1 POWER QUALITY ........................................................................................ ERROR! BOOKMARK NOT DEFINED. 1.1 POWER QUALITY PROBLEMS: ................................................................................. ERROR! BOOKMARK NOT DEFINED. 1.1.1 Transients: ........................................................................................................ Error! Bookmark not defined. 1.1.2 Interruptions: .................................................................................................... Error! Bookmark not defined. 1.1.3 Voltage sag: ...................................................................................................... Error! Bookmark not defined. 1.1.4 Under voltage: .................................................................................................. Error! Bookmark not defined. 1.1.5 Voltage swell: ................................................................................................... Error! Bookmark not defined. 1.1.6 Over voltage: .................................................................................................... Error! Bookmark not defined. 1.1.7 Voltage unbalance: ........................................................................................... Error! Bookmark not defined. 1.1.8 Wave form distortion: ....................................................................................... Error! Bookmark not defined. 1.1.9 Voltage fluctuations: ......................................................................................... Error! Bookmark not defined. 1.2 POWER QUALITY PROBLEMS EXAMPLES: ............................................................... ERROR! BOOKMARK NOT DEFINED. 1.3 POWER QUALITY SOLUTIONS ............................................................................................................................... 3 1.3.1 Reduce Effects on Sensitive Equipment............................................................. Error! Bookmark not defined. 1.3.2 Interconnected power system ............................................................................ Error! Bookmark not defined. 1.3.3 Deregulation ..................................................................................................... Error! Bookmark not defined. 1.3.4 Power conditioning equipment manufacturers ................................................. Error! Bookmark not defined. 1.3.5 Utilities ............................................................................................................. Error! Bookmark not defined. 1.3.6 End users........................................................................................................... Error! Bookmark not defined. 1.3.7 End-user equipment manufacturers .................................................................. Error! Bookmark not defined. 1.3.8 Monitoring-equipment manufacturers .............................................................. Error! Bookmark not defined. 1.4 POWER QUALITY IMPROVING DEVICES .................................................................. ERROR! BOOKMARK NOT DEFINED. 1.4.1 Line voltage regulators: .................................................................................... Error! Bookmark not defined. 1.4.2 M-G sets:........................................................................................................... Error! Bookmark not defined. 1.4.3 Fly wheel energy storage systems: .................................................................... Error! Bookmark not defined. 1.4.4 SMES Devices: .................................................................................................. Error! Bookmark not defined. 1.4.5 UPS: .................................................................................................................. Error! Bookmark not defined. 1.4.6 Custom power devices: ..................................................................................... Error! Bookmark not defined. 1.5 MERIT OF DVR OVER OTHER CUSTOM POWER DEVICES........................................ ERROR! BOOKMARK NOT DEFINED. 2 DYNAMIC VOLTAGE RESTORER ............................................................ ERROR! BOOKMARK NOT DEFINED. 2.1 DVR BASICS........................................................................................................ ERROR! BOOKMARK NOT DEFINED. 2.2 BASIC CONFIGURATION OF DVR ........................................................................... ERROR! BOOKMARK NOT DEFINED. 