MV および LV グリッドの超高調波歪み — 文書化された 4 つの悪影響と限界ギャップ
| 用紙の種類 | 包括的な分析レビュー — ジェノバ大学 & ボローニャ大学, イタリア |
| 対応する周波数範囲 | 超高調波: 2 kHz – 150 kHzの (従来の高調波解析を超えた) |
| 文書化された 4 つの効果 | 電力損失 & 加熱・絶縁劣化・MVケーブル終端不良・PLC干渉 |
| 伝播の発見 | 変電所間で測定された強い相関 16 km 離れた — SH は MV ネットワーク内で長距離に伝播します |
| MV/LVトランス転送 | 伝達率 0.5 へ 3.0 — some SH components are amplified when crossing from MV to LV |
| Capacitor interaction | Input capacitors of nearby loads attract SH currents — reducing propagation but accelerating capacitor aging and causing premature failures |
| Regulatory status | No planning or compatibility limits exist above 9 kHz in distribution network standards — active standardisation gap |
| ソース | Mariscotti A, Mingotti A. センサ 2024, 24(8), 2465. DOI: 10.3390/s24082465. Open access CC BY 4.0. |
01 Context — A New Frontier of Network Stress
The conventional power quality framework addresses harmonic distortion up to the 40th order — 2 kHz at 50 ヘルツ. Above 2 kHzの, the supraharmonic range (2–150kHz) was historically considered non-problematic: the power electronic devices of the 1980s and 1990s switched at frequencies below or only slightly above this threshold, and their emissions in the supraharmonic range were modest. This assumption no longer holds.
Modern power electronics — PV inverters, EVの充電器, battery storage converters, and LED drivers — use Silicon Carbide (SiC) and Gallium Nitride (GaN) switching devices at frequencies of 20–100 kHz or higher. These devices place their primary switching energy directly in the supraharmonic range. The result is a rapid and widespread contamination of distribution networks with conducted emissions in a frequency band where no emission limits exist, no measurement standards are adequate, and the negative effects on network assets and connected equipment are only beginning to be systematically documented.
ザ 2024 paper by Mariscotti and Mingotti at the Universities of Genova and Bologna provides the most comprehensive published analysis of supraharmonic effects on MV and LV distribution networks — covering four distinct negative effect categories, propagation characteristics, transformer transfer behaviour, and the implications for standardisation. It is based on approximately 70 documented references spanning a decade of supraharmonic research.
Supraharmonics are not simply “faster harmonics” — their propagation and aggregation behaviour differs fundamentally from classical harmonics. Classical harmonics (以下 2 kHzの) are synchronised to the mains frequency, propagate predictably through network impedances, and can be modelled by superposition. Supraharmonics have nearly random phase distribution between devices — they partially cancel when aggregated from multiple sources — but they also create network resonances that can amplify specific frequency components locally. Their time behaviour is intermittent and time-varying, unlike the relatively steady classical harmonic spectrum. These differences require different measurement approaches, different modelling tools, and ultimately different limit frameworks.
02 Four Documented Negative Effects
The study identifies and documents four principal categories of negative effects from supraharmonic distortion on MV and LV network assets and connected equipment:
Power Loss and Heating
At supraharmonic frequencies, skin effect concentrates current on the conductor surface, reducing the effective cross-section and increasing resistance. ケーブル, 変圧器巻線, and neutral conductors carrying supraharmonic currents run hotter than their power-frequency loading alone would predict. Standard thermal ratings based on power-frequency current are non-conservative in the presence of significant supraharmonic content. Dielectric losses in cable insulation also increase with frequency — the I²R heating mechanism is compounded by dielectric heating within the insulation material itself.
Dielectric Material Aging
Elevated electric field intensity at supraharmonic frequencies accelerates dielectric degradation through two mechanisms: partial discharge events (more likely at high field intensities) and dielectric loss heating. Both mechanisms are accelerated by higher frequency — the number of stress cycles per unit time increases proportionally with frequency. A dielectric material exposed to 50 kHz supraharmonics experiences 1,000 times more electrical stress cycles per second than at 50 ヘルツ. This dramatically accelerates aging in cable insulation, capacitor dielectrics, and transformer insulation — particularly in MV equipment where field intensities are already high.
MV Cable Termination Failure
The most severe documented consequence of supraharmonic distortion on MV network assets is failure of cable terminations. MV cable terminations are geometrically complex — the transition from the cable’s controlled electric field geometry to the air-insulated connection involves stress relief components (stress cones, field grading materials) designed for power-frequency operation. Supraharmonic currents produce localised heating and elevated electric field stresses at these terminations that the original design did not account for. The combination of dielectric stress and local heating has caused premature termination failures in MV networks with high renewable energy penetration.
