Patent Description:
Subsea power grids are installed for supplying electric power to subsea applications e.g. compressors used for compressing gas along the seabed, e.g. at a water depth of <NUM>. A subsea power grid may include transformers, switchgear, variable speed drives (VSDs), and uninterruptible power supply (UPS). A UPS is specifically advantageous when the subsea power grid is to be used to supply a critical load e.g. requiring backup power to safely shutdown the process if needed. Such critical load may e.g. be a control system, electric actuators or compressor active magnetic bearings.

The UPS or UPS arrangement may be a subsea UPS arrangement operating at the seabed. This typically save costs as the UPS can be fed with electric power from a subsea main power supply of the subsea power grid, and cables for the UPS need not to extend to a top side, or on shore UPS. Moreover, by arranging the UPS close to the corresponding load, power loss and load dependent voltage variations due to voltage drop in a long cable can be minimized. The subsea UPS arrangement typically includes batteries and control system housed in a pressure compensated container for providing a more desirable operating environment. An example of such UPS arrangement for subsea applications is given in <CIT>.

However, adaptations, modifications and an extensive subsea qualification program of the subsea UPS in response to the subsea environment, as e.g. the pressure compensated container, lead to higher equipment costs. This, together with the relatively few installations of subsea UPS worldwide, call for a need in making the subsea UPS arrangement more efficient and cost effective.

An object of the present invention is to overcome at least some of the above problems, and to provide an UPS arrangement which, at least to some extent, is improved compared to prior art solutions. This, and other objectives, which will become apparent in the following are accomplished by means of a UPS arrangement for subsea applications, and a power supply system comprising a UPS arrangement and a main power supply.

According to a first aspect of the present invention, an uninterruptible power supply, UPS, arrangement for subsea applications is provided. The UPS arrangement comprises:.

wherein the UPS arrangement is arranged and configured to vary its overall capacity based on at least the number of battery and UPS modules.

Hereby, an improved UPS arrangement compared to prior art solutions is provided, as the overall capacity of the UPS arrangement is easily adapted based on the number of battery modules and UPS modules. For example, the combined number battery modules and UPS modules are at least three. Thus, the overall capacity of the UPS arrangement may be varied by having at least one battery module and at least one or at least two UPS modules, or having at least two battery modules and at least one UPS module. For redundancy of the battery and UPS modules, at least two battery modules and at least two UPS modules are provided inside the container.

By providing an easy adaptation of the overall capacity of the UPS arrangement, at least the manufacturing process for various UPS arrangement is simplified. Moreover, qualification and testing can be simplified as the same type of main modules are used for different overall capacity of the UPS arrangement. That is, the same principal configuration (and possibly even the same container) can be used for manufacturing UPS arrangement of different overall capacity. I other words, the UPS arrangement can be scaled up or down based on the desired need of overall capacity of the UPS arrangement, using the same main modules, the scaling being based on at least the combined number of battery and UPS modules.

According to at least one example embodiment, the main modules comprises at least two battery modules and at least two UPS modules. According to at least one example embodiment, the main modules comprises a plurality of battery modules and/or a plurality of UPS modules, the plurality being more than two.

According to at least one example embodiment, the main modules are set up in discrete functional groups, each discrete functional group comprising at least one control module, at least one UPS module and at least one battery module, wherein the UPS arrangement is arranged and configured to vary its overall capacity based on the number of functional groups.

Hereby, an advantageous measure of, or technical means for, varying the overall capacity of the UPS arrangement is provided. Each discrete functional group may have its own discrete capacity, the sum of the discrete capacities being the overall capacity of the UPS arrangement. According to at least one example embodiment, the discrete capacity of at least two discrete functional groups are different to each other.

According to at least one example embodiment, at least one battery module, at least one UPS module, or at least one control module is shared between at least two functional groups.

Hereby, an efficient use of the main modules is provided. For example, a control module may be shared by at least two functional groups, and thus control the operation of at least two different battery-UPS module groups.

According to at least one example embodiment, the battery module is physically separated from the UPS module, and may be varied in number separately of each other.

In case of more than one battery module and/or UPS module, each one of the battery modules is typically physically separated from the UPS module. Thus, the battery module(s) and the UPS module(s) may be separately controlled, and separately arranged inside the container.

According to at least one example embodiment, the battery module(s) and the UPS module(s) are comprised in a respective canister, e.g. a steel canister or steel tube. Each canister is typically arranged and configured to withstand subsea environment and may be filled with gas, e.g. N2. Alternatively, the container is a pressure compensated container (to correspond to the pressure outside of the container) filled with a dielectric liquid, e.g. oil, wherein the battery module(s) and UPS module(s) will be subject to the pressure inside the container.

