Apparatus and method for controlling reactive power. In one embodiment, the apparatus comprises a bidirectional power converter comprising a switched mode cycloconverter for generating AC power having a desired amount of a reactive power component.

A load apparatus is connected to an AC power source and is supplied with power from the AC power source. An operation state control unit controls, based on a target value about a power-source quality including either a power-source power factor of the AC power source or a power-source harmonic of the AC power source and on a present power-source quality, an operation state of the load apparatus.

In prior art grid systems, power-line control is done by substation based large systems that use high-voltage (HV) circuits to get injectable impedance waveforms that can create oscillations on the HV power lines. Intelligent impedance injection modules (IIMs) are currently being proposed for interactive power line control and line balancing. These IIMs distributed over the high-voltage lines or installed on mobile platforms and connected to the HV power lines locally generate and inject waveforms in an intelligent fashion to provide interactive response capability to commands from utility for power line control. These IIMs typically comprise a plurality of impedance-injection units (IIUs) that are transformer-less flexible alternating current transmission systems interconnected in a series-parallel connection and output pulses that are additive and time synchronized to generate appropriate waveforms that when injected into HV transmission lines are able to accomplish the desired response and provide interactive power flow control.

The invention provides a method and system for operating an inverter based distributed power generation source with energy storage system, as a Flexible AC Transmission System (FACTS) device—a STATCOM. The inverter based distributed power generation source can provide reactive power compensation, voltage regulation, damping enhancement, stability improvement and other benefits provided by FACTS devices. These STATCOM functions are provided when the said energy storage based distributed power generation source is doing at least one of: i) not exchanging active power with said power grid system, or ii) exchanging active power less than a maximum inverter capacity with said power grid system. The present invention thus provides a technological improvement that opens up a new set of applications and potential revenue earning opportunities for energy storage based distributed power generation sources other than simply from exchanging (injecting or absorbing) active power.

Systems, methods, and devices relating to operating a power generation facility to contribute to the stability of the power transmission system. A controller operates on the power generation facility to modulate real power or reactive power or both in a decoupled manner to contribute to the stability of the power transmission system. Real power produced by the power generation facility can be increased or decreased between zero and the maximum real power available from the PV solar panels, as required by the power system. Reactive power from the power generation facility can be exchanged (injected or absorbed) and both increased or decreased as required by the power transmission system. For solar farms, the solar panels can be connected or disconnected, or operated at non-optimal power production to add or subtract real or reactive power to the power transmission system.

An energy transmission system is provided for a power generation plant including plural distributed power generation devices and a flow battery system that includes plural charging stacks including electrochemical flow cells, wherein each charging stack is associated with one or a group of the power generation devices of the power generation plant and wherein each charging stack is configured to receive electrical energy produced by the associated power generation device or group of power generation devices and to energize an electrolyte of the flow battery system by the received electrical energy; a central storage unit configured to store the electrolyte of the flow battery system; a discharging stack including electrochemical flow cells, wherein the discharging stack is configured to extract electrical energy from the electrolyte and to provide the electrical energy to a power grid. A wind farm including wind turbines and including such energy transmission system is further provided.

Apparatus and method for controlling reactive power. In one embodiment, the apparatus comprises a bidirectional power converter comprising a switched mode cycloconverter for generating AC power having a desired amount of a reactive power component.

Apparatus and method for controlling reactive power. In one embodiment, the apparatus comprises a bidirectional power converter comprising a switched mode cycloconverter for generating AC power having a desired amount of a reactive power component.

A converter includes an AC side to be connected to an AC network at a connecting point, a grid following controller configured to control a steady state current at the connecting point, and a grid forming controller configured to actively control frequency and voltage at the connecting point. The grid following controller and the grid forming controller share an underlying current controller. A method for operating the converter is also provided.

The invention provides a method and system for operating an inverter based distributed power generation source with energy storage system, as a Flexible AC Transmission System (FACTS) device—a STATCOM. The inverter based distributed power generation source can provide reactive power compensation, voltage regulation, damping enhancement, stability improvement and other benefits provided by FACTS devices. These STATCOM functions are provided when the said energy storage based distributed power generation source is doing at least one of: i) not exchanging active power with said power grid system, or ii) exchanging active power less than a maximum inverter capacity with said power grid system. The present invention thus provides a technological improvement that opens up a new set of applications and potential revenue earning opportunities for energy storage based distributed power generation sources other than simply from exchanging (injecting or absorbing) active power.