Single-tuned Harmonic Filters Research Articles

Multi-objective optimization of planning single-tuned harmonic filter utilizing interactive forest algorithm

This paper proposes an interactive forest algorithm for planning single-tuned harmonic filters for electric power distribution systems. The planning of harmonic filters is a complex problem that must consider multiple objectives, including minimizing the total cost of installed filters and the individual and total harmonic distortion while adhering to operational constraints, such as the voltage drop, the current loading and the harmonic limits. Moreover, system perturbations must be considered, such as frequency variations. This paper proposes a new method for multi-objective optimization of planning single-tuned harmonic filters utilizing the proposed interactive forest algorithm with a non-differentiable multi-objective function involving continuous and discrete variables. A multi-objective optimization technique based on the proposed interactive forest algorithm is proposed. In the interactive approach, planners set expectations for each objective and use the forest algorithm to figure out the optimization problems. The results of the Pareto Front are analyzed and the answers are searched through the interactive process to identify a solution that meets the planner’s expectations, allowing for practical compromise or satisfactory solutions. A case study is reported to show the superiority of the proposed method.

Mitigation of harmonic distortions in third rail electrical systems

<span lang="EN-US">The extensive use of power electronic converters in the third rail system increases the harmonic distortions on the rail electrical feeding systems. Electrical machines and transformers could be overheated causing premature failures of the devices. It is therefore important to address the harmonic distortions on the electrical networks during real-time operation, which includes the degraded operation, not just the normal operation. In this paper, the harmonic distortions of a third rail system are investigated using electrical transient and analysis program (ETAP) simulation software. Four operating scenarios, namely the normal operation and three degraded operations, are considered in the studies. The degraded operations occur when one of the bulk supply transformers or 33 kV feeders is out of service. The findings of the studies showed that the 11<sup>th</sup> and 13<sup>th</sup> order harmonics are the dominant harmonic orders due to the use of 12-pulse rectifiers on the third rail system. Single-tuned harmonic filters are designed and placed in the 33 kV feeders to mitigate the individual voltage harmonic distortion (IHD<sub>v</sub>) and the total voltage harmonic distortion (THD<sub>v</sub>) so that it is within the statutory of IEEE 519:2014.</span>

단일동조 저차 고조파 필터뱅크 과도회복전압

Industrial power systems include lots of non-linear loads which draw in non-sinusoidal currents. These non-sinusoidal currents are harmonic sources in the power systems, leading to power quality issues. A typical way to solve the power quality issues is to install single-tuned harmonic filter banks in parallel that provide low impedance paths for harmonic currents at their tuning orders, allowing for harmonic mitigation. Depending on harmonic orders, single-tuned harmonic filter banks have different switching characteristics: high amplitude and frequency back-to-back inrush currents of high-order harmonic filter banks; and high transient recovery voltage of low-order harmonic filter banks. This paper focuses on the latter to offer beneficial insights on power system design for safe and reliable harmonic filter bank switching. Theoretical analysis with electromagnetic transient studies describes how the high transient recovery voltage occurs in the low-order harmonic filter banks during the open operation of a circuit breaker. A field measurement on a second-order harmonic filter bank with 30 MVar and 33 kV proves that an excessive transient recovery voltage of approximately 92 kV can appear across the circuit breaker terminals. Lastly, this paper discusses the gap between this excessive voltage generated in a field and the test voltage specified in the IEC standard.

Optimal Harmonic Mitigation in Distribution Systems with Inverter Based Distributed Generation

In recent years, with the widespread use of non-linear loads power electronic devices associated with the penetration of various renewable energy sources, the distribution system is highly affected by harmonic distortion caused by these sources. Moreover, the inverter-based distributed generation units (DGs) (e.g., photovoltaic (PV) and wind turbine) that are integrated into the distribution systems, are considered as significant harmonic sources of severe harmful effects on the system power quality. To solve these issues, this paper proposes a harmonic mitigation method for improving the power quality problems in distribution systems. Specifically, the proposed optimal planning of the single tuned harmonic filters (STFs) in the presence of inverter-based DGs is developed by the recent Water Cycle Algorithm (WCA). The objectives of this planning problem aim to minimize the total harmonic distortion (THD), power loss, filter investment cost, and improvement of voltage profile considering different constraints to meet the IEEE 519 standard. Further, the impact of the inverter-based DGs on the system harmonics is studied. Two cases are considered to find the effect of the DGs harmonic spectrum on the system distortion and filter planning. The proposed method is tested on the IEEE 69-bus distribution system. The effectiveness of the proposed planning model is demonstrated where significant reductions in the harmonic distortion are accomplished.

