Power supply system and method for operating a power supply system

Abstract

A power supply system for providing, powered by an external power source, a load power to one or more loads is provided. The power supply system includes a power supply bus connectable to the external power source, a first electric component, a first feed forward data link, and a first synchronous condenser configured to output reactive power to the power supply bus. The first electric component is arranged in a first electric supply line between the power supply bus and a first load. The first electric component has a first determining unit configured for determining a first operating characteristic having information about fluctuations in the load power, particularly fluctuations in a reactive load. The first synchronous condenser has a first synchronous condenser controller configured for receiving, through the first feed forward data link, a first reference set point, the first reference set point being based on the first operating characteristic, and configured for controlling an operation of the first synchronous condenser based on the first reference set point.

Description

[0001] POWER SUPPLY SYSTEM AND METHOD FOR OPERATING A POWER SUPPLY SYSTEM

[0002] Field of the disclosure

[0003] The invention is in the area of power supply systems, particularly power supply systems having a synchronous condenser. Embodiments of the present application relate to a power supply system and a method for operating a power supply system.

[0004] Technical Background

[0005] Synchronous condensers are DC-excited synchronous motors having a free-spinning shaft that can be used to adjust conditions of an electric power supply system. A synchronous condenser is a rotational AC machine. Due to this reason, its response time to a dynamic event on the power system side is slow compared to power electronic based reactive power compensators like, for example, a static var compensator (SVC), a unified power flow controller (UPFC) or a static synchronous compensator (STATCOM).

[0006] Synchronous condenser may be installed to provide reactive power, inertia support and fault level support, particularly in weak grids. Electric power grids are transforming, reasons for this change include: More influx and influence of renewable energy sources like wind and solar in grids; Transition from traditional synchronous generators-based grid to renewable energy dominated grids or to pure renewable energy based grids with no interconnection to external grid, which are based on power electronic converter; Increase in weaker grids due to disconnection of traditional synchronous generators and fluctuating energy sources, leading to low short circuit power that can lead to undervoltage, overvoltage, flicker, and / or stability issues, or low inertia that can lead to frequency variation, and / or trips due to over- and underfrequency.

[0007] There is therefore a need for a synchronous condenser having a fast response time, particularly a power supply system with a synchronous condenser having a fast response time.

[0008] Summary of the disclosure

[0009] Reference will now be made in detail to the various embodiments of the present disclosure, one or more examples of which are illustrated in the figures. Generally, only the differences with respect to individual embodiments are described. Each example is provided by way of explanation and is not meant as a limitation of the present disclosure. Features illustrated or described as part of one embodiment can be used on or in conjunction with other embodiments to yield yet a further embodiment. It is intended that the description includes such modifications and variations.

[0010] In light of the above, a power supply system according to claim 1 and a method for operating a power supply system according to claim 12 is provided. Further aspects, advantages, and features are apparent from the dependent claims, the description, and the accompanying drawings.

[0011] The response time of synchronous condensers is composed of a measurement loop delay, a controller loop delay, a converter delay, and a field winding time constant. With the feed forward data link according to the present invention, a reference set point is sent to the field circuit of the synchronous condenser from an electric component. By directly sending the reference setpoint, the response can be faster since the measurement loop delay and controller loop delay can be avoided. Advantageously, the power supply system provides improved dynamics by having a faster response time due to the feed forward link, particularly during dynamic operating conditions.

[0012] To improve the response time of a synchronous condenser, a feed forward data link from an electric component to a synchronous condenser is provided. An operating characteristic having information about fluctuations in a load power, particularly a reactive load power, is determined by a determining unit of an electric component. A reference set point is determined based on the operating characteristic and fed forward to the synchronous condenser to adjust an operation of the synchronous condenser. By this approach, the response time is faster since the synchronous condenser is not using measured load fluctuation, i.e. fluctuations directly measured by the synchronous condenser, for the reference set point determination.

[0013] Throughout this description, multiple elements of a same type, e.g. a first feed forward data link and a second feed forward data link, or a first synchronous condenser and a second synchronous condenser, are described. It is understood that the elements of the same type are generally similar and / or identical. That is, unless otherwise indicated, when a feature is described for one element, e.g. the first feed forward data link, this applies to all elements of the same type, e.g. the features are also described for the second feed forward data link. Further, the multiple elements of the same type, e.g. a first feed forward data link and a second feed forward data link, or a first synchronous condenser and a second synchronous condenser, may generally be referred to by general terms, e.g. feed forward data links or synchronous condensers. Unless otherwise indicated, it is intended that when describing features of or in relation using the general terms, e.g. feed forward data links or synchronous condensers, these features are described for each element, e.g. the first feed forward data link and the second feed forward data link or the first synchronous condenser and the second synchronous condenser.

[0014] Throughout this description, a load power is described. The load power may be a power provided by the power supply system to one or more loads. The load power may be the total power received by the one or more loads from the power supply system. Particularly, the load power may describe multiple powers provided to the one or more loads, that are added up to the load power. The load power includes a reactive power part and an active power part. The reactive power part of the load power is referred to as the reactive load power. The active power part of the load power is referred to as the active load power.

[0015] Throughout this description, different transformers are referred to, such as source transformers, converter transformers or synchronous condenser transformers. It is understood, that the transformers referred to throughout this description can be any suitable type of transformer, such as 2-winding transformers or 3 -winding transformers. The transformers referred to throughout this description may be of oil or dry type.

[0016] According to an aspect, a power supply system for providing, powered by an external power source, a load power to one or more loads is provided. The power supply system includes a power supply bus connectable to the external power source, a first electric component, a first feed forward data link, and a first synchronous condenser configured to output reactive power to the power supply bus. The first electric component is arranged in a first electric supply line between the power supply bus and a first load. The first electric component has a first determining unit configured for determining a first operating characteristic having information about fluctuations in the load power, particularly fluctuations in a reactive load. The first synchronous condenser has a first synchronous condenser controller configured for receiving, through the first feed forward data link, a first reference set point, the first reference set point being based on the first operating characteristic, and configured for controlling an operation of the first synchronous condenser based on the first reference set point.

