IEC規格に基づく高調波検討 | 国際電力品質のディスカッション·フォーラム

このアプローチ, 基本的にヨーロッパで使われている, アジア, および他の多くの地域, IEEE 方式とは規範的な構造が異なります。, 特に測定技術とスペクトルのグループ化に関するもの .

1. IEC の規範枠組みと基本原則

IEEE のアプローチとは異なります, 接続点での制限に焦点を当てます, IEC アーキテクチャはモジュール式です. 測定方法を明確に区別します, 機器の排出制限, およびネットワーク分析技術.

1.1 IEC の構造 61000 シリーズ

総合的な高調波研究のために, 複数の標準間の相互作用を理解する必要がある:

IEC 61000-4-7: これが研究の技術的核心です. 測定を定義します “ツールボックス”: 楽器の使い方, サンプル, 高調波と次次高調波の信号を最大で処理します。 9 kHzの .
IEC 61000-4-30: これは測定機器の性能クラスを定義します。 (上級学習クラスA, guaranteeing the highest accuracy) .
IEC 61000-3-2 / -3-12: These set the harmonic current emission limits for individual equipment (≤16A and >16フェーズのA, それぞれ) .
IEC TR 61000-3-6 / -3-7: Technical reports (non-normative but authoritative) providing principles for determining connection limits for distorting installations in MV, HV, and EHV networks.

1.2 Key Definitions according to IEC 61000-4-7

The IEC introduces specific concepts to handle the non-stationary nature of harmonics:

Spectral Component (Ci): The RMS value of the Discrete Fourier Transform (DFT) output for a given frequency (5 Hz resolution) .
Harmonic Sub-group (HG): To combat spectral leakage effects, the exact harmonic line is grouped with the two immediately adjacent spectral lines. This value is used for comparisons against limits .
Interharmonic Sub-group (IG): The grouping of spectral components located between consecutive harmonics .

Frequency axis — 5 Hz bins (10-cycle window, 50 Hz system)

HG h = 1 (50 ヘルツ) IG between h=1 and h=2 HG h = 2 (100 ヘルツ)

$$G_{sg,H} = \sqrt{\sum_{i=-1}^{+1} C^2_{n \cdot h + 私}}$$

Harmonic subgroup HG

$$G_{isg,H} = \sqrt{\sum_{i=2}^{N-1} C^2_{n \cdot h + 私}}$$

Interharmonic subgroup IG(N = 10, so i = 2..9, 8 bins)

$$G_{sg,h+1} = \sqrt{\sum_{i=-1}^{+1} C^2_{N(h+1) + 私}}$$

Harmonic subgroup HG (h+1)

Harmonic subgroup (HG) — harmonic bin ± 1 neighbour Interharmonic subgroup (IG) - 8 bins between harmonics

図 1: Harmonic and Interharmonic Grouping according to IEC

Technical note: The harmonic sub-group of order n (HG_N) is the square root of the sum of the squares of the harmonic line n and the two adjacent spectral lines. This method reduces uncertainty due to fundamental frequency fluctuations .

2. Data Acquisition and Modeling

The accuracy of an IEC-based study relies on strict adherence to measurement parameters and detailed source characterization.

2.1 Grid Data and Point of Connection

Grid Impedance: Unlike the American approach, which often uses the short-circuit ratio, the European approach (aligned with guides like the UK’s G5/4 or G5/5) often requires harmonic impedance. 理想的に, the network operator providesimpedance loci 周波数の関数として .
Background Distortion: On-site measurements according toIEC 61000-4-30 クラスA (10-cycle window, precise synchronization) over a representative period (often one week) .

2.2 Non-Linear Load Data (Norton Model)

While IEC 61000-4-7 doesn’t prescribe a specific calculation model, industrial practice and newer standards (like IEC 61400-27-3 for renewables) require robust models :

Harmonic Current Source (Ih): The emission spectrum of the converter or load, measured in a laboratory according to IEC 61000-3-2.
Norton Impedance (Zh): The internal impedance seen from the load terminals. It is crucial for detecting resonance phenomena between the load and the network.

テーブル 1: Measurement Parameters according to IEC 61000-4-30 Instrument Class

Parameter	クラスA (Studies)	Class S (Surveys)
Measurement uncertainty (電圧)	±0.1% (for U > 1% あなた_nom)	±1.0%
Synchronization	Robust PLL with frequency tracking	May be less strict
Time aggregation	Very short (3の) and short (10分) values	Identical

For a compliance study intended for a network operator, the use of Class A instruments is mandatory .

