Harmonic Inflow and Outflow: Determining the Direction of Harmonic Current Using Phase Angle Analysis

01 Why Harmonic Direction Matters

Measuring the magnitude of harmonic voltage and current distortion at a point on the network tells you how bad the harmonic situation is. It does not tell you where the harmonics are coming from. In a real distribution network, multiple loads and multiple harmonic sources coexist on the same bus. When a harmonic compliance problem is identified, the first engineering question is: 이 설치는 네트워크로 흘러나오는 고조파를 생성합니까?, 아니면 네트워크에서 유입되는 고조파를 수신하고 있습니까?? 답변에 따라 완화 책임자가 누구인지 결정됩니다..

이러한 구별 — 고조파 유입과. 유출 - 일본 배전망 지침의 고조파 책임 할당의 기초이며 고조파 제한이 강화되고 여러 비선형 부하가 공통 버스를 공유함에 따라 다른 규제 프레임워크와 점점 관련성이 높아집니다.. 방향을 결정하려면 THD 측정 이상의 것이 필요합니다. 이를 위해서는 측정 지점에서 고조파 전압과 고조파 전류 간의 위상 관계 분석이 필요합니다..[1]

02 유입과 유출을 판단하는 두 가지 방법

방법 1 — 고조파 전력 극성

첫 번째 방법은 고조파 유효 전력의 부호를 사용합니다. (피_H) 각 고조파 차수에서. 고조파 전력은 고조파 전압의 산물입니다., 현재 고조파, and the cosine of the phase angle between them. A positive harmonic power indicates the installation is consuming that harmonic — inflow. A negative harmonic power indicates it is generating that harmonic — outflow.[1]

This method is theoretically clean but has a practical limitation: harmonic power levels decrease rapidly with increasing harmonic order. The 11th harmonic power is typically a small fraction of the 5th harmonic power. At higher orders, the harmonic power signal approaches the noise floor of the measurement instrument, making polarity determination unreliable. This method works well for the dominant low-order harmonics (3회, 5일, 7일) but becomes unreliable for the 11th, 13일, 이상.[1]

방법 2 — Harmonic voltage-current phase difference (θ)

The second method uses the phase angle difference between the harmonic voltage and the harmonic current at each harmonic order — denoted θ. This is a more robust approach because it is based on phase angle measurement rather than power magnitude, and phase angle can be determined accurately even when harmonic magnitudes are small.[1]

For 3-phase 3-wire installations using the 2-meter measurement method (3P3W2M,,ar,kV의 회로,,en,이 고조파 측정에 기초하여 고조파 출입 판정의 예,,en,3 상 2 와이어를 사용하여 설정,,en,3 상 전체 설치 유출입은 고조파 전류 전압 위상 차이에 의해 판단,,en,thsum,,el,그것은 90 0 -90 사이 인 경우,,en,그것은 유입이다,,en,합 사이 또는 -180 -90 90 180 유출되는 경우를 판정한다,,en,기본 파,,en,갈색,,en,소비는,,en,아래 그림과 같이,,en,제 5 고조파의 대부분,,en,녹색,,en,또한 유입된다,,en,고조파 전압 전류 위상차의 시간 플롯,,en,기본 및 제 5 고조파,,en,제 3 고조파,,en,아래 그래프에서와 같이 유출이고,,en,제 7 고조파,,en,푸른,,en,유출이다,,en,데이터는 위상차가 180을 초과하는 수직선으로 도시 -180로 되돌아,,en), the recommended metric is the sum phase angle θ_합집합 — the harmonic voltage-current phase difference computed from the sum of the measured quantities across both measurement channels. This sum approach provides a more stable and representative value than individual phase measurements for 3-phase systems.

