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Power Quality Improvement using

ASO Technique Gundala Srinivasa Rao

Electrical and Electronics Engineering, CMR College of Engineering &

Technology, Telangana, India 501401 drgundalasrinivasarao@gmail.com

B. Srikanth Goud Electrical and Electronics Engineering,

Anurag College of Engineering Ghatkesar, Telangana, India 501301

srikanth.b@anuraghyd.ac.in

Ch. Rami Reddy Electrical and Electronics Engineering, Malla Reddy Engineering College (A)

Maisammaguda, Telangana, India 500100 crreddy229@gmail.com

Abstract—Hybrid Renewable Energy Sources (HRES) combined with grid connection is becoming more important in meeting the massive demand for electrical power in the present environment. This integration reduces the use of fossil fuels even more, as well as environmental difficulties. In grid-connected systems, HRES such as photovoltaic (PV) systems, wind turbines (WT), and battery energy storage systems (BESS) are producing power quality issues (PQ). To address such challenges in the HRES system, Atom Search Optimization (ASO) in conjunction with a Unified Power Flow Controller (UPQC) is suggested. UPQC is one of many specialized power devices that are utilized to successfully minimize PQ concerns such as voltage/current sag, swell, and Total Harmonic Distortions. The fractional order PID controller is intended to drive a UPQC using control parameters developed using the ASO approach. The analysis is compared with PI and the best findings are achieved. The test system is modeled using the MATLAB/Simulink program.

Keywords- Power quality improvement, Atom Search Optimization (ASO, Unified Power Flow Controller (UPQC), Hybrid Renewable Energy Sources, FOPID controller.

I. INTRODUCTION Renewable energy sources (RES) are becoming more

significant since conventional sources face several issues connected to the usage of fossil fuels, which have a greater impact on the environment. RES has a better potential to reduce emissions and global warming. [1] Formalized paraphrase Because of advances in innovation and environmental concerns, RES-based distributed generation (DG) is becoming increasingly significant [2]. Numerous optimization methodologies have been created to monitor the enhanced flexibility of various power electronic devices when merging many alternative sources such as sun, wind, battery, and so on [3], all of which play an important part in meeting the large power demand [4]. The limits of conventional energy sources' power generation are more important to DGs since they give end-users with more efficient, high-quality, and on-demand electricity [5]. Power production has been a significant task due to expanding population and demand, hence RES has assumed its place since conventional sources alone cannot meet the needs. The wind is commonly used from a variety of solar sources [6]. The performance of RES may be increased by using electronic control equipment in the electricity grid. The HRES system is structured to meet the required load demand with one or more delivery system resources while also improving customer quality [7]. The main disadvantage is that this mix will exacerbate further PQ issues in the operation, such as sags, swell, interference harmonics, and so on, resulting in continuous fluctuation that causes continual tripping and may be repaired by operating according to grid standards later on.

In this proposed paper hybrid system, the energy storage device linked with the distribution system is studied with the combination of PV, wind, and batteries to provide the required load demand [8]. Hybrid DGs are to blame for the issue of insecurity. Power quality issues, such as sag, swell, harmonics, and so on, are mostly created in the unit. The system's Modular AC transmission systems (FACT) devices and filter circuits will address these power quality difficulties. Many applications are now viable and graded based on series and shunt devices, thanks to advancements in power electronic equipment and control approaches [9]. The Static Synchronous Series Compensator (SSSC) and Dynamic Voltage Restorer (DVR) are the voltage correcting instruments (DVR). Static compensators (STATCOM), Distribution STATCOM (DSTATCOM), and Thyristor Regulated Reactors (TCR) are used in voltage control mode to monitor load voltage and inject reactive and harmonic components in current mode [10]. To maintain stability and avoid power quality concerns in HRES-based DGs, an appropriate control strategy must be used. The remaining paper is organized as follows. Section II describes the test system, Section III describes the proposed method, Section IV presents the simulation results and lastly the conclusions are drawn in Section V.

II. TEST SYSTEM WITH DESCRIPTION Renewable energy sources such as solar and wind are

widely utilized in the distribution system. With the combination of PV and WT, system effectiveness and dependability are increased. HRES is regarded as the finest alternative [9-10]. In the distribution system, HRES must meet the load demand anticipated by consumers, which raises issues of flexibility and power quality dependability. These PQ difficulties must be avoided for the gadget to work smoothly [11]. FACT devices are used in the creation of power electronics to alleviate power quality concerns under nonlinear load. UPQC is intended to reduce power quality concerns such as voltage sag, current sag, and THD. The suggested HRES approach includes a grid-interfaced combination of PV and WT. Because the sources under consideration are intermittent, BESS is intended to meet load demand under adverse environmental circumstances. PQ difficulties arise in the HRES system as a result of non-linear and abrupt loads. [12] Formalized paraphrase Voltage instability and reactive power imbalances are caused by these issues. The HRES system is meant to alleviate these challenges by using UPQC to enhance the voltage regulation of the FOPID controller depicted in Fig.1. The control operation of the system is carried out employing optimization approaches such as ASO. The PV and wind power are obtained from the Perturb and Observe (P&O) MPPT implementation. The ASO generates a reference DC

bus voltage. When there is no solar energy, the DC relation voltage reference is set to its default value, and the HRES's power quality concerns are mostly attributable to faults, non-linear load, and unexpected grid side loads [13]. The suggested system is equipped with UPQC, which is utilized

to address all difficulties and ensure stable operation by compensating for the difficulties using series and shunt controllers and control methods.

Fig. 1: Proposed HRES system

Power compensation is achieved by supplying the best gain settings for the FOPID controller, which filters and injects the required power by choosing the optimum gain settings for the FOPID controller. An ASO controller controls the FOPID controller and is configured to determine the parameters required to conduct the control operation under PQ circumstances [14].