2.2.1 Energy Storage Unit: ........................................................................................ Error! Bookmark not defined. 2.2.2 VSC: .................................................................................................................. Error! Bookmark not defined. 2.2.3 Harmonic Filters: ............................................................................................. Error! Bookmark not defined. 2.2.4 Injection transformer: ....................................................................................... Error! Bookmark not defined. 2.2.5 Control Strategies ............................................................................................. Error! Bookmark not defined. 2.2.6 Operating Modes: ............................................................................................. Error! Bookmark not defined. 2.3 SAG/SWELL DETECTION TECHNIQUES: .................................................................. ERROR! BOOKMARK NOT DEFINED. 2.3.1 Fourier Transform (FT) method ....................................................................... Error! Bookmark not defined. 2.3.2 Phase Locked Loop (PLL) method .................................................................... Error! Bookmark not defined. 2.3.3 Peak value detection method............................................................................. Error! Bookmark not defined. 2.3.4 Root mean square (RMS) method ..................................................................... Error! Bookmark not defined. 2.3.5 Space Vector control ......................................................................................... Error! Bookmark not defined. 2.3.6 Wavelet Transform (WT) method ...................................................................... Error! Bookmark not defined. 2.4 VOLTAGE INJECTION METHODS: ............................................................................. ERROR! BOOKMARK NOT DEFINED. 2.4.1 Pre-sag/dip compensation method:................................................................... Error! Bookmark not defined. 2.4.2 In-phase compensation method: ....................................................................... Error! Bookmark not defined. 2.4.3 In-phase advanced compensation method: ....................................................... Error! Bookmark not defined. 2.4.4 Voltage tolerance method with minimum energy injection: .............................. Error! Bookmark not defined. 3 DVR CONTROL STRATEGIES ................................................................... ERROR! BOOKMARK NOT DEFINED. 3.1 SRF THEORY: ........................................................................................................ ERROR! BOOKMARK NOT DEFINED. BASICALLY, THE THREE REFERENCE FRAMES CONSIDERED IN THIS IMPLEMENTATION ARE: ................................................................................................................................. ERROR! BOOKMARK NOT DEFINED. 1. THREE-PHASE REFERENCE FRAME, IN WHICH VA, VB, AND VC ARE CO-PLANAR THREE-PHASE QUANTITIES AT AN ANGLE OF 120 DEGREES TO EACH OTHER. ............ ERROR! BOOKMARK NOT DEFINED. 2. ORTHOGONAL STATIONARY REFERENCE FRAME, IN WHICH VΑ (ALONG Α AXIS) AND VΒ (ALONG Β AXIS) ARE PERPENDICULAR TO EACH OTHER, BUT IN THE SAME PLANE AS THE THREE-PHASE REFERENCE FRAME. .............................................................. ERROR! BOOKMARK NOT DEFINED. 3. ORTHOGONAL ROTATING REFERENCE FRAME, IN WHICH VD IS AT AN ANGLE Θ (ROTATION ANGLE) TO THE Α AXIS AND VQ IS PERPENDICULAR TO VD ALONG THE Q AXIS. ..... ERROR! BOOKMARK NOT DEFINED. 3.1.1 Clarke Transformation.................................................................................................................................... 6 THE THREE-PHASE QUANTITIES ARE TRANSLATED FROM THE THREE-PHASE REFERENCE FRAME TO THE TWO-AXIS ORTHOGONAL STATIONARY REFERENCE FRAME USING CLARKE TRANSFORMATION. THE CLARKE TRANSFORMATION IS EXPRESSED BY THE FOLLOWING EQUATIONS: ..............................................................................................................................................................6 3.1.2 3.1.3 Inverse Clarke Transformation ....................................................................................................................... 6 Park Transformation ....................................................................................................................................... 