Isolated island detecting device and method based on load characteristic

Abstract

The invention discloses an isolated island detecting device and a method based on load characteristic. The concept of load characteristic is applied to new energy resource isolated island detection so that the isolated island can be well detected and the isolated island detecting time can be reduced. The isolated island detecting device based on load characteristic comprises the following structures or units: a grid-connected bus side current and voltage collecting unit, a current and voltage regulation circuit, an algorithm control unit, a driving circuit and an inverting unit, wherein the grid-connected bus side current and voltage collecting unit collects the data of the grid-connected bus side current and voltage; the current and voltage regulation circuit can filtrate and amplify the voltage and current signal obtained by sampling; the algorithm control unit analyzes the sampled data, controls the conduction of the inverting system and the power network according to the power network state, and controls PWM (pulse width modulation) signal output by the algorithm; the driving circuit reinforces the driving capability of the PWM control signal; and the inverting unit can reversely converts the direct-current signal into the alternating-current signal by the PWM control signal.

Description

technical field [0001] The invention relates to a detection device and method, in particular to an island detection device and method based on load characteristics. Background technique [0002] When the power supply of the power company trips due to a failure or maintenance, the solar grid-connected power generation system at each user end fails to detect the power failure in time and cuts itself off from the mains network, forming a grid-connected solar power system and The surrounding local load forms a self-sufficient power supply island that the power company cannot control. The grid-connected power generation system and the local load form an independent operating state. This state is the island effect of solar grid-connected power generation. The island effect does not only occur in solar grid-connected power generation systems, in fact, any distributed grid-connected power generation system may have island effect problems. [0003] The reasons for islands can be att...

AI Technical Summary

Problems solved by technology

[0004] (1) The shutdown of the large grid power generation system leads to a blackout of the entire grid, but the photovoltaic grid-connected system is still connected to the large grid through a switch, and its output capacity may maintain power supply to the grid for a certain period of time;

[0005] (2) A certain line in the large power grid or distribution network is disconnected or a switch trips, causing the photovoltaic grid-connected system and the connected load (may include some loads on the distribution network) to form an independent power supply system, and may enter a stable operation state;

[0006] (3) The gate switch of the photovoltaic grid-connected system is automatically or accidentally disconnected, but the grid-connected power generation system and the local network form an island operation

[0007] In the island state, the power company loses control of the line voltage and frequency, which will bring a series of potential safety hazards and accident disputes:

[0008] (1) Affect the action program of the protective switch on the power distribution system;

[0009] (2) The power grid cannot control the voltage and frequency of the power island area, which may cause damage to the user's electrical equipment due to unstable power supply voltage and frequency;

[0010] (3) endanger the safety of transmission line maintenance personnel;

[0011] (4) Affect the manual or automatic recovery of the power grid

[0030] GB / T 12325 power quality power supply voltage allowable deviation

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