Improved droop control method in micro electric network detached island operation control system

Abstract

The invention discloses an improved droop control method in an improved micro electric network detached island operation control system. The automatic adjustment of the droop coefficient and the rated output power at the direct-current side is added in the traditional droop control, so as to reduce the fluctuation in voltage amplitude and frequency due to load change is reduced. In case that k groups of inverters are connected in parallel in the micro electric network, the active power and the reactive power output by the k-th inverter are respectively Pk and Qk. In the traditional droop control, the control equation of the output voltage amplitude of the inverter and the frequency droop is represented in the description: the droop coefficients kP Omega and kQU are replaced by simple functions correlative with the active power and the reactive power, represented in the description: the rated output powers on the direct current side of a drawing-in system are Pn and Qn, the rated output voltage angle frequency and amplitude of the micro electric network system are Omega n and Un, the load power is detected at the real time, the Pn and Qn are automatically adjusted, thus the Pn and Qn gradually reach Pk and Qk in delta T time, at the same time, the system droop control equation is represented in the description: the detached island operation of the micro electric network is controlled using the droop control equation.

Description

technical field [0001] The invention relates to an operation control method of a microgrid, in particular to an improved droop control method in a microgrid island operation control system. Background technique [0002] From a system point of view, the microgrid combines generators, loads, energy storage devices, and control devices to form a single controllable unit that can supply electricity and heat to users at the same time. The microgrid contains multiple distributed generation (DG) and energy storage devices, which jointly supply power to the load. The entire microgrid is externally integrated and connected to the upper-level grid substation through a main isolating switch. The basic structure of a microgrid is figure 1 shown. [0003] The microgrid has two operating modes: grid-connected operation and islanded operation. Since many DGs are connected to the microgrid through inverters, when the microgrid is operating in an island, it is equivalent to multiple invert...

AI Technical Summary

Problems solved by technology

Although the droop coefficient can be arbitrarily small in theory, in practical applications, due to the influence of hardware errors and control accuracy, it is often necessary to take a compromise value

In traditional droop control, the droop coefficient is constant under different system loads, which may cause excessive droop of the output voltage and frequency, affecting the stability of the voltage amplitude and frequency of the microgrid

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