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With penetration growing of renewable energy sources which integrated into power system have caused problems on grid stability. Electric Vehicles (EV) are one of the renewable energy sources that can bring significant impacts to power system during their charging and discharging operations. This article established a model of single machine infinite bus (SMIB) power system considering EV as a case study of load disturbance for power system oscillation. The objective of this research is to enhance stability and overcome the drawbacks of traditional control algorithms such as power system stabilizer (PSS), PID controller and fuzzy logic controller (FLC). The implementation’s effect of FLC parallel with PID controller (Fuzzy-PID) has been shown in this paper. The speed deviation (?ω) and electrical power (Pe) are the important factors to be taken into consideration without EV (only change in mechanical torque), EV with change in the mechanical torque and sudden plug-in EV. The obtained result by nonlinear simulation using Matlab/Simulink of a SMIB power system with EV has shown the effectiveness of using (Fuzzy-PID) against all disturbances.

Power system operation is characterized by the random variation of the load condition, continuous change in generation schedule and network interconnection. Moreover, Power systems have usually more disturbances such as actions of different controllers, switching of lines or increasing loads in the system [

In the late 1950’s most of electric power systems used Automatic Voltage Regulators (AVR) for damping the power system oscillations and maintain the overall stability of the power system [

In a previous work, a conventional controller such as power system stabilizer (PSS) [

Recently, fuzzy logic controller (FLC) showed up as robust tool in control of complex power system. However, it has more merits than other controllers such as simplicity, low cost and its robustness and effectiveness [

This paper is organized as follows. In Section (2) presents the system configuration that consists of two subsections, which are driving the power system considering EV model and explains the conventional controller models (PSS and PID). Design of fuzzy-PID controller is considered in Section (3). Simulation results and analysis are presented in Section (4). Finally, the conclusion is given in Section (5).

Parameters K_{1}, K_{2}, ・・・, K_{6} are the constant of linearized model of synchronous machine. From the blocks diagram shown in

The speed deviation

The damping coefficient (Damp) is included in the swing equation. The eigenvalues of the matrix A should lie in LHP in the S-plane for the system to be stable. It is to be noted that the elements of matrix A are depended on the operating condition. The values of K_{1}, K_{2}, ・・・, K_{6} in the matrix A are to be calculated according to the operating conditions of the generation system and connected power System [

PSS is widely used in the power system to improve the damping oscillations of the power system; sometime it is called the damping controller. The PSS is considered as comprising two cascade connected blocks, commonly lead-lag structure [

The gain determine the amount of damping and it is chosen by trial and error method and The washout stage is used to prevent a steady-state voltage shift, then the washout time constant

The proportional integral and derivative (PID) controller is a one of the earliest industrial controllers. It has many advantages: Its cost is economic, simple easy to be tuned and robust [

In the parallel form of the PID controller, there are three simple gains

The proposed coordinated of Fuzzy-PID controller block diagram is given in

All inputs and output variable of (FLC) are seven linguistic fuzzy which are defined as NB, NM, NS, ZO, PS, PM and PB means Negative Big, Negative Medium, Negative Small, Zero, Positive Small, Positive Medium and Positive Big [

Inputs and output values which are speed deviation, acceleration inputs and reference voltage output lies between [−1:1] and we adjust inputs factors Ku1, Ku2 to normalize inputs and then we change Ku3 to obtain optimal result [

Designing the coordinated of (Fuzzy-PID) depends on designing FLC and PID, tuning PID controller by using PID tuner in Matlab/Simulink model. However, FLC needs the definition of control rules, we have used the algorithm [

The dynamic performance of SMIB considering EV has been analyzed with the proposed coordinated (Fuzzy-PID) controller, PSS and PID. The speed deviation (∆ω) and electrical power (P_{e}) are studied for three cases are considered:

Case 1: in this case, nominal parameters of the system are considered and the system is examined in the absence of EV disturbance as shown in

Case 2: in this case, plug-in electric vehicles as a load disturbance integrated to SMIB.

Case 3: in this case, suddenly plug-in electric vehicles as a load disturbance integrated to SMIB from (4:7) sec.

U_{Fuzzy} | ||||||||
---|---|---|---|---|---|---|---|---|

NB | NM | NS | ZO | PS | PM | PB | ||

NB | NB | NB | NB | NB | NM | NS | ZO | |

NM | NB | NM | NM | NM | NS | ZO | PS | |

NS | NB | NM | NS | NS | ZO | PS | PM | |

ZO | NB | NM | NS | ZO | PS | PM | PB | |

PS | NM | NS | ZO | PS | PS | PM | PB | |

PM | NS | ZO | PS | PM | PM | PM | PB | |

PB | ZO | PS | PS | PB | PB | PB | PB |

(Fuzzy-PID) coordination produce some undershoot than other but it has a good performance.

In this study, the coordination (Fuzzy-PID) controller is applied to SMIB power

system considering EVs which used as a case study as load disturbance for stability enhancement. A comparison study of the proposed coordinated (Fuzzy-PID) is

carried out with conventional controllers such as PID and PSS. The result observed by simulation showed that the coordination (Fuzzy-PID) obtained a robustness performance for all the cases study.

Magdy, G., Shabib, G., Elbaset, A.A., Kerdphol, T., Qudaih, Y. and Mitani, Y. (2017) A New Coordinated Fuzzy-PID Controller for Power System Considering Electric Vehicles. Energy and Power Engineering, 9, 425-435. https://doi.org/10.4236/epe.2017.94B048

・ Generator parameters:

Exciter parameters:

・ The K’s:

・ Transmission line:

・ Operating point:

・ Electric Vehicles

・ TEV = 0.1, PEV = 0.2 Pu

・ PSS Parameter

K = 50, T1 = 10, T2 = 0.25, T3 = 0.03, T4 = 0.05, T5 = 0.15