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EP-4738636-A1 - METHOD FOR OPERATING A MICROGRID, COMPUTER PROGRAM, CONTROL DEVICE FOR CONTROLLING A MICROGRID, AND MICROGRID

EP4738636A1EP 4738636 A1EP4738636 A1EP 4738636A1EP-4738636-A1

Abstract

The invention relates to a method for operating a microgrid (1), wherein the microgrid (1) comprises at least one power source (3) and at least one dynamic load (5), the at least one power source (3) and the at least one dynamic load (5) being electrically coupled via an AC bus as a common connecting point (7), wherein - in a first step S1: based on historical data comprising a historical input vector of at least one input quantity, a historical output vector of at least two output quantities (9) of the microgrid, and a reference trajectory comprising target values for the at least two output quantities, a control input vector (27) is calculated by minimizing a deviation between the target values and a predicted output vector (29), wherein - in a second step S2: the at least one power source (3) is controlled with at least a subset of the control input vector (27) as an actual control vector (11), and wherein - the at least two output quantities (9) comprise a voltage amplitude (9.1) and a frequency (9.2) at the AC bus, and the reference trajectory comprises nominal values for the voltage amplitude (9.1) and the frequency (9.2) as the target values.

Inventors

  • SINAT, Muhammet Hasan
  • EL BAKKALI-BELLINI, Issam

Assignees

  • Rolls-Royce Solutions GmbH

Dates

Publication Date
20260506
Application Date
20241030

Claims (15)

  1. Method for operating a microgrid (1), wherein the microgrid (1) comprises at least one power source (3) and at least one dynamic load (5), the at least one power source (3) and the at least one dynamic load (5) being electrically coupled via an AC bus as a common connecting point (7), wherein - in a first step S1: based on historical data comprising a historical input vector of at least one input quantity, a historical output vector of at least two output quantities (9) of the microgrid, and a reference trajectory comprising target values for the at least two output quantities, a control input vector (27) is calculated by minimizing a deviation between the target values and a predicted output vector (29), wherein - in a second step S2: the at least one power source (3) is controlled with at least a subset of the control input vector (27) as an actual control vector (11), and wherein - the at least two output quantities (9) comprise a voltage amplitude (9.1) and a frequency (9.2) at the AC bus, and the reference trajectory comprises nominal values for the voltage amplitude (9.1) and the frequency (9.2) as the target values.
  2. Method according to claim 1, wherein - in the first step S1: the control input vector (27) is calculated further based on an initial input vector (31) of the at least one input quantity and an initial output vector (33) of the at least two output quantities (9), wherein - in the second step S2: an actual output vector (35) of the at least two output quantities (9) is measured upon controlling the at least one power source (3) with the actual control vector (11), and wherein - the first and second steps S1 and S2 are repeated, wherein in the first step S1 the initial input vector (31) is updated with the actual control vector (11), and the initial output vector (33) is updated with the actual output vector (35).
  3. Method according to any of the preceding claims, wherein the control input vector (27) is calculated in the first step S1 using a direct data driven or behavioral predictive algorithm, and wherein preferably Data-Enabled Predictive Control (DeePC) is used as the behavioral or direct data driven predictive algorithm.
  4. Method according to any of the preceding claims, wherein at least two input quantities are used as the at least one input quantity, and preferably the at least two input quantities are an active power and a reactive power.
  5. Method according to any of the preceding claims, wherein as the control input vector (27), a sequence of N > 1 subsequent control vectors is calculated, wherein preferably only a subset of k < N of the subsequent control vectors are used as the actual control vector (11), wherein preferably N equals from 5 to 70, preferably from 10 to 50, and/or wherein k equals from 1 to 3, preferably 1.
  6. Method according to any of the preceding claims, wherein as the at least one power source (3) a grid forming voltage source converter (13) is controlled.
  7. Method according to claim 6, wherein additionally at least one grid following voltage source converter (15) is controlled as a further power source (3) of the at least one power source (3).
  8. Method according to any of the preceding claims, wherein the at least one power source (3) is a constant and/or controllable power source, or a variable power source (3).
  9. Method according to any of the preceding claims, wherein the historical data is - provided prior to operating the microgrid (1), preferably from prior test runs or a simulation, and/or - collected and updated during operation of the microgrid (1).
  10. Method according to any of the preceding claims, wherein the microgrid (1) is operated in an island mode.
  11. Computer program, comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method of at least one of claims 1 to 10.
  12. Control device (19) for controlling a microgrid (1), the control device (19) being adapted to carry out the method of at least one of claims 1 to 10.
  13. Microgrid (1), having at least one power source (3) and at least one dynamic load (5), wherein the at least one power source (3) and the at least one dynamic load (5) are electrically coupled via an AC bus as a common connecting point (7), wherein the microgrid (1) further comprises a control device (19) according to claim 12, the control device (19) being operatively connected to and adapted to control the at least one power source (3).
  14. Microgrid (1) according to claim 13, wherein the microgrid (1) comprises, as the at least one power source (3), an energy storage device (21) in combination with a voltage source converter (23).
  15. Microgrid (1) according to at least one of claims 13 and 14, wherein the microgrid (1) further comprises a photovoltaic plant (25) as the at least one power source (3).

