DC Active Filter Research Articles

Cascaded AC-DC Power Conversion Interface for Charging Battery

This paper develops a cascaded AC-DC power conversion interface (CADPCI) to convert AC power to charge the battery set. The proposed CADPCI is composed of a cascaded converter (CC) and a dual-input buck converter (DIBC). The CC is formed by connecting a full-bridge converter (FBC) and a bridgeless rectifier (BLR) in series. The CADPCI generates an 11-level input voltage and performs unity power factor correction. The switching loss is reduced because only the FBC with a lower DC port voltage is switched at a high frequency. The DIBC uses a buck converter and a selection switch set to generate a two-level DC voltage on the DC port of the BLR. By controlling the DC input voltage of the buck converter, the injected power of the BLR can match the input power of the utility. Therefore, the FBC does not require to handle the real power, saving an isolated converter for regulating the DC port voltage of the FBC, thus simplifying the power circuit of the CC. The buck converter also acts as a DC active filter to filter out low-frequency ripples of the charging current. A prototype is constructed to verify the performance of the proposed CADPCI.

Optimized Weight Point ADF using SOS Algorithm

Active dc filter (ADF) has become the most viable alternatives for the compensation of the harmonics in the power system analysis. These filters are capable enough to minimize the total harmonic distortion (THD) and provide compensation towards the power quality issues appearing in the transmission system. A simulated model of a HVDC system is designed in MATLAB and the disturbance is injected in the form of load change and the controller efficacy is checked. This paper basically deals with the operational characteristics of the active filter for specific voltage rating irrespective of load and used to reduce harmonics present in the output voltage of the HVDC converter when cascaded with the inverter. The gains of the ADF are optimized with Symbiotic Organism Search Optimization (SOS) with THD as a constraint.

Battery energy storage system with functions of wide AC voltage range and battery current filtering

ABSTRACT This paper develops a power conversion interface for a battery energy storage system (BESS). The power conversion interface is composed of a bidirectional DC-DC power converter and a three-port DC-AC power converter, and it has the functions of wide AC voltage range and battery current filtering. The three-port DC-AC power converter has a high-voltage DC port, a low-voltage DC port and an AC port. The high-voltage DC port and low-voltage DC port are, respectively, connected to the output of the DC-DC power converter and the battery set, and the AC port is connected to the grid. The three-port DC-AC power converter generates a five-level voltage or a three-level AC voltage at the AC port according to the amplitude of grid voltage. The bidirectional DC-DC power converter has two functions. One is to generate a higher DC voltage to the high-voltage DC port, and the other is to perform a DC active filter function for attenuating the low-frequency ripple of the charging/discharging current for the battery set. All or part of the charging/discharging power for the battery set is only processed by the three-port DC-AC power converter, which can improve the efficiency of the BESS. A hardware prototype with a digital signal processor controller is developed to verify the performance of the developed power conversion interface for the BESS.

Shunt Active DC Filter to Reduce the DC-Link Ripple Current Caused by Power Converters to Improve the Lifetime of Aluminum Electrolytic Capacitors

Electrolytic capacitors are commonly used as a dc-link in power electronics circuits and especially in renewable energy system applications. However, their life expectancy and reliability can be severely affected by the ripple current causing increased thermal stresses. Further, the switching of power electronics and the presence of harmonic components can increase the ripple current that may shorten the lifetime of the electrolytic capacitors. This article proposes the use of a shunt active dc filter to regulate the dc capacitor current to a near-constant value and hence mitigate the events that can reduce the capacitor life expectancy. The proposed filter reduces the ripple in the capacitor dc current irrespective of the frequency spectrum of the ripple. The design and the operation principles of the proposed filter are presented and discussed. The results from the simulation and experimental studies demonstrate the effectiveness of the proposed technique.

Power quality assurance in the electrical network of the Syrian Arab Republic, using the active power filter

The set of characteristics that determine the power quality (PQ) can be used to describe the state and efficiency of the power supply system in terms of the influence of electromagnetic interference. The impact of electromagnetic interference on electrical equipment is manifested in the reduction of uptime, additional losses of active power, data loss, etc. The most common sources of interference in modern conditions are consumers with non-linear volt-ampere characteristics. This type of electrical receivers creates a distortion of the current and voltage waveform. In view of the widespread use of these power consumers in daily life and industry, special attention should be paid to the problems of harmonic distortion. This article presents the results of measurements and analysis of the quality of electricity, and also shows the effect of applying an active filter (AF) to ensure the quality of electricity in the distribution network (66/20 kV) of the city of Lattakia in the Syrian Arab Republic. The definition of the optimal capacitance of the AF dc link using the particle swarm method is given in order to minimize the total non- sinusoidal current and voltage in the studied electrical network.