According to at least one example embodiment, the number of battery modules are different to the number of UPS modules.

Hereby, a single module of the battery module or UPS module may support another UPS module or battery module, respectively, thus making efficient use of the battery and UPS modules. For such embodiments, the combined number of battery and UPS modules are at least three.

According to at least one example embodiment, the overall capacity of the UPS arrangement is a UPS-battery capacity being the result of the combined battery capacity of the battery module or battery modules and the UPS capacity of the UPS module or UPS modules.

Thus, each battery module has a battery capacity, and each UPS module has a UPS capacity (e.g. being related to the number of battery modules, or battery capacity, being able to handle), wherein the combined capacity of theses two types of modules results in a UPS-battery capacity of the UPS arrangement.

According to at least one example embodiment, the UPS arrangement is arranged and configured to further vary its overall capacity based on at least the number control modules.

Thus, each control module has control capacity (e.g. related to the number of battery modules and UPS modules being able to handle), which control capacity is included in the overall capacity of the UPS arrangement.

According to at least one example embodiment, the at least one battery module and the at least one UPS module are internally arranged such that the heat losses from the UPS module are used to heat the battery module.

Hereby, an efficient use of energy is provided, and/or a more desired ambient temperature of the battery module(s) is provided. Thus, an external heating arrangement of the battery module may be reduced or even omitted. For example, the at least one battery module is internally arranged adjacent the at least one UPS module, such that the heat from the heat losses from the at least one UPS module is convectively and/or conductively transferred to the at least one battery module. Alternatively, the UPS arrangement comprises a separate heat transfer arrangement configured to transfer the heat from the heat losses from the at least one UPS module to the at least one battery module. For embodiments with at least three battery and UPS modules, the modules are arranged to optimize the heat transfer from the UPS module(s) to the battery module(s). For example, the battery module(s) may be arranged to at least partly enclose the UPS module(s).

According to at least one example embodiment, each one of the battery modules comprise a Li-Ion battery. Such batteries are preferably heated when operating at sea bottom temperature (<NUM>-<NUM>), wherein the arrangement for utilizing the heat losses from the UPS module(s) are particularly advantageous.

According to at least one example embodiment, the container comprises an outer enclosure forming an inner space housing at least the main modules, wherein the outer enclosure is adaptable to vary the size of the inner space.

Hereby, an easy and yet effective means for providing the possibility to scale up or down the UPS arrangement by varying the number of at least some of the main modules is provided. The container may e.g. be built up by sections of a predetermined size, wherein the number of sections determine the size of the inner space. Thus, if a larger inner space is needed, more sections is included in the container, and if a smaller inner space is needed, less sections is included in the container. For example, the size of the inner space is varied along a lengthwise direction of the container. In other words, the height of the container may be kept constant while the size of the inner space is varied.

According to at least one example embodiment, the container is a standardized container.

Thus, the container may be made in predetermined size(s). According to at least one example embodiment, the container is qualified for subsea applications (e.g. a water depth down to <NUM>) for a various of sizes, or the container comprising the adaptable outer enclosure is qualified for subsea applications.

According to at least one example embodiment, the main modules are qualified and/or standardized modules. Thus, each of the main module may be qualified for subsea applications (e.g. a water depth down to <NUM>) and/or be made of a predetermined size.

According to at least one example embodiment, the UPS arrangement is being arranged and configured to be connected in series with a main power supply and a load powered by the main power supply.

Hereby, the UPS arrangement may quickly and directly compensate for any power loss in the main power supply. Moreover, by having the UPS arrangement connected in series with the main power supply and the load (i.e. by being arranged in between the main power supply and the load), at least a part of the electric energy is transferred via the UPS arrangement, and the battery or batteries within the battery module(s) may be charged.

According to at least one example embodiment, the UPS arrangement is being arranged and configured to be connected in parallel with a main power supply in relation to a load powered by the main power supply.

According to at least one example embodiment, the UPS arrangement further comprises input and/or output power transformer(s).

The configuration of the input and output power transformers is preferably adapted based on the intended use of the UPS arrangement. For example, the input power transformer is arranged and configured to receive power from a power supply, such as e.g. a main power supply, and the output power transformer is arranged and configured to transmit power to the load.

According to at least one example embodiment, the at least one UPS module comprises power circuitry including protection and disconnection functionality.