03 Measurement Setup

The 3P3W2M configuration uses two current sensors and two voltage measurements to fully characterize the 3-phase 3-wire system. The “합집합” phase angle approach is specific to this configuration — it combines the measurements from both channels to produce a single θ_합집합 value per harmonic order that is representative of the overall 3-phase harmonic flow direction.[1]

04 Analysis Examples: Four Harmonic Orders, Four Different Behaviours

The following examples are drawn from measurements on a 6.6 kV circuit. The time plots show the harmonic voltage-current phase difference (θ_합집합) over time for each harmonic order. The inflow/outflow boundary is at ±90°.[1]

기본적인 (1st harmonic) and 5th harmonic — Inflow

무화과. 1. Time plot of θ_합집합 for the fundamental (brown) and 5th harmonic (green). Both remain within the −90° to +90° inflow zone throughout the measurement period, confirming that the installation is consuming both the fundamental power and the 5th harmonic. 출처: HIOKI E.E. 법인.[1]

The fundamental wave is in inflow — this is expected, as the installation is consuming real power from the network. The 5th harmonic is also predominantly inflow, indicating that the dominant 5th harmonic source is elsewhere on the network and this installation is receiving it. This installation is a victim of 5th harmonic pollution, not a source of it.

3rd harmonic — Outflow

무화과. 2. Time plot of θ_합집합 for the 3rd harmonic (붉은). The phase angle consistently falls outside the ±90° inflow zone, in the −180° to −90° or +90° to +180° range — confirming 3rd harmonic outflow. This installation is generating 3rd harmonic current that flows into the network. 출처: HIOKI E.E. 법인.[1]

The 3rd harmonic is outflow — this installation is a 3rd harmonic source. Note that the 3rd harmonic is characteristic of single-phase non-linear loads (스위치 모드 전원 공급 장치, fluorescent lighting) rather than 3-phase 6-pulse drives. Its presence as an outflow harmonic on a 6.6 kV circuit suggests single-phase loading on the secondary side of distribution transformers fed from this circuit.

7th harmonic — Outflow

무화과. 3. Time plot of θ_합집합 for the 7th harmonic (blue). Outflow confirmed — the phase angle remains outside the ±90° inflow zone. The 180° wrap-around is visible as vertical transitions in the trace. 출처: HIOKI E.E. 법인.[1]

The 7th harmonic is also outflow. Together with the 3rd harmonic outflow, this suggests the installation contains significant non-linear load generating harmonic current into the 6.6 kV 네트워크. The 5th harmonic inflow observed earlier indicates the 5th harmonic on this bus is coming from elsewhere — the local installation’s own 5th harmonic generation is being masked or dominated by an external 5th harmonic source.

Judgment Examples 1 과 2 — Applying the θ_평균 display

무화과. 4. Judgment Example 1 — θ_평균 harmonic time plot in HIOKI PQA HiVIEW Pro. The averaged phase angle display provides a cleaner basis for inflow/outflow determination than raw θ_합집합 point-by-point values. 출처: HIOKI E.E. 법인.[1]

무화과. 5. Judgment Example 2 — θ_평균 harmonic time plot. A second scenario demonstrating application of the inflow/outflow judgment methodology using the averaged phase angle display. 출처: HIOKI E.E. 법인.[1]

무화과. 6. HIOKI PQA HiVIEW Pro harmonic analysis display — tabular view of harmonic voltage-current phase difference results by harmonic order. 출처: HIOKI E.E. 법인.[1]

무화과. 7. HIOKI PQA HiVIEW Pro summary display of harmonic inflow/outflow judgment results across all monitored harmonic orders. 출처: HIOKI E.E. 법인.[1]

무화과. 8. HIOKI PQA HiVIEW Pro 유입/유출 영역 표시기가 있는 고조파 시간 플롯 - ±90° 경계가 표시됨, θ로부터 고조파 방향을 시각적으로 직접 확인할 수 있습니다._평균 추적하다. 출처: HIOKI E.E. 법인.[1]

05 일본 규제 체계: 고조파 유출 전류 제한

일본은 배전 수준에서 조화로운 책임 할당을 위한 가장 발전된 국가 프레임워크 중 하나를 보유하고 있습니다.. 경제산업부는 지난 9월 고조파 억제대책 지침을 발표했다. 1994 — 고전압 또는 초고압 공급을 받는 수요 측 고객의 고조파 유출 전류에 특별히 적용되는 제한 설정.[2]