[0017] When there is a power fluctuation from a load or a converter fed load, it causes fluctuations on the power supply bus, particularly the external power source, e.g. a grid. In order to respond faster, the first determining unit of the first electric component determines the first operating characteristic having information about the load power fluctuations, particularly the reactive load power fluctuations. The first reference set point is determined based on the first operating characteristic and fed forward to the synchronous condenser. Advantageously, this approach enables the synchronous condenser to react quicker. For example, the first electric component may be the load, a load converter, particularly the load converter may be a power electronics converter, a power quality system device (PQS) device, such as a static var compensator (SVC), a STATCOM, or a unified power flow controller (UPFC), or a grid forming converter. The first electric component may be a plant level controller, and / or a common master controller which is coordinating with multiple converter controllers. A plant level controller can also send a reference set point via a feed forward data link for plant level dynamic event support from synchronous condenser.

[0018] A feed forward data link as described herein can be implemented for a synchronous condenser in combination with various electric components. For example, a feed forward data link can be provided between a synchronous condenser and a direct grid connected load, a voltage source converter (VSC) with diode or thyristor front end or active front end (AFE), a current source converter (CSC), a rectifier, a chopper with diode front end, a chopper with AFE, a direct converter such as a cycloconverter or a matrix converter, a power quality system (PQS) device like an SVC, a STATCOM, UPFC or battery energy storage system (BESS), and / or a grid forming converter.

[0019] The present application is suitable for any type of industrial plant having a power supply system. For example, the present application can be provided in steel industry, hydrogen electrolysis, mining, aluminum smelters, or similar industrial plants. Future grids are characterized by low short circuit power and low inertia. Hence, installing synchronous condenser for example in industrial plants, grids, generation setup with renewable energy sources, or other similar system allows to provide inertia and lagging and leading reactive power. Further, fault level at the point of connection can be increased, a voltage support can be provided, a fault ride through can be provided, small signal and transient stability can be improved, and reactive power support can be provided.

[0020] The power supply system may be a power supply system for an industrial facility, particularly for an industrial facility requiring power in the MW range, that is more than 1 MW. The power supply system may be a hydrogen production facility. The power supply system may be a power supply system for a metal fabrication facility. The metal fabrication facility may have at least one electric arc furnace (EAF). The one or more loads may be one or more EAFs, particularly one or more electrodes of the one or more EAFs. The power supply system may provide the load power to the one or more EAFs of the metal fabrication facility, particularly to the electrodes of the one or more EAFs. Each EAF may comprise one or more electrodes. The load power may be provided to the electrodes of the one or more EAFs. The load power may be distributed over the one or more EAFs, particularly over the electrodes of the one or more EAFs. The load power may correspond to the total power provided to the one or more EAFs, particularly to the total power provided to the electrodes of the one or more EAFs.

[0021] The power supply system is connectable to an external power source for powering the power supply system. The external power source may be a traditional grid, a renewable energy based grid, a fossil fuel based grid, and / or a nuclear power based grid. The external power source may be an isolated grid and / or an island grid. The power supply system may be powered entirely by a renewable energy system. The renewable energy system may comprise one or more renewable energy sources. The renewable energy system may comprise one or more energy storage systems to store energy produced by the renewable energy sources. The renewable energy source may be a solar energy source, a wind energy source, a geothermal energy source, a hydropower energy source, an ocean energy source, a bioenergy source, or any combination thereof.

[0022] The power supply system comprises a power supply bus. The power supply bus is connectable to the external power source. The power supply bus may be a main bus for the power supply system. The further components of the power supply system may be connected to the power supply bus. The further components of the power supply system may be connected to the external power source through the power supply bus. The power supply system may provide a load power to one or more loads. Each of the one or more loads may be connected to the power supply bus, particularly through a corresponding power supply line. The power supply bus may be controlled to have it connected or disconnected to the external power source. The power supply bus may be connectable to the external power source through a switchgear.

[0023] The power supply system comprises a first electric component. The first electric component is arranged in a first electric power supply line between the power supply bus and a first load. The first electric power supply line connects the first load to the power supply bus. A first transformer may be provided in the first electric power supply line. The first electric component may be provided in the power supply line between the transformer and the load or between the power supply bus and the transformer. The first electric component may be a power electronic converter. The first electric component being a power electronic converter may be arranged in the first electric power supply line between the transformer and the load. The first load may be directly connected to the power supply bus. The first electric component may be the first load.

[0024] The first electric component has a first determining unit. The first determining unit is configured for determining a first operating characteristic. The first determining unit may be configured for determining the first operating characteristic in real time. The first determining unit may be integral with the first electric component. The first determining unit may be a controller of the first electric component. The first determining unit may be configured for controlling an operation of the first electric component. The first determining unit may be configured for transmitting the first operating characteristic through the first feed forward data link to the first synchronous condenser. The first determining unit may be configured for determining the first reference set point based on the first operating characteristic. The first determining unit may be configured for transmitting the first reference set point through the first feed forward data link to the first synchronous condenser.

[0025] The first operating characteristic has information about fluctuations in the load power. Particularly, the first operating characteristic may have information about fluctuations in the reactive load power and / or the active load power. Fluctuations in the load power can be caused by a load voltage, a load current, and / or a behavior of electric components in the power supply system, such as the first electric component. The first operating characteristic may have information about fluctuations in a load voltage, a load current, a reactive load power, and / or an active load power. In some embodiments, that can be combined with other embodiments described herein, the first operating characteristic comprises at least one of a voltage information, a current information, and / or a reactive load power information.

[0026] The first determining unit may determine the first operating characteristic in real time at the location of the first electric component. The location being the location of the first electric component in the electric network of the power supply system. Particularly, the first electric component is provided in the first electric supply line between the power supply bus and the first load. At the time when the first determining unit determines the first operating characteristic, the fluctuations about which the first operating characteristic has information, may not yet have been detected by the first synchronous condenser. Particularly, the fluctuations may not have been received at the location of the first synchronous condenser in the electric network of the power supply system. The first operating characteristic and / or the first reference set point may be fed forward from the first determining unit to the first synchronous condenser controller through the first feed forward data link. The power supply system has the first feed forward data link. The first feed forward data link may connect the first determining unit to the first synchronous condenser for sending data from the first determining unit to the first synchronous condenser, particularly to the first synchronous condenser controller. The first feed forward data link may be configured for sending any type of data. The first feed forward data link may be configured for sending the first operating characteristic and / or the first reference set point. The first feed forward data link may include and / or be in communication with one or more further elements. The first feed forward data link may have a first link speed. The first link speed describes a communication time for communicating data through the first feed forward data link. The first link speed may correspond to the communication time for communicating data from the first determining unit to the first synchronous condenser controller. The first link speed may be between 100 ms and 0.01 ms, particularly between 50 ms and 0.1 ms, particularly between 20 ms and 1 ms, particularly between 5 ms and 1 ms.

