A system architecture and method for enabling hierarchical intelligent control with appropriate-speed communication and coordination of control using intelligent distributed impedance/voltage injection modules, local intelligence centers, other actuator devices and miscellaneous FACTS coupled actuator devices is disclosed. Information transfer to a supervisory utility control is enabled for responding to integral power system disturbances, system modelling and optimization. By extending the control and communication capability to the edge of the HV power grid, control of the distribution network through FACTS based Demand response units is also enabled. Hence an integrated and hierarchical total power system control is established with distributed impedance/voltage injection modules, local intelligence centers, connected other actuator devices, miscellaneous FACTS coupled devices and utility supervisory all networked at appropriate speeds allowing optimization of the total power system from generation to distribution.

The present invention relates to a power conditioning system (PCS) efficiency-considered microgrid operation device comprising: a scheduling unit for scheduling outputs of a controllable load, a battery, and an emergency internal combustion generator operated in a microgrid; and an operation control unit for controlling the operation of the battery, the emergency internal combustion generator, and the controllable load according to charging/discharging of the battery, the output of the emergency internal combustion generator, and the output of the controllable load, which have been scheduled, by the scheduling unit, wherein the scheduling unit schedules charging/discharging by considering the efficiency of a PCS such that a state of charge (SOC) of the battery is maintained within a preset range. According to the present invention, the microgrid can be efficiently operated by considering the charging/discharging efficiency of the PCS.

The present invention relates to a method for controlling the frequency of a stand-alone microgrid wherein an energy storage device of the stand-alone microgrid is operated as a main power source by controlling a battery power conditioning system (PCS) of the stand-alone microgrid in a constant voltage constant frequency (CVCF) mode. According to the present invention, it is possible to operate the frequency stably while considering the fuel cost and power generation efficiency of a stand-alone microgrid.

A control system and photovoltaic system and micro-grid using the same and method thereof. The control system for controlling a photovoltaic converter includes: a first input, for receiving first signals indicating first sampling values of an input current of the photovoltaic converter provided by a solar panel; a second input, for receiving second signals indicating second sampling values of an input voltage of the photovoltaic converter provided by the solar panel; a third input, for receiving third signals indicating third sampling values of an output voltage of the photovoltaic converter; and a controller, for first regulating the output voltage of the photovoltaic converter in a direction towards a reference voltage based on the third sampling value by regulating the input voltage by first voltage change of a first predetermined level; wherein: the controller is further adapted for monitoring a trend of the input voltage and power provided by the solar panel based on the first sampling values and the second sampling values for the previous sampling time points and the current sampling time point, and suspending the first regulation in case that the trend changes. This allows for an improvement of transient response of the control system and preventing possible overshooting of a lower input voltage even when the solar panel operating point is relatively far away from the MPP.

A micro-grid system blending utility power with power from multiple renewable sources including energy storage devices provides power factor correction using the renewable sources and energy storage devices by adjustment of associated converters. A controller maximizes power factor correction by utility source subject to a cost weighting of penalties for exceeding a power factor threshold.

An uninterruptible power supply system, including: a plurality of uninterruptible power supply devices which are connected in parallel with respect to a load, and switch between power supplies supplying power to the load depending on states of the power supplies; a control unit controlling an operation of switching between the power supplies by the uninterruptible power supply devices; a storage battery connected to the plurality of uninterruptible power supply devices in common; a converter converting AC power; a contactor switching between the DC power converted by the converter and DC power input from the storage battery; and an inverter inverting the DC power and supplying the power to the load. The control unit deactivates the inverter which does not contribute to supplying a power amount required for the load, of a plurality of inverters.

This invention presents a new circuit topology formed by passive filter LCCL or LCC and voltage source DC/AC converter, which is named as fundamental forming unit. Compared with conventional LCL filter based DC/AC converter, the new converter circuits can handle wider range of power without suffering from disturbance by harmonic voltages and currents. For high voltage and high power application, circuits with multiple stages and multiple parallel branches are developed based on multiple fundamental forming units. Such circuits can be for general purpose application. They can also be for microgrid applications. Furthermore a new series of multistage DC/AC converters with LCL filter have also been developed to handle high power conversion at high voltage and high current levels. By applying such circuits to acting as grid-forming, grid-supporting and grid-feeding generators in a microgrid operating at constant frequency, the microgrid system can handle much higher power and can adapt to drastic change of renewable energy generation and load change. Such microgrid is operated using newly invented methods described in this disclosure.

A microgrid energy management system can include: a bus providing a power; a transmission line connected to the bus; a relay connected to the transmission line, sensing a microgrid according to a state of the transmission line, adjusting a relay setting, and generating a trip signal representing the relay setting; and a circuit breaker receiving the trip signal. In addition, the microgrid energy management system further includes an energy storage device connected to the bus.

A power system for power conversion between at least one power source and a grid is disclosed. The power system includes a power converter having a plurality of semiconductor switches, configured to adapt a power supply to a desired output; and a controller for controlling the power converter in an active mode and an active standby mode, the controller configured to: determine to enter into the active mode or the active standby mode; based on the active mode or the active standby mode is determined, control the power converter to be in a gating state with the grid or to be in a non-gating state with the grid.

Controlling a first renewable energy power plant by determining power delivery of the first renewable energy power plant to a collector bus; receiving data relating to power delivery from a second renewable energy power plant connected to the collector bus; determining the combined power delivery of the first and second renewable energy power plants to the collector bus; estimating the transmission line power loss on a first transmission line between the collector bus and a power grid point of interconnection (POI) based on the combined power delivery; and regulating the power delivery from the first renewable energy power plant to compensate for the estimated transmission line power loss.