PLCの干渉
Power line carrier communications — used for smart metering (DLMS/COSEM), デマンドレスポンス, grid control, and EV charging management — operate in the 9–148 kHz frequency range (CENELEC bands A–D). This frequency range overlaps directly with the supraharmonic range. Supraharmonic emissions from PV inverters, EVの充電器, and LED drivers can overwhelm PLC signals, causing metering errors, communication failures in demand response systems, and loss of remote monitoring capability. The circular interference problem in EV charging — where the EV charger’s switching emissions disrupt the PLC communication intended to manage EV charging — is an immediately practical manifestation of this effect.
03 Propagation — Further Than Expected
One of the most significant and practically important findings in the supraharmonic literature is the long-distance propagation of supraharmonic disturbances in MV networks. A strong correlation was measured between supraharmonic levels at two MV substations 16 km apart — demonstrating that a supraharmonic source at one point in the network can affect equipment at substations several kilometres away. This is far beyond the local neighbourhood coupling that engineers intuitively assume for high-frequency conducted emissions.
The Swedish MV network measurement
Field measurements on a real Swedish MV network with eight feeders — including a small wind farm — confirmed supraharmonic propagation across the entire network. The wind farm’s inverter switching frequencies were detectable at all monitoring points across the eight feeders, with the amplitude varying according to the network impedance at each location. The study also found that larger MV networks have more resonant frequencies but lower resonance peak amplitudes — a network impedance characteristic that affects how supraharmonics propagate and where they are amplified.
超高調波ソースの近くに接続された負荷の入力コンデンサは、高周波では低インピーダンス パスとして機能します。超高調波電流が引き寄せられ、それがなければネットワーク内にさらに伝播してしまいます。. これにより、超高調波エネルギーが発生源の近くに集中し、長距離の伝播が減少します。, これは遠方の機器にとって有益であると思われる. そのコストは、コンデンサ自体の劣化の加速と早期故障です。コンデンサ自体が、ネットワーク全体に広がるはずだったエネルギーを吸収しています。. これは典型的な隠れた障害メカニズムです: 遠くの機器を保護するには、近くの機器の劣化が加速するという犠牲が伴います。, コンデンサが故障するまで目に見えるインジケータはありません.
04 トランス転送 — 一部のコンポーネントが増幅されます
MV/LV 配電変圧器を介した超高調波の転送は単純な減衰プロセスではありません. 超高調波周波数でのトランス伝達率の測定では、次の範囲が示されています。 0.5 へ 3.0 — meaning that for some frequency components, the supraharmonic amplitude on the LV side is up to three times higher than on the MV side. Some supraharmonic components are amplified in crossing the transformer.
This amplification occurs due to the complex impedance interactions between the transformer’s leakage inductance, winding capacitances, and the capacitive loads connected to the LV side. At certain frequencies, the transformer and connected LV network form a resonant circuit that amplifies voltage at the resonant frequency. The resonant frequencies depend on the transformer design, the cable lengths, and the capacitance of connected loads — all of which vary with load configuration and feeder layout.
A utility engineer who measures supraharmonic distortion at the MV side of a distribution transformer and finds it within acceptable levels — if such levels existed — cannot conclude that the LV supply delivered to customers is also acceptable. For certain frequency components, the LV distortion can be significantly higher than the MV distortion. This means that MV-side monitoring alone is insufficient for assessing customer-side supraharmonic exposure. LV-side measurement is essential wherever supraharmonic effects on LV-connected equipment are of concern.
05 The Limits Gap — No Rules Above 9 kHzの
The most significant regulatory gap identified by Mariscotti and Mingotti is stark: no planning levels or compatibility limits currently exist in distribution network standards for supraharmonics above 9 kHzの. CENELEC JP 50160 標準, 公共 LV ネットワークの電圧特性を定義します。, 周波数偏差に対処する, 電圧の大きさ, 25次までの高調波, ちらつきがありますが、超高調波範囲には制限がありません. IEC 61000-2-2 LV ネットワークの互換性レベルに対応 2 kHzの. Above 2 kHzの, 関連する唯一の制限は CISPR 標準にあります (その上 150 kHzの, EMC用) そして狭いCENELEC信号周波数帯域は、全体を残します。 9 kHzまで 150 配電ネットワーク PQ の観点からは規制されていない kHz ウィンドウ.
