Low voltage failure rapid detection method
A low-voltage fault detection method technology, applied in the field of wind power generation, can solve the problems of detection algorithm delay, rotor current rise, etc., and achieve the effect of improving detection speed and low voltage ride-through ability
Inactive Publication Date: 2013-05-15
NR ELECTRIC CO LTD +1
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[0003] From the perspective of the generator, the stator side of the doubly-fed motor is directly connected to the grid, and the rise of the stator current is a direct influence. Due to the strong coupling between the rotor and the stator, the rapidly increasing stator current will cause the rotor current to rise. Therefore, the rotor current The rise is indirect, and there is a certain delay in the detection algorithm
[0004] Using grid voltage detection criteria, although this detection method can correctly detect voltage drop faults, the detection algorithm needs to convert the instantaneous value of AC voltage into DC, and there is still a certain delay
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[0021] The technical solutions of the present invention will be described in detail below in conjunction with the accompanying drawings.
[0022] The invention provides a low-voltage fault rapid detection method, which is applied to a doubly-fed wind power generation system and can cooperate with figure 1 As shown, wherein, Udc represents the DC bus voltage of the frequency converter, and Ids represents the stator current of the doubly-fed motor; the detection method includes the following steps:
[0023] (1) Real-time detection of the stator current of the double-fed motor and the instantaneous value of the DC bus voltage of the inverter;
[0024] (2) When the stator current or DC bus voltage exceeds the set threshold, enter step (3);
[0025] (3) If the inverter is in the normal starting state, it is determined that the grid voltage drop fault has occurred.
[0026] Threshold value of stator current I ds_lim Satisfies the formula:
[0027] 0.85I ds_max > I ds_lim >1.2I...
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The invention discloses a low voltage failure rapid detection method which comprises the following steps: detecting the current of a double-fed motor stator and the instantaneous value of frequency converter direct current bus voltage in real time, and judging the occurring of a network voltage drop failure when the current of the stator or the voltage of the direct current bus exceeds a set threshold value and a frequency converter is in a normal starting state. The low voltage failure rapid detection method is mainly applied to a doubly-fed type wind turbine system and can improve the low voltage traversing capacity of a wind turbine generator set.
Description
technical field [0001] The invention belongs to the field of wind power generation, and in particular relates to a low-voltage fault rapid detection method applied to a double-fed wind power generation system. Background technique [0002] Wind turbines have relatively large deficiencies in their ability to cope with grid failures. The failure of the power grid causes the terminal voltage of the wind turbine to drop, causing the stator current of the generator to increase. Due to the strong coupling between the rotor and the stator, the rapidly increasing stator current causes the rotor current to rise. When the rotor current rises beyond the maximum current that the inverter can withstand, the inverter will stop running, causing the unit to go off-grid. In addition, due to the slow adjustment speed of the wind turbine, the wind energy absorbed by the wind turbine will not be significantly reduced in the early stage of failure, and the generator set cannot normally transmi...
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Inventor 杨兵王宇杨浩吴小丹汪涛赵天恩方太勋刘为群
Owner NR ELECTRIC CO LTD