A method of, and system for, coordinated control of reactive power in renewable power systems

Abstract

There is provided a computer-implemented method of managing reactive power in a power microgrid for a hydrogen electrolyzer system, the power microgrid comprising a main bus and one or more power generation elements, one or more reactive power compensators and one or more voltage regulators, the main bus being connected to the hydrogen electrolyzer system and to an external utility power grid, the method comprising: a) determining, using a control system, a value of a reactive power exchange between the main bus and the external utility grid; and b) selectively controlling, using a control system, the one or more power generation elements, the one or more reactive power compensators and / or the one or more voltage regulators of the power microgrid in order to adjust or maintain the value of the reactive power exchange between the main bus and the external utility grid within a predefined operational range.

Description

A METHOD OF, AND SYSTEM FOR, COORDINATED CONTROL OF REACTIVE POWER IN RENEWABLE POWER SYSTEMSBACKGROUND OF THE INVENTION

[0001] The present invention relates to a method of, and system for, coordinated control of reactive power in renewable power systems.

[0002] An industrial gas production facility may comprise one or more process plants which produce, or are involved in the production of, gases. In non-limiting examples, these gases may comprise: industrial gases, commercial gases, medical gases, inorganic gases, organic gases, fuel gases and green fuel gases either in gaseous, liquified or compressed form.

[0003] A gas of significant commercial importance is hydrogen. Hydrogen may be industrially produced using electrolysis of water or steam, amongst others. Water or steam electrolysis is operable to produce hydrogen having high purity levels. In addition, electrolysis is more environmentally friendly than other methods.

[0004] There is considerable global interest in methods and systems for utilizing renewable energy sources for powering industrial gas plants and industrial gas production facilities. Renewable sources have significant benefits, including environmental benefits such as low or negligible CO2 emissions and low carbon intensity. However, a significant drawback of the use of renewable energy sources such as wind, solar and tidal power is the natural variability and transient nature of such energy sources.

[0005] Since the available renewable power is not demand-led and depends on the availability of the natural resources (e.g. wind, sunlight, tides), it can be challenging to match the available power to the required power for the industrial gas production facility. This is relevant in both power-limited and demand-limited scenarios.

[0006] In general, a constant or substantially constant power supply is preferred for an industrial gas plant or industrial gas production facility. The variable and intermittent nature of wind, solar and / or tidal power can be problematic and render it difficult to ensure maximum utilization of an industrial gas plant or industrial gas production facility utilizing such power sources whilst also avoiding shutdowns and other undesirable events resulting from temporarily insufficient power.

[0007] A further challenge is in demand-limited scenarios, where excess power above demand is available and must be handled appropriately to avoid operational issues and even potential damage to the renewable power grid and / or the industrial gas production facility.

[0008] Reactive power requires management in these systems. In AC power systems, capacitive and inductive elements cause the voltage and current of AC power signals to differ in phase. In other words, these elements can introduce a shift between voltage and current which reduces the useful amount of work that can be done with the supplied AC power. Reactive power is therefore a component of the instantaneous AC power supplied which cannot do useful work in electrical systems.

[0009] Reactive power is, in many cases, necessary for the proper operation of electrical transmission and distribution networks. However, it can have a direct impact on power stability and voltage stability and can affect the reliability and stability of power systems.

[0010] Reactive power control is therefore crucial in power systems, particularly in renewable energy-driven applications such as green hydrogen production, where it ensures system stability and voltage support. This is for two reasons.

[0011] First, whilst conventional generators typically provide reactive power, renewable generators have limited capacity in this regard. Secondly, hydrogen electrolyzers represent a highly reactive power demand when compared to more conventional electrical loads. To address these issues, additional reactive power support devices are often necessary. However, these devices can be costly and have finite capacities.

[0012] In scenarios where local resources are insufficient, reactive power may need to be sourced from the local or regional utility power grid (the “utility grid”). However, there are constraints on power exchange dictated by strict grid codes or carbon intensity agreements. These limitations ensure compliance with the desired agreement but can also restrict the system's operational flexibility.

[0013] In summary, effective management of reactive power is essential for ensuring the reliability and efficiency of renewable energy systems like green hydrogen production. It involves balancing local generation capabilities, leveraging support devices, and adhering to grid constraints to sustain optimal operational conditions and uphold regulatory requirements.

[0014] Therefore, there exists a need in the art to provide more effective reactive power control integration methods and arrangements to address these issues.SUMMARY OF THE INVENTION

[0015] The following introduces a selection of concepts in a simplified form in order to provide a foundational understanding of some aspects of the present disclosure. The following is notan extensive overview of the disclosure and is not intended to identify key or critical elements of the disclosure or to delineate the scope of the disclosure. The following merely summarizes some of the concepts of the disclosure as a prelude to the more detailed description provided thereafter.

[0016] Several preferred aspects of the methods and systems according to the present invention are outlined below.

[0017] Aspect 1 : A computer-implemented method of managing reactive power in a power microgrid for a hydrogen electrolyzer system, the power microgrid comprising a main bus and one or more power generation elements, one or more reactive power compensators and one or more voltage regulators, the main bus being connected to the hydrogen electrolyzer system and to an external utility power grid, the method comprising: a) determining, using a control system, a value of a reactive power exchange between the main bus and the external utility grid; b) selectively controlling, using a control system, the one or more power generation elements, the one or more reactive power compensators and / or the one or more voltage regulators of the power microgrid in order to adjust or maintain the value of the reactive power exchange between the main bus and the external utility grid within a predefined operational range.

[0018] Aspect 2: A computer-implemented method according to Aspect 1 , wherein step b) comprises: c) adjusting one or more control setpoints of the one or more power generation elements, the one or more reactive power compensators and / or the one or more voltage regulators of the power microgrid to adjust the reactive power output and / or reactive power flow in the power microgrid.

[0019] Aspect 3. A computer-implemented method according to Aspect 2, wherein step b) further comprises: d) utilizing a computational model to generate control setpoint values for the one or more control setpoints of the one or more power generation elements, the one or more reactive power compensators and / or the one or more voltage regulators of the power microgrid, the generated control setpoint values being selected to adjust or maintain the value of the reactive power exchange between the main bus and the external utility grid within a predefined operational range.

[0020] Aspect 4. A computer-implemented method according to Aspect 3, wherein the computational model comprises an objective function which is solved to generate the control setpoint values.

[0021] Aspect 5. A computer-implemented method according to Aspect 4, wherein the computational model comprises an objective function which is minimized or maximized to generate the control setpoint values.

[0022] Aspect 6. A computer-implemented method according to Aspect 4 or 5, wherein the objective function comprises a first functional expression representative of the reactive power exchanged between the main bus and the external utility grid, a second functional expression representative of a magnitude of a voltage at a respective power bus connection for each power generation element and a third functional expression representative of control setpoints for one or more voltage regulators.

[0023] Aspect 7. A computer-implemented method according to any one of Aspects 1 to 6, wherein the one or more reactive power compensators comprise one or more of: fixed capacitors or inductors, static series synchronous compensators (SSSC), unified power flow controllers (UPFCs) and static synchronous compensators (STATCOMs).

[0024] Aspect 8. A computer-implemented method according to any one of Aspects 1 to 7, wherein the one or more power generation elements comprise renewable power generation elements selected from the group of: wind power, solar power, tidal power and hydroelectric power.

[0025] Aspect 9. A computer-implemented method according to any one of Aspects 1 to 8, wherein the one or more voltage regulators comprise one or more OLTC transformers.

[0026] Aspect 10. A computer-implemented method according to any one of Aspects 1 to 9, wherein each power generation element comprises an associated power substation connected to the main bus via a power bus connection, each power substation comprising at least one reactive power compensator and at least one voltage regulator.

[0027] Aspect 11. A system for management of reactive power in a power microgrid for a hydrogen electrolyzer system, the power microgrid comprising: a main bus connected to the hydrogen electrolyzer system and to an external utility power grid; one or more power generation elements connected to the main bus; one or more reactive power compensators; and one or more voltage regulators, wherein the system comprises a control system comprising at least one hardware processor configured to: determine a value of a reactive power exchange between the main bus and the external utility grid; and selectively control the one or more power generation elements, the one or more reactive power compensators and / or the one or more voltage regulators of the power microgrid in order to adjust or maintain thevalue of the reactive power exchange between the main bus and the external utility grid within a predefined operational range.

[0028] Aspect 12. A system according to Aspect 11 , wherein the control system is further configured to: adjust one or more control setpoints of the one or more power generation elements, the one or more reactive power compensators and / or the one or more voltage regulators of the power microgrid to adjust the reactive power output and / or reactive power flow in the power microgrid.

[0029] Aspect 13. A system according to Aspect 12, wherein the control system is further configured to: utilize a computational model to generate control setpoint values for the one or more control setpoints of the one or more power generation elements, the one or more reactive power compensators and / or the one or more voltage regulators of the power microgrid, the generated control setpoint values being selected to adjust or maintain the value of the reactive power exchange between the main bus and the external utility grid within a predefined operational range.

[0030] Aspect 14: A system according to Aspect 13, wherein the computational model comprises an objective function which is solved to generate the control setpoint values.

[0031] Aspect 15: A system according to Aspect 14, wherein the computational model comprises an objective function which is minimized or maximized to generate the control setpoint values.

[0032] Aspect 16. A system according to Aspect 14 or 15, wherein the objective function comprises a first functional expression representative of the reactive power exchanged between the main bus and the external utility grid, a second functional expression representative of a magnitude of a voltage at a respective power bus connection for each power generation element and a third functional expression representative of control setpoints for one or more voltage regulators.

[0033] Aspect 17. A system according to any one of Aspects 11 to 16, wherein the one or more reactive power compensators comprise one or more of: fixed capacitors or inductors, static series synchronous compensators (SSSC), unified power flow controllers (UPFCs) and static synchronous compensators (STATCOMs).

[0034] Aspect 18. A system according to any one of Aspects 11 to 17, wherein the one or more power generation elements comprise renewable power generation elements selected from the group of: wind power, solar power, tidal power and hydroelectric power.

[0035] Aspect 19. A system according to any one of Aspects 11 to 18, wherein each power generation element comprises an associated power substation connected to the main bus via a power bus connection, each power substation comprising at least one reactive power compensator and at least one voltage regulator.

[0036] Aspect 20. A non-transitory computer readable storage medium storing a program of instructions executable by a machine to perform a method of managing reactive power in a power microgrid for a hydrogen electrolyzer system, the power microgrid comprising a main bus and one or more power generation elements, one or more reactive power compensators and one or more voltage regulators, the main bus being connected to the hydrogen electrolyzer system and to an external utility power grid, the method comprising: a) determining, using a control system, a value of a reactive power exchange between the main bus and the external utility grid; b) selectively controlling, using a control system, the one or more power generation elements, the one or more reactive power compensators and / or the one or more voltage regulators of the power microgrid in order to adjust or maintain the value of the reactive power exchange between the main bus and the external utility grid within a predefined operational range.BRIEF DESCRIPTION OF DRAWINGS

[0037] Embodiments of the present invention will now be described by example only and with reference to the figures in which:

[0038] FIGURE 1 is a schematic diagram of an industrial facility and power microgrid thereof;

[0039] FIGURE 2 is a schematic diagram showing further details of a control system and components of the power microgrid of Figure 1 according to an embodiment;

[0040] FIGURE 3 is a schematic diagram of the control and sensor elements of the control system and components of the power microgrid shown in Figure 2;

[0041] FIGURE 4 is a flow diagram of a method according to an embodiment; and

[0042] FIGURE 5 shows a schematic diagram of an alternative configuration of an industrial facility and power microgrid.