[0027] The power supply system comprises a first synchronous condenser. The first synchronous condenser is configured to output reactive power to the power supply bus. The first synchronous condenser may be connected to the power supply bus through a first synchronous condenser transformer. The reactive power may be positive, particularly such that the synchronous condenser feeds reactive power into the power supply bus. The reactive power may be negative, particularly such that the synchronous condenser draws reactive power from the power supply bus. The first synchronous condenser may output reactive power to the power supply bus according to a reactive load power in the power supply bus. The first synchronous condenser may provide a fixed reactive power to the power supply bus to maintain the reactive power load of the bus, particularly maintain the reactive power at or above a pre-determined reactive power level. The first synchronous condenser may provide a variable reactive power to maintain the voltage of the power supply bus, particularly maintain the voltage at or above a pre-determined voltage level. Particularly, the first synchronous condenser may output reactive power to the power supply bus such that the reactive load power in the power supply bus is kept constant or within a predetermined operating range of the reactive load power. The first synchronous condenser may be configured for compensating reactive power fluctuations in the power supply bus.

[0028] In an embodiment, the first synchronous condenser may be configured to output an active power to the power supply bus. The first synchronous condenser may provide the active power in the form of inertia. The value of active power outputted by the first synchronous condenser may be small compared to the value of reactive power outputted by the first synchronous condenser. A flywheel may be coupled with the first synchronous condenser. The flywheel may be configured for additionally outputting an active power in the form of inertia. Particularly additionally to the active power outputted by the synchronous condenser in the form of inertia. The active power may be positive, particularly such that the synchronous condenser adds active power in the form of inertia into the power supply bus. The reactive power may be negative, particularly such that the synchronous condenser draws reactive power from the power supply bus. The reactive power may be positive, particularly such that the synchronous condenser adds reactive power to the power supply bus. The first synchronous condenser may be coupled with a first energy storage system configured for outputting an active power to the power supply bus. The active power may be positive, particularly such that the energy storage systems feeds active power into the power supply bus. The reactive power may be negative, particularly such that the energy storage system draws reactive power from the power supply bus. The energy received by drawing power from the power supply bus may be stored in the energy storage system. The first synchronous condenser coupled with the first energy storage system may be configured for compensating reactive power fluctuations and active power fluctuations in the power supply bus. Instead of, or in combination with, a first energy storage system, the first synchronous condenser may be coupled to any suitable component configured for outputting an active power.

[0029] The first synchronous condenser has a first synchronous condenser controller. The first synchronous condenser controller may be integral with the first synchronous condenser. The first synchronous condenser controller may be configured for controlling an operation of the first synchronous condenser. The first synchronous condenser controller may be configured for controlling the output of reactive power to the power supply bus.

[0030] The first synchronous condenser controller is configured for receiving the first reference set point. The first synchronous condenser controller receives the first reference set point through the first feed forward data link. The first synchronous condenser controller is configured for controlling an operation of the first synchronous condenser based on the first reference set point. The first synchronous condenser controller may have a first response time. The first response time may correspond to a time between the receiving the first reference set point at the first synchronous condenser controller and the controlling of the first synchronous condenser based on said first reference set point. The first response time may be between 10 ms and 1000 ms, particularly between 100 ms and 500 ms, more particularly between 150 ms and 250 ms. The controlling an operation of the first synchronous condenser based on the first reference set point may comprise adjusting a set point of the first synchronous condenser according to the first reference set point. The first synchronous condenser controller may determine a first control signal based on the first reference set point. The first synchronous condenser controller may control the operation of the first synchronous condenser based on the first control signal.

[0031] The first synchronous condenser controller adjusts a field current of the first synchronous condenser to compensate the fluctuations in the load power. Particularly, to compensate fluctuations in the reactive load power and / or in the active load power. The first synchronous condenser controller may adjust the field current of the first synchronous condenser according to the first reference set point. The first synchronous condenser may adjust the field current according to the first control signal. Depending on the load fluctuations, the field current adjustment can result in the synchronous condenser operating in over- or under-excited mode. The first reference set point is based on the first operating characteristic. The first operating characteristic may be used to determine an expected fluctuation in a load power particularly in the reactive load power and / or in the active load power. The first reference set point may comprise information about an expected fluctuation in a load power. The first synchronous condenser can be controlled based on the first reference set point such that the first synchronous condenser outputs a power that is equal in value and has opposite sign of the expected fluctuation in the load power to compensate the fluctuations in the load power, particularly in the reactive load power. Additionally, the first synchronous condenser may output small amounts of active power in the form of inertia to compensate the active load power. The amount of active power outputted by the first synchronous condenser may be small compared to the amount of reactive power outputted by the first synchronous condenser. The first synchronous condenser may be coupled with a flywheel, an energy storage system, and / or other suitable systems configured to compensate active power. The first synchronous condenser coupled with a flywheel, an energy storage system, and / or other suitable systems configured to compensate active power can be controlled based on the first reference set point such that the flywheel, the energy storage system, and / or the other suitable systems outputs an active power that is equal in value and has opposite sign of the expected fluctuation in the active load power to compensate the fluctuations in the active load power. The first synchronous condenser can be controlled based on the first reference set point such that the first synchronous condenser outputs a power that compensates fluctuations in the load power to below a pre-determined threshold, particularly in the reactive load power and / or in the active load power. The first control signal may comprise information about an expected fluctuation in a load power. The first synchronous condenser can be controlled based on the first control signal such that the first synchronous condenser outputs a power that is equal in value and has opposite sign of the expected fluctuation in the load power to compensate the fluctuations in the load power, particularly in the reactive load power and / or in the active load power. The first synchronous condenser can be controlled based on the first control signal such that the first synchronous condenser outputs a power that compensates fluctuations in the load power to below a predetermined threshold, particularly in the reactive load power and / or in the active load power.

