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Operation control and island detection method and system for photovoltaic direct-current converter

A DC converter and islanding detection technology, which is applied to the operation control and islanding detection of distributed photovoltaic DC converters, the operation control and islanding detection of photovoltaic DC converters, and can solve the problem that does not take into account the photovoltaic and other new energy generation operation control Features and other issues, to achieve fast and accurate island status detection, meet its own characteristics, and fast detection speed

Pending Publication Date: 2020-10-09
SHANGHAI JIAO TONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the existing anti-islanding strategies for medium and low-voltage DC systems are all reflected in the output side of the converter, and do not take into account the unique operation control characteristics of new energy generation such as photovoltaics.

Method used

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  • Operation control and island detection method and system for photovoltaic direct-current converter
  • Operation control and island detection method and system for photovoltaic direct-current converter
  • Operation control and island detection method and system for photovoltaic direct-current converter

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Effect test

Embodiment 1

[0077] According to the active anti-islanding control strategy for photovoltaic direct current converters in medium and low voltage direct current systems provided by the present invention. Distributed power generally needs to be connected to medium and low voltage DC systems through interface converters. Taking distributed photovoltaics as an example, the system model is as follows: figure 2 shown. Among them, the photovoltaic array PV is connected to the medium and low voltage DC system through the Boost converter, and the maximum power tracking control is realized during normal operation. Photovoltaic array PV current source i pv with a parallel resistor R p Capacitor C represents the output capacitance of the Boost converter and the equivalent capacitance of the PCC bus; resistance R represents the local load at the PCC bus, and the resistive load is selected here because the resistive load has the largest detection blind zone; CB represents the open circuit on the grid...

Embodiment 2

[0154] The steps of the outer ring voltage disturbance scheme:

[0155] Step 1: The photovoltaic power generation unit is connected to the DC power distribution system through the interface DC converter. The DC converter adopts the double closed-loop control mode of the voltage outer loop and the current inner loop to realize the maximum power tracking (MPPT) control of photovoltaic power generation;

[0156] Step 2: The MPPT algorithm passes the collected photovoltaic array voltage u pv with current i pv Information, calculate the voltage reference value of the photovoltaic array

[0157] Step 3: Voltage Reference and photovoltaic array voltage feedback value u in Subtraction, through the outer loop compensator G v (s) Get the DC converter input current reference value

[0158] Step 4: Current Reference Value and DC converter input current feedback value i in Subtraction, through the inner loop compensator G i (s) Generate a switching signal with a certain duty ...

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Abstract

The invention provides an operation control and island detection method and system for a photovoltaic direct-current converter. The method comprises the steps of 1, enabling the direct-current converter to achieve the maximum power tracking control of photovoltaic power generation in a mode of double-closed-loop control of a voltage outer loop and a current inner loop; 2, superposing an external small-disturbance sinusoidal signal on the voltage reference value or the current reference value; 3, sampling a DC bus voltage signal; 4, enabling the DC bus voltage signal to pass through a band-passfilter and a feedback gain to form a feedback disturbance quantity; 5, superposing the feedback disturbance quantity on the external small-disturbance sinusoidal signal, and superposing the feedbackdisturbance quantity with the original voltage or current reference value to form a new voltage or current reference value; 6, applying the new voltage or current reference value to voltage or currentcontrol; and 7, detecting the DC bus voltage, and when the disturbance deviates from the preset operation range, judging that the DC power distribution network is in an island state. According to theinvention, the electric energy quality and the operation efficiency are improved.

Description

technical field [0001] The present invention relates to the technical field of photovoltaic grid-connected power generation and power electronic system control, in particular to a method and system for operation control and islanding detection of a photovoltaic DC converter. In particular, it relates to an operation control and islanding detection method of a distributed photovoltaic DC converter in a medium-low voltage DC system based on disturbance feedback. Background technique [0002] Solar energy has become the main object of current renewable energy development due to its advantages such as wide distribution of resources and convenient conversion and utilization. Photovoltaic power generation is the main form of large-scale development and utilization of solar energy resources. Adapting measures to local conditions, promoting the research and development and construction of various forms of photovoltaic power generation, and promoting technological innovation and heal...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J3/38G01R31/00
CPCH02J3/381H02J3/388G01R31/00H02J2300/26Y02E10/56
Inventor 朱淼胡皓徐莉婷李修一王晗蔡旭
Owner SHANGHAI JIAO TONG UNIV
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