[0043] Embodiments of the present disclosure and their advantages are best understood by referring to the detailed description that follows. It should be appreciated that like reference numbers are used to identify like elements illustrated in one or more of the figures, whereinshowings therein are for purposes of illustrating embodiments of the present disclosure and not for purposes of limiting the same.DETAILED DESCRIPTION OF THE INVENTION

[0044] Various examples and embodiments of the present disclosure will now be described. The following description provides specific details for a thorough understanding and enabling description of these examples. One of ordinary skill in the relevant art will understand, however, that one or more embodiments described herein may be practiced without many of these details. Likewise, one skilled in the relevant art will also understand that one or more embodiments of the present disclosure can include other features and / or functions not described in detail herein. Additionally, some well-known structures or functions may not be shown or described in detail below, so as to avoid unnecessarily obscuring the relevant description.

[0045] The present invention is directed to the technical field of power control systems for an industrial facility. More particularly, the present invention is directed to the technical field of power control systems for operating a hydrogen production plant by leveraging renewable energy sources whilst minimizing reliance on the fossil-fuel-powered grid. The present invention, in embodiments, relates to management of reactive power within the hydrogen production plant to enhance asset utilization and overall operational efficiency.

[0046] The technology described herein provides technical improvements to the known technology by utilizing a coordinated reactive power control approach. In embodiments, the present invention is operable to achieve a desired reactive power range that maximizes hydrogen production while ensuring that voltage levels at critical locations in a power microgrid remain within permissible limits.

[0047] By coordinating reactive power management across various sources — such as STATCOMs, wind generators, solar generators, and on load tap changer (OLTC) transformers, the present invention is operable to control these systems to adjust or maintain the reactive power exchange with the regional main grid within a predetermined operational range. In embodiments, the present invention is operable to control these systems to minimize the reactive power exchange with the regional main grid. In embodiments, this approach has the technical advantages of not only supporting efficient hydrogen production but also aligning with environmental goals by reducing dependency on fossil-fuel-generated power.

[0048] Consequently, a technical advantage of embodiments of the present invention is to provide a coordinated reactive power control methodology configured to operate an industrialfacility such as a hydrogen production plant by managing reactive power effectively, thereby enhancing renewable energy utilization and maintaining regional main grid stability within prescribed voltage tolerances.

[0049] Within this disclosure, electrical elements or features are referred to that generate and / or absorb reactive power. By this is meant that these elements are capable of changing the voltage magnitude and the phase between the current and voltage signals of a power signal in order to increase or decrease the reactive power in the system.

[0050] For example, a device capable of generating reactive power in an electrical system is capable of increasing the voltage magnitude and the phase difference between current and voltage signals of a power signal. An example of such an element is a capacitive device.

[0051] Alternatively or additionally, a device capable of absorbing reactive power in an electrical system has the effect of reducing the voltage magnitude and the phase difference between current and voltage signals of a power signal. An example of such an element is an inductive device.

[0052] Figure 1 shows a general schematic diagram of an industrial facility 1. The industrial facility 1 is connected to a power microgrid 50 including one or more renewable sources 60- 1, 60-2, and receives power from, or sends power to, a regional utility power grid 70. A power microgrid control system 100 is provided to control and coordinate the distribution of power.

[0053] The renewable energy sources 60-1, 60-2 may take any suitable form operable to generate electricity from a renewable energy source. In embodiments, the renewable energy sources 60-1 , 60-2 comprise a wind energy source 60-1 (which, in embodiments, may comprise one or more suitable wind farms each comprising a plurality of wind turbines) and a solar energy source 60-2 (which may comprise one or more solar farms each comprising a plurality of solar cells). In addition, other renewable energy sources may be used such as hydro-electric (not shown) and / or tidal power (not shown).

[0054] The features shown in Figure 1 will now be described below.

[0055] OVERVIEW OF INDUSTRIAL FACILITY

[0056] The industrial facility 1 is configured to carry out one or more industrial processes. In embodiments, the industrial facility 1 may comprise one or more gas production facilities and the industrial processes involved may comprise the production, compression liquefaction and / or storage of such gases. However, this is non-limiting and is intended to be merely exemplary.

[0057] In the embodiment of Figure 1 , the industrial facility 1 comprises a hydrogen production plant 1 . The hydrogen production plant 1 comprises an electrolyzer system 10 and a hydrogen processing system 20.

[0058] The electrolyzer system 10 is configured to electrolyze water or steam to form hydrogen and oxygen. Any suitable source of water or steam may be used. However, in embodiments in which sea water is used to produce the water for the electrolysis, the apparatus may further comprise at least one desalination and demineralization plant to for processing the sea water.

[0059] The electrolyzer system 10 comprises a plurality of electrolysis units or cells 12a, 12b ... 12n. In embodiments, the plurality of electrolysis units or cells 12a, 12b, 12n are combined or stacked into electrolyzer modules 14 that may also include process equipment such as pumps, coolers, and / or separators. In embodiments, an electrolyzer module 14 may have of the order of 300 stack cells 12a, 12b, 12n. In embodiments, the electrolyzer modules 14 each comprise a stack of cells 12a, 12b, 12n which may form a discrete and separate module.

[0060] In embodiments, each electrolyzer module 14 comprises electrically separate downstream power supply modules 16 connected to an electrolyzer AC power bus 18. In embodiments, the AC power supply may comprise power produced at least in part from renewable energy sources.

[0061] In embodiments, the downstream power modules 16 each comprise one or more step down transformers and rectifiers. Thus, the downstream power modules 16, in embodiments, comprise both the necessary rectification and down-conversion electronic elements to convert the incoming AC power supply to DC power supply for the connected electrolyzer module 14.

[0062] Each electrolyzer module 14 may comprise a plurality of stack cells 12a, 12, 12n which combine to produce a maximum capacity greater than 5 MW, although this is not intended to be limiting. In embodiments, the total capacity of each electrolyzer module 14 may be of the order of 5 to 50 MW or higher if required.

[0063] Any suitable type of electrolyzer may be used with the present invention in order to produce hydrogen. Generally, three conventional types of electrolyzer are utilized - alkaline electrolyzers; PEM electrolyzers; and solid oxide electrolyzers. Any of these types may be used with the present invention.

[0064] Alkaline electrolyzers transport hydroxide ions (OH-) through the electrolyte from the cathode to the anode with hydrogen being generated on the cathode side. Commonly, a liquid alkaline solution of sodium hydroxide or potassium hydroxide is used as the electrolyte.

[0065] A PEM electrolyzer utilizes a solid plastics material as an electrolyte, and water reacts at an anode to form oxygen and positively charged hydrogen ions. The electrons flow through an external circuit and the hydrogen ions selectively move across the PEM to the cathode. At the cathode, hydrogen ions combine with electrons from the external circuit to form hydrogen gas.

[0066] Solid oxide electrolyzers use a solid ceramic material as the electrolyte that selectively conducts negatively charged oxygen ions (O2-) at elevated temperatures. Water at the cathode combines with electrons from the external circuit to form hydrogen gas and negatively charged oxygen ions. The oxygen ions pass through the solid ceramic membrane and react at the anode to form oxygen gas and generate electrons for the external circuit.

[0067] Whilst three electrolyzer modules 14 are shown in Figure 1 arranged in parallel, this need not be the case and any suitable configuration of series and / or parallel modules 14 may be provided as required.

[0068] In embodiments, the hydrogen processing system 20 further comprises hydrogen compression and purification stages.

[0069] In embodiments, the compression stage comprises a multistage compression system having two sections 24, 26. The first section 24 comprises a low pressure (LP) section in which hydrogen gas is compressed from a first feed pressure from the electrolyzers to a second intermediate pressure greater than the first feed pressure.

[0070] The second section comprises a medium pressure (MP) section 26 in which the hydrogen gas is compressed from the second intermediate pressure to a third final pressure greater than the second pressure. The third pressure is selected as required for any downstream process(es).

[0071] In the non-limiting embodiment shown in Figure 1 , the first (LP) section 24 has two compressor stages 24a, 24b. However, any suitable number may be used. For example, the LP section 24 may have a single compressor or may have a plurality of compressors.

[0072] As shown in the non-limiting embodiment of Figure 1 , the second (MP) section 26 is shown as a single compressor arrangement for brevity. However, any suitable number of parallel trains and / or stages of compression may be provided as required. For example, aplurality of trains may be provided in parallel, with each train comprising a plurality of compression stages.

[0073] The compressors forming part of the first (LP) 24 and second (MP) 26 compression sections may take any suitable form. The person skilled in the art would readily be aware of the form, number and capacity of these compressors. For example, for a total electrolyzer capacity of 1 GW, 2 to 4 compressors would typically be required. 5 or more may be required for total electrolyzer capacity of 2GW.

[0074] The compressors used may also be selected as appropriate for the operational capacity and type of gas production plant. For example, for hydrogen applications, the LP section 24 may comprise one or more centrifugal compressors, whilst the MR section 26 may comprise one or more reciprocating compressors. However, this is not intended to be limiting and any suitable compression arrangements may be used as appropriate.

[0075] In the embodiment of Figure 1, a purification section 28 is provided. The purification section 28 may be required where, for example, any downstream processes require higher purity hydrogen (i.e., with reduced levels of water and / or oxygen inherently present in the compressed hydrogen gas produced by the electrolysis). However, this need not be the case and this section may be omitted if not required.

[0076] If provided, the purification section 28 comprises a “DeOxo" unit operable to remove oxygen. The DeOxo unit operates through the catalytic combustion of hydrogen to produce water compressed hydrogen gas from which Oxygen has been removed.

[0077] The purification section 28 may further comprise a drier. In this embodiment, the drier comprises a temperature swing adsorption (TSA) unit to produce dry compressed hydrogen gas for the downstream process(es). However, other suitable drier and / or adsorption technologies may be used here. In embodiments, the drier is downstream of the DeOxo unit.

[0078] Hydrogen may be stored in the hydrogen storage unit 30. The storage unit 30 may comprise of a plurality of short-term and longer-term storage options with different sizes, filling / discharge rates, and roundtrip efficiencies.

[0079] Typical storage system could include pressure vessels and / or pipe segments connected to a common inlet / outlet header. The pressure vessels may be spheres, for example, to about 25 m in diameter, or "bullets” which are horizontal vessels with large L / D ratios (typically up to about 12:1) with diameters up to about 12 m. In certain geographies,underground caverns may be included as storage systems to flatten out the seasonal variations associated with the renewable power.

[0080] The hydrogen storage 30 is connected downstream of the compressor section 22. An inlet supply line to the hydrogen storage 30 extends from the outlet header of the purification section 28 of the hydrogen production plant 20 to the hydrogen storage 30. Valves are located in the inlet and return supply lines to control selectively the flow of gas to / from the hydrogen storage 30.