[0032] The first feed forward data link allows to feed forward the first reference set point from the first electric component to the first synchronous condenser. The synchronous condenser can respond to fluctuations in the load power after a response time. The response time may be the sum of the first link speed and the first response time. The response time may be between 10 ms and 1000 ms, particularly between 100 ms and 500 ms, more particularly between 150 ms and 250 ms. The response time may be less than a delay time when operating a synchronous condenser without a feed forward data link. Particularly, the response time may be less than a response time of synchronous condensers in conventional power supply systems, that is composed of a measurement loop delay, a controller loop delay, a converter delay, and an field winding time constant. Advantageously, the first feed forward data link allows to adjust faster a reactive power output of the first synchronous condenser according to fluctuations in the load power, particularly reactive power fluctuations in the load power. This results in better compensation of power fluctuations. The power supply system according to the present application provides an improved compensation of fluctuations in the reactive load power.

[0033] The first electric component is an electric component that interacts with the first load. The first electric component may be a power electronic converter. The first electric component may be load connected directly to the power supply bus. The first electric component may be a load of the one or more loads that is connected directly to the power supply bus. The first electric component is an electric component that sees a behavior of the first load. The first electric component may be a direct grid connected load, a voltage source converter (VSC) with diode or thyristor front end or active front end (AFE), a current source converter (CSC), a rectifier, a chopper with diode front end, a chopper with AFE, a cycloconverter, a matrix converter, or a combination thereof. The first electric component may be in the first power supply line connecting the first load to the power supply bus. In some embodiments, that can be combined with other embodiments described herein, the first electric component is a direct grid connected load, a voltage source converter (VSC) with diode or thyristor front end or active front end (AFE), a current source converter (CSC), a rectifier, a chopper with diode front end, a chopper with AFE, a cycloconverter, a matrix converter, or a combination thereof.

[0034] In some embodiments, that can be combined with other embodiments described herein, the power supply system includes a second electric component having a second determining unit configured for determining a second operating characteristic having information about fluctuations in the load power, particularly fluctuations in the reactive load power, a second feed forward data link, and a second synchronous condenser configured to output reactive power to the power supply bus, the second synchronous condenser having a second synchronous condenser controller configured for receiving, through the second feed forward data link, a second reference set point, the second reference set point being based on the second operating characteristic, and configured for controlling an operation of the second synchronous condenser based on the second reference set point.

[0035] The second electric component, particularly the second determining unit, the second feed forward data link, and the second synchronous condenser, particularly the second synchronous condenser controller are generally similar to the first electric component, particularly the first determining unit, the first feed forward data link, and the first synchronous condenser, particularly the first synchronous condenser controller. Particularly, the features described above with respect the first electric component, particularly the first determining unit, the first feed forward data link, and the first synchronous condenser, particularly the first synchronous condenser controller also apply for the second electric component, particularly the second determining unit, the second feed forward data link, and the second synchronous condenser, particularly the second synchronous condenser controller.

[0036] The controlling an operation of the second synchronous condenser based on the second reference set point may comprise adjusting a set point of the second synchronous condenser according to the second reference set point. The second synchronous condenser controller may determine a second control signal based on the second reference set point. The second synchronous condenser controller may control the operation of the second synchronous condenser based on the second control signal.

[0037] The second feed forward data link may connect the second determining unit to the second synchronous condenser for sending data from the second determining unit to the second synchronous condenser, particularly the second synchronous condenser controller. The second feed forward data link may be configured for sending any type of data. The second feed forward data link may be configured for sending the second operating characteristic and / or the second reference set point. The second feed forward data link may include and / or be in communication with one or more further elements. The second feed forward data link may have a second link speed. The second link speed may be equal to the first link speed. The second link speed may correspond to the communication time for communicating data from the second determining unit to the second synchronous condenser controller. The second link speed may be between 100 ms and 0.01 ms, particularly between 50 ms and 0.1 ms, particularly between 20 ms and 1 ms, particularly between 5 ms and 1 ms.

[0038] In some embodiments, that can be combined with further embodiments described herein, the power supply system includes a second electric component having a second determining unit configured for determining a second operating characteristic having information about fluctuations in the load power, particularly fluctuations in the reactive load power, and a third feed forward data link. The first synchronous condenser controller is configured for receiving, through the third feed forward data link, a third reference set point, the third reference set point being based on the second operating characteristic, and configured for controlling an operation of the first synchronous condenser based on the third reference set point.

[0039] The third feed forward data link may connect the second determining unit to the first synchronous condenser for sending data from the second determining unit to the first synchronous condenser, particularly the first synchronous condenser controller. The third feed forward data link may be configured for sending any type of data. The third feed forward data link may be configured for sending the third operating characteristic and / or the third reference set point. The third feed forward data link may include and / or be in communication with one or more further elements. The third feed forward data link may have a third link speed. The third link speed may be equal to the first link speed and / or the second link speed. The third link speed may correspond to the communication time for communicating data from the second determining unit to the first synchronous condenser controller. The third link speed may be between 100 ms and 0.01 ms, particularly between 50 ms and 0.1 ms, particularly between 20 ms and 1 ms, particularly between 5 ms and 1 ms.

[0040] The first synchronous condenser controller may be configured for controlling an operation of the first synchronous condenser based on the third reference set point. The first synchronous condenser controller may be configured for controlling an operation of the first synchronous condenser based on the first reference set point and the third reference set point. The first synchronous condenser controller may determine a first control signal based on the first reference set point and the third reference set point. The first synchronous condenser controller may control an operation of the first synchronous condenser based on the first control signal.

[0041] In some embodiments, the power supply system comprises a fourth feed forward data link, and a second synchronous condenser configured to output reactive power to the power supply bus. The second synchronous condenser has a second synchronous condenser controller configured for receiving, through the fourth feed forward data link, a fourth reference set point, the fourth reference set point being based on the first operating characteristic, and configured for controlling an operation of the second synchronous condenser based on the fourth reference set point.

[0042] The fourth feed forward data link may connect the first determining unit to the second synchronous condenser for sending data from the first determining unit to the second synchronous condenser, particularly the second synchronous condenser controller. The fourth feed forward data link may be configured for sending any type of data. The fourth feed forward data link may be configured for sending the fourth operating characteristic and / or the fourth reference set point. The fourth feed forward data link may include and / or be in communication with one or more further elements. The fourth feed forward data link may have a fourth link speed. The fourth link speed may be equal to the first link speed, the second link speed and / or the third link speed. The fourth link speed may correspond to the communication time for communicating data from the first determining unit to the second synchronous condenser controller. The fourth link speed may be between 100 ms and 0.01 ms, particularly between 50 ms and 0.1 ms, particularly between 20 ms and 1 ms, particularly between 5 ms and 1 ms.