6 𝐕𝐝 = 𝐕𝛂𝐬𝐢𝐧𝛉 + 𝐕𝛃𝐜𝐨𝐬𝛉 𝐕𝐪 = 𝐕𝛃𝐜𝐨𝐬𝛉 − 𝐕𝛂𝐬𝐢𝐧𝛉...............................................................................................................................................6 3.1.4 Inverse Park Transformation .......................................................................................................................... 6 𝐕𝛂 = 𝐕𝐝𝐜𝐨𝐬𝛉 − 𝐕𝐪𝐬𝐢𝐧𝛉 𝐕𝛃 = 𝐕𝐪𝐜𝐨𝐬𝛉 + 𝐕𝐝𝐬𝐢𝐧𝛉 ........................................................................................................................................................7 3.2 PROPORTIONAL-INTEGRAL CONTROLLER ....................................................................................................................... 7 THE FUNCTION OF THE PROPORTIONAL ACTION IS TO RESPOND QUICKLY TO THE CHANGES IN THE ERROR DEVIATION. INTEGRAL ACTION IS SLOWER THAN THE PROPORTIONAL RESPONSE BUT USED TO REMOVE THE OFFSETS BETWEEN THE INPUT AND THE REFERENCE AT STEADY STATE. BEFORE THE DVR STARTS INJECTING VOLTAGE TO THE SYSTEM, A CONSIDERABLE TIME PERIOD WAS ALLOWED FOR THE SYNCHRONIZATION. THE SYNCHRONIZATION PROCESS WAS MADE ACCORDING TO THE POSSIBLE SYSTEM FREQUENCY DEVIATION. AS THE SYSTEM FREQUENCY IS NOT MUCH DEVIATE FROM 50 HZ THE FAST SYNCHRONIZATION IS NOT A NECESSITY. HENCE IT HELPS THE LOAD VOLTAGE WITHOUT PHASE JUMP. THEREFORE, THE DERIVATIVE ACTION IS NOT NEEDED AND THE NEED OF PID CONTROLLER WAS OMITTED. ..........7 3.3 HYSTERESIS VOLTAGE CONTROLLER .................................................................................................................. 7 FIG. 2: PRINCIPLE OF OPERATION OF HYSTERESIS VOLTAGE CONTROLLER ........................................8 3.4 FUZZY LOGIC CONTROLLER:................................................................................................................................. 8 3.4.1 Block diagram of fuzzy logic controller .......................................................................................................... 8 3.4.2 Membership function: ..................................................................................................................................... 9 4 SIMULATION: ......................................................................................................................................................15 4.1 4.2 4.3 4.4 SRFT WITH PI BASED DVR CONTROLLER.......................................................................................................... 15 PEAK DETECTION METHOD WITH HYSTERESIS CONTROLLER BASED DVR ............................................................................. 20 PHASE SEQUENCE ANALYZER WITH PI AND FUZZY CONTROLLER BASED DVR ....................................................................... 23 THD ANALYSIS:...................................................................................................................................................... 26 1.1 Power Quality Solutions There are four ways to solve and prevent power quality problems: Three-phase reference frame Two-phase reference frame Vb 120 o Vq Vβ o 120 Rotating reference frame Vd Va 120o Vα θ Vc Va α-axis Vb Vc Vβ Vα Vq Vd Figure 3.1 Reference Frames The combined representation of the quantities in all reference frames is shown in Figure 2. 5 Vb Vq Vβ Vd θ Va Vα I Vc Figure 3.2 Combined vector representation transformation theory 1.1.1 Clarke Transformation The three-phase quantities are translated from the three-phase reference frame to the two-axis orthogonal stationary reference frame using Clarke transformation. The Clarke transformation is expressed by the following equations: 𝟐 𝟏 𝐕𝐚 − (𝐕𝐛 − 𝐕𝐜 ) 𝟑 𝟑 𝟐 (𝐕 𝐕𝛃 = 𝟑 𝐛 − 𝐕𝐜 ) 𝐕𝛂 = 1.1.2 Inverse Clarke Transformation The transformation from a two-axis orthogonal stationary reference frame to a three-phase stationary reference frame is accomplished using Inverse Clarke transformation. The Inverse Clarke transformation is expressed by the following equations: 𝐕𝐚 = 𝐕𝛂 𝟏 √𝟑 𝐕 𝟐 𝛃 𝟏 √𝟑 𝐕 − 𝟐 𝐕𝛃 𝟐 𝛂 𝐕𝐛 = − 𝟐 𝐕𝛂 + 𝐕𝐜= − 1.1.3 Park Transformation The two-axis orthogonal stationary reference frame quantities are transformed into rotating reference frame quantities using Park transformation. The Park transformation is expressed by the following equations: 𝐕𝐝 = 𝐕𝛂 𝐬𝐢𝐧 𝛉 + 𝐕𝛃 𝐜𝐨𝐬 𝛉 𝐕𝐪 = 𝐕𝛃 𝐜𝐨𝐬 𝛉 − 𝐕𝛂 𝐬𝐢𝐧 𝛉 1.1.4 Inverse Park Transformation 𝐕𝛂 = 𝐕𝐝 𝐜𝐨𝐬 𝛉 − 𝐕𝐪 𝐬𝐢𝐧 𝛉 𝐕𝛃 = 𝐕𝐪 𝐜𝐨𝐬 𝛉 + 𝐕𝐝 𝐬𝐢𝐧 𝛉 Va, Vb, and Vc are three-phase quantities. Vα and Vβ are stationary orthogonal reference frame quantities. Vd, Vq are rotating reference frame quantities, θ is the rotation angle. 