An islanding detection method for distributed wind power converters
A wind power converter and island detection technology, applied in wind power generation, frequency measurement device, single grid parallel feeding arrangement, etc., can solve the difficulty of grid adjustment, large-scale centralized wind power fluctuation, and limited system peak regulation means problem, to achieve the effect of fast over-under-frequency anti-islanding protection, triggering over-under-frequency anti-islanding protection, and fast frequency change
Active Publication Date: 2016-04-13
河南许继电力电子有限公司 +2
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Problems solved by technology
The structure of the domestic power grid is dominated by coal power, and the means of system peak regulation are limited. The power fluctuation of large-scale centralized wind power makes power grid regulation more difficult
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[0018] In order to solve the islanding detection problem of distributed wind power generation, the islanding detection method of distributed wind power converter, by controlling the output reactive current I of the converter q , to I q A disturbance current of 1 Hz is applied. When the power grid is interrupted, because the system loses a stable reference power supply, the disturbance will cause a significant change in the system frequency, thereby detecting the islanding phenomenon.
[0019] The theoretical basis of the islanding test method for reactive current disturbance is:
[0020] When the distributed wind generator is connected to the grid, the power flow is as follows: figure 1 As shown, the variable names and symbols are shown in the table below, L r ,C r and R is the equivalent load of the inverter.
[0021] P—active power output by the converter; ΔP—active power delivered to the grid by the inverter when the grid is normal; Q—reactive power output by the conve...
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The invention relates to an island detection method of a distributed wind-power converter. The method comprises the following steps that: a sinusoidal reactive current disturbance Iq with a set frequency is added to a network side of a distributed wind-power converter, wherein the amplitude of the Iq is expressed by a formula: k1|deltaf|+k2Grid_Ia1; and an average value of a voltage frequency of a power grid is calculated and whether the average value is in a normal range is detected so as to determine whether an overfrequency or underfrequency phenomenon occurs; and when the overfrequency or underfrequency phenomenon occurs and a time segment is set, overfrequency or underfrequency protection is triggered and an island phenomenon is detected; and otherwise, no island phenomenon occurs. According to the invention, island detection is carried out by using the reactive current disturbance. When grid-connected operation of the system is carried out, the voltage at the load terminal is suppressed by the voltage of the power grid and is not influenced by the reactive power outputted by the converter basically. When an island state occurs, once the reactive power outputted by the converter is not matched with a load demand, the voltage amplitude or frequency of the load is changed; and after the reactive current of the converter is adjusted, the overfrequency or underfrequency phenomenon of the power grid can be detected rapidly, thereby achieving an objective of island detection.
Description
technical field [0001] The invention relates to an islanding detection method of a distributed wind power converter. Background technique [0002] In recent years, wind power has developed in the "big wind power" mode, which is characterized by large-scale, highly concentrated development, and long-distance, high-voltage transmission. The domestic grid structure is dominated by coal-fired power, and the means of system peak regulation are limited. The power fluctuations of large-scale centralized wind power make grid regulation more difficult. Distributed wind power generation, which is connected to the system in a decentralized manner and at a lower voltage level, can be used as a kind of "reverse load" management in power dispatching, with little impact on grid frequency and voltage. [0003] In the context of the increasingly serious problem of wind power consumption in the "Three North" region, the National Energy Administration has repeatedly convened relevant units to...
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IPC IPC(8): H02J3/38G01R23/02
CPCY02E10/76
Inventor 姚为正肖鹏刘刚赵宇许恩泽
Owner 河南许继电力电子有限公司