전압 왜곡 한계

• 6.6 kV 시스템: 총 고조파 전압 왜곡 ≤ 5%
• 초고압 시스템: 총 고조파 전압 왜곡 ≤ 3%

고조파 유출 전류 제한

The Japanese guideline expresses harmonic current limits in milliamperes per kilowatt of contracted power — a normalization that makes limits independent of customer size and directly proportional to the customer’s power contract. Upper limit values are specified per harmonic order, with lower limits for higher-order harmonics. The per-kW normalization means a larger customer has proportionally more harmonic current allowance — but must also comply at every harmonic order independently.[2]

This direction-based regulatory framework — limiting outflow rather than total harmonic current — is the key distinction from IEEE 519’s point-of-common-coupling approach. IEEE 519 limits the harmonic current a customer injects at the PCC, which is effectively an outflow limit. The Japanese guideline makes the outflow concept explicit and applies it at the individual harmonic order level with per-kW normalization. The measurement methodology described in this article — θ_합집합 phase angle analysis — is the tool that makes this outflow-based regulation auditable.

06 PQ 관점: Direction as a Diagnostic Tool

6.1 When direction analysis changes the diagnosis

The most important implication of harmonic direction analysis is that a high THD measurement at a customer’s service entrance does not automatically mean the customer is responsible for it. If the harmonic current is inflow — arriving from the network — the customer is a victim and the source is elsewhere on the feeder. Requiring the customer to install harmonic filters in this situation wastes money and may not improve the network harmonic situation at all.

거꾸로, a customer with modest THD levels at their service entrance may still be a significant harmonic outflow source if their contracted power is large — the per-kW Japanese limit could be exceeded even when absolute THD appears acceptable. Direction analysis at each harmonic order is the only way to correctly characterize responsibility.

6.2 Practical application in a harmonic investigation

A practical harmonic investigation sequence using this methodology:

1. Measure harmonic voltage and current at the point of interest — confirm that harmonic amplitudes are significant enough to justify direction analysis
2. Apply the θ_합집합 관심 있는 각 고조파 차수에 대한 기준
3. 유입되는 고조파 차수 식별 (네트워크 소스) 그리고 유출되는 것 (현지 소스)
4. 유출 고조파용: 책임이 있는 국지적 비선형 하중을 식별하고 완화 옵션을 평가합니다.
5. 유입 고조파용: 책임 있는 소스에 대한 네트워크 조사 - 동일한 피더에 있는 다른 고객, 네트워크 공명 조건, 유틸리티 장비

6.3 IPQDF 기사 시리즈에 대한 연결

이 시리즈의 기술 문서 (제1~3조) 6펄스 드라이브의 고조파 특성과 네트워크 구성 요소와의 상호 작용을 확립했습니다.. 사례 연구에서는 고조파가 완화되지 않은 상태로 방치될 때 어떤 일이 발생하는지 보여주었습니다.. 이 기술 참조는 그림의 다른 차원을 완성합니다: the measurement methodology needed to determine whether a given installation is a harmonic source or a harmonic receiver — the prerequisite for assigning responsibility and selecting the correct mitigation strategy.

The θ_합집합 phase angle method described here is instrument-specific in its implementation (HIOKI PQA HiVIEW Pro in this example) but the underlying principle — that harmonic current direction is determined by the phase relationship between harmonic voltage and harmonic current — is universal. Any power quality analyzer that reports harmonic phase angles can support this analysis, with appropriate interpretation of the measurement conventions used by that instrument.

참조

1. [1] HIOKI E.E. 법인, “유입과 고조파 유출,” 에 전력 품질 측정을위한 가이드 북, HIOKI E.E. 법인, Nagano, 일본. 사용 가능: hioki.com
2. [2] Ministry of Economy, Trade and Industry (METI), 일본, “Guideline for Harmonics Deterrence Countermeasures on Demand-Side that receives High Voltage or Extra High-Voltage,” Official Report, 9월 30, 1994.