Self-adaptive dynamic virtual inertia frequency modulation method for double-fed variable-speed pumped storage unit

Abstract

The invention relates to a self-adaptive dynamic virtual inertia frequency modulation method for a double-fed variable-speed pumped storage unit, and the method is suitable for a combined island system comprising the variable-speed pumped storage unit and a wind generating set. The method comprises the steps: starting the inertia response of the variable-speed pumped storage unit through an inertia control starting module; detecting the frequency deviation value change rate df / dt, introducing a correction factor to change the control coefficient, and automatically controlling the active outputof the unit, thereby achieving a purpose that the double-fed variable-speed pumped storage unit can provide dynamic frequency support for a power grid; stopping the inertia response of the variable-speed pumped storage unit through an inertia control stop module. When a system frequency accident occurs, compared with traditional droop control and fixed parameter virtual inertia control, the method can effectively improve the lowest frequency drop point of the system, reduce the frequency drop speed and reduce the frequency stabilization time by dynamically compensating the machine-side reference power of the double-fed converter, and has better inertia supporting capability and primary frequency modulation response capability for the power system.

Description

technical field [0001] The invention belongs to the technical field of power system operation and control, and in particular relates to an adaptive dynamic virtual inertia frequency modulation method for a doubly-fed variable-speed pumped-storage unit of a joint island system containing a variable-speed seawater pumped-storage unit and a wind power generation unit. Background technique [0002] In recent years, new energy power generation technology has developed rapidly, but the intermittent and fluctuating characteristics of new energy output have reduced the frequency stability of power systems. At present, the pumped storage system with multiple functions such as peak-shaving and valley-filling, frequency modulation and phase modulation, and emergency backup is one of the most economical and effective means to ensure the safe and stable operation of the power system. [0003] Compared with the traditional synchronous generator, the variable-speed pumped storage unit base...

AI Technical Summary

Problems solved by technology

However, a large number of existing virtual inertia control methods are mainly aimed at double-fed wind turbines, and a small number of methods only involve the feasibility analysis and modeling of virtual inertia control strategies for variable-speed pumped storage units.

However, the existing virtual inertia control method for variable speed pumped storage units also has some shortcomings.

Firstly, the virtual inertia control using the df / dt control link will have negative damping problems

Secondly, the virtual inertia control with a fixed control coefficient is adopted. The unit can simulate the inertia characteristics of the synchronous unit when the load is disturbed, provide short-term power support, and slow down the speed of the system frequency drop. However, the change in the operating conditions of the unit is ignored and the variable speed cannot be fully utilized. The real-time available capacity of the pumped storage unit is used to take advantage of the large speed adjustable range of the variable speed pumped storage unit

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