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United Arab Emirates University College of Engineering Electrical Engineering Department. Automatic Generation Control. Prepared by Abeer ALNuaimi Balqees ALDaghar Afra Ebrahim Lila Abdullah. 200203257 200324560 200310882. Project Advisor
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United Arab Emirates University College of Engineering Electrical Engineering Department Automatic Generation Control Prepared by Abeer ALNuaimi Balqees ALDaghar Afra Ebrahim Lila Abdullah 200203257 200324560 200310882 Project Advisor Dr. Abdulla Ismail
Contents • Introduction • Summary about our project. • Review GP1 task. • Gantt chart for GP2 • optimal control: • LFC with PI & optimal control • AVR with PI & optimal control
Contents Combination of LFC and AVR LFC with Fuzzy logic control LFC with Robust control Comparison for three controllers PI, Fuzzy & Robust Conclusion
AGC Overview • The system: • Power Generation system. • The problems: • Frequency and voltage variations • The consequences: • Machine damage. • Blackouts, or outages.
GP1 Overview • The Project: • Automatic Generation Control system • The Advantages: • Limits the variations. • Avoide machine damages • Avoide blackouts • Enhance the system reliability and security.
GP1 Overview Gp1
Optimal Linear Control Systems optimal control is a set of differential equations describing the paths of the control variables that concerned with operating a dynamic system to minimize the cost functional with weighting factors supplied by a engineer.
Optimal Linear Control Systems • Application of optimal control: • Mechanics of motion. • Economics. • Medicals. • Populations.
The targets for using the optimal linear control system: • Stable closed-loop system. • Reduce steady state errors. • Reach standard performance measures: • Peak Time, Tp. • Percent of overshoot. • Percent of under shoot. • Settling time, Ts. • Rise time, Tr.
State variable Input Minimization cost equation:
The LFC with the I and OPC • Model1: With the integral control.
The LFC with the I and OPC • MATLAB:Defining the Matrices. • A=[-12.5 0 -12.5 -5;3.33 -3.33 0 0;0 3.86 -2.70 0;0 0 0.87 0]; • B=[12.5;0;0;0]; F=[0;0;-1.93;0]; • C=[0 0 1 0]; • D=[0];
The LFC with the I and OPC SSR: t=25s US: 4%
The LFC with the I and OPC • Model1: With the integral control and optimal control.
The LFC with the I and OPC • MATLAB:Defining the Matrices. • Q=[10 0 0 0; 0 10 0 0 ;0 0 10 0 ;0 0 0 10];% • R=1; • [K,P,ev]=lqr(A,F,Q,R) • Ao=A-(F*K) • sys1=ss(Ao,F,C,D); • yo=lsim(Ao,F,C,0,u,t);
The LFC with the I and OPC SSR: t=10s US: 1.5%
The LFC with the I and OPC • The Integral and the Optimal control Advantages: • Undershoot Reduction from 4% to 1.5% • The steady state response deducted faster • The integral control helps in enhancing the steady state response from t=25s to t=10s. • The Optimal control helps in enhancing the Transient response.
System Models (AGC) Excitation system Automatic Voltage Regulator (AVR) Gen. field Voltage sensor Steam Turbine G Shaft Valve Control mechanism Load frequency control (LFC) Frequency sensor
Automatic Voltage Regulation • For efficient and reliable operation of Power Systems, the control of voltage should satisfy the following objective: • Voltages at the terminals of all equipment in the system are within acceptable limits. Maintaining voltages within the required limits is complicated due to the fact that: • The power system supplies power to vast number of loads and fed from many generating units.
Automatic Voltage Regulation 2) System voltage is closely related to the system reactive power which is a reactive loads such as inductors and capacitors dissipate zero power, yet the fact that they drop voltage and draw current gives the deceptive impression that they actually do dissipate power. 3) The proper selection and coordination of equipment for controlling the system voltage and the reactive power are among the major challenges in power system operation and control.