[0043] The second synchronous condenser controller may be configured for controlling an operation of the second synchronous condenser based on the fourth reference set point. The second synchronous condenser controller may be configured for controlling an operation of the second synchronous condenser based on the second reference set point and the fourth reference set point. The second synchronous condenser controller may determine a second control signal based on the second reference set point and the fourth reference set point. The second synchronous condenser controller may control an operation of the second synchronous condenser based on the second control signal.

[0044] In some embodiments, that can be combined with further embodiments described herein, the power supply system includes a second feed forward data link, wherein the second synchronous condenser controller is configured for receiving, through the second feed forward data link, a second reference set point, the second reference set point being based on the second operating characteristic, and configured for controlling an operation of the second synchronous condenser based on the second reference set point.

[0045] The second electric component may be connected to the power supply bus. The second electric component may be arranged in the first electric supply line. The second electric component may be arranged anywhere in the first electric supply line between the power supply bus, the first electric component, the first transformer, and the first load. The second electric component may be provided in a second power supply line. The second power supply line may connect the second electric component to the power supply bus. The second power supply line may connect a second load to the power supply bus. The second electric component may be provided in the second power supply line between the power supply bus and the second load. A second transformer may be provided in the second power supply line. The second electric component may be arranged in the second power supply line anywhere between the power supply bus, the second transformer, and the second load. In some embodiments, the second electric component is arranged in a second power supply line between the power bus and a second load.

[0046] The second electric component may be an electric component that interacts with the first load and / or the second load. The second electric component may be an electric component that sees a behavior of the first load and / or the second load. The second electric component may be a direct grid connected load, a voltage source converter (VSC) with diode or thyristor front end or active front end (AFE), a current source converter (CSC), a rectifier, a chopper with diode front end, a chopper with AFE, a cycloconverter, a matrix converter, or a combination thereof. The second electric component may be a power quality unit. The second electric component may be a SVC, a STATCOM, a UPFC, a battery energy storage system (BESS), a grid forming converter, or a combination thereof. In some embodiments, that can be combined with other embodiments described herein, the second electric component is a direct grid connected load, a voltage source converter (VSC) with diode or thyristor front end or active front end (AFE), a current source converter (CSC), a rectifier, a chopper with diode front end, a chopper with AFE, a cycloconverter, a matrix converter, a SVC, a STATCOM, a UPFC, a battery energy storage system (BESS), a grid forming converter, or a combination thereof.

[0047] The power supply system may comprise one or more processing units for determining the reference set points. A first processing unit may be communicatively coupled to the first feed forward data link for receiving the first operating characteristic. The processing unit may determine the first reference set point based on the first operating characteristic and feed the first reference set point forward to the first synchronous condenser controller, particularly within the first link speed. Similarly, further processing units may be communicatively coupled to the second feed forward data link, the third feed forward data link, and / or the fourth feed forward data link. The same processing unit may be communicatively coupled to the first feed forward data link, the second feed forward data link, the third feed forward data link, and / or the fourth feed forward data link. The power supply system may comprise a single processing unit configured for determining the reference set points based on the corresponding operating characteristic. The processing unit may be communicatively coupled to each of the feed forward data links. In some embodiments, the power supply system includes one or more processing units communicatively coupled to one or more of the feed forward data links for determining reference set points based on the corresponding operating characteristic.

[0048] While the above embodiments are described with two elements of a same type, e.g. first electric component and second electric component, or first synchronous condenser and second synchronous condenser, it is understood that the above also applies in a similar manner to a plurality of element of the same type, e.g. a plurality of electric components or a plurality of synchronous condensers. The above description provided for two elements of the same type applies accordingly to embodiments having a plurality of elements of the same type. In some embodiments, that can be combined with other embodiments described herein, the power supply system includes a plurality of electric components comprising the first electric component, particularly comprising the second electric component, each electric component having a determining unit for determining an operating characteristic having information about fluctuations in the load power, particularly fluctuations in the reactive load power, and a plurality of feed forward data links. The first synchronous condenser controller is configured for receiving, through the plurality of feed forward data links, a plurality of reference set points based on the corresponding operating characteristics, and configured for controlling an operation of the first synchronous condenser based on the plurality of reference set point.

[0049] Preferably each of the synchronous condensers is configured to receive, via the plurality of feed forward data links, one or more reference set points, the one or more reference set points being based on the operating characteristic of each of the plurality of electric components. The power supply system may comprise several loads that can be operated at the same time and be connected in parallel to one point of common coupling (PCC). One or more synchronous condensers may be used to compensate several loads. This can be achieved by providing several feed forward data links between the corresponding electric components, particularly the determining units, associated with the several loads and the one or more synchronous condensers, particularly the synchronous condenser controller. The converters and the synchronous condensers may be operated in a master-follower configuration.

[0050] According to another aspect, a method for operating a power supply system for providing, powered by an external power source, a load power from a power supply bus to one or more loads is provided. The method includes determining a first operating characteristic of a first electric component in real time, the first operating characteristic having information about fluctuations in the load power, particularly fluctuations in the reactive load power, determining a first reference set point based on the first operating characteristic, feeding forward the first reference set point to a first synchronous condenser controller of a first synchronous condenser, and controlling an operation of the first synchronous condenser based on the first reference set point to adjust a reactive power output of the first synchronous condenser to the power supply bus.

[0051] In some embodiments, the first operating characteristic comprises at least one of a voltage information, a current information, and / or a reactive load power information.

[0052] In some embodiments, the method includes determining a second operating characteristic of a second electric component in real time, the second operating characteristic having information about fluctuations in the load power, particularly fluctuations in the reactive load power, determining a second reference set point based on the second operating characteristic, feeding forward the second reference set point to a second synchronous condenser controller of a second synchronous condenser, and controlling an operation of the second synchronous condenser based on the second reference set point to adjust a reactive power output of the second synchronous condenser to the power supply bus.

