Power quality improvement of dispersed generation systems using hybrid filter

A hybrid filter constructed of a shunt active filter and distributed passive filters used for power quality improvement in dispersed generation system is presented. The distribution system consists of two wind turbines using induction generators for producing the required active power and several dynamic nonlinear loads. The power quality problems of dispersed generation LV or MV systems are introduced and the necessity of using hybrid filters instead of active or passive filters alone are discussed. The simulation is done with PSCAD/EMTDC software for a distribution system with dynamic nonlinear loads and wind turbines without any filters, with usage of just shunt active filter or passive filters and the hybrid filter structure, introduced in the paper. Studying and comparing the waveforms, frequency spectrums, harmonic contents and THD of the system current with different filter structures mentioned, proves power quality improvement by the applied hybrid filter

Simulation and Performance Evaluation of Shunt Hybrid Power Filter for Power Quality Improvement Using PQ Theory

This work proposes the design of shunt hybrid filter using instantaneous power theory to improve the power quality and simulation has been carried out for 3 phase distribution system feeding different types of non linear loads. The proposed filter consists of parallel combination of 5th and 7th tuned selective harmonic elimination passive filters, which is connected in series with a small rating IGBTs based voltage source inverter. In this work, principle of compensation and filtering behavior of the system has been discussed in detail. Instantaneous real and reactive power theory based controller has been designed to estimate the reference current from the distorted current. In order to reduce the harmonics, generated reference currents are tracked by voltage source inverter using hysteresis band current controller. The performance of the hybrid scheme is evaluated for various nonlinear loads using Matlab/ Simulink tool. The detailed analysis has been carried out on harmonics reduction and DC bus voltage regulation and the simulation result ensures the feasibility of suggested control strategy. The proposed topology improves the filtering performance of the passive filter in hybrid scheme

Active and hybrid filters in medium voltage distribution power systems

This paper presents the design of different topologies of active power filters to compensate reactive power and harmonics in the medium voltage level of a distribution power system. One pure active filter and two hybrid topologies, are implemented. A pure active compensation is obtained with a Shunt Active Power Filter (SAPF). The shunt combination of SAPF and passive filter, form one of the hybrid topologies implemented, named Shunt Hybrid Active Power Filter (SHAPF). The other hybrid topology, called Hybrid Shunt Active Power Filter (HSAPF), connects the active filter in series with two shunt passive filters. The control algorithm are implemented with the d-q theory measuring the system current to compensate the load, setting a feedback control loop, rather than a simple feedforward compensation. Simulation for different load demands and distortions are performed. Finally a comparative evaluation of the different filters is carried out.Instituto de Investigaciones Tecnológicas para Redes y Equipos Eléctricos (IITREE

An Elegant Solution Using Hybrid Power Filter to Improve the Line Current Spectrum of Multiphase PWM Locomotive Rectifiers with Load Unbalance

Locomotive PWM Rectifiers employed in A.C traction systems represent several megawatts of electrical load. Typically they use multiple rectifiers/converters in parallel in order to secure high power ratings and high frequency operation. The rectifiers are supplied from a single-phase A.C. traction transformer with multiple secondaries of high leakage inductance. The switching instants of the PWM rectifiers are phase shifted and interlaced in order to achieve high ripple current cancellation, assuming that the converter loads are balanced. This would ensure the rectifiers to provide better harmonic performance and also redundancy of operation with multiple units in operation. However, in practice, rectifiers may be closely coupled to a traction inverter supplying an axle or a group of axles and the real power developed will depend upon the traction conditions. Creep and slip can give rise to variations in power and perfect power balance at the rectifiers is an improbable proposition.There is high degree of interest to examine the possibility locomotive systems that degrade gracefully with equipment failure. Failure of one traction inverter would lead to load unbalance for the rectifier modules. Or sometimes, partial failures may result in unbalanced operation which can cause reduced ripple current cancellation and generate switching frequency harmonic current components. This may adversely impact the signalling systems and/or result in over voltage effects due to resonance in the overhead supply system. This paper examines a 4 MW locomotive with three rectifier modules and a device switching frequency of 900 Hz. This results in a 5400 Hz ripple frequency in the mains current. And this paper will consider what may be the most frequently occurring case; that of loss of load in one traction motor due to wheel slip. Current ripple cancellation is partially lost in this case and lower frequency current components can be produced. Traditionally, number of solutions has been employed in the industry like passive filters, active filters etc., for this type of a problem. However, this paper explores an elegant, attractive and economical solution of using hybrid filters in order to achieve a level of acceptable satisfactory harmonic performance and thereby improving the power quality of the rail systems

PERBANDINGAN PENGGUNAAN MODEL FILTER PASIF DAN FILTER AKTIF SERI TIGA PHASA UNTUK MENINGKATKAN KUALITAS DAYA LISTRIK AKIBAT

