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 arrangement for reactive power compensation at an electric energy transmission line includes at least one first reactive power compensation device including a first type of power electronic switches, at least one second reactive power compensation device including a second type of power electronic switches and a transformer having a first secondary coil connected to the first device, a second secondary coil connected to the second device and a primary coil connectable to the electric energy transmission line. The primary coil has more windings than any of the first and second secondary coils.

It is proposed herein to employ thyristor firing angles as a fast prediction of flicker in power supply for an electric arc furnace. It is further proposed to actively modify operating variables for the electric arc furnace to maintain the flicker below a predefined threshold. Aspects of the present application use the thyristor firing angles in combination with control ranges of variable reactance devices to predict the flicker severity level generated by the electric arc furnace with thyristor-controlled variable reactance devices. Based on the predicted flicker level, at least one operating variable of the electric arc furnace may be changed, if required, to maintain flicker to acceptable limit.

An electric power method for an electric arc furnace includes regulating the electric power frequency of a power voltage and a power current of the electrodes, independently from the mains frequency.

An arrangement for reactive power compensation at an electric energy transmission line includes at least one first reactive power compensation device including a first type of power electronic switches, at least one second reactive power compensation device including a second type of power electronic switches and a transformer having a first secondary coil connected to the first device, a second secondary coil connected to the second device and a primary coil connectable to the electric energy transmission line. The primary coil has more windings than any of the first and second secondary coils.

A lighting network for altering a power factor of an alternating current, AC, supply (5). The lighting network comprises luminaires (2, 3) having reactive components of a first reactive type which are controllably coupled, by a controller, to the AC supply so as to adjust the power factor of the AC supply. The controller controls the coupling of the luminaires based on a power factor signal indicative of a power factor of the AC supply, which is influenced by an appliance (6) with a reactive load of a second reactive type, which appliance is different to any one of the luminaires. Preferably, the first reactive type is capacitive, and the second reactive type is inductive.

A reactive power compensation device includes a power converter and a converter control unit, and compensates reactive power of an AC power grid by output reactive power of the power converter. The converter control unit includes an AC voltage detection unit and an output limit unit. The AC voltage detection unit detects voltage information of the AC power grid to which the power converter is connected. The output limit unit determines whether or not the output reactive power of the power converter needs to be limited, on the basis of the voltage information detected by the AC voltage detection unit, and in a case where the output reactive power needs to be limited, limits the output reactive power of the power converter.

A series circuit includes a capacitor connected in series with a power converter output terminals. The power converter provides an auxiliary voltage and a controller controls the power converter auxiliary voltage according to a selected function, such that the series circuit behaves as a capacitor, an inductor, or an impedance, based on the selected function. The controller may sense a voltage across the capacitor and use the sensed voltage to control the power converter auxiliary voltage according to the selected function. The series circuit may be connected in parallel with output terminals of an AC-DC converter, wherein the series circuit operates according to a selected mode to produce the auxiliary voltage, and the auxiliary voltage substantially cancels a low frequency AC voltage ripple across the capacitor, such that a substantially pure DC output voltage is delivered to the load.

Provided is a hybrid control device for a static synchronous compensator (STATCOM), the device including: a first arithmetic operation unit calculating the deviation between a reference voltage desired to be controlled by the STATCOM and output voltage to be output so as to output the same; a proportional integral (PI) controller performing PI control on the deviation output from the first arithmetic operation unit within a range between a new inductive reactive current maximum value and a new capacitive reactive current maximum value, so as to output a reactive current output value; and a second arithmetic operation unit adding the preset reactive current set value to the reactive current output value output from the PI control unit so as to output a reactive current reference value.

In order to create a full variable shunt reactor having two magnetically controllable high-voltage throttles which is compact and at the same time can also provide capacitive reactive power, auxiliary windings are used which are inductively coupled to the high-voltage throttles. The auxiliary windings are connected to at least one capacitively acting component.