979-8-3503-4743-2/23/$31.00 ©2023 IEEE Harmonic Compensation in Ship Power System Using Peak Detection Control Strategy Based Shunt Active Power Filter Dimitar Tsvetanov Electrical Department Nikola Vaptsarov Naval Academy Varna, Bulgaria d.tsvetanov@naval-acad.bg Julia Djagarova Electrical Department Nikola Vaptsarov Naval Academy Varna, Bulgaria julija_d@abv.bg Nikolay Djagarov Electrical Department Nikola Vaptsarov Naval Academy Varna, Bulgaria jagarov@ieee.bg Frede Blaabjerg Department of Energy Technology Aalborg University Aalborg, Denmark fbl@energy.aau.dk Georgi Enchev Electrical Department Nikola Vaptsarov Naval Academy Varna, Bulgaria g.enchev@nvna.eu Abstract – The expanding use of non-linear loads in ma- rine electrical systems leads to new challenges in main- taining and enhancing the power quality and overall sys- tem stability. One of the main problems caused is the de- terioration of the waveform of the current and voltage. The primary aim of this study is to examine and evaluate the application of a shunt active power filter (SAPF) with a peak detection control system in a shipboard power sys- tem and the possibility of reducing the THD (total har- monic distortion) at PCC (point of common coupling) of the nonlinear loads. Using a proposed mathematical model and simulation software different case studies are presented with a comparative analysis of the power sys- tem performance with and without the presence of SAPF. Keywords - power quality; nonlinear loads; ship power systems; total harmonic distortion; shunt active power filter; I. INTRODUCTION Marine power systems and in particular the ships power systems are isolated power systems with specific dynamic processes and commensurability between source and load power ratings [1]. These attributes, coupled with the compar- atively significant impedance during a short circuit [2] make such power systems especially vulnerable to the power qual- ity phenomena. In contemporary ship power systems, the de- ployment and establishment of DC distribution grids, large electric propulsion systems, and generally increased usage of power converters are present [3], [4], [5], [6]. The disruptions that can affect the parameters of power quality are both temporary (transient) and continuous (steady-state). [7], [8]. Disturbances such as impulses, volt- age fluctuations, voltage swell, and voltage sags are classified as transient. Flickers, harmonic distortion, and unbalance are classified as steady-state disturbances [9].The issue of wave- form distortions and in particular harmonic distortion is the subject of this paper. An array of issues can arise from the presence of high levels of harmonic distortion. Malfunction- ing of electrical devices, excessive heat generation, reduction in power efficiency, measurement issues, and higher mainte- nance and operational cost along with safety issues are typical examples [10], [11]. The main types of devices used to deal with these problems are passive and active power filters [12], [13]. While the passive filters have their limitation as fixed compensation capabilities, overcompensation of reactive power, poor dynamics, and the potential danger of parallel resonance occurring with the grid impedance, the active power filters are capable to automatically adapt to the changes in the system and the load fluctuations [13]. The pos- sibility of voltage regulation, harmonic suppression, and re- active power compensation makes APF highly applicable. Fig.1 Block diagram depicting SAPF The active power filters are categorized depending on their topology, principle of control, converter type, and the characteristic of compensation. The main types based on to- pology are series, shunt (fig.1), and hybrid active power fil- ters. The hybrid type is a combination of shunt and series compensation and is called also universal or unified power quality conditioner. To deal with the issues caused by waveform distortions in power systems SAPF (shunt active power filter) is primarily used. The principle of the compensation of the harmonics in the power system is in injecting equal but opposite by form- ing compensating value of the distorted signal. In a specific scenario where a nonlinear load is present, the active power filter operates as a nonsinusoidal current source in order to effectively mitigate harmonic distortion. Depending on the system parameters and characteristics the needed reference signal for the compensation is obtained with various control techniques. For the needs of SAPF ref- The study was funded by Bulgarian Research Fund, Competition for Finan- cial Support for Basic Research Projects 2021, Project title: “Integrated wire- less sensor networks for diagnostics of ship electrical equipment”