Distributed generation-based grid connection transition operation mode coordination comprehensive protection method

Abstract

The invention discloses a distributed generation-based grid connection transition operation mode coordination comprehensive protection method. When the DG capacity is continuously increased, the short-circuit current level is improved, the DG is changed from a "pure load" into a "small power supply", and a problem that conventional protection and switching breakpoints cannot meet the transition condition is solved. Based on the conventional protection and the switching breakpoints, the scheme provided by the invention performs continuous matching with a primary operation model and is continuously optimized, and the information and the state quantity are continuously exchanged to form a protection control interface adapted to a primary system, so that dual purposes of safe operation of a system and continuous power supplying are achieved. The fault isolation range is determined by collecting a new boundary which is determined by the switching breakpoints, and that whether the system sectionalizing and the island operation mode generated as a boundary point is determined is stable or not is comprehensively considered.

Description

technical field [0001] The invention relates to a coordinated comprehensive protection method based on distributed power generation grid-connected transition operation mode. Background technique [0002] In the early stage of distributed power network construction, due to its uncertain scale and small grid-connected capacity, the short-circuit current provided to the system is limited and has little impact on the protection of existing systems. At this time, it can be regarded as a "pure load" nature. However, when the capacity of distributed power sources continues to increase (>5MVA), DGs have the ability to provide relatively high fault current feeds. For example, DGs directly connected to 10-35kV buses can provide about 6 times the rated current, and the fault current of the DG unit connected to the inverter can also reach 4 times the rated current. At this time, it can no longer be treated as the nature of the load, but at this time the corresponding protection dev...

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Problems solved by technology

[0004] In order to solve the above problems, the present invention proposes a coordinated comprehensive protection method based on the distributed power generation grid-connected transition operation mode. This method solves the problem of DG changing from a simple "load" property to a "small load" through the optimization of the grounding mode and the secondary protection system. The complexity of the transition of the nature of "power supply", under the condition that the existing protection and automatic devices remain unchanged, through relevant technical means, the purpose of basically meeting the safe operation of the regional power grid after DG is connected

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