This paper presents a method for evaluating the harmonic contributions of multiple harmonic sources to voltage distortion at the point of common coupling (PCC). The proposed method quantitatively represents harmonic contributions based on the equivalent voltage models of harmonic sources. The equivalent voltage models can be estimated using the recursive least square (RLS) algorithm and measured voltage and current at the PCC. The assessment of harmonic contribution heavily depends on the accuracy of equivalent model estimation. Many existing studies have assumed that the equivalent model parameters of harmonic sources are not changed. However, because harmonic source parameters and system operating conditions are not constant in real power systems, this assumption can lead large errors in harmonic contribution assessment. In this paper, we propose a new assessment method based on variable forgetting factor RLS and parameter change detection to solve the problem. The proposed method is also effective for evaluating comprehensive harmonic contributions as well as individual harmonic contributions. The case studies show that the proposed method is superior to the previous one even under parameter changing conditions.

This paper deals with a method of quantifying the harmonic contribution of each harmonic source to system voltage distortion. Assessing the harmonic contribution of individual harmonic sources is essential for mitigating and managing system harmonic levels. Harmonic contributions can be evaluated using the principle of voltage superposition with equivalent voltage models for harmonic sources. In general, the parameters of equivalent voltage models are estimated numerically because it is difficult to measure them directly. In this paper, we present an effective method for estimating equivalent model parameters based on the random sample consensus (RANSAC) and recursive least square (RLS) with a variable forgetting factor. The procedure for quantifying harmonic contributions using equivalent models is also introduced. Additionally, we propose a network diagram of harmonic contributions that makes it easy to understand the harmonic distortion contributions of all harmonic sources.

수처리 시스템에 적용하기 위한 보론 흡착용 기본 수지로 poly(St-co-DVB) 가교중합체를 현탁중합으로 합성하였다. 기본 수지에 대하여 염화메틸화 반응을 거쳐 글루카민기가 도입된 킬레이트 수지를 평균 입경 500 μm 구형의 고다공성 수지로 합성하였다. 이러한 반응과정에서 혼합용매와 상용화 용매를 사용하여 상분리 없이 반응단계를 간소화하여 킬레이트 수지를 합성하였다. 글루카민기의 입체장애에 따라 글루카민 치환반응이 원활히 진행되지 못하는 문제점을 하이드록시기를 갖는 저분자량 아미노알코올을 사용하여 해결함으로써 보론 이온 흡착률이 30% 이상 향상된 새로운 구조의 킬레이트 수지를 합성하였다. 이러한 킬레이트 수지에 대해서 가교제 함량, 글루카민기 및 아미노알코올기 도입이 보론 흡착특성에 미치는 영향을 조사하였다.

This paper presents a novel method to assess voltage sags by taking into account the voltage tolerance characteristic of loads. In general, the tolerance characteristic is expressed in the form of a two-dimensional curve of voltage magnitude and duration. Also, the shape of characteristic curves depend on the type of loads. In order to estimate the expected sag frequency affecting sensitive loads, it is necessary to perform a voltage sag assessment considering the voltage tolerance curves of loads. However, because most existing methods of voltage sag assessment only focus on voltage sag magnitudes, these methods have limitations in reflecting various types of tolerance curves. In this paper, an effective method for reflecting various thresholds of sag magnitude and duration is proposed. The proposed method performs voltage sag assessment based on the area of vulnerability for given voltage thresholds and sag durations are estimated using a probability model on the historical operation data of protection system. In addition, we propose an effective assessment scheme based on the concept of measuration by division for a slope-shape tolerance curve.