Description

The invention relates to a method for operating a microgrid, a computer program, a control device for controlling a microgrid, and a microgrid. An isolated AC power grid, also referred to as a microgrid, which is powered by at least one power source, or distributed generating assets, such as power electronics power conversion systems or conventional rotating generators, distributed particularly in the sense that they do not communicate with each other, but only receive setpoints from a superseding central controller, has its output quantities at an AC bus as a common connecting point, such as voltage and frequency, typically deviating from desired nominal values in the case of fast load ramps on a time scale of, e.g. less than one second. Only after a certain time the nominal values are again reached. However, heavy oscillations may happen, and in severe cases these oscillations remain in steady-state, i.e., the nominal voltage and frequencies are not reached at all. This phenomenon is especially observable when a control latency - in particular caused by a measurement latency - is larger than a few tens of milliseconds. Conventional control devices are not designed for latencies as large as, e.g. 500 ms, as they cannot guarantee that the voltage and frequency at the AC bus converge to the nominal values following a load ramp. It is therefore an objective of the invention to provide a method for operating a microgrid, a computer program, a control device for controlling a microgrid, and a microgrid which preferably at least in part overcomes the above stated issues. This objective is achieved by providing the present technical teachings, in particular the teachings of the independent claims as well as the teachings of the dependent claims and the preferred embodiments disclosed in the description. According to a first aspect, the objective is in particular achieved by providing a method for operating a microgrid, wherein the microgrid comprises at least one power source and at least one dynamic load, the at least one power source and the at least one dynamic load being electrically coupled via an AC bus as a common connecting point, wherein in a first step S1: based on historical data comprising a historical input vector of at least one input quantity, a historical output vector of at least two output quantities of the microgrid, and a reference trajectory comprising target values for the at least two output quantities, a control input vector is calculated by minimizing a deviation between the target values and a predicted output vector, preferably using a direct data driven or behavioral predictive algorithm, whereinin a second step S2: the at least one power source is controlled with at least a subset of the control input vector as an actual control vector, and whereinthe at least two output quantities comprise a voltage amplitude and a frequency at the AC bus, and the reference trajectory comprises nominal values for the voltage amplitude and the frequency as the target values. By calculating the control input vector based on historical data and the reference trajectory comprising the target values for the at least two output quantities, i.e. nominal values for the voltage amplitude and the frequency, the output quantities can easily achieve a speedy and steady return to their nominal values, without showing heavy oscillations or persistent deviations from the target values after undergoing a load ramp, even in less than one second. Further, it is not necessary to have or establish a physical or parametric model for the microgrid in order to achieve these results. Still further, the method easily provides for handling even larger control latencies of the order of, e.g., 500 ms. Preferably, the method is repeated - i.e. the first and second steps S1 and S2 are repeated - with a frequency from 0.2 Hz to 100 Hz, preferably from 0.5 Hz to 50 Hz, preferably from 0.7 Hz to 20 Hz, preferably from 1 Hz to 10 Hz. In particular in this case, a most speedy return to the nominal values can be achieved even in the case of fast load ramps of less than one second. In the context of the present technical teachings, a microgrid is in particular understood to mean a local electrical grid which is at least capable to operate in an island mode. The island mode is a mode in which the microgrid operates electrically isolated from - or in other words not connected to - a wider electric power system such as a supra-regional, national or transnational power grid. In an embodiment, the microgrid is operated in the island mode. However, it is conceivable that the microgrid additionally is capable to be operated in a grid-connected mode, synchronous with a larger grid such as a supra-regional, national or transnational power grid. In particular, the microgrid is adapted to control frequency and voltage amplitude at the common connecting point, namely the AC bus, independent from external requirements or provisions. In the context o