III. ATOM SEARCH OPTIMIZATION The ASO [15] is shown in Fig. 3, is used to create

appropriate FOPID controller parameters pulses. The error values and FOPID controller settings are used to populate ASO at the start. A fitness function (1) is used to create the ideal pulses. The following is a formulation of the optimization issue of FOPID controller parameters shown in Table.I

Fitnessfunction = 𝑀𝑖𝑛0𝑒(𝑠)5(1)

The mathematical expression of the FOPID controller depicted in Fig. 2 and it is expressed as (2)

(2)

Fig. 2: FOPID Controller

3 phase gridNon-linear load

DC-DC converter(MPPT

(perturb and observer))

Rectifier(AC-DC

converter)

DC-DC converter(MPPT

(perturb and observer))

UPQC

Series APF Shunt APF

Proposed Voltage

controllerPWM

FOPID

Proposed Series Controller

Proposed Current

controller

PWM

FOPID

Proposed Shunt Controller

PulsesPulses

PV WT

Ra

RbRc

La

LbLc

Rse, Lse (a)Rse (b), Lse (b)Rse, Lse (c)

Rsh, Lsh (a)Rsh, Lsh (b)

Rsh, Lsh (c)

Ta

Tb

Tc

Battery

( ) ( ) ( )pu s K K D e s K D e si dµl-= + +

Atom Search Optimization

pK

iK

dK

pK iK dK1d l

1d µ

1d µ

1d l

( )e s( )u ssum

Table I: FOPID Controller Parameters Kp Ki λ Kd µ

49.426 29.7500 1 0.3953 0.82

IV. RESULTS AND DISCUSSION The following test system is evaluated at constant

irradiance and wind speed and observed under the nonlinear load condition

Fig. 3 Flow chart of ASO

A. Condition for constant irradiance and wind speed By adding non-linear load to the HRES with grid linked

system under this condition. The PV irradiation conditions are assumed to be 1000 W/m2. Energy is created in the system, which is utilized to compensate for the load demand, based on the irradiance level of PV. Based on the pace at which the WT produced the power, the WT speed is assumed to be 12m/s. As a result, HRES has produced enough electricity to fulfill the load demand while also compensating for PQ difficulties. Only key situations of PV and WT energy storage systems are enabled by the battery in the system. Fig. 4 shows the PV and WT characteristics together with the produced electricity. In the constant irradiance situation of 1000W/m2, the PV generates 30KW of electricity, as shown in Fig. 3. Similarly, with a constant wind speed of 12 m/s, wind power is created at 80KW.

B. Condition for Nonlinear load In this mode of operation, the proposed HRES system

provides power to the PCC. The inverter, which is the grid's interface, is utilized to transmit electricity from RES to the PCC to increase PQ. PCC is coupled to a non-linear load, often uncontrolled diode rectifier with series RL. The RES provides real and reactive power to the local load, with any surplus real power being sent to the grid. To investigate the dynamic performance of nonlinear time-varying loads by adding a nonlinear load variation. In this case, a non-linear load is a diode rectifier with RL load. At t= 0.1s, an additional R-L load is applied to the current load, and it is removed at 0.22s. As a result, the load current is raised from 55A to 62.2A. Fig.5 depicts the dynamic behavior of the PCC voltage Vs, supply current Is, load current IL, and compensatory currents IC. Grid current THD is decreased from 25.15% before compensation to 20.92% after compensation, with load current THD of 18.99% and 18.98% owing to voltage interruption caused by an increase in PCC current. Fig. 6 depicts the THD comparison before and after compensation. Table. II represents the THD values in harmonic order before and after compensation.

Start

Calculate atoms mass

Compute the fitness function FF = min((es )) and find the best atom

Determine K neighbors for each atom

StopCriteria is reached

Generate initial Population FOPID Gain {λ,µ,P,I,D }, current error , voltage error {e(S)}

Calculate the interaction force and constraint force

Calculate atom s acceleration

Update atom s velocity

Update atom s position

Finish

Return best atom

Fig. 4: (a) Irradiance, (b) PV Power, (c) Wind speed, (d) Wind Power

Fig. 5 Source voltage (Vs), Source current (Is), Load current (IL), Compensation current (Ic)

Fig. 6: THD comparison before and after compensation

Table II: THD Comparison Analysis S. No Methods

Harmonic level

5 7 11 13 17 19 23 25 29

Before UPQC

1 Proposed 21 15 32 28 22 61 45 26 32

2 PI 82 35 25 12 48 41 38 45 32

After UPQC

1 Proposed 12 6 3 5 10 3 5 0 1

2 PI 35 12 13 17 21 12 7 5 1

V. CONCLUSION Improving power quality in the HRES has emerged as a

viable research subject for mitigating difficulties in the grid-connected system. The device's power quality issues are exacerbated by the growing usage of non-linear load, unstable load, and high-frequency switching characteristics on the load side. The FACTS unit is one of the potential techniques for handling PQ issues. As a result, the correctly managed UPQC was created in this research to tackle power efficiency concerns and adjust for load demand in the HRES framework. For the HRES approach, the PV, WT, and BESS structures were set. The BESS device has been used to balance the load demand under environmental circumstances or when the power generated by PV and WT is insufficient to balance the grid's load needs with the load. The UPQC was outfitted with two suggested controllers in a series of active power filters and shunt active power filters by merging the FOPID controller with BWO. Voltage and existing power efficiency issues are minimized with the help of the UPQC system. The proposed framework was designed in MATLAB/Simulink and verified under nonlinear load three different cases such as sag, swell, disturbance, and harmonics during non-linear load and validated with various existing PI controllers.

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