Island detection method based on multi-frequency-band harmonic voltage and frequency

A harmonic voltage and islanding detection technology, which is applied in the direction of measuring electricity, measuring devices, and measuring electrical variables, etc., can solve the problems of inability to detect islands in a timely and effective manner, maloperation of harmonic islanding detection methods, damage to users and power distribution equipment, etc. problems, achieve good engineering practicability, do not damage the power quality, and reduce the effect of blind detection

Active Publication Date: 2018-01-19
NARI TECH CO LTD
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Problems solved by technology

[0003] Among the common island detection methods, the over/under frequency and over/under voltage island detection methods have relatively large detection blind spots, and cannot detect islands in a timely and effective manner. In addition, when the frequency of the system is low, the anti-islanding over\underfrequency criterion is easy to remove photovoltaics by mistake. At this time, the power grid needs the power support of the power supply most. Worse, even lead to large-scale power outages; harmonic island detectio

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  • Island detection method based on multi-frequency-band harmonic voltage and frequency
  • Island detection method based on multi-frequency-band harmonic voltage and frequency
  • Island detection method based on multi-frequency-band harmonic voltage and frequency

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Embodiment 1

[0035] This embodiment combines the changes of harmonic voltage and frequency before and after the island to form an island detection method. The implementation logic of the island protection is as follows: figure 2 As shown, that is, after the islanding, the harmonic voltage rises and the frequency shifts to a certain extent, and the islanding is judged when both of them meet the operating conditions. Since the frequency does not change when the grid background harmonic is large, misjudgment is avoided. Moreover, due to the combination of harmonic voltage, the frequency criterion is not easy to misjudge, and a relatively small frequency action threshold can be set, thereby improving sensitivity, reducing detection blind spots, and avoiding over / under frequency detection and harmonic detection methods when used alone Existing problems. Specific steps are as follows:

[0036] Step 1: Set the inverter switching frequency as f C , modulation frequency f S 50Hz, collect and c...

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Abstract

The invention discloses an island detection method based on multi-frequency-band harmonic voltage and frequency, and belongs to the technical field of photovoltaic power generation systems. An islandis determined when an action condition is satisfied since a harmonic voltage rises and the frequency is deviated at a certain degree after the island. Through adoption of the island detection method,misjudgment can be avoided. Moreover, the harmonic voltage is considered, so that wrong frequency judgment is prevented, and a relatively small frequency action threshold can be set. Thus, the sensitivity is increased; the detection blind zone is reduced; and the problems in independent use of over/under-frequency detection and harmonic detection methods are solved.

Description

technical field [0001] The invention belongs to the technical field of photovoltaic power generation systems. More precisely, the invention relates to an islanding detection method based on multi-band harmonic voltage and frequency. Background technique [0002] The island effect refers to the grid-connected photovoltaic power generation system is disconnected from the grid due to grid failure or maintenance, forming an isolated island where the photovoltaic power generation system supplies power to the load, such as figure 1 shown. The occurrence of isolated islands will bring a series of hazards. If the isolated island system does not have the ability to adjust voltage and frequency, the voltage and frequency in the isolated system may fluctuate greatly, causing damage to the equipment; when the isolated island system is connected to the grid again, the photovoltaic The power generation device of the power generation system may not be synchronized with the power grid, whi...

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Application Information

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IPC IPC(8): H02J3/38G01R31/00
Inventor 陈永华王森唐冠军陈汹李雪明许士光薛峰罗剑波陈勇周汝勇邹亚平凌超
Owner NARI TECH CO LTD
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