[0053] In some embodiments, that can be combined with other embodiments described herein, the method includes determining a second operating characteristic of a second electric component in real time, the second operating characteristic having information about fluctuations in the load power, particularly fluctuations in the reactive load power, determining a third reference set point based on the second operating characteristic, feeding forward the third reference set point to a first synchronous condenser controller, and controlling an operation of the first synchronous condenser based on the third reference set point to adjust the reactive power output of the first synchronous condenser to the power supply bus. In some embodiments, that can be combined with other embodiments described herein, the method includes determining a fourth reference set point based on the first operating characteristic, feeding forward the fourth reference set point to a second synchronous condenser controller of a second synchronous condenser, and controlling an operation of the second synchronous condenser based on the fourth reference set point to adjust a reactive power output of the second synchronous condenser to the power supply bus.

[0054] In some embodiments, that can be combined with other embodiments described herein, the method includes determining a second reference set point based on the second operating characteristic, feeding forward the second reference set point to a second synchronous condenser controller of a second synchronous condenser, and controlling an operation of the second synchronous condenser based on the second reference set point to adjust the reactive power output of the second synchronous condenser to the power supply bus.

[0055] The controlling an operation of the first synchronous condenser based on the first reference set point may be within 300 ms after determining the first operating characteristic upon which the first control signal is based. In some embodiments, the operation of the synchronous condenser is adjusted according to the reference set point in less than 300 ms after determining the first operating characteristic upon which the reference set point is based.

[0056] In some embodiments, the power supply system is a power supply system according to embodiments described herein. The first operating characteristic is determined by the first determining unit, the first reference set point is feed forward through the first feed forward data link, and the operation of the first synchronous condenser is controlled by the first synchronous condenser controller.

[0057] Those skilled in the art will recognise additional features and advantages upon reading the following detailed description, and upon viewing the accompanying drawings.

[0058] Brief description of the drawings

[0059] So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be by reference to embodiments. The accompanying drawings relate to embodiments of the disclosure and are described in the following:

[0060] Fig. 1 is a schematic illustration of a power supply system. Fig. 2 is a schematic illustration of a power supply system.

[0061] Fig. 3 is a schematic illustration of a power supply system.

[0062] Fig. 4 is a schematic illustration of a power supply system.

[0063] Fig. 5 is a schematic illustration of a method for operating a power supply system.

[0064] Detailed description of the drawings

[0065] Reference will now be made in detail to the various embodiments, one or more examples of which are illustrated in each figure. Each example is provided by way of explanation and is not meant as a limitation. For example, features illustrated or described as part of one embodiment can be used on or in conjunction with any other embodiment to yield yet a further embodiment. It is intended that the present disclosure includes such modifications and variations.

[0066] Within the following description of the drawings, the same reference numbers refer to the same or to similar components. Generally, only the differences with respect to the individual embodiments are described. Unless specified otherwise, the description of a part or aspect in one embodiment can apply to a corresponding part or aspect in another embodiment as well.

[0067] Fig. 1 is a schematic illustration of a power supply system 100 according to embodiments described herein. The power supply system comprises a power supply bus 105 connectable to an external power source 150. The power supply system 100 can be connected to the external power source 150 to power the power supply system 100 by the external power source 150. The power supply bus 105 may be connectable to the external power source through a source transformer 155. The external power source may be connected to a high voltage (HV) side of the source transformer. The power supply bus 105 may be connected to a medium voltage (MV) side of the source transformer. The power supply system can provide, powered by the external power source 150, a load power to a first load 160A. The first load 160A may be an electric arc furnace (EAF), particularly an electrode of an EAF.

[0068] The power supply system 100 includes first electric component 110A. The first converter 110A has a first determining unit 135 A. The first converter 110A is provided in a first power supply line 120 A between the power supply bus 105 and the first load 160 A. The first power supply line 120 A connects the first load 160 A to the power supply bus 105. The first load 160 A can be connected to the external power source 150 through the power supply bus 105. A first transformer 125A may be provided in the first power supply line 120A. As shown in Fig. 1, the first electric component is provided between the first transformer 120A and the first load 160A. In other embodiments, the first electric component 110A may be provided between the power supply bus 105 and the first transformer 125 A.

[0069] The power supply system 100 includes a first synchronous condenser 140 A. The first synchronous condenser 140 A includes a first synchronous condenser controller 145 A. The first synchronous condenser 140A is connected to the power supply bus 105. The first synchronous condenser 140 A may be connected to the power supply bus 105 through a first synchronous condenser transformer 147 A. The first synchronous condenser 140 A may be provided in parallel to the first converter 110A. The first synchronous condenser may be configured to compensate fluctuations in the load power, particularly fluctuations in the reactive load power. The first synchronous condenser may provide reactive power to the power supply bus 105. The first synchronous condenser 140 A may provide a positive reactive power to the power supply bus 105, i.e. feed reactive power to the power supply bus 105. The first synchronous condenser 140A may provide a negative reactive power to the power supply bus 105, i.e. to draw reactive power from the power supply bus 105.

[0070] The power supply system 100 includes a first feed forward data link FFn. The first feed forward data link FFn may connect the first determining unit 135 A to the first synchronous condenser controller 145 A for sending data from the first determining unit 135 A to the first synchronous condenser controller 145 A. The first synchronous condenser controller may receive the first reference set point through the first feed forward data link FFn.

[0071] The power supply system may include a processing unit 170. The processing unit 170 may be communicatively coupled to the first feed forward data link FFn. The processing unit 170 may receive the first operating characteristic from the first feed forward data link FF 11 and determine the first reference set point. The processing unit 170 may feed the first reference set point forward to the first synchronous condenser controller 145 A.

[0072] Fig. 2 is a schematic illustration of a power supply system according to a further embodiment. The power supply system is similar to the power supply system shown in Fig. 1 and includes a second electric component HOB having a second determining unit 135B. The second electric component is connected to the power supply bus 105.

[0073] The power supply system 100 includes a third feed forward data link FF2I. The third feed forward data link FF2I may connect the second determining unit 135B to the first synchronous condenser controller 145 A for sending data from the second determining unit 135B to the first synchronous condenser controller 145 A. The first synchronous condenser controller 145 A may receive the third reference set point through the third feed forward data link FF2I.

[0074] The processing unit 170 may further be communicatively coupled to the third feed forward data link FF2I for receiving the second operating characteristic. The processing unit 170 may determine the third reference set point based on the second operating characteristic. The processing unit 170 may feed the third reference set point forward to the first synchronous condenser controller through the third feed forward data link FF2i.