Hereby, a UPS module may be disconnected in case of internal failure. Each UPS module may further comprise all necessary power, interface and control functions required for supplying power to the load.

According to at least one example embodiment, the at least one battery module comprises power circuitry including protection and disconnection functionality.

Hereby, a battery module may be disconnected in case of internal failure. Each battery module may further comprise battery cells and BMS required for a standalone battery module or battery energy storage.

According to at least one example embodiment, the at least one control module comprises all necessary power, control, protection and disconnection functionality required for interfacing and managing the UPS module(s) and the battery module(s).

According to a second aspect of the present invention, a power supply system comprising a UPS arrangement according to the first aspect of the invention, and a main power supply connectable to a load, is provided.

Effects and features of the second aspect of the invention are largely analogous to those described above in connection with the first aspect of the invention, at least with reference to the UPS arrangement. Embodiments mentioned in relation to the first aspect of the invention are largely compatible with the second aspect of the invention, of which some are exemplified below.

According to at least one example embodiment, the UPS arrangement and the main power supply are connected in series such that the UPS arrangement, in use, is at least partly transferring electrical energy from the main power supply to the load.

According to at least one example embodiment, the UPS arrangement is arranged and configured, in use, to use at least a part of the transferred electrical energy to charge the battery module(s).

According to at least one example embodiment, the UPS arrangement and the main power supply are connected in parallel in relation to the load.

Any standard or qualifications mentioned in the present application are to be based on instructions valid on the date of priority of the present application. Further advantages and features of the present invention are disclosed and discussed in the following description and the accompanying drawings.

These and other aspects of the present inventive concept will now be described in more detail, with reference to the appended drawings showing an example embodiment of the inventive concept, wherein:.

In the following description, for purposes of explanation and not limitation, specific details are set forth such as particular components, interfaces, techniques, etc. in order to provide a thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.

<FIG> schematically shows an uninterruptible power supply arrangement <NUM> for subsea applications. The term uninterruptible power supply will from here on being abbreviated UPS. The UPS arrangement <NUM> comprises a container <NUM>, here schematically illustrated as an enclosing box <NUM>, and three different types of main modules <NUM> housed or enclosed in the container <NUM>. The three types of the main modules <NUM> are a first type being a battery module, a second type being an UPS module, and a third type being a control module. In the particular example of <FIG>, the UPS arrangement <NUM> comprises a first battery module <NUM> and a second battery module <NUM> (commonly referred to as the battery modules <NUM> ,<NUM>), a first UPS module <NUM>, a second UPS module <NUM> and a third UPS module <NUM> (commonly referred to as the UPS modules <NUM>, <NUM>, <NUM>), and a first control module <NUM> and a second control module <NUM> (commonly referred to as the control modules <NUM> ,<NUM>). Each one of the battery modules <NUM>, <NUM> has a predetermined battery capacity, and each one of the UPS modules <NUM>, <NUM>, <NUM> has a predetermined UPS capacity related to the governing of the battery module(s) <NUM>, <NUM>. For this purpose, each UPS module is typically equipped with associated power circuitry including e.g. components for protection and connection/disconnection possibilities. Moreover, the UPS arrangement <NUM> comprises input power transformer <NUM> and output power transformer <NUM> for adequately transforming and transferring electrical energy from a main power supply to a load, respectively (as further shown in <FIG>).

As also shown in <FIG>, the battery modules <NUM>, <NUM> are physically separated from the UPS modules <NUM>, <NUM>, <NUM>, preferably by that each of the battery and UPS modules <NUM>, <NUM>, <NUM>, <NUM>, <NUM> is being contained in a canister, e.g. a steel canister or steel tube. Moreover, in <FIG>, the number of battery modules <NUM>, <NUM> is different to the number of UPS modules <NUM>, <NUM>, <NUM>. In the embodiment of <FIG>, the battery modules <NUM>, <NUM> are electrically connected to a bridge <NUM>, to which each one of the UPS modules <NUM>, <NUM>, <NUM> are also connected. The battery modules <NUM>, <NUM> and the UPS modules <NUM>, <NUM>, <NUM> are arranged adjacent to each other in the container <NUM>, such that the heat losses from the UPS modules <NUM>, <NUM>, <NUM> are used to heat the battery modules <NUM>, <NUM>. Hereby, the ambient temperature of the battery modules <NUM>, <NUM> may be brought into a more favorable condition with regards to the operation of the battery modules <NUM>, <NUM>. It should be noted that the battery modules <NUM>, <NUM> and the UPS modules <NUM>, <NUM>, <NUM> need not to be arranged adjacent to each other in the container <NUM>, for transporting heat from the UPS modules <NUM>, <NUM>, <NUM> to the battery modules <NUM>, <NUM>, but that a separate heat transfer arrangement may be provided for this purpose.