Shunt active DC filter based on intelligence controller for HVDC link

A shunt active DC filter (ADF) with current injection suppresses current harmonics from high-voltage DC (HVDC) transmission systems. This paper proposes an ADF based on artificial neural networks (ANNs). The ANNs are very generic, accurate and convenient statistical models. They can emulate numerical model components, which are of complicated non-linear input/output relationships. The neural network in the control system of the ADF estimates the harmonic components of the load current and voltage. The ANN is trained offline using databases from the conventional controller. The simulation is carried out by MATLAB/Simulink and its results confirm that the proposed controller can offer better performance such as suppression of the current variations (current harmonics) in the DC-transmission line.

Generalisation of an averaged model approach to estimate the period‐doubling bifurcation onset in power converters

The usual method of estimating the onset of bifurcation and studying non-linear phenomena in power electronic devices consists of defining the discrete-time model. This model provides more precise results than an averaged model. However, the discrete-time model cannot be developed easily for some particular systems. In this study, a continuous-time averaging model is developed for a boost converter in the continuous-conduction mode (CCM). This proposed model is used to obtain the eigenvalues of the system to predict the stable operation of the period-1 orbit. It is observed that the loss of the asymptotic stability of the proposed model corresponds to the onset of period-doubling bifurcation in the discrete-time model. The generalisation of this method is investigated by applying the proposed method to a DC active filter converter connected in parallel with a CCM boost converter. Using this model, it is possible to obtain the eigenvalues of the system to investigate robustness properties with regards to system parameter variations. To confirm the validity of the proposed method, simulation and experimental results are presented.

A Grid Connected Flyback Inverter with a DC Active Filter for Photovoltaic Cells

This paper presents the design and control of a grid-connected flyback inverter with a DC active filter for photovoltaic (PV) cells. The proposed topology consists of a flyback DC-AC inverter and a DC active filter that can operate independently. The flyback inverter, controlled in digital peak current mode, regulates the full-wave rectified sinusoidal current later, which is alternately inverted and injected into the grid. The DC active filter regulates the smooth current/power drawn from a PV module by using cascaded proportional-integral (PI) controllers. Analysis, design and control of the proposed topology are presented. A 100W/220V/50Hz prototype is developed and tested. The experimental results show that the proposed flyback inverter with a DC active filter is capable of regulating a sinusoidal current fed into the grid, actively filtering the DC current/power and achieving reasonably high energy conversion efficiency.

Design of the Shunt Liner Active Power Filter for the Hybrid-Magnet Superconducting Outsert Power Supply

The power supply scheme for the superconducting outsert of Steady High Magnetic Field Facility (SHMFF) in High Magnetic Field Laboratory of Chinese Academy of Sciences is a switching power supply with active DC power filter. In this paper, a novel shunt liner active power filter (SLAPF) is designed to overcome the disadvantages of existing dc active filter schemes. The system structure and working principle are presented at first. Then the design flow is described, which includes the control method of the current compensator, the analysis of topology chosen for auxiliary power supply, At last, the experimental results show that the filtering effect of SLAPF is good enough to make the power supply meet the technical requirements.

Optimization and Coordination of HAFDV PINN Control by Improved PSO

The new hybrid active filter (HAF) is composed of the larger-capacity passive filter banks and the smaller-capacity active filter. It is difficult to tune the parameters of a PI controller using the DC capacitor voltage control. In this paper, the improved particle swarm optimization (improved PSO) algorithm is proposed to solve the coordinated design problem, and the neural network weights as the particle swarm optimization are adopted to optimize the system parameters. Comparing with the conventional PI controller, the results of PINN controller prove the effectiveness of designed method on both the transient and steady-state performance of the hybrid active filter DC bus voltage (HAFDV) controllers.

A new shunt DC active filter of power supply in a steady high magnetic field facility

A DC active power filter is an indispensable part in a high power and high stability power supply system, especially in the power supply system of the Steady High Magnetic Field Facility, which requires that the current ripple should be limited to 50 parts per million. In view of the disadvantages of the series DC active power filter and shunt Pulse Width Modulation DC active filter, this paper puts forward a novel DC active filter by combining the advantages of the transistor regulator and the shunt type. The structure and principle of the new shunt linear active filter are introduced. Meanwhile, the design of several key components that construct the new shunt linear active filter is also analyzed. The simulation model and an experimental prototype of the shunt linear active filter are developed, and the results verify that the parameter design is reasonable and the shunt active filter has a good filter effect.

Harmonic suppression in HVDC system using a modified control method for hybrid active DC filter

SUMMARYA shunt hybrid active DC filter (HADF) is applied to eliminate DC transmission line current harmonics in HVDC transmission system. Since the harmonics increase transmission line losses and disturb control and monitoring equipments so HADF are used to suppress harmonics on DC transmission lines. In this paper a modified method is presented to control the shunt HADF which is not dependent on HVDC circuit parameters. HADF by injecting the compensating current to DC transmission line with the modified method suppresses the DC transmission line current harmonics significantly. Six major problems in design of modified control method have been discussed thoroughly. The principle of operation is described and the theoretical analyses are indicated to verify the control strategy. HVDC system is simulated by PSCAD/EMTDC software. Simulation results and comparisons prove and validate the accuracy of these claims. Copyright © 2011 John Wiley & Sons, Ltd.

