Evaluation of Reduced-Switch Seven-Level Converter-Based upqc with Hybrid Fuzzy-Feedforward Neural Network Algorithm

Varampati, Veera Nagi Reddy; Kota, Venkata Reddy; Venkata, Ashok Kumar Devarasetty

doi:10.1590/1678-4324-2025240682

Article - Engineering, Technology and Techniques • Braz. arch. biol. technol. 68 • 2025 • https://doi.org/10.1590/1678-4324-2025240682 linkcopy

Evaluation of Reduced-Switch Seven-Level Converter-Based upqc with Hybrid Fuzzy-Feedforward Neural Network Algorithm

Authorship SCIMAGO INSTITUTIONS RANKINGS

To improve the performance of end-user equipment in an electric utility distribution network, it is necessary to improve power quality (PQ). This paper presents PQ improvement in electric distribution network using seven-level five switch converter based Unified Power Quality Conditioner (7LFSC-UPQC). Nowadays, power quality plays a vital role in the power distribution sector in the use of highly non-linear loads. Industrial non-linear loads produce electrical imbalances, thereby causing various voltage and current quality related problems, large amounts of harmonics, voltage swell, voltage sag, voltage interruption, etc. This paper proposes the design of a 7LFSC -UPQC based fuzzy-multilayer feed forward multi-layer neural network (FFMLNN) controller to mitigate PQ issues such as voltage sags, swells and current harmonics. A multi-layer feed forward neural network, in which a back-propagation algorithm is used to generate the appropriate reference voltage and current signals, and a shunt compensator of a seven-level unified power quality conditioner (UPQC). This proposed control scheme also controls the DC-link voltage and terminal voltage using an intelligent fuzzy controller. The performance of the proposed FFMLN-fuzzy based 7LFSC-UPQC configuration for simultaneous voltage swell, sag and total harmonic distortion is demonstrated and a comparative analysis of 7LFSC-UPQC and five level UPQC with PI-controller, fuzzy-controller and FFMLNN-controller is conducted using MATLAB/SIMULINK software.

Keywords:
Three phase seven-level five switch UPQC; Feed forward multi-layer neural network; Fuzzy logic; Three phase five level converter; Power Quality; Back Propagation algorithm.

Introduces a FFMLNN and fuzzy logic control scheme for a 7-level 5-switch converter-based UPQC.

Demonstrates substantial reductions in source current THD compared to conventional controllers.

Shows superior performance of the proposed scheme under non-linear load and polluted power supply.

Parameter	Value
Supply Voltage	415 V, 50 Hz
Supply impedance	0.1 Ohms, 0.9mH
Filter impedance	0.001Ohms, 10mH
Load impedance	Resistance -30Ω, Inductance -6mH
DC-Link Voltage	700V

S1	S2	S3	S4	S5	S6	S7	S8	Voltage
1	1	0	0	1	1	0	0	V_DC
1	1	0	0	0	1	0	1	$V_D C / 2$
0	1	0	1	0	1	0	1	0
0	0	1	1	0	1	0	1	- $V_D C / 2$
0	0	1	1	0	0	1	1	-V_DC

S1	S2	S3	S4	S5	S6	S7	S8	S9	S10	S11	S12	Voltage
1	1	0	0	1	1	0	0	1	1	0	0	V_DC
1	1	0	0	1	1	0	0	0	1	0	1	$\frac{2 V_{D C}}{3}$
1	1	0	0	0	1	0	1	0	1	0	1	$\frac{V_{D C}}{3}$
0	1	0	1	0	1	0	1	0	1	0	1	0
0	0	1	1	0	1	0	1	0	1	0	1	$- \frac{V_{D C}}{3}$
0	0	1	1	0	0	1	1	0	1	0	1	$- \frac{2 V_{D C}}{3}$
0	0	1	1	0	0	1	1	0	0	1	1	-V_DC

S1	S2	S3	S4	S5	Voltage
0	0	11	1	0	V_DC
0	1	0	1	0	$\frac{2 V_{D C}}{3}$
1	0	0	1	0	$\frac{V_{D C}}{3}$
0	0	0	0	0	0
0	0	1	0	1	$- \frac{V_{D C}}{3}$
0	1	0	0	1	$- \frac{2 V_{D C}}{3}$
1	0	0	0	1	-V_DC

Error\∆e	NB	NM	NS	Z	PS	PM	PB
PB	Z	PS	PM	PB	PB	PB	PB
PM	NS	Z	PS	PM	PB	PB	PB
PS	NM	NB	Z	PS	PM	PB	PB
Z	NB	NB	NS	Z	PS	PM	PB
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Non-linear load with 0.7 P.F & Polluted Power Supply with 5th & 7th harmonics	Before Compensation			Formal PI Controller		Fuzzy logic Controller		FFMLNN-Fuzzy Controller
		Fundamental Component	%THD	Fundamental Component	%THD	Fundamental Component	%THD	Fundamental Component	%THD
		Fundamental Component	%THD	Fundamental Component	%THD	Fundamental Component	%THD	Fundamental Component	%THD	Five-level MLC-UPQC	V_S	338.85V	30.53%	338.85V	30.53%	338.85V	30.53%	338.85V	30.53%
V_L	338.85V	30.53%	343.8 V	3.98%	343.8 V	3.03%	343.3 V	1.61%
I_S	21.72 A	64.27%	21.81A	8.49%	21.81 A	5.74%	23.1 A	3.62%
Seven-level MLC-UPQC	V_S	338.85V	30.53%	338.85V	30.53%	338.85V	30.53%	338.85V	30.53%
	V_L	338.85V	30.53%	335.9V	3.60%	336.4V	2.26%	335.6V	1.39%
	I_S	21.72 A	64.27%	19.47 A	2.11%	19.46A	1.80%	23.13A	1.24%

	No. of switches per phase	Total No. of switches for three-phase series and shunt MLC of UPQC	%THD
Five-level MLC Output voltage	8	48	32.03%
Proposed Seven-level MLC Output voltage	5	30	29.06%

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Instituto de Tecnologia do Paraná - Tecpar Rua Prof. Algacyr Munhoz Mader, 3775 - CIC, 81350-010 , Tel: +55 41 3316-3054 - Curitiba - PR - Brazil
E-mail: babt@tecpar.br

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