Diesel-storage independent micro-grid and virtual dynamic synchronous control method and system thereof

Abstract

The invention discloses a diesel-storage independent micro-grid and a virtual dynamic synchronous control method and system thereof, and self-adaptive dynamic synchronous torque and a pre-synchronous compensation phase angle are introduced into an energy storage converter control system to realize output voltage and power synchronization before and after the system is connected in parallel. According to the method, on one hand, the phase angles of the diesel generator and the energy storage converter are kept consistent before parallel connection by compensating a pre-synchronization phase angle, and current impact in the parallel connection process is reduced; on the other hand, by introducing the self-adaptive dynamic synchronous torque, after the systems are connected in parallel, the diesel generator can adaptively and dynamically adjust the virtual torque of the energy storage converter according to the current acceleration of the diesel generator and the energy storage converter under the condition that the inertia parameter of the diesel engine is black box; and the phenomenon that angular acceleration changes are inconsistent due to inertia difference is eliminated, the angular acceleration difference between the diesel engine and the energy storage converter is reduced, system power oscillation caused by impact loads is avoided, and synchronous power supply of the diesel engine and the energy storage converter is achieved.

Description

technical field [0001] The invention relates to the fields of power supply and control of sea islands, ports, wharves, and ships, in particular to an independent microgrid for diesel storage and its virtual dynamic synchronous control method and system. Background technique [0002] The diesel-storage independent microgrid system has a small power supply scale and weak energy support capability. It requires the parallel synchronous output of diesel engines and energy storage converters to improve the voltage support capability to meet the power supply requirements of national defense and civilian high-power impact special loads. However, due to the inertia of the diesel generator set, when the energy storage converter with conventional droop control is connected in parallel with the diesel engine, the power distribution will be unbalanced in the dynamic process of the system, which will easily cause overcurrent of the power electronic equipment. Therefore, in order to match ...

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Problems solved by technology

However, when the VSG simulates the inertia of the diesel generator, it inevitably introduces the oscillation characteristics of the synchronous motor rotor. Therefore, in the parallel system of the diesel engine and multiple distributed power sources with virtual inertia, the sudden change of load often causes the active power of the system to oscillate. , although the existing oscillation suppression technology can suppress the active power oscillation when multiple VSGs are connected in parallel, most of them introduce virtual inertia in the dynamic process to make it much larger than their own virtual inertia, so that the equivalent inertia coefficients of each station are approximately the same. Ensure consistent transients to avoid system power oscillations

VSGs all work in the virtual synchronous control mode, and parameters such as virtual inertia and damping coefficient are known and adjustable variables, and the control system and parameters can be modified, but they are not suitable for diesel storage independent microgrid systems. Once the diesel engine is developed, parameters such as the inertia coefficient, output impedance, damping coefficient and the control system of the diesel engine cannot be changed. Under operating conditions, the power of the system changes frequently, and the energy storage unit working in the voltage source mode is prone to continuous power oscillation with the diesel generator set, causing the converter to over-current, and even damage the converter in severe cases

[0003] Although the dynamic synchronous torque control of the high-overload energy conversion power supply provided by the invention patent application CN112271723A can also solve the problem of power oscillation caused by high-energy pulse loads, the invention uses the difference between the angular velocity of the diesel generator and the angular velocity of the converter to calculate the dynamic synchronous torque , and the dynamic torque coefficient cannot be adjusted adaptively, and the dynamic adjustment speed is relatively slow. For pulsed loads with a short period, it is easy to have an unbalanced transient output power of the diesel generator and the energy storage converter, thus causing both Output power low frequency oscillation problem

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