Automatic Voltage Regulation • Reactive Power (QV) is one of the two main elements in the power system must be controlled. • Any voltage error in the system is sensed, measured, and transformed into reactive-power command signal. • The objective of the AVR is to keep the system terminal voltage at the desired value by means of feedback control
Block diagram of a simple automatic voltage regulator (AVR) KE=200 TE =0.05KG=1 TG =0.2KR=0.05 TR =0.05 KA=0.15 TA=10
Block diagram of a simple automatic voltage regulator (AVR) • Voltage error is improved by controlling the rotor field-current generator EMF. • The steady state voltage error can be eliminated using an integral controller. • The AVR has a substantial effect on transient stability when varying the field voltage to maintain the terminal voltage constant.
AVR Model • Case 1: • AVR without PI (Proportional and Integral ) controller. • Case 2: • AVR with PI controller. • Case 3: • AVR with optimal control. 31
Case 1:AVR without PI (Proportional and Integral ) controller. Block diagram of AVR model without PI controller
Steady state error Overshoot The output voltage response without controller Overshoot error Steady State error ∆V Time (s) The output voltage response when Ka of the amplifier is 0.15 The output voltage response when Ka of the amplifier was changed to 0.1
Case 2: AVR with PI controller. Block diagram of AVR model with Ki and Kp gains
The output voltage response when Ki=0.2 and Kp= 1.5 Overshoot The output voltage response with PI controller V Time (s)
Case 3: AVR with optimal control. Block diagram of AVR model with feedback gains
Step2: Find A,B, C, D matrices • State differential Equation: • Output Equation: A=[-5 5 0 0; 0 -20 4000 0; 0 0 -0.1 -0.01;20 0 0 -20] B=[0;0;0.01;0] C=[1 0 0 0] D=[0]
Step 3:MATLAB command to find the feedback gains MATLAB Function values of feedback gains k1,k2,k3,k4 MATLAB command A=[-5 5 0 0; 0 -20 4000 0; 0 0 -0.1 -0.01;20 0 0 -20] Q=[5 0 0 0; 0 5 0 0; 0 0 5 0; 0 0 0 5] B=[0;0;0.01;0] R=5 [F,P,ev]=lqr(A,B,Q,R) Result of running the program: F = -0.0230 0.0582 206.0278 -0.0899 P = 1.0e+005 * 0.0000 0.0000 -0.0001 0.0000 0.0000 0.0000 0.0003 0.0000 -0.0001 0.0003 1.0301 -0.0004 0.0000 0.0000 -0.0004 0.0000 ev = -20.6225 + 3.4261i -20.6225 - 3.4261i -2.9577 + 3.1290i -2.9577 - 3.1290i
The output voltage response with optimal and integral control V Time (s)
AGC system AVR LFC
AVR and LFC Combination x3 Load Frequency Control Auto Voltage Regulator
AVR and LFC Combination • Forming A, B, C, D and F Matrices: • State Differential Equation. • Output Equation. • MATLAB. • Tuning K1,K2,K3,K4 and K5 Between 0 and 1: • Trial and Error: • K1 has no affect on either one of the two systems. • K2 has an affect on the LFC response. • K3 has an affect on both the LFC and the AVR system stability. • K4 and K5 both have an affect on the AVR overshoot.
AVR and LFC Combination • Tuning K1,K2,K3,K4 and K5 Between 0 and 1: • K at which the responses of both AVR and LFC are behaving normally: • K1= 1 • K2= 0.8 • K3= 0.1 • K4= 0 • K5= 1
AVR response AGC response LFC response
AVR and LFC Combination x3 Load Frequency Control Auto Voltage Regulator
AVR response AGC response LFC response
AVR response AGC response LFC response
AVR and LFC Combination • The Combination of both AVR and LFC systems might cause slight changes in their responses. • Fortunately the undershoots and overshoots never exceeded 20%. • AVR stand alone system • Overshoot = 2.2% • With the optimal control the overshoot almost eliminated. • AVR within AGC system • Overshoot= 0.2% • LFC stand alone system • Undershoot= 2.8% • LFC within AGC system • Undershoot= 2.5%
Fuzzy logic control It is the process of formulating the mapping from a given input to an output using fuzzy logic. The mapping of FL done based on human operator’s behavior.