Utility grid, transmission networks, distribution systems, DER integration
电压骤升 (1.1–1.8 pu, 0.5 周期来 1 分钟) cause MOV failures, VFD过压跳闸, 绝缘应力, and PLC reboots — often with delayed, hidden damage. Three causes: SLG fault on ungrounded MV (max 1.73 pu on healthy phases), large load rejection, and capacitor bank switching. PT. PLN Sibolga field case: 3-phase fault produced 1.724 pu swell on phase A — DVR reduced to 0.997 pu simultaneously with sag recovery on phase C.
85 符合IEC 61000-4-30 Class A monitoring sites across 50 substations in the German transmission system — 38 在 110 千伏, 21 在 220 千伏, 26 在 380 千伏. Hierarchical clustering reveals which sites are redundant and which are uniquely informative. Ensemble forecasting of weekly 95th-percentile PQ parameters outperforms any individual model. The first dataset to demonstrate systematic, recurring PQ correlation structures at transmission level driven by inverter-based generation.
Interharmonics — frequency components that are not integer multiples of the fundamental (例如，. 75 赫兹, 130 赫兹上 50 赫兹系统) — are produced by PV inverters, 风力涡轮机, 电动车充电器, cycloconverters, and HVDC links. Their most dangerous effect: 间谐波在 58 Hz creates an 8 Hz beat frequency — squarely in the range of peak human visual sensitivity. 现场案例: simultaneous PV + 电动车充电器 + microwave on one LV circuit produces stochastic interharmonics causing light flicker. Standard IEC 61000-4-7 analysers cannot correctly characterise them.
Four documented negative effects of supraharmonic distortion (2–150kHz) on MV and LV distribution networks: power loss and heating from skin effect, dielectric material aging at accelerated stress cycle rates, MV cable termination failures from combined dielectric stress and local heating, and PLC interference in smart metering and demand response systems. 主要发现: MV/LV transformer transfer ratio is 0.5–3.0 — some supraharmonic components are amplified crossing from MV to LV. Strong correlation measured at substations 16 相距公里. No planning or compatibility limits currently exist above 9 千赫.
等级 2 EV chargers at 7.2 kW produce third-harmonic dominant current that accumulates in the neutral conductor and causes voltage unbalance increasing with distance from the transformer. Monte Carlo simulation across multiple penetration levels shows uncontrolled charging at 30%+ penetration can push VUF beyond 2% at feeder end buses. Smart charging eliminates the problem without hardware mitigation. EV chargers also produce supraharmonic emissions (2–150kHz) that can disrupt the PLC communications intended to manage EV charging itself.
Single-phase PV panels can either worsen or improve voltage unbalance on LV feeders — depending entirely on the existing load phase distribution. UPM Madrid analysis on the IEEE European LV Test Feeder shows PV reduced mean VUF from 1.255% 至 0.702% in a medium-unbalance scenario, but increased it from 0.787% 至 0.963% in a low-unbalance scenario. Equally important: IEEE PVUR1 and PVUR2 indices can overestimate the true VUF by a factor of 10–16× in DER-rich networks — the CIGRE index is the only reliable alternative that requires only line voltage magnitudes.
Voltage unbalance measurements at three 132 kV grid stations in Oman’s Main Interconnected System. All measurements within EN 50160 and Omani code limits. 主要发现: the HV transmission network is balanced — unbalance problems at industrial equipment terminals originate downstream, not from the utility.
Supraharmonic emissions (2–150kHz) from grid-connected PV inverters. Three emission types: narrowband at switching frequency, broadband from switching transients, time-varying with MPPT. Intermodulation between PV inverters and EV chargers creates new frequencies. No regulatory limits currently exist in this range.
Mirus International demonstrates why DOE 2016 transformer efficiency ratings miss the mark for harmonic-rich environments. Weighted average loading at harmonic-producing loads requires adjusted efficiency equations — the ULLTRA transformer design achieves high efficiency across the full load spectrum, not just at nameplate rating.
Czech Technical University analysis of distribution network device failure data from multiple utilities. Identifies patterns in outage causes and proposes reliability improvement strategies using advanced materials and network restructuring. Provides a methodology for uniform cross-utility reliability benchmarking.
A crow in medium-voltage switchgear triggered a line-to-ground fault affecting 200+ customers simultaneously across several miles. Four GPS-synchronised I-Sense monitors confirmed a single utility-caused grid event — not 200 separate problems. One customer experienced a 13-hour shutdown from a 3-cycle sag. Utility relay operation records confirmed the cause with microsecond accuracy.
Non-characteristic harmonics — orders not predicted by the standard 6k±1 formula for 6-pulse rectifiers — appear in power systems with converter firing angle asymmetry, supply unbalance, or multiple overlapping non-linear loads. Schlumberger/IEEE paper presents an identification methodology using harmonic fingerprinting to detect unhealthy power systems from their non-characteristic harmonic signature.
South African distribution network with two resonant points at different harmonic orders — a single-tuned filter addresses one resonance but can amplify the other. Case from Cape Peninsula University of Technology documents the filter design process for a network with two resonant frequencies, requiring a carefully detuned double-tuned filter to address both simultaneously.
