Presenter: NGOGA B. Julius Email: Ngogajls@gmail.com Session: - PowerPoint PPT Presentation

The implementation of UPQC technology to mitigate both current & Voltage based power quality problems in modern distribution grid. Presenter: NGOGA B. Julius Email: Ngogajls@gmail.com Session: 2B.1 @ 13:45 -14:10 03 rd Oct. 2018

• Smart Grid: Main Goal Electrical Infrastructure-Conv “ Smart/Intelligent” Infrastructure Linking electricity system stakeholder objectives Upgrade the grid in Smart way

• 1.Introduction 1.1 Background:  Because of non linear loads that are  The quality of the electrical power supply has connected to the grid ,Power quality a direct impact on the corrective function and problems like load current harmonic operation of equipments connected to the distortion, unbalanced voltage, public electricity supply network . source voltage swells(over voltage) and sags(under voltage) are introduced.  When power utility consumers think of  Ever since,Researchers and utility PQ, they think of reliable power supply service providers have always suggested at the load centres and at their and implemented many useful consumer equipments that is free of technologies to mitigate the Voltage and interruption, and clean power that is current based PQ problems. free from any disturbances at any time of service 3

• Introduction-cont.... 1.3 Objectives:  The Main objective of my work is to make a  To Investigate the Series APF to detailed analysis on how to simulteneously purposely mitigate under voltages and mitigate both voltage and current based power over voltages from the source and quality problems in distribution power grid using make load voltage perfectly balanced UPQC system. and sinusoidal in nature.  To Investigate the Shunt APF for compensating load current harmonics and so that the current  To narrate the behavior of active drawn from supply is completely sinusoidal in and reactive Power flow through- nature . out the entire UPQC system  In pursuit of these objective:  An elaborated simulation is carried out in MATLAB/SIMULINK2016.b to validate the perfomance of APFs and the whole UPQC equipment in General.  FFT analysis techniques are used to enhance and prove the correctness of the compensation techniques based on IEEE- 519 Std 4

2.Unified Power Quality Conditioner Working principle and system topology: Electric utility System + Transfomer + Feeder Load Fif. 1: Single line diagram of a real system with out CP devices Fig 2: Single line diagram of a real system with CP devices

UPQC -conti.... L s R s V L V t i s ＋ i L V sr L O Load bus V s A ＋ D V sh Fig 4: The equivalent circuit for UPQC V :Voltage at the power supply s :Series-APF for voltage compensation V SR The source voltage can be expressed as: Fig 3 : Detailed topology of UPQC   V V V s sr L ❖ The terminal source current in the shunt APF is ❖ To obtain a balance sinusoidal load voltage with fixed harmonic free sinusoidal and has the same phase amplitude V,the output voltage of the series-APF should be angle as the phase voltage at the load terminal: given by:           V ( V V )sin( wt Q ) V ( ) t V t ( )     i I cos( wt Q )sin i i sr 1 p 1 p Ln  k k 2 L 1 p 1 p 1 p Ln  LK k 2 V :The positive sequence voltage 1 p   i i i Q :The initial phase of voltage for positive seq. s L Sh 1 p  wt    sin( )cos I :Negative sequence component V 1 p 1 p 1 p 6 1 n

3. Subsystem II: Shunt APF 3.1 Shunt APF system topology: ❖ The role of SAPF is to supply the desirable current components such that the utility source supply only the active current component required by the load. The primary input is the load current   i i i L , abc 1 , abc h , abc Shunt APF system topology ❖ The load current at fundamental frequency is given by :   i i i 1 , abc L , abc h , abc Equivalent circuit of SAPF 7

Shunt APF -conti.... 3.2 Harmonic current detection algorithm: ❖ The performance of SAPF strictly depends on the features of the current- detection algorithms and controllers. The figure shows the SAPF control system. ❖ Based on TTA an d F FT techniques, the operation principle of the proposed harmonic current extraction algorithm is introduced and analyzed: ❖ The three phase load currents can be drawn into positive and negative components as follows :            2 2 l 2 2 l          i n ( )  I sin  nk  I sin  nk   x 1 k 1 k 2 k 2 k       N 3 N 3  k 1 Shunt APF control system   o x a     l 1 x b    2 x c 8

