A method of operating a power generating system for a wind turbine connected to an electrical grid, the power generating system comprising a power generator, a converter, a transformer and a tap changer, the method comprising; monitoring a signal for detecting an over-voltage condition in the electrical grid which requires a reduction in the output voltage from the power generating system; initiating a convertor response mode configured to provide at least part of the required voltage reduction; and initiating a transformer response mode configured to provide at least part of the required voltage reduction; wherein the transformer response mode comprises operating the tap changer to adjust the output voltage from the power generating system.

A transformer assembly for electric grids including: an electric transformer including a magnetic core, a first side including one or more first windings enchained with said magnetic core and adapted to be electrically connected to a first grid section and a second side including one or more second windings enchained with said magnetic core and adapted to be electrically connected to a second grid section; a tap changer operatively associated with said electric transformer to vary the number of turns enchained with said magnetic core for said first windings; a control unit to: acquire input data indicative of an electrical connectivity condition of said second grid section with said second windings; determine whether said transformer is in a load condition or in a no-load condition; and, in a no-load condition, command said tap changer to set a maximum available number of turns for said first windings.

A method for multi-time scale reactive voltage control based on reinforcement learning in a power distribution network is provided, which relates to the field of power system operation and control. The method includes: constituting an optimization model for multi-time scale reactive voltage control in a power distribution network based on a reactive voltage control object of a slow discrete device and a reactive voltage control object of a fast continuous device in the power distribution network; constructing a hierarchical interaction training framework based on a two-layer Markov decision process based on the model; setting a slow agent for the slow discrete device and setting a fast agent for the fast continuous device; and deciding action values of the controlled devices by each agent based on measurement information inputted, so as to realize the multi-time scale reactive voltage control while the slow agent and the fast agent perform continuous online learning.

A method for feeding electric power into an electrical supply grid by means of a local feed unit. The feed unit is connected to a grid link point connected to a transformer point directly or via a supply connection. The transformer point is connected to a grid section via a transformer. The method includes feeding electrical real power into the electrical supply grid at the grid link point, feeding electrical reactive power into the electrical supply grid at the grid link point, detecting a change to be made in the real power to be fed in, and changing the fed-in real power in accordance with the detected change to be made. The method includes limiting a change in the fed-in reactive power over time when changing the fed-in real power and/or immediately thereafter or temporarily activating voltage control on the basis of the change in the fed-in real power.

A method for controlling the parallel running of a plurality of transformers T1, T2, . . . , TN) in a parallel circuit (10) is disclosed, wherein each of the transformers (T1, T2, . . . , TN) is assigned a measuring/control device (12) and all the measuring/control devices (12) are connected to one another via a communication connection (16). In the absence of a standby signal of at least one measuring/control device (12), interruption (16) of the communication (14) is displayed. The measured values determined at the time (t) of the interruption remain constant for the duration of the interruption (16) and are also included in the calculation of the control errors during the interruption (16), in order to minimise a circuit reactive current of the transformers (T1, T2, . . . , TN).

The disclosure discloses a virtual impedance comprehensive control method for an inductive power filtering (IPF) system. According to the disclosure, harmonic damping control at grid side and zero impedance control of filters are organically combined according to a technical problem which is unsolved and process difficulty in equipment manufacturing in an existing filtering method, so that the problem of performance reduction of passive filtering equipment caused by a change in an impedance parameter of a power grid system is solved on one hand, optimization control over a quality factor of the passive filtering equipment may be implemented to reduce dependence on an equipment production process level on the other hand, a quality factor of the single-tuned filters may meet a design requirement, and an overall filtering characteristic is further improved.

An auto-transformer rectifier system comprising an 18-pulse (or multiple of 18-pulse) autotransformer rectifier unit ATRU having three, or a multiple of three, diode bridge rectifiers and a balancing resistor to balance the power flow through the diode bridge rectifiers, wherein the balancing resistor has a variable resistance, and further comprising a controller configured to identify imbalances between power flows of the respective diode bridge rectifiers and to adjust the resistance of the balancing resistor in response to the detected imbalance.

A system and a method for locally controlling delivery of electrical power along the distribution feeder by measuring certain electricity parameters of a distribution feeder line using a substation phasor measurement unit (PMU) electrically coupled to a substation distribution bus at a first node on the feeder line, and at least one customer site PMU electrically coupled to a low voltage end of a transformer at a customer site, wherein the transformer is coupled by a drop line to a second node on the distribution feeder line and the customer site is coupled by another drop line to the transformer, and by controlling at least one controllable reactive power resource and optionally a real power resource connected to the second node or at the customer site. Related apparatus, systems, articles, and techniques are also described.

A method of controlling a wind turbine transformer is provided. The transformer has a primary side with a primary winding coupled to a power grid and a secondary side with a secondary winding coupled to an electrical power generating system of the wind turbine. The wind turbine transformer further includes an electronic on-load tap changer having semiconductor switches that are controllable to change a turns ratio of the primary winding to the secondary winding of the wind turbine transformer. The method includes the step of monitoring a voltage on the primary side of the wind turbine transformer, a voltage on the secondary side of the wind turbine transformer, or both. In response to detecting a change in the monitored voltage, the semiconductor switches of the electronic on-load tap changer are automatically controlled to adjust the turns ratio of the wind turbine transformer to compensate for the change.

A centralized voltage control device connected, via a communication network, to local voltage control devices connected to voltage control apparatuses, including: a transmission and reception unit receiving the number of times a tap position is changed per fixed time of the voltage control apparatus from the local voltage control device; a dead-zone-width updating unit increasing a dead zone width when the number of times a tap position is changed in a voltage control apparatus of a transformer type is a threshold or larger; and a voltage-upper-and-lower-limit-value determining unit determining the voltage upper limit value and the voltage lower limit value for each local voltage control device and issuing a command regarding these values to each local voltage control device, and determining the voltage upper limit value and the voltage lower limit value of the voltage control apparatus of a transformer type on the basis of the dead zone width.