Tujuan penelitian adalah membandingkan penggunaan model filter pasif dan filter aktif seri untuk meningkatkan kualitas daya akibat beban non-linier di industri. Ada dua mode operasi beban yaitu rangkaian terhubung pada beban non-linier seimbang dan tidak seimbang di industri. Parameter kualitas daya meliputi harmonisa arus dan tegangan, arus dan tegangan tidak seimbang, perbaikan nilai faktor daya masukan atau power factor corection (PFC) menggunakan model filter pasif dan filter aktif seri. Rangkaian filter dimodelkan secara matematis dengan teknik kendali arus menggunakan pulse width modulation (PWM) dan Teori Dual Instantaneous Reactive Power. Aspek penelitian adalah total harmonics distortion (THD) tegangan dan arus sumber, arus dan tegangan tidak seimbang, perbaikan faktor daya rangkaian terhubung beban non-linier (seimbang dan tidak seimbang) berdasarkan Standar IEEE-519, ANSI/IEEE 241-1990, dan Standar PLN. Hasil penelitian adalah rangkaian sistem pada tiga kondisi kompensasi terhubung beban non-linier tidak seimbang, menghasilkan THD rata-rata arus lebih kecil dibandingkan pada sistem terhubung beban non-linier seimbang. Penggunaan filter aktif seri mampu menurunkan THD arus sesuai Standar IEEE 519-1992. Pada kondisi sistem sama, rangkaian terhubung beban non-linier tidak seimbang, menghasilkan nilai arus tidak seimbang lebih besar dibandingkan sistem terhubung beban non-linier seimbang. Rangkaian terhubung beban non-linier tidak seimbang, mampu menghasilkan nilai faktor daya sedikit  lebih tinggi dibandingkan beban non-linier seimbang. Nilai THD tegangan sistem berbeban non-linier seimbang dan tidak seimbang untuk semua kondisi tanpa dan menggunakan kompensasi, nilainya relatif kecil dan berada dibawah level 1% serta sudah memenuhi batas harmonisa tegangan sesuai Standar IEEE 519-1992. Nilai tegangan tidak seimbang kondisi tanpa dan menggunakan filter pada kedua mode relatif stabil. Sistem terhubung dua mode beban non-linier mampu meningkatkan nilai harmonisa arus dan arus tidak seimbang, namun tidak berdampak signifikan terhadap perubahan harmonisa tegangan dan tegangan tidak seimbang

Implementation and comparison of different switching techniques for shunt active power filters

This paper presents a comparison between three switching techniques that can be used in three-phase four-wire Shunt Active Power Filters (SAPFs). The implemented switching techniques are: Periodic-Sampling (PS), Triangular Carrier Pulse-Width Modulation (TC-PWM) and Space Vector PWM (SVPWM). The comparison between them is made in terms of the compensated currents THD%, implementation complexity, necessary CPU time and SAPF efficiency. To perform this comparison are presented and analyzed several experimental results, obtained with a 20 kVA Shunt Active Power Filter prototype, specially developed for this purpose. The control system of the developed SAPF is based in the p-q Theory with a grid synchronization algorithm p-PLL

Analisa Perancangan Filter LCL Pada Penyearah PWM Satu Fasa Full Bridge

Electronics devices need a direct current power supply although now only one alternating current power supply is available. Therefore, ac-dc converters which can convert an alternating current power supply to a direct current power supply will be needed. However, the use of this ac-dc converters will cause distortion in the form of current waves which are called harmonics. This harmonics can fault the work of the other electric devices which are attached to the same power source. Therefore, it is recommended that the harmonics generated by rectifiers should be under IEC 61000-3-2 standard. In this research will the reduction of harmonics by using LCL filter. At load of 2 kW, R of 5 ï—, L of 0,05 H at PWM rectifiers single phase full bridge with RL load produce the third harmonics current of 2.57 amperes, the installed LCL filter produces the third harmonics current of 1.26 amperes. According to IEC-61000-3-2 standard, the allowed third harmonics current is 2.3 amperes

Perancangan Filter LCL Pada Penyearah Terkendali Satu Fasa Full Converter

Abstrak Perkembangan elektronik yang dewasa ini cukup pesat telah menghasilkan banyak peralatan elektronik baik untuk kebutuhan rumah tangga, perkantoran maupun industri. Umumnya peralatan ini membutuhkan catu daya sumber tegangan arus searah, sementara catu daya yang tersedia merupakan sumber tegangan arus bolak balik. Oleh karena itu, dibutuhkan konverter ac-dc yang berfungsi mengubah sumber tegangan arus bolak balik yang ada menjadi sumber tegangan arus searah. Namun, pemakaian peralatan konverter ac-dc, menghasilkan distorsi pada bentuk gelombang arus, yang dikenal dengan harmonisa yang dapat mengganggu kerja peralatan listrik lainnya yang terpasang pada sumber tegangan yang sama. Jadi, haruslah diupayakan agar harmonisa yang dibangkitkan oleh konverter ac-dc sekecil mungkin dibawah standar yang diizinkan. Pada penelitian ini hanya meneliti konverter ac-dc berupa penyearah terkendali satu fasa full converter. Banyak metoda yang dapat dilakukan untuk mengurangi harmonisa yang dibangkitkan oleh kedua penyearah ini, salah satu cara adalah dengan menggunakan filter LCL pada sisi inputnya. Pada daya beban sebesar 2 kW, pada penyearah terkendali satu fasa full converter dengan beban RL menghasilkan arus harmonisa ke tiga sebesar 40,36 Ampere, sesudah dipasang filter LCL arus harmonisa ke 3 menjadi 0,02 Ampere. Sedang menurut standard IEC-1000-3-2, arus harmonisa ketiga yang diizinkan adalah sebesar 2,3 Ampere

Active and hybrid filters in medium voltage distribution power systems

This paper presents the design of different topologies of active power filters to compensate reactive power and harmonics in the medium voltage level of a distribution power system. One pure active filter and two hybrid topologies, are implemented. A pure active compensation is obtained with a Shunt Active Power Filter (SAPF). The shunt combination of SAPF and passive filter, form one of the hybrid topologies implemented, named Shunt Hybrid Active Power Filter (SHAPF). The other hybrid topology, called Hybrid Shunt Active Power Filter (HSAPF), connects the active filter in series with two shunt passive filters. The control algorithm are implemented with the d-q theory measuring the system current to compensate the load, setting a feedback control loop, rather than a simple feedforward compensation. Simulation for different load demands and distortions are performed. Finally a comparative evaluation of the different filters is carried out.Instituto de Investigaciones Tecnológicas para Redes y Equipos Eléctricos (IITREE