Subsynchronous source-network combination damping inhibition method for offshore wind plant

Abstract

The invention relates to a subsynchronous source-network combination damping inhibition method for an offshore wind plant, and the method comprises the steps: S1, building a linearized state space model of an offshore wind plant based on a double-feed wind turbine generator through a VSC-HVDC grid-connected system; S2, recognizing the subsynchronous oscillation modal of a system; S3, calculating aparticipation factor through modal analysis, and screening a state variable which is strongly correlated with the subsynchronous oscillation modal at each order; S4, analyzing the impact on the subsynchronous oscillation modal damping from the strongly correlated state variable through a root-locus method; S5, designing the parameters of DFIG_SEDC and VSC_SSDC according to a locus analysis result, and reducing the mutual impact between the subsynchronous oscillation modals at all orders, and inhibiting the plurality of subsynchronous oscillation modals. Compared with the prior art, the methodsolves a problem of cost in adding a FACTS device, and a designed source-network combination damping controller can inhibit the plurality of subsynchronous oscillation modals, improves the subsynchronous stability of a system, and guarantees the safe and stable operation of the transmission of new energy power.

Description

technical field [0001] The invention relates to a damping control method of an offshore wind farm, in particular to a subsynchronous source-grid combined damping suppression method for an offshore wind farm. Background technique [0002] In recent years, wind power, as a renewable clean energy, has developed rapidly due to its low power generation cost, abundant resource reserves and many other advantages. In particular, the proportion of offshore wind power has grown rapidly and has a broad market prospect. With the increase of offshore wind farm scale and grid-connected transmission distance, traditional AC transmission presents various disadvantages, while voltage source-based high-voltage direct current transmission (VSC-HVDC) has the ability to independently control the transmitted active and reactive power As well as many advantages such as power supply to passive networks, it is currently an ideal power transmission solution for large-scale offshore wind farm power tr...

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Problems solved by technology

The second point: due to the larger wind turbines used in offshore wind turbines, the elastic coefficient of the shaft system is larger than that of inland wind turbines, resulting in a higher frequency of natural torsional vibration of the shaft system, which will cause wind speed disturbance or power grid failure. There is a risk of sub-synchronous torsional interaction (SSTI) in the shaft system of the fan. The torsional vibration of the shaft system will seriously affect the service life of each component of the shaft system, and even the bearing may break, resulting in a long downtime

The third point: the currently popular measure to suppress subsynchronous oscillation is to install FACTs equipment, but the use of FACTs equipment is expensive and occupies a large area, which will increase the investment cost of the system. Some literature also proposes to install a damping controller to suppress subsynchronous Synchronous oscillation, but most of the research done so far only focuses on a certain type of subsynchronous oscillation. For some new problems of subsynchronous oscillation, its generation mechanism, impact indicators and suppression methods need to be further studied

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