[0081] Finally, the hydrogen may be liquified for onward distribution into a supply network S1 using hydrogen liquefier 32.

[0082] Typically, hydrogen liquefaction involves some degree of initial compression using a compression system, followed by cryogenic cooling using one or more heat exchangers to around 30K. An expansion step may then take place in an expander. The gas is then passed through a separator before being stored or transferred to the onward supply network S1 .

[0083] POWER MICROGRID STRUCTURE

[0084] Electricity for powering the industrial facility 1 is provided by the power microgrid 50. The power microgrid 50 has a main microgrid bus 52. Renewable power sources 60-1 , 60-2 feed electricity into the main microgrid bus 52 for onward distribution to subsystems of the industrial facility 1 .

[0085] The renewable energy sources comprise wind energy sources 60-1 (e.g. a suitable wind farm comprising a plurality of wind turbines) and / or solar energy sources 60-2 (via a solar farm comprising a plurality of solar cells) although other forms of renewable energy may also be utilized (for example, tidal or hydroelectric power sources). The number and type of renewable energy sources may be varied as appropriate and the examples given are not intended to be limiting. Any suitable renewable energy source or number of renewable energy sources may be utilized with the present invention.

[0086] Elements 60-1 , 60-2 feed into the main microgrid bus 52 as shown in Figure 1. Each of the wind and solar energy sources 60-1 , 60-2 has a respective power substation 54, 56 connected between the energy sources 60-1 , 60-2 and the main microgrid bus 52. The features and operation of each power substation 54, 56 will be described below with reference to Figures 1 , 2 and 3.

[0087] Elements 60-1 , 60-2, power substations 54, 56 and the main bus 52 are electrically connected by means of power lines. As shown in Figure 2, in embodiments, the power linescomprise distribution lines 54P1 , 56P1 and transmission lines 54P2, 56P2. The distribution and transmission lines 54P1 , 56P1 , 54P2, 56P2 are shown schematically in Figures 2 and 3 and represented electrically as passive resistive / reactive elements 54P1 , 54P2, 56P1 , 56P2.

[0088] Distribution line 54P1 comprises, in embodiments, a 33 kV power line which is configured to connect the wind power source 60-1 to the power substation 54. Transmission line 54P2 is configured to connect the power substation 54 to the main bus 52. In embodiments, transmission line 54P2 comprises a high voltage line which is configured to transmit at voltages greater than 70kV. In embodiments, transmission line 54P2 may transmit at 380kV.

[0089] Distribution line 56P1 is configured to connect the solar power source 60-2 to the power substation 56. In embodiments, distribution line 56P1 may comprise a 33 kV power line. Finally, transmission line 56P2 is configured to connect the power substation 56 to the main bus 52. In embodiments, transmission line 56P2 comprises a high voltage line which is configured to transmit at voltages greater than 70kV. In embodiments, transmission line 54P2 may transmit at 380kV

[0090] In embodiments, the impedance of the transmission lines 54P1 , 54P2, 56P1 , 56P2 can impact on the control decisions which need to be made. The impedance of the transmission lines 54P1 , 54P2, 56P1 , 56P2 is a function of the distance they need to cover, i.e. the distance between the components of the power microgrid 50.

[0091] In embodiments, the physical distance between the wind and solar sources 60-1 , 60- 2 and their respective power substations 54, 56 may be of the order of 3 to 5 km. However, the distance between the power substations 54, 56 and the main bus 52 may be an order of magnitude greater or more. In examples, this may be of the order of 100 - 200 km. As a result, the impedance of the distribution lines 54P1 , 56P1 can be considered to be effectively negligible but the impedance of the transmission lines 54P2, 56P2 may be significant.

[0092] The electrolyzer system 10 is connected to the main microgrid bus 52 and is operable to draw AC power therefrom. In order to address any reactive current issues resulting from the electrical load from the electrolyzer system 10, the power microgrid 50 further comprises a static synchronous compensator (STATCOM) 58. In addition, the electrolyzer system 10 also has active filters (in embodiments, STATCOMs) and passive filters (capacitor and inductors) at the low voltage side of the transformers to provide a portion of reactive power demand and filter harmonics caused by rectifiers.

[0093] A STATCOM is a fast-acting electrical element operable to provide or absorb a reactive current and as a result regulate the voltage at the point of connection to the microgrid bus 52. In examples, STATCOM 58 may utilize voltage source converters (VSCs) having semiconductor valves in a modular configuration. This will be described in more detail below.

[0094] The main microgrid bus 52 is, as shown in Figures 1 and 2, connected to local or regional power grid infrastructure (utility grid) 70. The utility grid 70 is outside the scope of the power microgrid 50. However, the utility grid 70 is considered as an AC source connected to the power microgrid 50 for frequency and voltage references and is required as a backup in the event elements 60-1, 60-2 are temporarily unavailable and power from external sources such as the utility grid 70 is required to prevent shutdown of the critical load of subsystems of the industrial gas production facility 10.

[0095] In addition, excess power generated by elements 60-1, 60-2 may be fed to the utility grid 70 via the microgrid bus 52 as required.

[0096] POWER SUBSTATIONS

[0097] Figure 2 shows the power microgrid 50 and power substations 54, 56 in more detail.

[0098] POWER SUBSTATION 54

[0099] Power substation 54 is operable to handle incoming AC power generated by the wind energy source 60-1. Power substation 54 comprises a static volt-ampere reactive (VAR) compensator 54-1. The static VAR compensator 54-1 may take any suitable form which is operable to provide fast-acting reactive power and voltage control for wind generators and substation voltage support, respectively.

[0100] In embodiments, the static VAR compensator 54-1 takes the form of a STATCOM 54- 1. As described, a STATCOM comprises a shunt-connected, reactive compensation device. The STATCOM 54-1 comprises power electronics components such as a voltage-source converter operable to function as either a source or a sink for reactive AC power. In embodiments, the STATCOM 54-1 may comprise one more insulated gate bipolar transistors (IGBTs).

[0101] The STATCOM 54-1 may take any suitable form such as, for example, a two-level converter, a three-level converter or may comprise multi-modular converter (MMC) technologies. However, any suitable configuration or topology may be used.

[0102] The STATCOM 54-1 is configured to operate based on changing the current flow to alter the resulting voltage. As a result, the IV characteristics of the STATCOM 54-1 define its performance. In a voltage regulation (V) mode, the STATCOM 54-1 either supplies capacitive VARs to increase the voltage or consumes inductive VARs to lower the voltage. The rate at which this is performed may be programmable and can be set to desired levels.

[0103] The STATCOM 54-1 may alternatively be operated in a VAR (or Q) control mode, where the device is operable to supply or consume a certain reactive power setpoint output. The selection of Voltage control or VAR control modes will depend on the system conditions and requirements as described below.

[0104] The STATCOM 54-1 may be controlled using a suitable controller. In embodiments, the controller may be a proportional-integral controller. In embodiments, the controller may be a closed loop proportional integral derivative (PID) controller. This will be described in relation to the control system 100 below.

[0105] The power substation 54 further comprises a transformer 54-2. The transformer 54-2 is provided to step up the voltage of the AC power generated by the wind energy source 60-1 to that of the main bus 52. In embodiments, the step up required by the transformer 54-2 is approximately a factor of 10. In embodiments, the AC power generated by the wind energy source 60-1 is at a voltage of 33 kV and the main bus 52 is at a voltage of 380 kV.

[0106] In embodiments, the transformer 54-2 may comprise an autotransformer. An autotransformer has only a single coil winding. The AC power is provided on the primary side to the coil winding through two input terminals, and one or more secondary terminals at tap points are provided on the secondary side.

[0107] The secondary terminals, at least one of which is usually common with one primary terminal, enables voltage control in the manner of a voltage regulator. More than one output can be connected to the secondary terminals. In this case, the outputs of the secondary terminals are electrically connected through mutual inductance.

[0108] Alternatively, the transformer 54-2 may take the form of an on-load tap changer (OLTC). An OLTC is operable to enable adjustment of the turn ratio during operation. On-load tap changers may comprise mechanical, electronically assisted, or fully electronic systems. A mechanical tap changer physically makes a new connection before releasing the previous connection and utilizes multiple tap selector switches. An electronic tap changer may utilize thyristor devices for switching.

[0109] In embodiments, a typical OLTC may comprise up to 25 taps, a rated center tap and sixteen additional taps to increase and decrease the turn ratio to enable stepped voltage regulation of the output voltage.

[0110] In embodiments, the transformer 54-2 is controllable by the control system 100 by adjusting the turn ratio of the transformer 54-2, thereby varying the output voltage as required. Alternatively, transformer 54-2 may be controlled locally.

[0111] In embodiments, the physical distance between the wind source 60-1 and the power substation 54 may be of the order of 3 to 5 km, whereas distance between the power substation 54 and the main bus 52 may be an order of magnitude greater or more. In examples, this may be of the order of 100 - 200 km.

[0112] As a result, in this arrangement, the impedance of the distribution line 54P1 will be effectively negligible but the impedance of the transmission line 54P2 may be significant and have an impact on reactive power management. Thus, control of the transformer 54-2, which can vary the voltage transmitted on the transmission line 54P2 may be a significant factor in balancing the reactive power of the microgrid 50.

[0113] It is noted that although the above embodiment describes and illustrates the power substation 54 as a separate entity remote from the wind source 60-1 , this need not be the case. In embodiments, the power substation 54 may comprise a part of the wind source 60-1 itself, or alternatively components of the power substation 54 need not be located in a specific single location and may be distributed as required on the connection line between the wind source 60-1 and the main bus 52.

[0114] By “critical bus” is meant a branch or node in the power microgrid 50 which has a significant impact on the overall performance and reliability of the power microgrid 50. In other words, a failure or performance reduction or deviation of a critical bus may cause significant loss of power, system instability or deviation in overall power system performance.

[0115] The bus 54B of the wind power substation 54 is considered to be a critical bus where, in embodiments, the voltage magnitude (Vw) of the bus 54B is controlled within a specific range to ensure that a required power is transferred from the wind source 60-1 to the main bus 52.

[0116] For clarity and ease of understanding, the first power bus 54B is shown at the point at which the voltage Vwis sampled immediately downstream of the components of the power substation 54 between the power substation 54 and the transmission line 54P2 which connects to the main bus 52.

[0117] However, the first power bus 54B may be considered on an electrical configuration basis to be at any suitable location between the connection or node to the main bus 52 and the power substation 54, i.e. the first power bus 54B may be considered to be at the node between the transmission line 54P2 and the main bus 52, as shown between the power substation 54 and the transmission line 54P2, or part way on the transmission line 54P2. Since the transmission line 54P2, in this embodiment, does not comprise any active or reactive elements and only presents an impedance to the power microgrid 52, the voltage VPVof the first power bus 54B will be the same at any of these points.

[0118] POWER SUBSTATION 56

[0119] Power substation 56 is operable to handle incoming AC power generated by the solar (photovoltaic (PV)) energy source 60-2. Power substation 56 comprises a static volt-ampere reactive (VAR) compensator 56-1. The static VAR compensator 56-1 may take any suitable form which is operable to provide fast-acting reactive power for high-voltage electricity networks to support the substation busbar voltage and transmission line system 56P1 , 56P2. The static VAR compensator 56-1 may take the same form as the static VAR compensator 54-1 or may take any other suitable form.