1.2 Proportional-Integral Controller PI Controller is a feedback controller which drives the plant to be controlled with a weighted sum of the error and the integral of that value. The proportional response can be adjusted by multiplying the error by constant KP, called proportional gain. The contribution from integral term is proportional to both the magnitude of error and duration of error. The error is first multiplied by the integral Gain, Ki and then was integrated to give an accumulated offset that have been corrected previously. PI CONTROLLER Kp Vref KI / S PWM VSI Vin Fig 3.3 Block diagram of PI controller control circuit Proportional Integrate controller was used to regulate the error between the measured (supply) and the reference phase angle to zero. a) Proportion controller: 1) Accelerates the process response with increase in gain. 2) Produces a steady state deviation in the absence of integrator in the transfer function. This offset decrease with increase in proportional gain. b) Integral Controller 1) Eliminates the steady state deviation. 2) Response is sluggish with long oscillations. 3) Increase of gain makes the system more oscillatory and leads to instabilities. Reasons for selecting a PI controller The function of the proportional action is to respond quickly to the changes in the error deviation. Integral action is slower than the proportional response but used to remove the offsets between the input and the reference at steady state. Before the DVR starts injecting voltage to the system, a considerable time period was allowed for the synchronization. The synchronization process was made according to the possible system frequency deviation. As the system frequency is not much deviate from 50 Hz the fast synchronization is not a necessity. Hence it helps the load voltage without phase jump. Therefore, the derivative action is not needed and the need of PID controller was omitted. 1.3 Hysteresis Voltage Controller Here we are using a conventional hysteresis voltage control technique which is one type of nonlinear voltage control based on voltage error. Hysteresis controller is easy to implement, has simple operation and very fast response. Hysteresis controller work on the error signal between injection voltage and reference voltage of DVR and produces proper gate pulses for converter. Fig.2 shows the principles of hysteresis voltage control. It consists of a comparison between the output voltage Vo and the tolerance limits (VH, VL) around the reference voltage Vref. While the output voltage Vo is between upper limit VH and lower limit VL. When the error is going from lower to upper limit switch 1 is ‘on’ for that duration and switch 2 is ‘off’. And when the error is going from upper to lower limit switch 2 is ‘on, and switch 1 is ‘off’. Fig. 2: principle of operation of hysteresis voltage controller 1.4 Fuzzy logic controller: The concept of Fuzzy Logic (FL) was conceived by Lotfi Zadeh, a professor at the University of California at Berkley, and presented not as a control methodology, but as a way of processing data by allowing partial set membership rather than crisp set membership or non-membership. This approach to set theory was not applied to control systems until the 70's due to insufficient small-computer capability prior to that time. Professor Zadeh reasoned that people do not require precise, numerical information input, and yet they are capable of highly adaptive control. If feedback controllers could be programmed to accept noisy, imprecise input, they would be much more effective and perhaps easier to implement. The performance of Fuzzy Logic Controllers is well documented in the field of control theory since it provides robustness to dynamic system parameter variations as well as improved transient and steady state performances The drawbacks of PI controller are improper tuning of Kp and Ki values which will lead to increase in settling time of the system stability and the continuous usage of controller with fixed PI parameters leads to reduce the life time of DVR. These drawbacks can be overcome by using Fuzzy Logic controller. In the Boolean logic, there are two existing states i.e. 0 and 1 or true or false. There are no other states are available in the Boolean logic other than these two values. On the other hand, fuzzy logic, unlike the Boolean logic can have number of different states (membership values) between 0 and 1. One of the most important features of the fuzzy logic is the, use of linguistic variables instead of numerical variables. In linguistic variables, variables are defined in natural languages sentence e.g. Big, small, High, low etc. These linguistic variables are represented by fuzzy sets 1.4.1 Block diagram of fuzzy logic controller It consists of 4 main blocks 1. 