Voltage Distortion Compensation Research Articles

DISTRIBUTION OF THE POWER OF THE A POWER ACTIVE FILTER BOOSTER TRANSFORMER FOR REGULATING OF THE NONLINEAR VOLTAGE DISTORTIONS COEFITIENT

Purpose. Investigate the parameters of the mode and distribution of the power of the transformer of the booster when adjusting the coefficient of the nonlinear distortion of the voltage.Methodology. Methods of electrical engineering, numerical simulation methods, Fourier series methods.Findings. The analysis of the transformer is carried out, the processes taking place in the transformer are considered, the filter model is developed in the visual programming environment, based on the analysis of which the application efficiency of the proposed solution is shown by the load voltage distortion. To assess the influence of the transformer on the operating mode of the device, a series of experiments was carried out. In the case of distortion of supply voltage, a serial active power filter is used that connects to the network through series transformers, which results in changes in the parameters of the equivalent power load circuit. As a result of the research it was established that the transformer of a series power active filter in the series mode, in case of compensation of voltage distortion of the network in general, has the voltage and current of the windings, the harmonic composition of which is different, this leads to a broad harmonious composition of the power of the transformer, which needs to account for the growth of losses in windings. and the magnetic circuit. The conclusions are drawn that to the effect of the parameters of the transformer on the operation of the active filter.Originality. For the first time a model of an equivalent force single-phase sequential filter has been developed, which, unlike the existing one, takes into account the effect of the series transformer on the parameters of the mode.Practical value. The internal resistance of the transformer and the load current lead to the emergence of voltage harmonics, which additionally affects its quality, and in the case of an experiment made up 2,35%. An increase in power losses in a transformer of a power active filter requires an adjustment of the method of its selection, taking into account distortion of voltage and current.

Harmonic Power Sharing With Voltage Distortion Compensation of Droop Controlled Islanded Microgrids

Harmonics are found to have deleterious effects on power system equipment including transformers, capacitor banks, rotating machines, etc. However, the distributed generation interfacing converters (DICs) are able to improve power quality and system efficiency in case of adding a flexible control strategy. This paper describes the voltage distortion generated by nonlinear loads and proposes a new harmonic droop control to reduce the voltage harmonic distortion at the point of common coupling (PCC) and to share the harmonic power between parallel islanded inverters controlled by classical frequency droop method. The main objective it to effectively compensate the harmonic currents drawn by each DIC to supply the nonlinear loads in parallel with voltage harmonic damping at PCC. The operation principle of the proposed harmonic droop is explained in details. Modeling and stability analysis are developed in order to define the control parameters suitable for proper operation. Simulation and experimental results are presented to show the competence of the proposed algorithm in achieving harmonic power sharing and in improving the voltage harmonic distortion at the PCC.

An Improved Centralized Control Structure for Compensation of Voltage Distortions in Inverter-Based Microgrids

Recently, increased use of non-linear loads has intensified the harmonic distortion and voltage unbalance in distribution systems. Inverter Based Distributed Generators (IBDGs) can be employed as distributed compensators to improve the power quality, as well as to supply distribution systems. In this paper, an enhanced hierarchical control scheme for the compensation of voltage disturbance in an AC Micro Grid (MG) that includes of two control levels is proposed. The secondary control level is performed by a centralized controller. Data of voltage harmonics and voltage unbalance at the MG Sensitive Load Bus (SLB) is sent to the centralized controller by a measurement unit. A general case with a combined voltage harmonic and unbalance distortion is considered. The compensation coefficients for IBDG units are computed by the centralized controller, and reference commands are sent to the local controllers of the IBDG units that act as a primary level of control. In the secondary control level, harmonic analysis is performed for the MG in order to provide a guide for properly assigning the harmonics and unbalance compensation priorities to IBDGs at different locations in the distribution system. Some buses have more participation in exciting the MG resonance modes; therefore, larger harmonic compensation factors are considered for the IBDGs that are near to these buses. For other IBDGs, the voltage unbalance compensation factor is selected bigger. The control system of the IBDGs mainly includes a current controller, a virtual damping resistor loop, and a load compensation block. Effectiveness of the proposed control scheme is demonstrated through simulation studies.

Sensorless Control of PMSM by a Four-Switch Inverter with Compensation of Voltage Distortion and Adjustment of Position Estimation Gain

This paper proposes performance improvement schemes for sensorless PMSM control drive using a four-switch three-phase inverter (so-called B4 inverter). In the proposed scheme, the back-EMF estimation-based sensorless control algorithm is used to control the brushless PMSM without position sensors. In order to have stable operation, this paper presents a gain adjustment scheme that compensates the reduction of stable sensorless operation range as long as the rotor speed increases. In B4 topology, the center point of dc-link capacitors is connected to 3-phase load, and it is prone to have the load current distortion. Hence, to mitigate this problem, a distortion compensation scheme by modifying voltage commands using measured dc-link potentials is proposed in this paper. The validity of the proposed method is evaluated by simulations and experiments.

A Precise Voltage Distortion Compensation Strategy for Voltage Source Inverters

To achieve precise voltage value for modern model-based motor control strategies, an accurate voltage distortion compensation method for voltage source inverters is proposed in this paper. The voltage distortion principles of a mosfet -based inverter and an IGBT-based inverter are analyzed and compared. A graphical solution of compensating voltage error is proposed, all the voltage distortion factors are considered. A current observer is designed to overcome time delay, achieve precise current in each switching period for compensation. The proposed method is of high precision, intuitive, and easy to implement. The effectiveness of the proposed method is verified by experiments.

