CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a National Stage of International Application No. PCT/KR2018/015697, filed on Dec. 11, 2018, which claims the benefit of earlier filing date and right of priority to Korean Application No. 10-2018-0007537 filed on Jan. 22, 2018, the contents of which are all hereby incorporated by reference herein in their entirety.

FIELD OF THE INVENTION

The present disclosure relates to a system for stabilizing a voltage of a power system. More specifically, the present disclosure relates to a system for stabilizing a voltage of a power system by controlling a magnitude of a reactive power to be supplied to the power system.

BACKGROUND OF THE INVENTION

In recent years, use of fossil fuels as a major energy source has caused severe side effects such as climate variation, and thus restrictions on use thereof have been intensified. Recently, renewable energy has been spotlighted due to depletion of coal and oil. Accordingly, importance of renewable energy based power generation to generate eco-friendly power, and to supply the generated power stably and efficiently is emerging.

In general, a source of the renewable energy has characteristic that an output thereof changes over time. Accordingly, a power generation amount resulting from the renewable energy based generation may change rapidly over time.

For example, when using solar power or wind power, a solar radiation quantity or a wind speed changes over time. Accordingly, the power amount generated using the solar power or the wind power changes over time.

In a grid or power system-connected renewable energy based generation system, the aforementioned variation in the power amount affects a frequency and a voltage of the power system or the gird. The higher the variation of the frequency and voltage of the power system, the lower a quality of the power.

Further, when a large-scale wind power based generation facility currently being built is connected to the power system, a serious problem in terms of the power system stability may occur. For example, when a reduction amount of a maximum output of the wind power based generator exceeds a power reserve for operating the power system, this may cause a serious problem that the power system collapses.

Accordingly, there is a need for a method of stabilizing the voltage of the power system in order to secure the power system stability.

BRIEF SUMMARY OF THE INVENTION

A purpose of the present disclosure is to provide a system for stabilizing a voltage of a power system, in which a magnitude of a reactive power to be supplied from an ESS (Energy Storage System) to the power system is controlled to maintain a current voltage value of the power system within a predefined range from a reference voltage of the power system, thereby securing power system stability.

Further, another purpose of the present disclosure is to provide a system for stabilizing a voltage of a power system, in which a magnitude of a reactive power is gradually controlled based on a difference between a current voltage value of the power system and a reference voltage of the power system, so that the current voltage value of the power system quickly follows the reference voltage thereof.

Further, still another purpose of the present disclosure is to provide a system for stabilizing a voltage of a power system, in which when a current voltage value of the power system is outside a control limit range, creation of a command value is stopped, and an ESS and a renewable energy based generator are disconnected with the power system, such that the power system is protected when an output of a renewable energy source fluctuates excessively.

Purposes of the present disclosure are not limited to the above-mentioned purpose. Other purposes and advantages of the present disclosure as not mentioned above may be understood from following descriptions and more clearly understood from embodiments of the present disclosure. Further, it will be readily appreciated that the purposes and advantages of the present disclosure may be realized by features and combinations thereof as disclosed in the claims.

A system for stabilizing a voltage of a power system according to one embodiment according to the present disclosure to achieve the above purposes includes a power generator for generating power using a renewable energy source, and for supplying the generated power to the power system; an energy storage system (ESS) for storing the generated power from the power generator into a battery or supplying the power stored in the battery to the power system in a form of an active power and an reactive power, based on a command value; and a power management system (PMS). When a current voltage value of the power system is outside a reference voltage range thereof, the PMS is configured to change the command value based on the current voltage value of the power system to control a magnitude of the reactive power to be supplied to the power system so that the current voltage value of the power system changes to a value within the reference voltage range.

In accordance with the present disclosure, the magnitude of the reactive power to be supplied from the ESS (Energy Storage System) to the power system is controlled to maintain the current voltage value of the power system within a predefined range from a reference voltage of the power system, thereby securing power system stability.

Further, in accordance with the present disclosure, the magnitude of the reactive power is gradually controlled based on a difference between the current voltage value of the power system and a reference voltage of the power system, so that the current voltage value of the power system quickly follows the reference voltage thereof.

Furthermore, in accordance with the present disclosure, when the current voltage value of the power system is outside a control limit range, creation of the command value is stopped, and the ESS and the renewable energy based generator are disconnected with the power system, such that the power system is protected when an output of the renewable energy source fluctuates excessively.