[0120] In embodiments, the static VAR compensator 56-1 takes the form of a STATCOM 56- 1. As described in relation to the STATCOM 54-1 , the STATCOM 56-1 comprises a shunt- connected, reactive compensation device. The STATCOM 56-1 comprises power electronics components such as a voltage-source converter operable to function as either a source or a sink for reactive AC power. In embodiments, the STATCOM 56-1 may comprise one more insulated gate bipolar transistors (IGBTs).

[0121] The STATCOM 56-1 may take any suitable form such as, for example, a two-level converter, a three-level converter or may comprise multi-modular converter (MMC) technologies. However, any suitable configuration or topology may be used.

[0122] The STATCOM 56-1 is configured to operate based on changing the current flow to alter the resulting voltage. As a result, the IV characteristics of the STATCOM 56-1 define its performance. In a voltage regulation mode, the STATCOM 56-1 either supplies capacitive VARs to increase the voltage or consumes inductive VARs to lower the voltage. The rate at which this is performed may be programmable and can be set to desired levels. The STATCOM 56-1 may alternatively be operated in a VAR control mode, where the device is operable to supply or consume a maximum reactive output.

[0123] The STATCOM 56-1 may be controlled using a suitable controller. In embodiments, the controller may be a proportional-integral controller. In embodiments, the controller may be a closed loop proportional integral derivative (PID) controller. This will be described in relation to the control system 100 below.

[0124] The power substation 56 further comprises a transformer 56-2. The transformer 56-2 is provided to step up the voltage of the AC power generated by the solar energy source 60- 1 to that of the main bus 52. In embodiments, the step up required by the transformer 56-2 is approximately a factor of 10. In embodiments, the AC power generated by the solar energy source 60-2 is at a voltage of 33 kV and the main bus 52 is at a voltage of 380 kV.

[0125] In embodiments, the transformer 56-2 may comprise a two winding transformer with OLTC.. The AC power is provided on the primary side to the primary coil winding through two input terminals, and one or more secondary terminals at tap points are provided on the secondary winding side.

[0126] The secondary terminals, at least one of which is usually common with one primary terminal, enables voltage control in the manner of a regulator. More than one output can be connected to the secondary terminals. In this case, the outputs of the secondary terminals are electrically connected through mutual inductance.

[0127] Alternatively, the transformer 56-2 may take the form of an on-load tap changer (OLTC). An OLTC is operable to enable adjustment of the turn ratio during operation. On-load tap changers may comprise mechanical, electronically assisted, or fully electronic systems. A mechanical tap changer physically makes a new connection before releasing the previous connection and utilizes multiple tap selector switches. An electronic tap changer may utilize thyristor devices for switching.

[0128] In embodiments, a typical OLTC may comprise 25 taps to increase and decrease the turn ratio to enable stepped voltage regulation of the output voltage. In embodiments, the transformer 56-2 is controllable by the control system 100 to vary the input / output voltage ratio as required.

[0129] In embodiments, the physical distance between the solar source 60-2 and the power substation 56 may be of the order of 3 to 5 km, whereas distance between the power substation 56 and the main bus 52 may be an order of magnitude greater or more. In examples, this may be of the order of 100 - 200 km.

[0130] As a result, in this arrangement, the impedance of the distribution line 56P1 will be effectively negligible but the impedance of the transmission line 56P2 may be significant and have an impact on reactive power management. Thus, control of the transformer 56-2, which can vary the voltage transmitted on the transmission line 56P2 may be a significant factor in balancing the reactive power of the microgrid 50.

[0131] It is noted that although the above embodiment describes and illustrates the power substation 56 as a separate entity remote from the solar source 60-2, this need not be the case. In embodiments, the power substation 56 may comprise a part of the solar source 60-2 itself, or alternatively components of the power substation 56 need not be located in a specific single location and may be distributed as required on the connection line between the solar source 60-2 and the main bus 52.

[0132] By “critical bus” is meant a branch or node in the power microgrid 50 which has a significant impact on the overall performance and reliability of the power microgrid 50. In other words, a failure or performance reduction or deviation of a critical bus may cause significant loss of power, system instability or deviation in overall power system performance.

[0133] The second power bus 56B of the solar power substation 54 is considered to be a critical bus where, in embodiments, the voltage magnitude (Vpv) of the bus 56B is controlled within a specific range to ensure that a required power is transferred from the solar source 60- 2 to the main bus 52.

[0134] For clarity and ease of understanding, the second power bus 56B is shown at the point at which the voltage Vwis sampled immediately downstream of the components of the power substation 56 between the power substation 56 and the transmission line 56P2 which connects to the main bus 52.

[0135] However, the second power bus 56B may be considered on an electrical configuration basis to be at any suitable location between the connection or node to the main bus 52 and the power substation 56, i.e. the second power bus 56B may be considered to be at the node between the transmission line 56P2 and the main bus 52, as shown between the power substation 56 and the transmission line 56P2, or part way on the transmission line 56P2. Since the transmission line 56P2, in this embodiment, does not comprise any active or reactive elements and only presents an impedance to the power microgrid 52, the voltage Vwof the second power bus 56B will be the same at any of these points.

[0136] ELECTROLYZER POWER MANAGEMENT

[0137] The power microgrid also comprises the STATCOM 58 which is operable to provide reactive power for the electrolyzer system 10 and support the voltage at the main bus 52.

[0138] In addition, the electrolyzer system 10 may comprise components such as transformers, autotransformers and rectifiers (these components are illustrated in the Figure 5 embodiment) which have reactive power demands and need to be managed. Further, the electrolyzer system 10 also has active filters (in embodiments, STATCOMs) and passive filters (capacitor and inductors) at the low voltage side of the transformers to provide a portion of reactive power demand and filter harmonics caused by rectifiers.

[0139] POWER MICROGRID CONTROL SYSTEM 100

[0140] Elements of the power microgrid 50 of Figure 1 can be controlled by the power microgrid control system 100. In embodiments, the present invention provides a method of, and system for, controlling processes within the power microgrid 50. In embodiments, the control system 100 is operable to receive inputs from technical sources and determine optimum operating parameters to maintain or adjust the potential reactive power exchange with the main grid 70 to within a predefined operational range.

[0141] A schematic diagram of the components of the power microgrid control system 100 is shown in Figure 3. The power microgrid control system may take the form of an electrical power monitoring system (EPMS) which is operable to measure energy usage and enables analysis of the operation and performance of the electrical network. This may take the form of the control center of the microgrid 50 and comprise a plurality of different control functionalities for the power microgrid 50 such as active power control, reactive power control and energy management. Other functions such as economic dispatch and unit commitment may also be controlled. However, in embodiments, reactive power management is the focus of this disclosure.

[0142] The power microgrid control system 100 comprises a sensor and control network 110 comprised of a plurality of sensor devices 110S-1 to 110S-9 and / or control devices 110C-1 to 110C-7 and a power control center 120. These components are communicatively connected by means of a network 130.

[0143] The network 130 may take any suitable form and may be a local network (for example, a Wi-Fi or Ethernet LAN network), a cloud network (through internet or cellular communication connections), fiber optic communication cables with different industrial communication protocols (DNP3, IEC104, TCP / UDP IP, Modbus, etc.) or a mixed network utilizing alltechnologies. The network 130, therefore, places no specific location constraints on the components of the system 100 such as the power control center 120 which may be located within or remote from the industrial facility 1.

[0144] The sensor and control network 110 is shown schematically in Figure 3. In practice, the sensor and control network 110 may comprise a plurality of sensor devices 110S-1 to 11 OS-9 and control devices 110C-1 to 110C-7 which may be connected individually to the power control center 120 or may be inter-connected to form a more distributed network. Sensor devices 110S-1 to 11 OS-9 and control devices 110C-1 to 110C-7 may take any suitable form and may comprise sensor measurement devices, control devices or a combination of both.

[0145] It is to be understood that the numbering and configuration of sensor devices 110S-1 to 11 OS-9 and control devices 110C-1 to 110C-7 in Figure 3 is purely schematic and not indicative of any particular configuration or physical structure of devices. For example, any sensor and / or control devices indicated as separate devices may be combined in a single device with other sensor and / or control devices as appropriate or may comprise multiple separate devices. No specific physical or electronic limitation is implied or indicated by the schematic illustration of the sensor and control network 110 which may take any suitable form of devices as required to measure specific parameters of the industrial facility 1 and control any suitable control elements of the described devices.

[0146] The power control center 120 comprises a computer system such as a server device operable to process and analyze data from sensor and control network 110. The power control center 120 comprises at least one hardware processor 122, a memory 124, and a process controller 126. The process controller 126 may comprise one or more computational models. The functionality of the process controller 126 will be discussed below.

[0147] The power control center 120 is communicatively connected to the sensor and control network 110 via the network 130. The power control center 120 is also configured to send signals and / or commands to one or more of the sensor devices 110S and one or more of the control devices 110C.

[0148] It will be understood that terms such as “module”, “block”, “controller” and “element” are non-limiting terms and do not necessarily imply any interconnection or grouping between the component parts of the system 100 which may be illustrated in a common grouping for clarity purposes only.

[0149] The sensor devices 110S and control devices 110C will now be described.

[0150] SENSOR DEVICES

[0151] The sensor devices 11 OS are configured to determine or measure values or condition of parameters such as voltage and current magnitudes, active power and reactive power of the power microgrid 50 and / or the renewable power sources 60-1 , 60-2. In addition, conditions of parameters such as transformer tap position may also be determined or measured.

[0152] The sensor devices 11 OS comprise sensor devices 110S-1 to 11 OS-9. Sensor devices 110S-1 to 110S-3 are operable to measure parameters of the power substation 54. Sensor device 110S-1 is operable to measure the time-dependent reactive power Qwof the wind energy source 60-1 in units of mega or kilo volt ampere of reactive power (MVAr or kVAr). Sensor device 11 OS-2 is operable to measure the time-dependent reactive power QSTAT, w of the static VAR compensator 54-1 in the form of the STATCOM 54-1 , again in units of MVAr or kVAr.

[0153] Sensor device 11 OS-3 is operable to measure the voltage Vwoutput to the main bus 52 from the power substation 54. The voltage Vwis a function of the tap position of the OLTC transformer 54-2 as described below. The above three sensor devices are operable to measure values or conditions of the electrical properties of the power substation 54 associated with the wind energy source 60-1.

[0154] Sensor device 11 OS-4 is operable to measure the reactive power Qexcexchanged between the main bus 52 and the regional power grid 70. Sensor device 11 OS-4 may also measure the voltage magnitude Vgrjd at this point.

[0155] Sensor device 11 OS-5 is operable to measure the reactive power QSTAT from the STATCOM 58 connected to the main bus 52. Sensor device 110S-6 is operable to measure the power load QLOAD consumed by the electrolyzer system 10. In embodiments, the sensor device 110S-6 may measure other parameters of the STATCOM 58, for example reactive power, voltage, current and / or power factor.