As shown in <FIG>, the first and second control modules <NUM>, <NUM> are communicatively connected to the UPS modules <NUM>, <NUM>, <NUM> and battery modules <NUM>, <NUM> for controlling the operation of, e.g. interfacing and managing, the battery modules <NUM>, <NUM> and the UPS modules <NUM>, <NUM>, <NUM>. In more detail, the UPS arrangement <NUM> is built up of discrete functional groups of the main modules <NUM>, each functional group comprising at least one control module <NUM>, <NUM>, at least one UPS module <NUM>, <NUM>, <NUM> and at least one battery module <NUM>, <NUM>. It should be noted that a particular module of the main modules <NUM> may be comprised in more than one discrete functional group (i.e. may be shared between the discrete functional groups). The number of discrete functional groups may be adapted based on the desired overall capacity of the UPS arrangement <NUM>, and thus the total numbers of the main modules <NUM> in the UPS arrangement <NUM> may be varied. Stated differently, the UPS arrangement <NUM> is configured to vary its overall capacity based on at least the number of battery modules <NUM>, <NUM> and UPS modules <NUM>, <NUM>, <NUM>. In more detail, the UPS arrangement <NUM> has an overall capacity being a UPS-battery capacity which is the result of the combined capacities of the battery modules <NUM>, <NUM> and the UPS modules <NUM>, <NUM>, <NUM>, i.e. the combination of the combined battery capacity of the battery modules <NUM>, <NUM> and the combined UPS capacity of the UPS modules <NUM>, <NUM>, <NUM>. Additionality, the UPS arrangement <NUM> may be further arranged and configured to vary its overall capacity based on at least the number control modules <NUM>, <NUM>.

For example, a first discrete functional group may consist of the first battery module <NUM>, the first and second UPS modules <NUM>, <NUM>, and the first control module <NUM>, and a second discrete functional group may consist of the second battery module <NUM>, the third UPS module <NUM> and the second control module <NUM>. Thus, the UPS arrangement <NUM> may be scaled down by removing the second discrete functional group, resulting a fully functional scaled down UPS arrangement based solely on the first discrete functional group. Correspondingly, the UPS arrangement <NUM> may be scaled up by including a third discrete functional group comprising e.g. a fourth UPS module and third battery module (while still making use of the first or second control module <NUM>, <NUM> as control module in the third discrete functional group).

The container <NUM>, only shown schematically in <FIG>, comprises an outer enclosure <NUM> forming an inner space <NUM> in which at least the main modules <NUM> are housed. The input and output power transformer <NUM>, <NUM> may as well be housed in the inner space <NUM> with only the respective outer connectors extending outside of the outer enclosure <NUM>, or alternatively the input and output power transformer <NUM>, <NUM> are arranged outside of the inner space <NUM>, with inner connectors extending inside the inner space <NUM> through the outer enclosure <NUM>. In order vary the number of main modules <NUM>, or at least the number of battery modules and UPS modules, as described previously, the outer enclosure <NUM> is adaptable to vary the size of the inner space <NUM>. For example, the outer enclosure <NUM> may be made longer as more main modules <NUM> (or discrete functional groups) are added to the UPS arrangement.

<FIG> is a perspective view of an example UPS arrangement <NUM> comprising main modules <NUM> including at least one battery module <NUM>, at least one UPS module <NUM> and at least one control module <NUM>. In principle the same configuration with regards to the main modules <NUM> as in <FIG> may be used for the main modules <NUM> in <FIG>. Thus, the configuration of the main modules <NUM> and any connections thereof of <FIG> may replace the main modules <NUM> in <FIG> (their main functions not being repeated here again). In <FIG>, the outer enclosure <NUM> forming an inner space <NUM> in which at least the main modules <NUM> are housed is better shown than in <FIG>. Moreover, the input and output power transformer <NUM>, <NUM> with the respective outer connectors <NUM>, <NUM> are arranged outside of the outer enclosure <NUM>. As for <FIG>, in order vary the number of main modules <NUM>, or at least the number of battery modules <NUM> and UPS modules <NUM>, as described previously, the outer enclosure <NUM> is adaptable to vary the size of the inner space <NUM>. For example, the outer enclosure <NUM> may be made longer as more main modules <NUM> are added to the UPS arrangement <NUM>, by adding or removing a section <NUM>.