Mariscotti と Mingotti は、機器の感度データから高調波限界を導き出すのに適用されるのと同じ物理的推論を使用して、文書化された効果しきい値に基づいて超高調波歪みの指標限界を導き出します。. Their derived limits provide a quantitative framework that did not previously exist in the literature. These limits have been submitted to the ongoing standardisation process at IEC SC 77A WG9, which is actively revising IEC 61000-4-30 to address supraharmonic measurement. しかしながら, the gap between documented effects, derived limits, and enforceable standards remains wide — and in the interim, network operators have no regulatory basis for requiring equipment manufacturers to control their supraharmonic emissions.
The absence of limits has two practical consequences for distribution network engineers. 最初の, there is no objective basis for requiring mitigation when supraharmonic disturbances are identified — making it difficult to compel action from the equipment owner whose device is the source. 2番目の, when equipment fails prematurely — a capacitor, a cable termination, a PLC metering system — the connection to supraharmonic disturbance is difficult to establish because no baseline measurements were required, no alarm levels were defined, and no monitoring was in place.
06 電力品質の観点
This case study is a companion to CS04 (PV Inverter Supraharmonics) and CS07 (EV Charger Supraharmonics) — it addresses the network-level consequences of the source-level emissions documented in those case studies. CS04 and CS07 characterise what individual devices emit. CS08 documents what happens to the network and its assets when those emissions are present at scale.
ユーティリティエンジニアリングの観点から, the MV cable termination failure finding is the most immediately actionable. Cable termination failures in MV networks are expensive — replacement requires switching out the affected cable section, mobilising a jointing crew, and managing customer interruptions. If supraharmonic distortion from renewable energy converters connected to the same MV feeder is contributing to accelerated termination aging, the utility is bearing maintenance and capital costs caused by the behaviour of customer-side equipment, with no regulatory mechanism to attribute those costs or require the source to mitigate its emissions.
You cannot manage what you do not measure. The practical first step for any distribution network operator concerned about supraharmonic effects is deployment of supraharmonic-capable monitoring — instruments with sampling rates above 300 kHzの, capable of capturing the full 2–150 kHz range. The cost of a Class A PQ monitor with supraharmonic capability has fallen dramatically in the last five years, and the EU-funded ADMIT project (Accurate Measurement of Distorted Instruments and Transformers) is developing the instrument transformer accuracy standards needed for MV-level supraharmonic measurement. For utilities with high renewable penetration on MV feeders — wind, PV, バッテリーストレージ — 超高調波ベースラインを今確立することは、根本原因分析をサポートするための測定履歴なしで、後で MV インフラストラクチャの早期障害を説明するよりもはるかに低コストになります。.
参照
- Mariscotti A, Mingotti A. “MV および LV AC グリッドにおける超高調波歪みの影響。” センサ, 24(8), 2465, 2024. DOI: 10.3390/s24082465. Open access CC BY 4.0.
- レンベルク SK, ウォールバーグ・M, ボールMHJ. “超高調波共振伝播のための中電圧ネットワークの評価。” エネルギー, 14(4), 1093, 2021. DOI: 10.3390/en14041093.
- IEC 61000-4-30:2015+AMD1:2021. 電磁両立性 - パート 4-30: 電力品質測定方法. IEC, ジュネーブ. (超高調波に対処するために、SC 77A WG9 による改訂中。)
- IN 50160:2010+A3:2019. 公共電力網から供給される電力の電圧特性. CENELEC, ブリュッセル.
- IEC 61000-2-2:2002+AMD1:2017. 電磁両立性 — LV 供給システムの互換性レベル, 0–2kHz. IEC, ジュネーブ.
- アドミットプロジェクト. Accurate Measurement of Distorted Instruments and Transformers. EUの資金提供による研究プロジェクト. 利用可能: 承認プロジェクト.eu
Mariscotti A, Mingotti A. “MV および LV AC グリッドにおける超高調波歪みの影響。” センサ (MDPI), フライト. 24, しない. 8, P. 2465, 4月 2024.
DOI: 10.3390/s24082465 ・・ 全文はPMCで→ — オープンアクセス CC BY 4.0.
このケーススタディは、教育目的のために概要と解説の形で提示されています。. SVG 図と PQ パースペクティブ セクション (セクション 6) Denis Ruest によるオリジナルの IPQDF 編集コンテンツです, 修士号. (適用済み), P.Eng. (レット。). IPQDF は元の研究の著者であることを主張していません.