3. Step-by-Step Analysis Methodology according to IEC

3.1 Frequency Scan Analysis

Before calculating distortions, identify the resonance frequencies of the combined system (grid + ケーブル + transformers of the installation).

方法: Inject a current of 1 A at a variable frequency and calculate the resulting impedance.
客観: Identify parallel impedance peaks.
Specific IEC Risk: Interharmonic sub-groups (IG) can excite these resonances, even if integer harmonics are filtered.

Impedance |で| (Z) Inductive ωL Capacitive 1/ωC 共振 (250 ヘルツ)

F_res = 250 ヘルツ — 5th harmonic order で_ピーク ≈ 38 Z — parallel resonance Q ≈ 8 — quality factor

図 2: Frequency Scan and Resonance Risk

An impedance peak at 250 Hz would amplify the 5th harmonic. If the peak is at 275 ヘルツ, the interharmonic components around that frequency will be the problem.

3.2 Calculation of the Installation's Contribution (Incremental)

The IEC approach, adopted by guides like G5/5, distinguishes between your site'sincremental contribution とtotal distortion.

Formula: Using the Norton model. $で_{H, inc} = \frac{で_{grid} (H) \times で_{ロード} (H)}{で_{grid} (H) + で_{ロード} (H)} \times {私は}_{H, ソース}$ In practice, ソフトウェア (PowerFactory, ETAP, EMTP) solves the system for each frequency.
Verification: This incremental voltage must not exceed a certain percentage of the background voltage (頻繁 1% へ 2% depending on national guides).

3.3 Calculation of Harmonic Sub-groups

This is the most characteristic step of the IEC approach. You do not present the exact 250 Hz line, but the HG5 sub-group.

Perform the DFT on a10-cycle window (200 ms for 50 ヘルツ, ~166.6 ms for 60 ヘルツ) .
Obtain the spectral components C_i with a 5 Hz step.
Calculate the sub-group for harmonic order *n*:

$H G_{N} = \sqrt{\sum_{私 = - 1}^{+ 1} ℃_{私}^{2}}$

どこ $℃_{0}$ is the exact harmonic line, と $℃_{- 1}$ and $℃_{+ 1}$ are the adjacent lines .

3.4 Time Aggregation and Statistical Evaluation

IEC 61000-4-30 requires aggregation to smooth out variations :

Very short values (3 秒): Aggregation of the 15 windows of 200 MS.
Short values (10 分): Aggregation of the 200 values of 3s.
Comparison: Compliance is generally verified on the short values (10 分), ensuring that 95% of the values (または 99% depending on the contract) are below the planned limits.

4. Compliance and Study Report

4.1 Comparison with Compatibility and Planning Levels

IEC TR 61000-3-6 defines three distinct levels :

Emission Level: What your installation injects (the calculated HGs and IGs).
Planning Level: An internal limit for the network operator, stricter than the compatibility level, to maintain a safety margin.
Compatibility Level: The reference disturbance level (例えば, THDv = 8%) at which 95% of equipment is expected to function correctly .

報告書は、あなたの貢献と背景の歪みの合計が共通結合点での計画レベルを下回っていることを証明する必要があります。 (PCC).

4.2 緩和とフィルタリング

制限を超えた場合, 研究では解決策を提案する必要がある:

パッシブフィルター: 問題のある高調波サブグループ向けに調整 (HG).
アクティブ·フィルタ: 電流を注入してリアルタイムで高調波をキャンセルします.
デチューニング: インピーダンスを変更する (例えば, ラインリアクトルの追加) 共振ピークを臨界周波数からずらす.

4.3 最終報告書の内容

IEC 準拠のレポートには次の内容を含める必要があります。:

単線図 インストールと上流ネットワークの.
入力データ: グリッドインピーダンス, 負荷電流スペクトル (IECに準拠した測定または認証の証明付き 61000-3-2).
シミュレーション結果: 通常および緊急時の動作条件における HG および IG の表.
統計分析: 限界と比較した、計算されたレベルの累積確率曲線 .

結論: コンプライアンスの明示的な声明または是正措置の計画.