Harmonic Analysis of Reactor and Capacitor in Single-tuned Harmonic Filter Application

Industrial power distribution system includes many kinds of non-linear loads, which produce the harmonics during energy conversion transition. The single-tuned passive filter is widely used to absorb the harmonics and attenuate its undesirable effect in the distribution system. However, the passive filter might be severely stressed, and sometimes even damaged, due to the absorption of harmonics. There is voltage rise on the capacitor when the single-turned harmonic filter is applied. When the capacitor voltage rose above the allowable limit, the expected life of the capacitor will considerably deteriorate. On the other hand, the reactor can experience the spike voltage even if the voltage and current of the capacitor are within the allowable limit, and this accumulated voltage stress of the reactor causes its premature fault. In this paper, we analyzed and compared the harmonic voltage and current of the reactor and capacitor in a single-tuned harmonic filter through the EMTP software and verified them with the experimental results.

Optimal sizing and limitations of passive filters in the presence of background harmonic distortion

In this paper, the optimal sizing and limitations of shunt, passive, single-tuned harmonic filters for industrial loads are examined. The investigation takes into account not only harmonic current sources due to nonlinear loads, but also the presence of background voltage harmonic distortion. First, an analytical approach in simplified cases is developed, which leads to closed form expressions. These expressions help in gaining a deeper insight into the role of the filter branches and the influence of the various parameters of the system. They also show, both quantitatively and qualitatively, the limitations of passive filters with respect to harmonic control. Next, the general case of this constrained optimization problem is formulated and solved using genetic algorithms. The constraints ensure acceptable solutions in accordance with Standard recommendations, utility regulations and filter parameter variations. The proposed objective function to be maximized is a modified version of the power factor and ensures the optimal solution among acceptable ones. Through extensive simulations of an example system for a variety of voltage and current harmonic levels, potentialities and limitations of filter branches are thoroughly investigated. Practical conclusions drawn can be considered as guidance on engineering judgment for harmonic control in any specific application.

Goal-attainment method for optimal multi-objective harmonic filter planning in industrial distribution systems

A formulation of multi-objective optimisation for single-tuned harmonic filter planning in industrial distribution systems is presented. The objectives are total harmonic current distortion at the point of common coupling, total harmonic voltage distortion and harmonic filter investment cost. The minimisation of all the objectives is required in harmonic filter planning. The reactive power compensation constraints, the harmonic distortion constraints, the power source variation constraints and the filter de-tuning constraints are all taken into consideration. The goal-attainment method based on the simulated annealing approach is applied to solving general multi-objective harmonic filter planning problems by assuming that the decision-maker has goals for each of the objective functions. A desirable, global optimal solution generated is guaranteed by the solution methodology. Results of application of the proposed method to general multi-objective harmonic filter planning are also presented.

An advanced computer code for single-tuned harmonic filter design

The objective of this paper is to present a novel approach for limiting harmonic and improving reactive compensation for industrial power systems using single-tuned filters. The unique feature of the developed power distribution model is that it incorporates both the filter capacity and resonant point as design parameters. The model also considers the detuning effects due to temperature and frequency variations, as well as manufacturing tolerances. The proposed approach was implemented as a PC-based computer code, and it was integrated with a user-friendly graphical user interface. The developed analysis tool was employed to solve the harmonic problems of several industrial plants, and the results all showed great improvements after using this computer tool.

Selecting ratings for capacitors and reactors in applications involving multiple single-tuned filters

This paper focuses on the selection of ratings for capacitors and air-core reactors used in multiple single-tuned harmonic filter configurations. Digital transient simulations of an example power system demonstrate the exceptionally high voltage and current stresses placed upon filter components in these configurations. Design guidelines for increasing the component ratings to account for the extra stresses are described. A comparison between traditional rating methods and the proposed methods are presented for the example system. >