IMPROVING THE TRANSIENT STABILITY OF NIGERIAN 330KV TRANSMISSION NETWORK USING STATIC VAR COMPENSATION PART I: THE BASE STUDY

In this paper, the base study for improving the transient stability of Nigerian 330kV transmission network using Static Var Compensation (SVC) is conducted with the focus of developing indices that can appropriately size and locate SVC within the network. The study is performed using commercially available software Dig SILENT Power Factory. The overloaded lines which could excite instability in the network are identified. Fixed capacitor thyristor controlled reactor is used to model the SVC and is appropriately sized and located within the network. Transient stability of the network is analysed by determining the critical clearing time of the acute generators when a balanced three phase fault is applied to the middle of the critical lines within the network using step-by step technique. Some of the key results reveal that the lines: Jebba- Osogbo, Shiroro-Kaduna, Benin-Sapele and Benin-Onitsha are the critical lines within the network. The Critical Clearing Times (CCTs) of the acute generators when 3-phase fault is applied at Jebba- Osogbo and Shiroro-Kaduna transmission lines are 380ms and 480ms, respectively. However, generators located at Afam and Sapele that are close to Benin-Sapele and Benin-Onitsha transmission line, respectively are always losing synchronism to 3-phasefault of any duration.  Appropriately sized SVCs with values 124Mvar, 73Mvar, 62Mvar and 110Mvar located at Osogbo, Kaduna and Benin compensated the network and increase the CCTs to 470ms, 500ms, 220ms and 120ms, respectively. http://dx.doi.org/10.4314/njt.v35i1.2

Is the Public willing to help the Nigerian Police during the Boko Haram crisis? A look at moderating factors.

This paper sought the opinion of 200 Nigerians on their willingness to cooperate with the Police during the Boko Haram crisis. Public perceptions of Police effectiveness during the crisis, residence location, gender and religious affiliation were used as moderators. Data was analysed using an explanatory factor analysis and structural equation modelling. Results indicated a strong association between perceived effectiveness and willingness to report to the Police with respondents who question the effectiveness of the Police being less likely to be willing to report criminal activity about Boko Haram. Further to this, the impact of religion on willingness to report was at least partially mediated by perceived effectiveness of the Police with the results showing that Christian respondents perceived the Police as less effective. Females and those living in the North were significantly less willing to report criminal activity to the Police The findings are then discussed in relation to the BH crises and directions for future research are given

Simulation of a-Si PV system linked to the grid by DC boost and three-level inverter under cloud scope

This paper is about a PV system linked to the electric grid through power converters under cloud scope. The PV system is modeled by the five parameters equivalent circuit and a MPPT procedure is integrated into the modeling. The modeling for the converters models the association of a DC-DC boost with a three-level inverter. PI controllers are used with PWM by sliding mode control associated with space vector modulation controlling the booster and the inverter. A case study addresses a simulation to assess the performance of a PV system linked to the electric grid. Conclusions regarding the integration of the PV system into the electric grid are presented. © IFIP International Federation for Information Processing 2015