External centralized disturbance type impedance measurement island detection method suitable for multimachine cluster
A technology of impedance measurement and island detection, which is applied in measuring devices, measuring electrical variables, measuring resistance/reactance/impedance, etc., can solve the problems of damaging system stability and power quality, achieve good power quality, ensure practicability, and improve accuracy degree of effect
Active Publication Date: 2016-02-17
NORTH CHINA ELECTRIC POWER UNIV (BAODING)
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However, as the system develops towards multi-inverter and multi-power source type grid connection, the disturbance signal of the active method can be amplified to destroy the system stability and power quality, and can also cancel each other, resulting in the failure of island detection. The effectiveness of its islanding detection faces new challenges, so it is necessary to study the islanding detection technology suitable for multi-type power supplies and multiple grid-connected inverter cluster systems
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[0034] The present invention will be described in detail below in conjunction with the accompanying drawings.
[0035]The structure of distributed generation grid-connected system is as follows: figure 1 As shown, it consists of distributed power sources, local loads and power grid. During normal operation, the power supply and load are connected to the main grid. When there is a fault or a large disturbance in the system, the circuit breaker will operate, and the distributed power supply will be disconnected from the main network, forming an isolated island with the nearby load.
[0036] The external concentrated disturbance type measurement impedance method proposed by the present invention has an equivalent structure shown as figure 2 , different from the traditional disturbance method at the inverter machine end, the present invention adopts independent centralized disturbance injection at the PCC.
[0037] Its injection point measurement impedance characteristics and ...
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The invention relates to the technical field of electric power system analysis and especially relates to an external centralized disturbance type impedance measurement island detection method suitable for a multimachine cluster. The method is characterized by, to begin with, generating a disturbance current signal iInj having a certain magnitude and waveform by utilizing an independent external centralized disturbance generation device; monitoring the voltage uPCC at the place of a system common coupling point, carrying out intermittent zero-crossing-point injection control at the place of the system common coupling point, and meanwhile, carrying out impedance measurement characteristic quantity calculation after data processing of the collected voltage uPCC at the place of the system common coupling point and the disturbance current signal iInj obtained in the injection process; and judging island state according to the change of characteristic quantity. The method is suitable for a distributed power supply system having a plurality of inverters, and meanwhile, is suitable for a power supply, having no inverter, of a synchronous generator and the like, thereby improving impedance measurement accuracy and reducing requirement for DC voltage grade of an injection device; and broad-frequency domain high-frequency reactance calculation enables island characteristic quantity difference to be enlarged, and the method has higher detection sensitivity and precision.
Description
technical field [0001] The invention relates to the technical field of power system analysis, in particular to an external centralized disturbance impedance measurement island detection method suitable for multi-machine clusters. Background technique [0002] The demand for efficient energy utilization and the development of power electronics technology have prompted a large number of new energy distributed power sources such as photovoltaics and wind power to be connected to the grid to supply power to nearby loads. After the distributed generation (DistributedGenerator, DG) is connected to the network, the unplanned island operation of DG and nearby loads due to the failure of the main network and the malfunction of the switch will endanger the life safety of the grid line maintenance personnel and users; affect the normal operation of the equipment in the island system operation and reclosing action. Therefore, the distributed grid-connected power generation system must ...
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IPC IPC(8): G01R27/02
Inventor 贾科郇凯翔魏宏升毕天姝任哲锋
Owner NORTH CHINA ELECTRIC POWER UNIV (BAODING)
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