[0075] Fig. 3 is a schematic illustration of power supply system 100 according to a further embodiment. The power supply system is similar to the embodiment shown in Fig. 2. The power supply system comprises a second power supply line 120B connecting a second load 160B to the power supply bus 105. The second load 160B may be connected to the external power source 150 through the power supply bus 105. The second electric component is provided in the second power supply line 120B between the power supply bus 105 and the second load 160B. A second transformer 125B may be provided in the second power supply line 120B. As shown in Fig. 3, the second electric component is provided between the second transformer 125B and the second load 160B. In other embodiments, the second electric component HOB may be provided between the power supply bus 105 and the second transformer 125B.

[0076] The power supply system 100 includes a second synchronous condenser 140B. The second synchronous condenser 140B includes a second synchronous condenser controller 145B. The second synchronous condenser 140B is connected to the power supply bus 105. The second synchronous condenser 140B may be provided in parallel to the second converter HOB. The second synchronous condenser may be configured to compensate fluctuations in the load power, particularly fluctuations in the reactive load power. The second synchronous condenser may provide reactive power to the power supply bus 105. The second synchronous condenser 140B may provide a positive reactive power to the power supply bus 105, i.e. feed reactive power to the power supply bus 105. The second synchronous condenser 140B may provide a negative reactive power to the power supply bus 105, i.e. draw reactive power from the power supply bus 105.

[0077] The power supply system 100 includes a second feed forward data link FF22. The second feed forward data link FF22may connect the second determining unit 135B to the second synchronous condenser controller 145B for sending data from the second determining unit 135B to the second synchronous condenser controller 145B. The second synchronous condenser controller may receive the second reference set point through the second feed forward data link FF22.

[0078] The power supply system 100 includes a third feed forward data link FF2I. The third feed forward data link FF2I may connect the second determining unit 135B to the first synchronous condenser controller 145 A for sending data from the second determining unit 135B to the first synchronous condenser controller 145 A. The first synchronous condenser controller may receive the third reference set point through the third feed forward data link FF2b

[0079] The power supply system 100 includes a fourth feed forward data link FF,2. The fourth feed forward data link FF,2may connect the first determining unit 135 A to the second synchronous condenser controller 145B for sending data from the first determining unit 135 A to the second synchronous condenser controller 145B. The second synchronous condenser controller may receive the fourth reference set point through the fourth feed forward data link FF,2.

[0080] Fig. 4 is a schematic illustration of a power supply system 100 according to embodiments described herein. The power supply system has a plurality of electric components (110 A, HOB, 110N) including the first electric component (110A) and the second electric component (HOB). Each electric component (110A, 110B, 110N) has a determining unit (135A, 135B, 135N) for determining an operating characteristic having information about fluctuations in the load power, particularly fluctuations in the reactive load power.

[0081] The power supply system 100 includes a plurality of feed forward data links (FFibFFi2, FFiM, FF2bFF22, FF2M, FFNFFN2, FFNM) including the first feed forward data link (FFn), particularly including the second feed forward data link (FF22), the third feed forward data link (FF2I), and / or the fourth feed forward data link (FFn).

[0082] The power supply system includes the first synchronous condenser. The first synchronous condenser controller (145 A) is configured for receiving, through one or more feed forward data links (FFn, FF2bFFNi) of the plurality of feed forward data links (FFn, FFi2, FFiM, FF2bFF22, FF2M, FFNbFFN2, FFNM), a plurality of reference set points based on the corresponding operating characteristics, and configured for controlling an operation of the first synchronous condenser (140A) based on the plurality of reference set point.

[0083] The power supply system may include a plurality of synchronous condensers (140 A, MOB, MOM) including the first synchronous condenser (140 A), particularly including the second synchronous condenser (MOB). Each of the synchronous condensers (140A, MOB, MOM) has a synchronous condenser controller (145A, 145B, 145M) configured to receive a reference set point from one or more feed forward data link of the plurality of feed forward data links (FFn, FFn, FFIM, FF2I, FF22, FF2M, FFNbFFN2, FFNM). Each electric component of the plurality of electric components (110A, HOB, 1 ION) may be connected to each synchronous condenser of the plurality of synchronous condensers (140A, MOB, MOM), by a respective feed forward data link of the plurality of feed forward data links (FFn, FFi2, FFiM, FF2i, FF22, FF2M, FFNi, FFN2, FFNM).

[0084] Fig. 5 is a schematic illustration of a method 500 for operating a power supply system. The power supply system is connectable to an external power source for providing, powered by the external power source, a load power to one or more loads. The power supply system may be according to embodiments described herein.

[0085] At step 510 a first operating characteristic of a first electric component is determined in real time, the first operating characteristic having information about fluctuations in the load power, particularly fluctuations in the reactive load power.

[0086] At step 520 a first reference set point is determined based on the first operating characteristic.

[0087] At step 530 the first reference set point is fed forward to a first synchronous condenser controller of a first synchronous condenser.

[0088] At step 540 an operation of the first synchronous condenser is controlled based on the first reference set point to adjust a reactive power output of the first synchronous condenser to the power supply bus.

[0089] While the foregoing is directed to embodiments, other and further embodiments may be devised without departing from the basic scope, and the scope is determined by the claims that follow.

Claims

Claims1. A power supply system (100) for providing, powered by an external power source (150), a load power to one or more loads (160A, 160B), the power supply system comprising: a power supply bus (105) connectable to the external power source (150); a first electric component (110A), arranged in a first electric supply line (120 A) between the power supply bus (105) and a first load (160 A), the first electric component (110A) having a first determining unit (135A) configured for determining a first operating characteristic having information about fluctuations in the load power, particularly fluctuations in a reactive load power; a first feed forward data link (FFn); and a first synchronous condenser (140 A) configured to output reactive power to the power supply bus (105), the first synchronous condenser having a first synchronous condenser controller (145 A) configured for receiving, through the first feed forward data link (FFn), a first reference set point, the first reference set point being based on the first operating characteristic, and configured for controlling an operation of the first synchronous condenser (140 A) based on the first reference set point.

2. The power supply system (100) of claim 1, wherein the first operating characteristic comprises at least one of a voltage information, a current information, and / or a reactive load power information.

3. The power supply system of any one of claims 1 through 2, wherein the first electric component (110A) is a direct grid connected load, a voltage source converter (VSC) with diode or thyristor front end or active front end (AFE), a current source converter (CSC), a rectifier, a chopper with diode front end, a chopper with AFE, a cycloconverter, a matrix converter, or a combination thereof.

