tripoli Regional Control Center (TRCC) in the Western part and the Benghazi Regional Control Center (BRCC) in the East, both parts responsible for controlling and operating the substation 220 kV. In addition, the Distribution Control Center is responsible for the medium and low voltage network lines of 66 kV, 30 kV and 11 kV. Whereas NCC, TRCC and BRCC are supervised by the General Control Department. The Distribution Control Center (DCC) is under the control of the General Distribution department and the Medium Voltage General Department. These control centers are linked to the generation stations and substations and are controlled by a fiber optic system. This system consists of ground cables, Optic Ground Wires (OPGW) transmission towers, and some old power carriers and microwave connections [6].

After the uprising in 2011, the transmission lines were mostly damaged due to the civil war, which results in losing communication links one by one and a huge loss in each fiber optic-based data and voice communications links between the power plants and network substation.

The mentioned problems in the communication links and some Remote Terminal Units (RTUs) in the stations, led to a loss of 80% of the data compared to the year 2011, where there is only a 2% loss. The NCC and TRCC computer system only controls 20% of the data that covers main points in the network, which provides a partial picture to the control engineers [6]. Some lost data is covered by Supervisory Control and Data Acquisition (SCADA) and the rest of the data is manually entered to give a fair picture of the network. Consequence, NCC is completely dependent on the operators in all stations and on voice communications linked with the operators to effectively control the network [6].

Through investigations and studies for the GECOL Control General Department, it was established that the four causes of the blackouts in 2017 were for the following reasons; firstly, the interruption of some transmission lines has shaking the operative reliability of the electrical power grid. Secondly, outages in some transmission lines, which weakened the operational capacity of GECOL power system. Thirdly, all blackouts were due to in faults in the transmission network and as a result the loss of some generation units. Fourth, the southern region suffers from voltage instability, which caused the network frequency to rise, followed by a transmission failure, following the initial transmission fault clearance. Finally, the recorded data of frequency and voltage response after the fault is removed, indicates the possibility of a "Fault-induced delayed voltage recovery" (FIDVR), causing an increase in frequency and loss of generation. This phenomenon has been observed to occur in the electrical power grid with large loads of inductive motors, specifically the loads of air conditioners. The Libyan electrical power grid is full and saturated with air conditioner loads, which is easy to assure that at the end of the summer and with temperate temperatures, particularly in a two-week period of September 2017, peak loads decreased by 2 GW because consumers did not need to use their air conditioners. So there is no sure solution to this problem, which requires more research and studies to solve the problem and avoid the consequences resulting from it [6].