[0156] Sensor devices 11 OS-7 to 11 OS-9 are operable to measure parameters of the power substation 56. Sensor device 110S-7 is operable to measure the voltage Vpvoutput to the main bus 52 from the power substation 56. The voltage Vpvis a function of the tap position of the OLTC transformer 56-2 as described below. Sensor device 11 OS-8 is operable to measure the time-dependent reactive power QSTAT,Pv of the static VAR compensator 56-1 in the form of the STATCOM 56-1.

[0157] Sensor device 11 OS-9 is operable to measure the time-dependent reactive power Qpvof the solar energy source 60-2 in units of MVAr. The above three sensor devices are operable to measure values or conditions of the electrical properties of the power substation 56 associated with the solar / photovoltaic energy source 60-2.

[0158] In addition, other data measurement elements may be provided as required. These data input elements are not limited to sensors and sensor data and may include reporting or determined technical values on additional elements of the power microgrid 50, energy sources 60-1 , 60-2, electrolyzer system 10 or any other elements.

[0159] CONTROL DEVICES

[0160] Control devices 110C are provided to enable control of power elements of the power microgrid 50. Control systems typically maintain a control setpoint and may be associated with one or more sensors 110S in a closed feedback system or may obtain control data from the power control center 120 and / or process controller 126. Control devices 110C may comprise any suitable controller. In embodiments, the control devices 110C may comprise proportionalintegral controllers. In embodiments, the control devices 110C may be closed loop proportional integral derivative (PID) controllers.

[0161] Each power control element 54-1 , 54-2, 56-1 , 56-2 will, in practice, have a maximum and a minimum operational value. In general, in a dynamic operation a maximum rate of change will apply. These constraints are typically set by safety, mechanical, electronic, material or other physical constraints within the equipment.

[0162] The difference between the maximum and minimum operating points defines the range of operation. Process constraints place constraints on the maximum and minimum capacity for each process, together with constraints on the rate of change (i.e. ramp rates) in response to controller setpoint changes. Physical equipment limitations, quality and / or safety parameters may also apply. The above limitations may be determined by the process controller 126 and a setpoint value either determined locally or provided by the process controller 126.

[0163] Control device 110C-1 is configured to enable properties of the wind energy source 60-1 to be modified. In embodiments, this may be to generate control signals operable to control the generator of the wind energy source 60-1 to change the reactive power balance as a function of time or to perform other functions.

[0164] Whilst direct control of wind turbines forming part of the wind energy source 60-1 is outside the scope of this disclosure, nevertheless control signals operable to request particular power variations or levels or other such functionality can be used to control or modify the behavior of the wind energy source 60-1 to affect the measured values of reactive power generated as a function of time.

[0165] Control device 110C-2 is operable to control the STATCOM 54-1 to change the reactive power absorbed or generated therefrom and to control the control mode of the STATCOM 54-1 . In embodiments, the control modes may comprise a Q mode and a V mode.

[0166] Control device 110C-3 is operable to change the tap position of the OLTC transformer 54-1 to vary the output voltage. A typical OLTC may comprise 25 taps in total to increase and decrease the turn ratio to enable stepped voltage regulation of the output voltage. However, this is to be taken as non-limiting and any suitable number of taps may be provided. In embodiments, the transformer 54-2 is controllable by the control device 110C-3 to vary the input / output voltage ratio as required.

[0167] Control device 110C-4 is operable to control the main bus STATCOM 58 to change the reactive power absorbed or generated therefrom and to control the control mode of the STATCOM 58. In embodiments, the control modes may comprise a Q (reactive power) mode and a V (voltage) mode. Q and V modes will be described in detail below.

[0168] Control device 110C-5 is operable to change the tap position of the OLTC transformer 56-2 to vary the output voltage. As for transformer 54-2, a typical OLTC may comprise 25 taps to increase and decrease the turn ratio to enable stepped voltage regulation of the output voltage. In embodiments, the transformer 56-2 is controllable by the control device 110C-5 to vary the input / output voltage ratio as required.

[0169] Control device 110C-6 is operable to control the STATCOM 56-11 to change the reactive power absorbed or generated therefrom and to control the control mode of the STATCOM 54-1. In embodiments, the control modes may comprise a Q mode and a V mode.

[0170] Control device 110C-7 is configured to enable properties of the solar / photovoltaic energy source 60-2 to be modified. In embodiments, this may be to generate control signals operable to control the generator of the solar / photovoltaic energy source 60-2 to change the reactive power balance as a function of time or to perform other functions.

[0171] Whilst direct control of PV cells forming part of the wind energy source 60-1 is outside the scope of this disclosure, nevertheless control signals operable to request particular powervariations or levels or other such functionality can be used to control or modify the behavior of the solar / photovoltaic energy source 60-2 to affect the measured values of reactive power as a function of time.

[0172] CONTROL OPERATIONS

[0173] To efficiently operate the industrial facility (which, in embodiments, may take the form of a hydrogen production plant 1), leveraging renewable energy sources 60-1 , 60-2 is crucial for electrolysis-based hydrogen production while minimizing reliance on the fossil-fuel- powered grid. Efficient and / or optimized management of reactive power within the facility is essential to enhance asset utilization and overall efficiency. More particularly, management of the reactive power exchange between the industrial facility 1 and the utility grid 70 is of significant importance.

[0174] In addition, a further parameter for efficient operation of the industrial facility 1 (which, in embodiments, is in the form of a hydrogen power plant 1) is voltage stability which ensures that the hydrogen electrolyzer system 10 of the hydrogen power plant 1 operates at a required level of performance to produce as much hydrogen as possible for the available input renewable power.

[0175] The regional power (utility) grid 70 has an operational voltage level and typically operates within a permissible voltage range of the operational voltage level. This level and range may take any suitable value. In embodiments, the operational voltage level may be 380 kV. In embodiments, the voltage range may be defined by operational requirements, local legal requirements and / or system configurations. In embodiments, the permissible voltage range may be + / - 10% of the operational voltage level. In embodiments, the permissible voltage range may be + / -5% of the operational voltage level.

[0176] The permissible voltage range has a direct influence on the reactive power requirements necessary to maintain stable voltage levels at critical bus locations such as the first power bus 54B and second power bus 56B. Insufficient reactive power and voltage violation can reduce hydrogen production from the electrolyzer system 10 and can limit the use of available renewable energy resources effectively. Conversely, excessive reactive power can lead to over-voltage issues, posing safety risks and potentially causing system shutdowns which again have a significant impact on hydrogen production.

[0177] Furthermore, the operation of the regional utility grid 70 at varying voltage conditions within the permissible voltage range influences reactive power requirements to maintain stable voltage levels at critical electrical points such as the main bus 52 and power subsystems 54,56. Failure to manage these variations effectively can result in breaches of operational agreements, potentially impacting hydrogen production or even leading to system instability.

[0178] In addition, the electrolyzer system 10 load also has a significant reactive power demand due to the use of one or more rectifiers to convert AC power to DC for the electrolyzer current (as described below in the Figure 5 embodiment). As a result, this can impact on the operation of the system.

[0179] In embodiments, the present invention utilizes a coordinated reactive power control approach. In embodiments, the present invention is operable to achieve a desired reactive power range that maintains reactive power exchange with the utility grid 70 within predefined bounds (i.e. within a predefined operational range). In addition, the system may also operate to maximize hydrogen production and / or operate to ensure that voltage levels at critical locations in the power microgrid 50 (such as the first and second critical buses 54B, 56B) remain within permissible limits.

[0180] By coordinating reactive power management across various reactive power sources and sinks such as the STATCOMs 54-1 , 54-2, STATCOM 58, wind sources 60-1 , solar sources 60-2, and OLTC transformers 54-1 , 54-2, the control system 100 is operable to control these systems to minimize reactive power exchange with the regional utility grid 70. In embodiments, this approach has the technical advantages of not only supporting efficient hydrogen production but also aligning with environmental goals by reducing dependency on fossil-fuel-generated power.

[0181] Consequently, a technical advantage of embodiments of the present invention is to provide a coordinated reactive power control methodology configured to operate an industrial facility such as a hydrogen production plant 1 by managing reactive power effectively, thereby enhancing renewable energy utilization and maintaining regional utility grid 70 stability within prescribed voltage tolerances.

[0182] The sensor 11 OS and control systems 110C have been described above. The process controller 126 of the power control center 120 is configured to process and analyze data from sensor and control network 110. In embodiments, the process controller 126 and power control center 120 are also configured to send signals and / or commands to one or more of the sensor devices 11 OS and one or more of the control devices 110C to coordinate various resources such as STATCOMs 55-1 , 56-1 , 58, OLTC transformers 56-1 , 56-2, and renewable generators 60-1 , 60-2 under different control modes.

[0183] PROCESS CONTROLLER 126 CONTROL MODES

[0184] In embodiments, the process controller 126 may utilize different control modes to achieve different control aims. In embodiments, the control modes may comprise voltage (V) and reactive power (Q) modes. In embodiments, these modes may be configured to comply with reactive power exchange agreements and / or ensure voltage stability but also, in embodiments, to maintain connectivity and meet carbon intensity requirements.

[0185] In embodiments, maintaining stable voltage levels is of importance for the operational efficiency and system reliability of an electrolyzer system 10. Voltage stability may be managed through V and Q modes. The modes will be described below:

[0186] Voltage (V) Mode: When operating in this mode, the process controller 126 is operable to control the reactive power output to regulate the magnitude of critical bus voltages Vwand Vpvat the critical buses 54B, 56B within acceptable limits. This mode is provided to ensure that voltage variations across the grid, typically within + / -10% or + / -5% of the operational voltage level, do not exceed predetermined thresholds. In embodiments, these thresholds may represent critical thresholds.

[0187] Reactive Power (Q) Mode: In this mode, the process controller 126 is operable to control reactive power flow to meet operational demands. In the Q mode, the overriding objective is to generate or absorb a certain reactive power (Q) from / to each reactive power source (which in embodiments may comprise one or more STATCOMs 54-1 , 56-1 , 58, wind generator 60-1 and solar (PV) generator 60-2) by a predetermined reactive power setpoint for each reactive power source to achieve an overall reactive power exchange with the utility grid 70. In embodiments, when the control system 100 is operating in the Q mode, the voltage magnitude Vwand Vpvat the critical buses 54B, 56B is not controlled.

[0188] In embodiments, the Q mode may operate in order to adhere to regulatory constraints. Regulatory constraints may include but are not limited to managing reactive power exchange with the utility grid 70 within specific agreed or predefined limits. This may be done to align with carbon intensity agreements and / or minimize reliance on non-renewable energy sources.

[0189] PROCESS CONTROLLER 126 OPERATION

[0190] The process controller 126 is operable to control specific groups or classes of electrical components within the power microgrid 50 to achieve the above aims. These groups or classes comprise one or more of: reactive power compensators; voltage regulators; and power generation elements.

[0191] The group of reactive power compensators comprise electrical resources capable of providing reactive power compensation. In embodiments, reactive power compensators may comprise one or more devices such as: fixed capacitors or inductors, static series synchronous compensators (SSSC), unified power flow controllers (UPFCs) and static synchronous compensators (STATCOMs) as exemplified by the STATCOMS 54-1 , 56-1 , 58. These reactive devices provide fast-reacting reactive power compensation (i.e. generation and / or absorption), dynamically adjusting output to stabilize voltage levels and manage utility grid interactions effectively.