2. 3. 4. Fuzzification Knowledge base Inference mechanism De fuzzification Data base input Fuzzification output Interface system De fuzzification Rule base Fig 3.4 Block diagram of FLC In FLC, a basic control action through a set of linguistic rules to finding by the system, since the mathematical modeling of system variables is not required in FLC because of numerical variables are transferred into linguistic variables. Fuzzification converts a crisp input signals error, and change in error into fuzzified signals that can be identified by level of memberships in the fuzzy sets The knowledge base is composed of data base and rule base. Data base consists of input and output membership functions and provides information for appropriate fuzzification and De fuzzification operations. The rule-base consists of a set of linguistic rules relating the fuzzified input variables to the desired control actions. The inference mechanism uses the collection of linguistic rules to convert the input conditions to fuzzified output. Finally, the De fuzzification converts the fuzzified outputs to crisp control signals using the output membership function. The output generated by fuzzy logic controller must be crisp which is used to control the PWM generation unit. 1.4.2 Membership function: The membership function is a graphical representation of the magnitude of participation of each input. It associates a weighting with each of the inputs that are processed, define functional overlap between inputs, and ultimately determines an output response. There are different membership functions associated with each input and output response. Some features to note are: Triangular MF. Gaussian MF. Trapezoidal MF. Z-shaped MF. S-shaped MF. Generalized bell MF. SHAPE - triangular is common. More complex functions are possible but require greater computing overhead to implement. HEIGHT or magnitude (usually normalized to 1). WIDTH (of the base of function), SHOULDERING (locks height at maximum if an outer function. Shouldered functions evaluate as 1.0 past their center) CENTER points (center of the member function shape) OVERLAP (N&Z, Z&P, typically about 50% of width but can be less). Fig 3.5 Triangular membership function The input membership functions for error and change in error are shown in Fig 5&6 respectively, f6 Error mamdani ( ) Actuating-signal Error-Rate Fig 3.6 Fuzzy inference systems for 2 input and 1 output variable Membership function plots zero FIS Variables neg pos 1 Error Actuating-signal 0.5 Error-Rate 0 -15 -10 -5 0 5 10 input variable "Error" Fig 3.7 Membership Function for Input Variable Error Fig 3.8 Membership Function for Input Variable Error rate 15 Membership function plots zero FIS Variables negbig negsmall possmall 1 Error Actuating-signal 0.5 Error-Rate 0 -0.3 -0.2 -0.1 0 0.1 0.2 output variable "Actuating-signal" 0.3 Fig 3.9 output membership function for change in control input Table 3.1 fuzzy control linguistic rules set Error/Error rate Error neg zero pos neg negbig negsmall zero zero negsmall zero possmall pos zero possmall posbig posbig 8 Control strategy of DVR Voltage Reference Vinput Va,Vb,Vc Convert to dqo Convert to dqo Coordinate system Coordinate system Compare PLL Convert to Vabc Coordinate system Generate signal for PWM 2 SIMULATION: 2.1 SRFT with PI based DVR controller In this simulation SRFT based PI controller is used: In this SIMULINK model, the system consists of 13Kv 3-phase source is stepped using 3-winding T/F, and it is feeding to two parallel lines of same parameters but one is compensated, and other kept as it is this control topology mitigates all balanced and unbalanced types of faults (sags & swells) at a reduced harmonic distortion. It will compensate up to 80% of sag and swells and in the control circuit I am used a fault detection algorithm if the faults is greater than 2 cycles then only DVR injects/absorbs power and if the faults duration is greater than 10 cycles then DVR stops (and you can use your own standby generator if the fault is sustained), in practical implementation DVR injection cycles must be greater than (2-10 cycles). But due to simulation