Belgian MV distribution network segment used to study the impact of distributed generation technologies (风, 光伏, CHP) on power quality and voltage stability. Four cable feeders from a 14 MVA 70/10 kV transformer. Analysis shows how DG penetration affects voltage profiles, harmonic injection, and voltage stability — with practical implications for network planning with high DG penetration.
Six-pulse converter transformer selection and rating when harmonic spectrum is known. John Wiley Handbook of Power Quality chapter covers K-factor calculation, additional loss estimation, and de-rating methodology for transformers feeding rectifier loads. Provides the calculation procedure engineers need to correctly specify transformers for non-linear load environments.
IEC flicker prediction methodology applied to the connection of a new three-phase welding machine to an existing 15 千伏网络. The study uses simplified assessment methods from IEC 61000-3-7 to evaluate whether the new load will cause the Pst limit to be exceeded at the PCC — a planning tool for utilities evaluating new industrial connection requests.
超过 90% of worldwide facilities operate at voltages higher than required — a consequence of distribution network design that delivers minimum voltage at the far end of the feeder. MicroPlanet’s voltage reduction technology captures wasted energy by operating equipment at optimal voltage, reducing heat losses in electronic components without affecting performance.
An Australian utility serving remote outback areas via Single Wire Earth Return systems faced severe power quality complaints — lights flickering, unstable voltage, and very low voltage levels at remote customers. MicroPlanet’s Low Voltage Regulator restored voltage stability and reduced flicker to acceptable levels in areas where traditional network reinforcement was not economically viable.
A Hawaiian utility’s water supply pumps — driven by 3-phase motors — were burning out within one year of installation due to high voltage and phase imbalance. Voltage unbalance caused negative-sequence currents to overheat motor windings, dramatically shortening service life. MicroPlanet voltage regulation and balancing equipment extended motor life to near-nameplate expectancy.
HIOKI PW3198 Channel 4 is isolated from the three voltage measurement channels — enabling DC power supply monitoring, second-circuit measurement, or neutral current measurement simultaneously with three-phase voltage. Practical measurement configurations for complex industrial monitoring scenarios.
Remote monitoring of a power quality analyser via LAN using the HTTP server function — no special software required. HIOKI PW3198 screen mirroring at 0.5 second refresh rate with password protection for setting changes. Eliminates the need for on-site technician visits during extended monitoring campaigns.
GPS clock synchronisation of the HIOKI PW3198 to UTC with ±2ms accuracy — enabling multi-point power quality measurement under a common time reference. Essential for correlating lightning strike propagation, voltage sag source attribution, and power outage spread across geographically separated monitoring locations.
Solar PV power conditioners maintain output by monitoring grid voltage and frequency — but malfunction when grid voltage rises above threshold or frequency deviates. Problems include inverter trips, inability to sell back power due to overvoltage, and high-order harmonic injection from neighbouring PV systems. Field measurement identifies the dominant disturbance type.
HIOKI technical guide to determining whether harmonics are flowing from a facility into the grid or from the grid into the facility — the fundamental question for harmonic source attribution. Covers power direction measurement methods, Japanese utility guideline compliance assessment, and field measurement examples showing both inflow and outflow scenarios with the HIOKI PW3198.
HIOKI headquarters building distribution panel recorded 4 voltage dips caused by lightning during a 2-month summer measurement period. Residual voltages and durations documented for each dip — the 6.6 kV supply was affected via the HV distribution network. Lightning-caused voltage dips cannot be prevented by utilities but can be mitigated with surge protection and ride-through equipment at sensitive loads.
One year of monitoring at HIOKI’s 6.6 kV receptacle captured 6 voltage dips in 3 consecutive days during August lightning season. One dip on the T-R phase showed 4.708 kV residual voltage for 109 ms — a severe sag by any standard. IN 50160 classification mode counted simultaneous three-phase events as single events for statistical reporting.
Rural transformer failure at the end of a medium-voltage feeder serving an apartment complex, dairy farm, and golf course. Fluke investigation found the transformer failed from sustained overloading combined with harmonic current from a variable-speed pump at the dairy farm. Demonstrates that harmonics contribute to transformer failure through additional winding losses — even in rural settings with “clean” loads.
Consolidated Edison New York deployed Dranetz Encore Series and legacy PQNode instruments across their distribution network. Electrotek’s PQView Fault Analysis Module identifies and characterises faults automatically — enabling automatic distribution fault location from power quality monitoring data without requiring field crew dispatch.
Wind generation plant interconnection requires assessment of harmonics, 闪烁, 电压波动, frequency deviation, and fault ride-through capability. Dranetz monitoring solutions cover both temporary commissioning assessment and permanent 24/7 monitoring for continuous interconnection compliance verification on wind farms of any size.
A manufacturer of muffler hangers added large automated welders — producing a 12-cycle, 4% voltage sag at 30-second intervals that caused utility complaints from all circuits at the same substation. The utility faced an impossible choice: lose the 200-employee manufacturer or continue receiving complaints from all other customers. American Superconductor’s PQ-SVC resolved both problems simultaneously.