4. The power supply system (100) of any one of claims 1 through 3, comprising: a second electric component (HOB) having a second determining unit (135B) configured for determining a second operating characteristic having information about fluctuations in the load power, particularly having information about fluctuations in the reactive load power; a second feed forward data link (FF22); and a second synchronous condenser (140B) configured to output reactive power to the power supply bus (105), the second synchronous condenser having a second synchronous condenser controller (145B) configured for receiving, through the second feed forward data link (FF22), a second reference set point, the second reference set point being based on the second operating characteristic, and configured for controlling an operation of the second synchronous condenser (140B) based on the second reference set point.

5. The power supply system (100) of any one of claims 1 through 3, comprising: a second electric component (HOB) having a second determining unit (135B) configured for determining a second operating characteristic having information about fluctuations in the load power, particularly having information about fluctuations in the reactive load power; and a third feed forward data link (FF2i); wherein the first synchronous condenser controller (145A) is configured for receiving, through the third feed forward data link (FF2i), a third reference set point, the third reference set point being based on the second operating characteristic, and configured for controlling an operation of the first synchronous condenser (140 A) based on the third reference set point.

6. The power supply system (100) of any one of claims 1 through 3, and 5, comprising:a fourth feed forward data link (FFi2); and a second synchronous condenser (140B) configured to output reactive power to the power supply bus (105), the second synchronous condenser having a second synchronous condenser controller (145B) configured for receiving, through the fourth feed forward data link (FFI2), a fourth reference set point, the fourth reference set point being based on the first operating characteristic, and configured for controlling an operation of the second synchronous condenser (140B) based on the fourth reference set point.

7. The power supply system (100) of claim 6 being dependent on claim 5, comprising a second feed forward data link (FF22), wherein the second synchronous condenser controller (145B) is configured for receiving, through the second feed forward data link (FF22), a second reference set point, the second reference set point being based on the second operating characteristic, and configured for controlling an operation of the second synchronous condenser based on the second reference set point.

8. The power supply system of any one of claims 4 through 7, wherein the second electric component is arranged in a second power supply line between the power supply bus (105) and a second load (160B).

9. The power supply system of any one of claims 4 through 8, wherein the second electric component is a direct grid connected load, a voltage source converter (VSC) with diode or thyristor front end or active front end (AFE), a current source converter (CSC), a rectifier, a chopper with diode front end, a chopper with AFE, a cycloconverter, a matrix converter, a SVC, a STATCOM, a UPFC, a battery energy storage system (BESS), a grid forming converter, or a combination thereof.

10. The power supply system of any one of claims 1 through 9, comprising one or more processing units (170) communicatively coupled to one or more of the feed forward data links (FFn, FFi2, FF2I, FF22) for determining reference set points based on the corresponding operating characteristic.

11. The power supply system of any one of claims 1 through 10, comprising: a plurality of electric components comprising the first electric component (110A), particularly comprising the second electric component (HOB), each electric component having a determining unit for determining an operating characteristic having information about fluctuations in the load power, particularly fluctuations in the reactive load power; and a plurality of feed forward data links; wherein the first synchronous condenser controller (145A) is configured for receiving, through the plurality of feed forward data links, a plurality of reference set points based on the corresponding operating characteristics, and configured for controlling an operation of the first synchronous condenser (140A) based on the plurality of reference set point.

12. A method for operating a power supply system (100) for providing, powered by an external power source (150), a load power from a power supply bus (105) to one or more loads (160 A, 160B), the method comprising: determining a first operating characteristic of a first electric component (110A) in real time, the first operating characteristic having information about fluctuations in the load power, particularly fluctuations in the reactive load power; determining a first reference set point based on the first operating characteristic; feeding forward the first reference set point to a first synchronous condenser controller (145 A) of a first synchronous condenser; andcontrolling an operation of the first synchronous condenser (140 A) based on the first reference set point to adjust a reactive power output of the first synchronous condenser to the power supply bus (105).

13. The method of claim 12, wherein the first operating characteristic comprises at least one of a voltage information, a current information, and / or a reactive load power information.

14. The method of any one of claims 12 and 13, comprising: determining a second operating characteristic of a second electric component (HOB) in real time, the second operating characteristic having information about fluctuations in the load power, particularly fluctuations in the reactive load power; determining a second reference set point based on the second operating characteristic; feeding forward the second reference set point to a second synchronous condenser controller (145B) of a second synchronous condenser; and controlling an operation of the second synchronous condenser (140B) based on the second reference set point to adjust a reactive power output of the second synchronous condenser to the power supply bus (105).

15. The method of any one of claims 12 through 13, comprising: determining a second operating characteristic of a second electric component (HOB) in real time, the second operating characteristic having information about fluctuations in the load power, particularly fluctuations in the reactive load power; determining a third reference set point based on the second operating characteristic; feeding forward the third reference set point to a first synchronous condenser controller(145 A); and 1controlling an operation of the first synchronous condenser (140A) based on the third reference set point to adjust the reactive power output of the first synchronous condenser to the power supply bus (105).

16. The method of any one of claims 12 through 13, and 15, comprising: determining a fourth reference set point based on the first operating characteristic; feeding forward the fourth reference set point to a second synchronous condenser controller (145B) of a second synchronous condenser; and controlling an operation of the second synchronous condenser (140B) based on the fourth reference set point to adjust a reactive power output of the second synchronous condenser to the power supply bus (105).

17. The method of any one of claims 15 and 16, comprising: determining a second reference set point based on the second operating characteristic; feeding forward the second reference set point to a second synchronous condenser controller (145B) of a second synchronous condenser; and controlling an operation of the second synchronous condenser (140B) based on the second reference set point to adjust the reactive power output of the second synchronous condenser to the power supply bus (105).

18. The method of any one of claims 12 through 14, wherein the operation of the synchronous condenser is adjusted according to the reference set point in less than 300 ms after determining the first operating characteristic upon which the reference set point is based.

19. The method of any one of claims 12 through 18, wherein the power supply system is a power supply system of any one of claims 1 through 10, particularly, wherein: the first operating characteristic is determined by the first determining unit (135A); the first reference set point is feed forward through the first feed forward data link (FFn); and the operation of the first synchronous condenser (140A) is controlled by the first synchronous condenser controller (145A).

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