The container <NUM> of the UPS arrangement <NUM> may be a standardized container of a predetermined size. The container <NUM> in <FIG> is a pressure compensated container <NUM>, wherein the pressure means is provided by pressure compensators <NUM>. Hereby, the pressure inside and outside of the container <NUM> may be equalized. The container may be filled with a dielectric fluid (e.g. an incompressible, or almost incompressible, electric isolating and none corrosive medium) e.g. oil. Moreover, each type of the three types of main modules <NUM>, may be a standardized module of a predetermined size and capacity. Thus, each of the main modules <NUM> may be qualified separately and added based on the desired overall capacity of the UPS arrangement <NUM>.

<FIG> is a schematic view of a power supply system <NUM> comprising a UPS arrangement <NUM>, e.g. the UPS arrangement <NUM> of <FIG> or UPS arrangement <NUM> of <FIG>, and a main power supply <NUM> connected to a load <NUM>. Thus, in <FIG>, the UPS arrangement <NUM> and the main power supply <NUM> are connected in series with the load <NUM>, such that the UPS arrangement <NUM> during operation is arranged between the main power supply <NUM> and the load <NUM> and is at least partly transferring electrical power from the main power supply <NUM> to the load <NUM>. Hereby, at least a part of the transferred electrical power may be used to charge the battery module(s) of the UPS arrangement <NUM>. Thus, the UPS arrangement <NUM> of <FIG>, or UPS arrangement <NUM> of <FIG>, may be arranged and configured to be supply the load <NUM> in parallel with the main power supply <NUM>. This is e.g. embodied by the UPS module(s) <NUM>, <NUM>, <NUM>, <NUM> and/or configuration of the input and output power transformers <NUM>, <NUM>, <NUM>, <NUM> of <FIG> and <FIG>.

<FIG> is a schematic view of an alternative power supply system <NUM> comprising a UPS arrangement <NUM> and a main power supply <NUM> connected to a load <NUM>, e.g. the same load as in <FIG>. In <FIG>, the UPS arrangement <NUM> is arranged in a parallel configuration with the main power supply <NUM> in relation to the load <NUM>. That is, the UPS arrangement <NUM> is still arranged to be supplied with power from the main power supply <NUM>. e.g. for maintenance charging of the battery and for the supply of control power for internal control functions, but the power to load <NUM> is bypassed the UPS arrangement. In case of failure of the main power supply <NUM>, the UPS arrangement <NUM> is automatically change into supplying the load <NUM> with power (as in <FIG>). The UPS arrangement <NUM> of <FIG>, or UPS arrangement <NUM> of <FIG>, may be used in the power supply system <NUM> of <FIG> as well, e.g. by arranging the UPS module(s) <NUM>, <NUM>, <NUM>, <NUM> and/or configuration of the input and output power transformers <NUM>, <NUM>, <NUM>, <NUM> of <FIG> and <FIG>.

<FIG> is a schematic view of an example UPS module <NUM>, which e.g. can be used as one or several of the UPS modules <NUM>, <NUM>, <NUM> in <FIG>, or as the UPS module <NUM> (one or several) of <FIG>. The UPS module <NUM> comprises power circuitry <NUM> for enabling adequate connections and corresponding functionality of the UPS module <NUM>, protection and disconnection circuitry <NUM>, circuitry for parallel supply <NUM> of load, and connection and control interface <NUM> for connection with a battery module and control module. Moreover, the power circuitry <NUM> comprises input converter <NUM>, output converter <NUM> and battery interface <NUM>. Moreover, protection and disconnection circuitry <NUM> comprises input protection and disconnect function <NUM>, output protection and disconnect function <NUM>, and battery module protection and disconnect function <NUM>.

Claim 1:
An uninterruptible power supply, UPS, arrangement (<NUM>, <NUM>, <NUM>, <NUM>) for subsea applications, comprising:
- a container (<NUM>, <NUM>) arranged and configured for subsea operation, and
- the following main modules (<NUM>, <NUM>) arranged inside said container:
- at least one battery module (<NUM>, <NUM>, <NUM>) of a predetermined battery capacity,
- at least one UPS module (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>) governing the battery module, the UPS module having a predetermined UPS capacity,
- at least one control module (<NUM>, <NUM>, <NUM>) configured for interfacing and managing the battery module and the UPS module,
the UPS arrangement being arranged and configured to vary its overall capacity based on at least the number of battery and UPS modules, wherein the at least one battery module and the at least one UPS module are internally arranged such that the heat losses from the UPS module are used to heat the battery module.