[0192] The group of voltage regulators may comprise any suitable voltage regulation devices operable to change and / or regulate voltages to ensure stable voltage profiles at one or more locations. In embodiments, the voltage regulators may comprise transformers exemplified by the OLTC transformers 54-2, 56-2 described in the above embodiments. OLTC devices 54-2, 56-2 facilitate voltage regulation by adjusting transformer taps based on load conditions, contributing to maintaining stable voltage profiles at the first and second critical buses 54B, 56B.

[0193] The group of power generation elements comprises any suitable electrical power generators having a variable output or parameters which can be used to vary the electrical properties thereof. In embodiments, the power generation elements comprise one or more renewable energy sources. In embodiments, the renewable energy sources may comprise the wind energy source 60-1 and the solar / photovoltaic energy source 60-2. These components contribute to reactive power support through their inherent capabilities with reactive current control systems.

[0194] The present invention, in embodiments, enables coordinated management of power compensators, voltage regulators and power generation elements under the described control modes. In embodiments, these control modes take the form of V and Q control modes.

[0195] In embodiments, this can ensure voltage stability, meet reactive power exchange requirements, and support efficient hydrogen production while adhering to carbon intensity regulations. The holistic approach of embodiments of the present invention has the technical advantages of not only enhancing system reliability but also, in embodiments, advancing sustainability goals in the energy sector.

[0196] The process controller 126 is configured to achieve reactive power management by coordinating electronic devices within the groups of power compensators, voltage regulatorsand power generation elements to manage the reactive power exchange with the utility grid 70.

[0197] A further objective may, in embodiments, be to maximize hydrogen production while ensuring voltage levels at critical buses such as the first and second power buses 54B, 56B of power substations 54, 56 respectively remain within permissible operating ranges. A number of control scenarios will now be described.

[0198] Scenario 1: Excessive Reactive Power Import from the Utility Grid 70

[0199] In scenarios where there is a surplus of reactive power imported from the utility grid 70, the control system 100 is operable to optimize the flexibility of different reactive power sources. This involves increasing the supply of reactive power from the power compensator devices and adjusting OLTC positions of transformers of the voltage regulator devices to maintain voltage stability at critical buses such as the first and second power buses 54B, 56B.

[0200] Scenario 2: Excessive Reactive Power Export to the Utility Grid 70

[0201] Conversely, when there is an excess of reactive power exported to the utility grid 70, the system 100 coordinates various reactive power sources such as the power compensator devices to absorb more reactive power within the power microgrid 50. In embodiments, the system 100 also adjusts OLTC positions of transformers of the voltage regulator devices to ensure voltage levels at critical buses such as the first and second power buses 54B, 56B remain within permissible limits.

[0202] PROCESS CONTROLLER CONFIGURATION AND PROCESSING

[0203] The process controller 126 may implement the control of the above elements in any suitable manner. In embodiments, the process controller 126 may comprise a control system operable to selectively control one or more of the power generation elements, one or more of reactive power compensators and / or one or more voltage regulators of the power microgrid 50 in order to adjust or maintain the value of the reactive power exchange between the main bus and the external utility grid within a predefined operational range.

[0204] The process controller 126 may utilize the control devices 110C in order to achieve this. For example, the process controller 126 may comprise a control system configured to adjust one or more control setpoints of the one or more power generation elements, the one or more reactive power compensators and / or the one or more voltage regulators of the power microgrid to adjust the reactive power output and / or reactive power flow in the power microgrid 50.

[0205] In embodiments, this may be done in accordance with any suitable methodology. The process controller 126 may comprise a computer model operable to determine one or more setpoint values for the control setpoints of the one or more power generation elements, the one or more reactive power compensators and / or the one or more voltage regulators of the power microgrid. In embodiments, the generated control setpoint values are selected to adjust or maintain the value of the reactive power exchange between the main bus and the external utility grid within a predefined operational range.

[0206] The computer model may comprise any suitable methodology or control system. For example, the computer model may utilize empirical, statistical or stochastic methodologies. Alternatively or additionally, the computer model may comprise one or more machine learning models or fuzzy logic modules.

[0207] In embodiments, the computer model is operable to solve a suitable objective function to determine the control setpoints. In embodiments, the computer model is operable to perform minimization or maximization operations on a suitable objective function f(x).

[0208] In embodiments, the computer model is operable to minimize a value of Qexc(the reactive power exchange with the grid) which is determined as follows:

[0209] Qexc= J] Qgen,i — s Qload.i ~ Qloss

[0210] where Qgen, > is the reactive power from reactive power generation or compensation element / (i.e.. solar source 60-2, wind source 60-1 , STATCOMs 54-1 , 56-1 , 58 and any capacitors), Qioad, i is the reactive power demand from the electrolyzer system 10 from load / and Qioss is the reactive power on transmission lines (which can take a negative or positive value).

[0211] In other words, the reactive power exchange with the grid Qexccomprises a function of the sum of the generated reactive power in the power microgrid 50 from reactive power generation or compensation elements I, minus any reactive power demand (i.e. absorption of reactive power from load components such as the electrolyzer system 10) and any reactive power losses in the power microgrid 50.

[0212] In embodiments, the objective function f(x) comprises a function of Qexcand the computer model may be operable to determine control setpoint values for the control devices 110C in order to minimize the value of Qexc(or, in embodiments, maximize a parameter which minimizes the value of Qexc).

[0213] In embodiments, f(x) is minimized by determining control setpoints of the control variables making up x, i.e.:

[0214] X = [<2ST 47’ QSTAT,PV QSTAT, W Qpv QW ^380, PV ^380, w ^aPchange, w ^aPchange, Pvl

[0215] where QSTAT is the reactive power from the STATCOM 58 connected to the main bus 52, QSTAT, w is the time-dependent reactive power of the static VAR compensator 54-1 in the form of the STATCOM 54-1 , QSTAT,PV is the time-dependent reactive power of the static VAR compensator 56-1 in the form of the STATCOM 56-1 , Qpvis the time-dependent reactive power of the solar energy source 60-2, Qwis the time-dependent reactive power of the wind energy source 60-1 , Vwis the voltage magnitude at power bus 54B, Vpvis the voltage magnitude at power bus 56B and tap changeworpvis the tap change value at the OLTC transformers 54- 2, 56-2 respectively.

[0216] It is noted that the above parameters are applicable to the embodiments of Figures 1 to 3 and correspond to the devices shown and described. However, this is to be taken as nonlimiting and any suitable combination of power generation elements, reactive power compensators and / or voltage regulators may be used depending on the system configuration, components and layout of the industrial facility 1.

[0217] In embodiments, the objective function f(x) may comprise a plurality of functional elements: 1) a function of the exchanged reactive power with the regional utility grid 70 (wi); 2) a deviation of the voltage of critical buses (power substations 54, 56) (W2); and 3) values of the tap change operation of OLTCs 54-2, 56-2 at power substations 54, 56 (W3). All of these parameters are to be minimized.

[0218] In embodiments, the process controller 126 may seek to minimize the objective function comprising the above functional elements and the objective function may take the form of:

[0219]

[0220] In embodiments, the objective function and the system 100 may be minimized subject to a number of constraints on the operational range of the controlled elements. This includes at least: 1) limits on reactive power exchange with the grid to, in embodiments, adhere to regulatory requirements and environmental agreements.

[0221] In addition, the objective function may comprise additional constraints: 2) Voltage constraints at critical buses (such as power buses 54B, 56B) to maintain stability and operational reliability; and / or 3) Maximum and minimum limits for OLTC positions oftransformers (e.g. transformers 54-2, 56-2) to optimize voltage regulation and reactive power management.

[0222] These constraints can be expressed as the following ranges of parameters as set out in Table 1, where BL denotes a below limit and UL denotes an upper limit, where the units for both limits are defined in in MVAr (Megavolt-ampere reactive).

[0223] Table 1

[0224] The LL and UL values may take any suitable system dependent values as required, and are not intended to be limiting. For Vi, the BL and UL may take the form of 1 - s <<1 + 8 where s may be a non-limiting value such as 0.05 or 0.1 (corresponding to a variation of 5% or 10% respectively). However, none of the above LL / UL values need be symmetrical.

[0225] In embodiments, exemplary values for the embodiments of Figures 1 and 2 may be as shown in Table 2 below:

[0226] Table 2

[0227] Further, the form of the objective function set out above is not intended to be limiting and other suitable functions may be used with the present invention. For example, the optimization problem may be solved using a linear equation solver, heuristics or a minimum function solver.

[0228] Considering more specific optimization problem algorithms, a constrained nonlinear multivariable function such as fmincon may be utilized. In embodiments, fmincon seeks a constrained minimum of a scalar function of a number of variables based on an initial estimate. This comprises a constrained nonlinear optimization.

[0229] Alternatively or additionally, the optimization problem may be solved using a mixed integer programming solver. In embodiments, this may comprise a genetic algorithm. A genetic algorithm is operable to solve both constrained and unconstrained optimization problems. A genetic algorithm iteratively modifies a population of individual solutions byselecting parent values from the current population to be used as child values for the next generation. A genetic algorithm may have applicability in scenarios where an objective function is nondifferentiable, stochastic, discontinuous or nonlinear.

[0230] The above embodiments describe performing minimization on an objective function in order to minimize the reactive power exchange Qexcbetween the main bus 52 and the utility grid 70. However, in embodiments, the minimization may comprise an iterative or stepwise process towards a minimum. Minimization does not necessarily imply that a value of Qexcof, or close, to zero is required.

[0231] In embodiments, the process controller 126 is operable to maintain the value of Qexcwithin a predefined operational range. This may be any suitable value and the upper and lower limits of the range may be defined by any technical, regulatory, reliability, efficiency and / or safety parameters as required.

[0232] In other words, the process controller 126 may operate to adjust the value of Qexcto within the predefine operational range (if Qexcis outside the range) or maintain the value of Qexcwithin the predefined operational range. After sufficient iterations the minimization may converge on a local or global minimum. However, the power microgrid 50 represents a fastchanging and dynamic system where seeking a particular fixed minimum may not be practicable or feasible.

[0233] In addition, the process controller 126 may selectively perform optimization and / or minimization as required. By this is meant that process controller 126 may be optionally engaged when required.

[0234] In a mode of operation the process controller 126 may only operate to determine minimized control setpoints when the value of Qexcexceeds the upper or lower bound of the predefined operational range. Alternatively or additionally, the process controller 126 may constantly performing minimization and generating control setpoints.

[0235] Alternatively or additionally, the process controller 126 may constantly performing minimization and generating control setpoints but may only be engaged by an operator of the industrial facility 1 when required or if the process controller 126 can offer an improved solution than currently implemented.

[0236] METHOD

[0237] Figure 4 shows a method 200 according to an embodiment. In embodiments, there is provided a computer-implemented method of coordinating management of powercompensators, voltage regulators and power generation elements. In embodiments, the above elements may be controlled under the described V and Q control modes.