times very large so I take limed number of cycles. Fault duration: 1st cycle – 15th cycle (sag). DVR working times: 3rd cycle – 11th cycle. Fig 2.9 Main Simulink block of SRFT based DVR Fig 3.0 DVR control circuit Fig 3.1 2 cycle sag detector Fig 3.3 10 cycle sag detector Fig 3.4 Open loop error generator Fig 3.5 Measurements Ideal Source Voltage 1.5 Voltage in p.u 1 0.5 0 -0.5 -1 -1.5 0 0.05 0.1 0.15 0.2 0.25 0.3 0.25 0.3 Un Compensated Load Voltage Voltage in p.u 2 1 0 -1 -2 0 0.05 0.1 0.15 0.2 Time in secs Fig 1.2 Waveforms of Ideal source voltage and uncompensated load voltage x 10 Voltage in volts 1 Converter Output Voltage 4 0.5 0 -0.5 -1 0 0.05 0.1 0.15 0.2 0.25 0.3 0.25 0.3 Voltage in volts Converter Output Voltage After LPF 4000 2000 0 -2000 -4000 0 0.05 0.1 0.15 0.2 Time in secs Fig 1.3 Waveforms of Converter output voltage Compensated Load Voltage(PI) Voltage in p.u 2 1 0 -1 -2 0 0.05 0.1 0.15 0.2 0.25 0.3 0.25 0.3 Compensated Load Voltage after APF(PI) Voltage in p.u 2 1 0 -1 -2 0 0.05 0.1 0.15 0.2 Time in secs Fig 1.4 Waveforms of Compensated load voltage System patameters: Table 4.1 System parameters for SRFT with PI based DVR S.No System parameters 1 3-phase source 2 Dc Battery 3 Load1 Values 13KV, 50Hz 7e3 11KV, 10e3KW,4e3KVAR 4 Load2 11Kv, 10e3Kw, 4e3Kvar 5 Step up (Υ/Δ/Δ) 6 Step down-1 (Δ/Υ) 132/11 Kv 7 Step down-2 (Δ/Υ) 132/11 Kv 8 Line length 50Km 9 Carrier frequency 1080Hz 10 Kp, Ki 10, 1 13/132/132 Kv 2.2 Peak detection method with hysteresis controller based DVR In this simulation, peak detection method with hysteresis controller based DVR is used: In this Simulink model, the system consists of 380V is connected to nonlinear load in series with DVR, I am created sag and swell at different instances and DVR compensates sag and swell and harmonics present in the Load voltage. Fault duration: 1st cycle – 3rd cycle (sag) and 5th cycle – 8th cycle (swell). Fig 2.9 Main Simulink block of Peak detection with hysteresis controller based DVR Fig 3.3 DVR control circuit Fig 3.8 VSC circuit Grid Voltage Volts 500 0 -500 0 0.05 0.1 0.15 0.2 0.15 0.2 0.15 0.2 Load Voltage Volts 500 0 -500 0 0.05 0.1 Injected Voltage Volts 200 0 -200 0 0.05 0.1 Time in secs Fig 4.9 Waveforms of Grid voltage, load voltage and injected voltage Table 4.2 peak detection method with hysteresis controller based DVR S.No System Parameters Values 1 3-Phase source 380V, 50Hz 2 Load (non-linear) 3 Dc Battery 60ohm, .15e-3H 400V 2.3 Phase sequence analyzer with PI and Fuzzy controller based DVR In this simulation, phase sequence analyzer with PI and Fuzzy controller based DVR used: In this Simulink model, the system consists of 13Kv 3-phase source is stepped up to 66Kv feeding to 11Kv load through Pi line of 30kms and stepped down to 11kv in series with DVR. In this model, PI and fuzzy logic controller comparative study is to be analyzed. But this type of controller is used for balanced type of faults only. Because the phase sequence analyzer produces only positive sequence signals produced because for the generation of gate pulses to the converter reference 3 phase sinusoidal signal is required otherwise under unbalanced condition it produces 9 signals so after processing the converting of these positive, negative and zero sequence signals into 3 – phase signal requires additional circuit then we go for balanced faults only. Fault duration: 5nd cycle – 10th cycle (sag). Fig 4.0 phase sequence analyzer with PI controller based DVR Fig 4.1 phase sequence analyzer with Fuzzy controller based DVR Fig 4.2 Converting of per unit error signal 3-phase error signal Table 4.3 phase sequence analyzer with PI and Fuzzy controller based DVR S.No System parameters Values 1 3-Phase source 11KV, 50Hz 2 Step up (Υ/Δ) 11/66 KV 3 Step down (Δ/Υ) 66/11 KV 4 Load 5 11KV, 1e3KW,1e3KVAR Line length (Pi model) 30KM Compensated Load Voltage (PI) 1.5 Voltage in p.u 1 0.5 0 -0.5 -1 -1.5 0 0.05 0.1 0.15 0.2 0.25 0.3 0.2 0.25 0.3 Grid Voltage 1.5 Voltage in p.u 1 0.5 0 -0.5 -1 -1.5 0 0.05 0.1 0.15 Time in secs Fig 4.5 Waveforms of Compensated load voltage (PI), grid voltage Compensated Load Voltage(Fuzzy) 1.5 1 Voltage in p.u 0.5 0 -0.5 -1 -1.5 0 0.05 0.1 0.15 0.2 0.25 0.3 Time in secs Fig 4.6 Waveforms of Compensated load volatge (Fuzzy) 2.4 THD analysis: Table 4.4 THD analysis S.No 1 Type of Controller SRFT (PI) 2 Peak value detection method (Hysteresis) 3 Phase sequence analyzer 1) (PI) 2) (Fuzzy) 1) 2) %THD %THD (Without controller) 1.88 25.56 0.26 3.30 0.623 0.578 1) 2.98 2) 2.98