Shunt APF -conti....         2 2 l 2 2 l         ❖ Therefore, the fundamental current component is (1) sin   sin   i I n I n x 1 11 11 21 21     3 3 N N expressed as follows:         2 2 l 2 2 l       I sin  n  cos I sin  n  sin 11   11 11   11 N 3 N 3        2 2 l 2 l ❖ Figure below shows the block diagram         I sin n cos 21    21  N 3 3 of the proposed current-detection        2 2 l 2 l algorithm:         I cos n sin 21 21     N 3 3 Current detection block diagram 9

Shunt APF -conti.... 3.3 Shunt APF simulation results: ❖ The figure shows the simulation model of shunt APF where the load current waveform is non sinusoidal due to nonlinear load and the source current waveform may be sinusoidal but due to nonlinear load there is small variation in source current ❖ For example,the nonlinear load is formed by using three-phase uncontrolled rectifier module. The output current of this load has big percentage of harmonic content. Compansation current is generated by the Shunt APF and is injected in anti-phase with the load current at the point of common coupling- PCC. 10 Load current ,grid current and grid voltage

Shunt APF -conti.... ❖ The results represent the robustness of the proposed algorithm for estimating compensating current even when the supply is distorted and unbalanced and the proposed algorithm is fast enough to give the response in less than one cycle. Proposed harmonic current extraction approach Single phase component of load,fundamental and Load current, fundamental component and harmonic 11 harmonic currents component.

Shunt APF -conti.... ❖ After compensating the current harmonic using SAPF/ TTA approach, it is observed that the total harmonic distortion is now 0.13% within IEEE- 519 limits and the correctness of the approach used can be proved here below by studying the FFT analysis of the fundamental componen t. FFT analysis of the current before compansation FFT analysis of the current before compansation FFT analysis of fundamental component 12

Shunt APF -conti.... ❖ A sample case of distorted current supply with fifth and seventh harmonic is ❖ Calculating the corresponding considered for the simulation study and the frequency for seventh order waveforms corresponding to above case are harmonic: shown   F 7*50 350 Hz ❖ Calculating the corresponding 7 th  frequency for fifth order harmonic: Phase 2* pi F * 7 th 7 th    F 5*50 250 Hz 700 pi 5 th  Phase 2* pi * F 5 th 5 th  500 pi Load current, fifth order component and harmonic Load current, Seventh order component and harmonic component. 13 component.

4. Subsystem II: Series APF 4.1 Series APF system topology: ❖ A series active power filter is a power distribution equipment that is used to remove all the voltage problems from supply voltage and make load voltage perfectly balanced and regulated i a a V ca . i b v a Vsa b . Electrical power V cb Non linear Load Grid . Vsb i c . v b c V cc . . v c Vsc . n Series APF topology ❖ The series APF is connected between the supply  v c a and load terminals using three single phase V sa  v V sb c b transformers. In addition to injecting the voltage, V sc Converter controller  v i a c c these transformers are used to filter the i b switching ripple of the series active filter and i c also help to compansate the distorted supply Series APF voltage. An equivalent series APF power circuit 14

Series APF -conti.... 4.2 Voltage Sag/Swell Detection V amp-s Sag/swell Detection ❖ The voltage sag/swell detection method based is based on E-PLL approach and is shown in the figure below: ❖ By subtracting the error C(t) signal from the ideal Enable voltage magnitude , the voltage sag/swell depth (Sprop) Gate signals of can be detected. VSI-1 Supply Voltage V PLL-S V err-S Vs ＋ Comparator Reference Sag/swell computation Phase E-PLL Detection signal E-PLL Sprop   voltage c t - - Method ＋ Hysteresis comparator Structure of series APF control   1 V V V g f h Reference Proposed sag detection methods Where: • Vg is the grid voltage • Vf is the fundamental voltage • Vh is the harmonic voltage and • Vc is the compansation voltage 15