[0238] Step 200: Obtain sensor data

[0239] At step 200, sensor data from the sensor network 110 is obtained. In embodiments, the sensor data may comprise the value of the reactive power Qexcexchanged between the main bus 52 and the regional utility power grid 70. This may be obtained from the sensor device 110S-4 or derived from other measurements.

[0240] Optionally, other sensor data may be obtained as required. Sensor device 110S-3 may measure the voltage Vwoutput to the main bus 52 from the power substation 54 at the first power bus 54B and the transformer condition such as tap position. The voltage Vwis a function of the tap position of the OLTC transformer 54-2 as described below.

[0241] Sensor device 110S-7 may be operable to measure the voltage Vpvoutput to the main bus 52 from the power substation 56 and the transformer condition such as tap position. The voltage Vpvis a function of the tap position of the OLTC transformer 56-2 as described below.

[0242] Other data may also optionally be measured.

[0243] Sensor data relating to determined or measured electrical properties of one or more electrical components selected from the groups of: power compensators; voltage regulators; and power generators.

[0244] In embodiments, sensor devices 110S-1 to 110S-3 measure parameters of the power substation 54. Sensor device 110S-1 measures the time-dependent reactive power Qwof the wind energy source 60-1 in units of megavolt ampere of reactive power (MVAr). Sensor device 110S-2 measures the time-dependent reactive power QSTAT. W of the static VAR compensator 54-1 in the form of the STATCOM 54-1 , again in units of MVAr.

[0245] The above three sensor devices are operable to measure values or conditions of the electrical properties of the power substation 54 associated with the wind energy source 60-1.

[0246] Sensor device 110S-4 measures the reactive power Qexcexchanged between the main bus 52 and the regional power grid 70. Sensor device 11 OS-4 may also measure the voltage magnitude Vgrjd at this point.

[0247] Sensor device 11 OS-5 measures the reactive power QSTAT from the STATCOM 58 connected to the main bus 52. Sensor device 110S-6 is operable to measure the power load QLOAD consumed by the electrolyzer system 10.

[0248] Sensor devices 11 OS-7 to 11 OS-9 measures of the power substation 56 like voltage magnitude of the bus (Vpv) and tap position of the transformer. Sensor device 11 OS-8 measures the time-dependent reactive power QSTAT,PV of the static VAR compensator 56-1 in the form of the STATCOM 56-1 .

[0249] Sensor device 11 OS-9 measures the time-dependent reactive power Qpvof the solar energy source 60-2 in units of MVAr. The above three sensor devices measure values or conditions of the electrical properties of the power substation 56 associated with the solar / photovoltaic energy source 60-2.

[0250] Once sensor data is obtained, the method proceeds to step 210.

[0251] Step 210: Solve objective function

[0252] In embodiments, the process controller 126 is operable to solve a mathematical optimization problem to generate the necessary control setpoints. In embodiments, the process controller is operable to solve an objective function to determine the relevant control setpoint values.

[0253] In embodiments, the objective function is configured to be solved to derive an operational condition. In embodiments, the operational condition comprises determining control setpoints to achieve a reactive power exchange with the regional utility grid 70 within a predefined range. In embodiments, the operational condition comprises determining setpoints to achieve a minimum reactive power exchange with the regional utility grid 70. In embodiments, the operational setpoints may be determined in substantially near real-time.

[0254] In embodiments, the computer model is operable to perform minimization or maximization operations on a suitable objective function f(x). In embodiments, the computer model is operable to minimize a value of QeXc (the reactive power exchange with the grid) which is determined as follows:

[0255] Qexc= £ Qgen,i — 2 Qload, i ~ Qloss

[0256] where Qgen, > is the reactive power from reactive power generation or compensation element / (i.e. solar source 60-2, wind source 60-1 , STATCOMs 54-1 , 56-1 , 58 and any capacitors), Qioad, i is the reactive power demand from the electrolyzer system 10 from load / and Qioss is the reactive power on transmission lines (which can take a negative or positive value).

[0257] In other words, the reactive power exchange with the grid Qexccomprises a function of the sum of the generated reactive power in the power microgrid 50 from reactive power generation or compensation elements I, minus any reactive power demand (i.e. absorption of reactive power from load components such as the electrolyzer system 10) and any reactive power losses in the power microgrid 50.

[0258] In embodiments, the objective function f(x) comprises a function of Qexcand the computer model may be operable to determine control setpoint values for the control devices 110C in order to minimize the value of Qexc(or, in embodiments, maximize a parameter which minimizes the value of Qexc).

[0259] In embodiments, f(x) is minimized by determining control setpoints of the control variables making up x, i.e.:

[0260] x = [QSTATQSTAT, PV QSTAT, W Qpv QW ^380, PV ^380, w TaPchange, w TaP chang e , PV ]

[0261] where QSTAT is the reactive power from the STATCOM 58 connected to the main bus 52, QSTAT, w is the time-dependent reactive power of the static VAR compensator 54-1 in the form of the STATCOM 54-1 , QSTAT,PV is the time-dependent reactive power of the static VAR compensator 56-1 in the form of the STATCOM 56-1 , Qpvis the time-dependent reactive power of the solar energy source 60-2, Qwis the time-dependent reactive power of the wind energy source 60-1 , Vwis the voltage magnitude at power bus 54B, Vpvis the voltage magnitude at power bus 56B and tap changeworpvis the tap change value at the OLTC transformers 54- 2, 56-2 respectively.

[0262] It is noted that the above parameters are applicable to the embodiments of Figures 1 to 3 and correspond to the devices shown and described. However, this is to be taken as nonlimiting and any suitable combination of power generation elements, reactive power compensators and / or voltage regulators may be used depending on the system configuration, components and layout of the industrial facility 1.

[0263] In embodiments, the objective function f(x) may comprise a plurality of functional elements: 1) a function of the exchanged reactive power with the regional utility grid 70 (wi); 2) a deviation of the voltage of critical buses (power substations 54, 56) (w2); and 3) values of the tap change operation of OLTCs 54-2, 56-2 at power substations 54, 56 (w3). All of these parameters are to be minimized.

[0264] In embodiments, the process controller 126 may seek to minimize the objective function comprising the above functional elements and the objective function may take the form of:

[0265]

[0266] In embodiments, the objective function and the system 100 may be minimized subject to a number of constraints on the operational range of the controlled elements. This may include: 1) limits on reactive power exchange with the grid to, in embodiments, adhere to regulatory requirements and environmental agreements.

[0267] In addition, the objective function may comprise additional constraints: 2) Voltage constraints at critical buses (such as power buses 54B, 56B) to maintain stability and operational reliability; and / or 3) Maximum and minimum limits for OLTC positions of transformers (e.g. transformers 54-2, 56-2) to optimize voltage regulation and reactive power management.

[0268] These constraints can be expressed as ranges of parameters as set out in Table 1 above, with exemplary values in Table 2 above. However, the above parameters and values are not intended to be limiting and may be equipment- and scenario-specific as required by a particular configuration or power installation.

[0269] Further, the form of the objective function set out above is not intended to be limiting and other suitable functions may be used with the present invention. For example, the optimization problem may be solved using a linear equation solver, heuristics or a minimum function solver.

[0270] Considering more specific optimization problem algorithms, a constrained nonlinear multivariable function such as fmincon may be utilized. In embodiments, fmincon seeks a constrained minimum of a scalar function of a number of variables based on an initial estimate. This comprises a constrained nonlinear optimization.

[0271] Alternatively or additionally, the optimization problem may be solved using a mixed integer programming solver. In embodiments, this may comprise a genetic algorithm. A genetic algorithm is operable to solve both constrained and unconstrained optimization problems. A genetic algorithm iteratively modifies a population of individual solutions by selecting parent values from the current population to be used as child values for the next generation. A genetic algorithm may have applicability in scenarios where an objective function is nondifferentiable, stochastic, discontinuous or nonlinear.

[0272] In addition, the process controller 126 may selectively perform optimization and / or minimization as required. By this is meant that process controller 126 may be optionally engaged when required. In a mode of operation the process controller 126 may only operate to determine minimized control setpoints when the value of Qexcexceeds the upper or lower bound of the predefined operational range. Alternatively or additionally, the process controller 126 may constantly performing minimization and generating control setpoints.

[0273] Alternatively or additionally, the process controller 126 may constantly performing minimization and generating control setpoints but may only be engaged by an operator of the industrial facility 1 when required or if the process controller 126 can offer an improved solution than currently implemented.

[0274] Once the objective function is determined and solved, control setpoint values can be generated as described in step 220.

[0275] Step 220: Generate control setpoint values

[0276] At step 220, a set of control setpoints can be generated for the electrical devices selected from the groups of: reactive power compensators; voltage regulators; and power generation elements. The setpoints may alternatively or additionally be utilized to minimize the objective function and, in embodiments, coordinate management of the power compensators, voltage regulators and power generators under V and Q control modes.

[0277] In step 210, minimization on the objective function is performed in order to generate control setpoints in step 220 which minimize the reactive power exchange Qexcbetween the main bus 52 and the utility grid 70. However, in embodiments, the minimization may comprise an iterative or stepwise process towards a minimum. Minimization does not necessarily imply that a value of Qexcof, or close, to zero is required.

[0278] In embodiments, in step 220, control setpoints may be generated to adjust or maintain the value of Qexcwithin a predefined operational range. This may be any suitable value and the upper and lower limits of the range may be defined by any technical, regulatory, reliability, efficiency and / or safety parameters as required.

[0279] In other words, at step 220 control setpoints may be generated to adjust the value of Qexcto within the predefine operational range (if Qexcis outside the range) or maintain the value of Qexcwithin the predefined operational range. After sufficient iterations in step 210 the minimization may converge on a local or global minimum. However, the power microgrid 50represents a fast-changing and dynamic system where seeking a particular fixed minimum may not be practicable or feasible.

[0280] Once the control setpoint values have been generated, the method proceeds to step 230.

[0281] Step 230: Adjust control set point values

[0282] At step 230, the control setpoints are sent to the sensor and control system 110 to control the industrial facility 1 by adjusting one or more control setpoints of the power microgrid 50 including the energy sources 60-1 , 60-2. In other words, the control setpoints are operable to adjust one or more reactive sources / sinks and one or more voltage regulators.

[0283] Control setpoints sent to control device 110C-1 enables properties of the wind energy source 60-1 to be modified. This may be to control the generator of the wind energy source 60-1 to change the reactive power balance as a function of time or to perform other functions.

[0284] Control setpoints sent to control device 110C-2 enables control of the STATCOM 54- 1 to change the reactive power absorbed or generated therefrom and to control the control mode of the STATCOM 54-1. In embodiments, the control modes may comprise a Q mode and a V mode.

[0285] Control setpoints sent to control device 110C-3 are operable to change the tap position of the OLTC transformer 54-1 to vary the output voltage. A typical OLTC may comprise 25 taps to increase and decrease the turn ratio to enable stepped voltage regulation of the output voltage at the substation 54. In embodiments, the transformer 54-2 is controllable by the control device 110C-3 to vary the input / output voltage ratio as required.

[0286] Control setpoints sent to control device 110C-4 are operable to control the main bus STATCOM 58 to change the reactive power absorbed or generated therefrom and to control the control mode of the STATCOM 58. In embodiments, the control modes may comprise a Q mode and a V mode.