On-load voltage distortion compensation method using disturbance observer for SPM machines with closed slot

On-load voltage distortion compensation method using disturbance observer for SPM machines with closed slot

A Single-Phase Active Device for Power Quality Improvement of Electrified Transportation

A transformerless hybrid series active filter is proposed to enhance the power quality in single-phase systems with critical loads. This paper assists the energy management and power quality issues related to electric transportation and focuses on improving electric vehicle load connection to the grid. The control strategy is designed to prevent current harmonic distortions of nonlinear loads to flow into the utility and corrects the power factor of this later. While protecting sensitive loads from voltage disturbances, sags, and swells initiated by the power system, ridded of the series transformer, the configuration is advantageous for an industrial implementation. This polyvalent hybrid topology allowing the harmonic isolation and compensation of voltage distortions could absorb or inject the auxiliary power to the grid. Aside from practical analysis, this paper also investigates on the influence of gains and delays in the real-time controller stability. The simulations and experimental results presented in this paper were carried out on a 2-kVA laboratory prototype demonstrating the effectiveness of the proposed topology.

보상전압 첨가를 통한 B4 인버터 성능향상

This paper proposes a current ripple reduction method to improve the control performance of B4 type inverter that is studied for cost-effective drive systems. B4 inverters employ only four switches and they have a center-tapped connection between the split dc-link capacitors and one phase of a three-phase motor or load. In the B4 topology, unbalanced three-phase voltages will be generated due to the dc-link voltage ripple. To solve this problem, this paper presents a voltage distortion compensation method that adjusts the voltage reference with the consideration of dc-link voltage ripple. The validity of the proposed method is verified by simulation and excremental results with an induction machine.

Mitigation of Voltage Disturbances Using Dynamic Voltage Restorer Based on Direct Converters

In this paper, two new topologies are proposed for three-phase dynamic voltage restorers (DVRs). These topologies are based on direct converters. The proposed topologies do not require dc-link energy storage elements. As a result, they have less volume, weight, and cost. They can also compensate long-time voltage sags and swells. The proposed DVRs can compensate several types of disturbances, such as voltage sags, swells, unbalances, harmonics, and flickers. Moreover, due to the fact that the compensation voltage for each phase is taken from all three phases, the proposed topologies can compensate one-phase outages. In the proposed topologies, three independent three-phase to single-phase direct converters are used. Each converter operates independently and, as a result, the proposed DVRs properly compensate unbalanced voltage sags and swells. The used converters can be constructed by four or six power switches. Depending on the structure of the used converters, the compensation ranges will be different. A new control method is also proposed for using direct ac/ac converters. The experimental and simulation results verify the capabilities of the proposed topologies in compensation of voltage distortions.

Online observation and compensation of voltage distortion in PWM VSI for PMSM

In general, there exists a voltage difference between the reference and the output voltages in a pulse-width-modulated (PWM) voltage-source inverter (VSI). This difference or distortion is caused partly by the intended blanking time and partly by the inherent characteristics of the switching devices, which are dependent on the operating conditions. The voltage distortion in a PWM VSI is analysed and a new online estimation method for a permanent magnet synchronous motor (PMSM) is proposed to compensate for the time-varying voltage distortion. This new estimation method is not based on a direct voltage observation but on an indirect observation of the intermediate parameter, and the voltage distortion and the compensation voltage are calculated from this intermediate parameter. The former method gives an observation delay due to the lowpass filter, however, the latter method gives almost the same results as the real one.

Analysis and Compensation of Voltage Distortion by Zero Current Clamping in Voltage-Fed PWM Inverter.

In voltage-fed PWM inverter, the relation between the reference voltage and the output voltage is nonlinear. Especially, when the currents are around zero point, the nonlinear voltage distortion invokes the most serious problems in the system performance. In this paper, the analysis of the voltage distortion by the zero current clamping phenomenon is discussed. From this analysis, a novel distortion voltage compensation strategy that eliminates zero current clamping is presented. Experimental results are also presented to demonstrate the validity of the proposed method.

Direct method for voltage distortion compensation in power networks by series converter filter

A novel method of voltage distortion compensation and a novel power circuit for a power converter filter are proposed. The new method does not require calculation of an active current or voltage component and in this way a delay in compensator response is avoided. This approach is verified by measurements in a low-power model.

Measurement aspects of the voltage distortion compensation

AbstractA complete solution of the compensator controller, allowing to eliminate voltage distortion in power system is presented. The two‐step circuit identification procedure based on the interpolating “Fast Fourier Transformation “ (FFT) has been successfully used to damp the 3rd, 5th and 7th harmonic by 60 dB at selected buses. Interpolating, flat‐top and coherent sampling methods, when used to 10 bit A/D converted (noised) signals, have been compared and simulated. It is shown that the shortest signal record requested to perform step calculations is of only one voltage period when a modified windowed coherent sampling method is used. The proposed method is tolerant to the coherency mistuning, so easy to implement even if a very simple hardware frequency multiplier is used to generate the sampling signal. A background to the presented solutions is given, allowing easily to solve similar compensating problems with different constraints.

Voltage-Distortion Compensation in Electrical Plants Supplying Static Power Converters

Voltage distortion compensation is a problem that must often be tackled in electrical plants supplying nonlinear loads, such as static power converters, both to ensure reliable behavior of apparatus sensible to harmonics and to comply with standard limits. Analysis of the compensation system constituted by harmonic filters and protection reactance is carried out, to clarify their contribution to voltage distortion factor improvement and fundamental project criteria. To this end a study of the current commutation transient, cause of voltage notches and, hence, of voltage distortion, is performed in the presence of filters, and the distortion factor is calculated by means of two separate methods. Comparison between these methods, based on voltage notches and harmonic voltage drop, respectively, and determination of the expressions for estimating the overlap angle after filter insertion allow the influence of filters on the line and the converter to be analyzed.