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A wide area monitoring system (WAMS) with reliable telecommunication infrastructure can be expanded and enhanced with additional protection and control functionalities using synchronized phasor data measurements. With that aim, we have developed a multifunctional line protection (MFLP) model with both system and back-up protection functions. Theoretical premises based on transmission and relay protection system knowledge, together with the experience gathered from the operation of existing wide area systems, were used to develop the proposed model. Four main groups of simulation scenarios were defined in order to test the newly implemented functions. The results of the simulation process confirm the assumptions underlying the design of our MFLP module. Simulation results are then used for definition of the protection criteria required for implementation of the wide area protection algorithm in a control center. Conclusions drawn from the protection responses of the proposed algorithm that strengthen the algorithm design process are elaborated in the paper. The main contribution of the paper is the design and development of a centralized MFLP algorithm based on synchronized phasor data that is able to issue a trip command to a circuit breaker before an out-of-step condition occurs.

The paper analyses the impact of Electric Vehicle (EV) integration into different power systems and their flexibility potential in mitigating the uncertainty and variability of renewable energy sources (RES) generation. The problem is cast as Mixed Integer Linear Programming (MILP) unit commitment, modelling different generation mix/technologies over a number of scenarios. The results, as expected, show that different EV charging strategies have different impacts on power system operation and unit scheduling. In addition, the analyses support the premises that the greater number of EVs, with coordinated charging strategies, can have environmental benefits in terms of reducing CO 2 emissions in addition to reducing wind curtailment and system operation costs. These benefits are more obvious in low flexible power systems characterized by dominantly thermal power plants, while they are less pronounced in balanced hydro thermal systems.Keywords-electric vehicles; renewable energy sources integration; mixed integer linear programming (MILP); power generation scheduling; spinning reserve; power system flexibility NOTATIONThe notation used is listed below for quicker reference. Parameters Δ Time period [h] ρ Frequency response slope η h Efficiency of hydro power plants [%] η hp Pumping efficiency of pump-storage [%] A Fixed cost of thermal units [$/h] A h Fixed cost of hydro units [$/h] B Variable cost of thermal units [$/MWh] B h Variable cost of hydro units [$/MWh] C shed Load shedding penalties [$/MWh] C shut Shut-down cost [$] C start Start-up cost [$] C over Generation shedding penalties [$/MWh] E mc Carbon emissions penalties [$/kgCO 2 ] E mr Carbon emissions rate [kgCO 2 /MWh] E mrstart Start-up carbon emissions rate [kgCO 2 ] F dn Total downward frequency response [MW] F up Total upward frequency response [MW] G Total number of thermal units of type i Gh Total number of hydro units of type i H Hydro power plant head [m] I Hydro power plant inflow [m 3 /s] kv Reservoir water loss coefficient [%] Ni, Nih and N EV Number of thermo, hydro and EV types n arr Number of EVs arriving to the grid n g Number of EVs connected to the grid n leav Number of EVs leaving the grid P evmax , P evmin Maximum and minimum EVs charge, discharge [MW] P MAX ,P MIN Generation limits of thermal PP [MW] P MAXh ,P MINh Generation limits of hydro PP [MW] Q max , Q min Turbine outflow limits [m 3 /s] R up ; R dn , Total upward/downward reserve [MW] S cons Energy accumulated in one EV of type i after trip [MWh] S ev0 Initial energy stored in EVs [MWh] S max Max capacity of one EV of type I [MWh] T dn , T up Minimum down/up time of thermal PP [h] V k Water storage reservoir limit [m 3 ] V dn , V up Ramp down/up rate [MW/h] Variables η c EVs charging efficiency η d EVs discharging efficiency Ω Wind curtailment [MW] a g , a p Pump-storage decision variable C HE Hydro power plant total cost [$] C TE Thermal power plant total cost [$] Em Total carbon emissions [kgCO 2 ] e minus Load shedding [MW] e plus Generation shedding [MW] f dn ; f up Frequen...