[0287] Control setpoints sent to control device 110C-5 are operable to change the tap position of the OLTC transformer 56-2 to vary the output voltage. As for transformer 54-2, a typical OLTC may comprise 25 taps to increase and decrease the turn ratio to enable stepped voltage regulation of the output voltage. In embodiments, the transformer 56-2 is controllable by the control device 110C-5 to vary the input / output voltage ratio as required.

[0288] Control setpoints sent to control device 110C-6 enable control of the STATCOM 56-1 to change the reactive power absorbed or generated therefrom and to control the control mode of the STATCOM 56-1 . In embodiments, the control modes may comprise a Q mode and a V mode.

[0289] Control setpoints sent to control device 110C-7 enables properties of the solar / photovoltaic energy source 60-2 to be modified. This may be to control the generator of the solar / photovoltaic energy source 60-2 to change the reactive power balance as a function of time or to perform other functions.

[0290] By control of the above devices, the value of Qexccan be adjusted to within, or maintained within, the predefined operational range.

[0291] It is noted that in embodiments, Vpvand Vwmay also be subject of the minimization process and the control setpoints selected to maintain these values within predetermined operational ranges in addition to Qexc.

[0292] The process may be repeated as required or may be maintained on a continuous operational loop.

[0293] Figure 5 shows a detailed schematic of a specific embodiment of the system. An electrolyzer system 310 is shown in detail and comprises 24 electrolyzer modules 312. The modules 312 are grouped in pairs and Figure 5 also shows an example of the configuration of power elements for each pair of electrolyzer modules 312.

[0294] The configuration comprises a variable transformer 314 on the input AC power line which may comprise an OLTC transformer. The AC power is provided on the primary side to the coil winding through two input terminals, and one or more secondary terminals at tap points are provided on the secondary side.

[0295] The secondary terminals, at least one of which is usually common with one primary terminal, enables voltage control in the manner of a regulator. More than one output can be connected to the secondary terminals. In this case, the outputs of the secondary terminals are electrically connected through mutual inductance.

[0296] Active filters (STATCOMs) and passive fillers (capacitors and inductors) are equipped with THD (total harmonic distortion) and VAR (reactive) filters 316 are provided in parallel with the AC power line to smooth harmonic distortion on the AC side and control power factor of the load at a certain level via reactive power support. In this embodiment, the THD filter comprises a harmonic filter (HF) and the VAR filter comprise a STATCOM.

[0297] Each transformer 314 can supply two electrolyzer modules 312. Downstream of the autotransformer 62, on each power line branch is located a rectifier and a transformer. A rectifier 318 is provided in each branch upstream of the respective electrolyzer module 312.

[0298] The electrolyzer modules 312 are separated into four groups 322 having six modules each. Two groups are powered from a single transformer 320 having two secondary windings. This transformer is operable to down convert the incoming 380kV supply from the main bus 52 to the 33kV necessary for subsequent DC conversion and powering the electrolyzer modules 312.

[0299] The remaining components of Figure 5 correspond to those as described above in relation to Figures 1 , 2 and 3 albeit illustrating a different configuration and layout of components not necessarily configured within specific power substations as discussed above.

[0300] It will be appreciated by the person of skill in the art that various modifications may be made to the above-described examples without departing from the scope of the invention as defined by the appended claims.

[0301] While the invention has been described with reference to the preferred embodiments depicted in the figures, it will be appreciated that various modifications are possible within the spirit or scope of the invention as defined in the following claims.

[0302] It will be understood that the term "control " as used herein may, in embodiments, refer to a systematic plan or set of actions designed to manage and optimize the operation of one or more hydrogen production facilities, in order to produce fuel with a defined carbon intensity value, while considering factors such as feedstock carbon intensity, demand data, and process constraints.

[0303] It will be understood that the term "control" as used herein may refer to the management and regulation of the operations of the industrial plants of the industrial processing facility, ensuring that the production of hydrogen and / or hydrogen fuel adheres to the defined carbon intensity value and other constraints set by the optimization model.

[0304] In this specification, unless expressly otherwise indicated, the word "or" is used in the sense of an operator that returns a true value when either or both of the stated conditions are met, as opposed to the operator "exclusive or" which requires only that one of the conditions is met. The word "comprising" is used in the sense of "including" rather than to mean "consisting of".

[0305] Where applicable, various embodiments provided by the present disclosure may be implemented using hardware, software, or combinations of hardware and software. Also, where applicable, the various hardware components and / or software components set forth herein may be combined into composite components comprising software, hardware, and / or both without departing from the spirit of the present disclosure. Where applicable, the various hardware components and / or software components set forth herein may be separated into sub-components comprising software, hardware, or both without departing from the scope of the present disclosure. In addition, where applicable, it is contemplated that software components may be implemented as hardware components and vice-versa.

[0306] Software, in accordance with the present disclosure, such as program code and / or data, may be stored on one or more computer readable mediums. It is also contemplated that software identified herein may be implemented using one or more general purpose or specific purpose computers and / or computer systems, networked and / or otherwise. Where applicable, the ordering of various steps described herein may be changed, combined into composite steps, and / or separated into sub-steps to provide features described herein.

[0307] While various operations have been described herein in terms of “modules”, “units” or “components,” these terms should not limited to single units or functions. In addition, functionality attributed to some of the modules or components described herein may be combined and attributed to fewer modules or components.

[0308] It will be apparent to those of ordinary skill in the art that changes, additions or deletions may be made to the disclosed embodiments without departing from the spirit and scope of the invention. For example, one or more portions of methods described above may be performed in a different order (or concurrently) and still achieve desirable results.

Claims

CLAIMS1 . A computer-implemented method of managing reactive power in a power microgrid for a hydrogen electrolyzer system, the power microgrid comprising a main bus and one or more power generation elements, one or more reactive power compensators and one or more voltage regulators, the main bus being connected to the hydrogen electrolyzer system and to an external utility power grid, the method comprising: a) determining, using a control system, a value of a reactive power exchange between the main bus and the external utility grid; and b) selectively controlling, using a control system, the one or more power generation elements, the one or more reactive power compensators and / or the one or more voltage regulators of the power microgrid in order to adjust or maintain the value of the reactive power exchange between the main bus and the external utility grid within a predefined operational range.

2. A computer-implemented method according to claim 1 , wherein step b) comprises: c) adjusting one or more control setpoints of the one or more power generation elements, the one or more reactive power compensators and / or the one or more voltage regulators of the power microgrid to adjust the reactive power output and / or reactive power flow in the power microgrid.

3. A computer-implemented method according to claim 2, wherein step b) further comprises: d) utilizing a computational model to generate control setpoint values for the one or more control setpoints of the one or more power generation elements, the one or more reactive power compensators and / or the one or more voltage regulators of the power microgrid, the generated control setpoint values being selected to adjust or maintain the value of the reactive power exchange between the main bus and the external utility grid within a predefined operational range.

4. A computer-implemented method according to claim 3, wherein the computational model comprises an objective function which is solved to generate the control setpoint values.

5. A computer-implemented method according to claim 4, wherein the computational model comprises an objective function which is minimized or maximized to generate the control setpoint values.

6. A computer-implemented method according to claim 4, wherein the objective function comprises a first functional expression representative of the reactive power exchanged between the main bus and the external utility grid, a second functional expression representative of a magnitude of a voltage at a respective power bus connection for each power generation element and a third functional expression representative of control setpoints for one or more voltage regulators.

7. A computer-implemented method according to claim 1 , wherein the one or more reactive power compensators comprise one or more of: fixed capacitors or inductors, static series synchronous compensators (SSSC), unified power flow controllers (UPFCs) and static synchronous compensators (STATCOMs).

8. A computer-implemented method according to claim 1 , wherein the one or more power generation elements comprise renewable power generation elements selected from the group of: wind power, solar power, tidal power and hydroelectric power.

9. A computer-implemented method according to claim 1 , wherein the one or more voltage regulators comprise one or more OLTC transformers.

10. A computer-implemented method according to claim 1 , wherein each power generation element comprises an associated power substation connected to the main bus via a power bus connection, each power substation comprising at least one reactive power compensator and at least one voltage regulator.

11. A system for management of reactive power in a power microgrid for a hydrogen electrolyzer system, the power microgrid comprising: a main bus connected to the hydrogen electrolyzer system and to an external utility power grid; one or more power generation elements connected to the main bus; one or more reactive power compensators; and one or more voltage regulators, wherein the system comprises a control system comprising at least one hardware processor configured to: determine a value of a reactive power exchange between the main bus and the external utility grid; and selectively control the one or more power generation elements, the one or more reactive power compensators and / or the one or more voltage regulators of the power microgridin order to adjust or maintain the value of the reactive power exchange between the main bus and the external utility grid within a predefined operational range.

12. A system according to claim 11 , wherein the control system is further configured to: adjust one or more control setpoints of the one or more power generation elements, the one or more reactive power compensators and / or the one or more voltage regulators of the power microgrid to adjust the reactive power output and / or reactive power flow in the power microgrid.

13. A system according to claim 12, wherein the control system is further configured to: utilize a computational model to generate control setpoint values for the one or more control setpoints of the one or more power generation elements, the one or more reactive power compensators and / or the one or more voltage regulators of the power microgrid, the generated control setpoint values being selected to adjust or maintain the value of the reactive power exchange between the main bus and the external utility grid within a predefined operational range.

14. A system according to claim 13, wherein the computational model comprises an objective function which is solved to generate the control setpoint values.

15. A system according to claim 14, wherein the computational model comprises an objective function which is minimized or maximized to generate the control setpoint values.

16. A system according to claim 14, wherein the objective function comprises a first functional expression representative of the reactive power exchanged between the main bus and the external utility grid, a second functional expression representative of a magnitude of a voltage at a respective power bus connection for each power generation element and a third functional expression representative of control setpoints for one or more voltage regulators.

17. A system according to claim 11 , wherein the one or more reactive power compensators comprise one or more of: fixed capacitors or inductors, static series synchronous compensators (SSSC), unified power flow controllers (UPFCs) and static synchronous compensators (STATCOMs).

18. A system according to claim 11 , wherein the one or more power generation elements comprise renewable power generation elements selected from the group of: wind power, solar power, tidal power and hydroelectric power.

19. A system according to claim 11 , wherein each power generation element comprises an associated power substation connected to the main bus via a power bus connection, each power substation comprising at least one reactive power compensator and at least one voltage regulator.

20. A non-transitory computer readable storage medium storing a program of instructions executable by a machine to perform a method of managing reactive power in a power microgrid for a hydrogen electrolyzer system, the power microgrid comprising a main bus and one or more power generation elements, one or more reactive power compensators and one or more voltage regulators, the main bus being connected to the hydrogen electrolyzer system and to an external utility power grid, the method comprising: a) determining, using a control system, a value of a reactive power exchange between the main bus and the external utility grid; and b) selectively controlling, using a control system, the one or more power generation elements, the one or more reactive power compensators and / or the one or more voltage regulators of the power microgrid in order to adjust or maintain the value of the reactive power exchange between the main bus and the external utility grid within a predefined operational range.

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