Ripple Current Reduction of a Fuel Cell for a Single-Phase Isolated Converter Using a DC Active Filter With a Center Tap

A ripple current reduction method is proposed that does not require additional switching devices. A current ripple that has twice the frequency component of the power supply is generated in the dc part when a single-phase pulsewidth-modulated inverter is used for a grid connection. The current ripple causes shortening of the lifetime of electrolytic capacitors, batteries, and fuel cells. The proposed circuit realizes a dc active filter function without increasing the number of switching devices, because the energy buffer capacitor is connected to the center tap of the isolation transformer. In addition, the buffer capacitor voltage is controlled by the common-mode voltage of the inverter. The features of the proposed circuit, control strategy, and experimental results are described, including the result of ripple reduction, to approximately 20% that of the conventional circuit.

Study on the Control of Shunt Active DC Filter for HVDC Systems

A shunt active dc filter (ADF) has been applied in high-voltage dc transmission systems for harmonic suppression. Some key problems in the design of ADF control systems have not been investigated thoroughly due to high harmonic frequency and the complexity of system modeling. In this paper, a high-gain feedback control strategy is proposed, which is independent of circuit parameters. The authors draw a comparison between the harmonic suppression effects of ADF and that of a passive filter and prove that the former can increase the series impedance of the hybrid filter, while the latter can decrease the equivalent voltage. Based on circuit analyses, solutions, such as selection of the dc-side voltage, regulation of the modulation index, system stability conditions, filter design, and switching noise are presented. The consistency between theory analyses and experimental results verifies the feasibility of the proposed control strategy.

Harmonic cancellation for HVDC systems using a notch-filter controlled active DC filter

A notch-filter controlled active DC filter is applied to suppress the current harmonics in a high-voltage-direct-current (HVDC) system. The design principle of the notch filter controller is discussed and the sensitivity and stability of the proposed control scheme are analysed. Simulation results obtained show effective and robust cancellation of unwanted harmonics on the DC transmission line and demonstrate that the controller outperforms the conventional Proportional + Integral (P+I) based approach. Simulation also shows that the control scheme is insensitive to the changes of AC system frequency.

Analysis on the control principle of the active DC filter in the Lindome converter station of the Konti-Skan HVDC link

The control principle of a hybrid passive-active DC filter installed in the Lindome HVDC converter station is analyzed in this paper. The controller of the active filter includes two basic functions: an integrator and a compensator. The main advantage of the Lindome controller is its simple structure for implementation in a digital signal processor (DSP). The drawbacks of this controller are its long response time, low stability margin and the filtering of an unnecessary number of frequencies. An alternative control strategy using a number of notch filters has been investigated. The notch filters can be tuned to those frequencies that need to be damped. This controller gives a much shorter system response time and improved stability margin.

The Smoothing Transformer: A New Concept in DC Side Harmonic Reduction of HVDC Schemes

Direct connection schemes have been a subject of recent investigation, offering operational flexibility and substantial reductions in AC components. In these schemes, the use of active DC filters has been suggested to replace the conventional tuned passive filter design. This paper presents the smoothing transformer as a new means for reducing DC harmonics at characteristic and noncharacteristic frequencies using only passive components. A realistic smoothing transformer design is examined using the New Zealand HVDC power system operating in the direct connection mode. The steady-state and transient performance of the smoothing transformer design is compared with that of the existing DC smoothing reactor and filter bank.

The smoothing transformer, a new concept in DC side harmonic reduction of HVDC schemes

Direct connection schemes have been a subject of recent investigation, offering operational flexibility and substantial reductions in AC components. In these schemes, the use of active DC filters has been suggested to replace the conventional tuned passive filter design. This paper presents the smoothing transformer as a new means for reducing DC harmonics at characteristic and noncharacteristic frequencies using only passive components. A realistic smoothing transformer design is examined using the New Zealand HVDC power system operating in the direct connection mode. The steady-state and transient performance of the smoothing transformer design is compared with that of the existing DC smoothing reactor and filter bank.

95/06090 Active DC filters for HVDC systems

95/06090 Active DC filters for HVDC systems

Active DC filter for HVDC systems

In pursuit of higher performance and lower cost for harmonic filtering in high-voltage direct current (HVDC) power transmission systems, a prototype of an active DC filter was developed and installed on the DC line at the Lindome converter station of the KontiSkan 2 HVDC link between Sweden and Denmark at the end of 1991. This installation provides practical evidence that an active filter is possible for high voltage transmission systems and that this could be a better and cheaper alternative than the conventional passive filter. The filter is described as is its control and protection.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>