Power management for mining or construction machines

Abstract

A method of stabilizing electrical operation of an electrical mining and / or construction machine (2) connected to a local electric power grid of a mine involves measuring an electrical strength of the local electrical power grid (10) based on determined voltage and an distance between two points of connection (14, 18), determining that measured strength of the local electrical power grid (10) fails to meet a grid strength threshold criterion; and in response to this determination, controlling at least one power reference parameter and / or control parameter of the electrical mining and / or construction machine (2) by means of a power converter (102). En electrical mining and / or construction machine (2) with a controller adapted to perform the method is also provided.

Description

POWER MANAGEMENT FOR MINING OR CONSTRUCTION MACHINESTechnical field

[0001] The present invention relates generally to controlling the operation of electrical mining and / or construction machines and more particularly to a method of stabilizing grid power of an electrical power grid to which an electrical mining and / or construction machine is connected as well as an electrically powered mining and / or construction machine operating according to the method.Background art

[0002] Mining and / or construction machines, such as rock drilling rigs, are used for several purposes, such as exploration drilling, which aims to identify the location and quality of a mineral, and production mining and quarrying, used in the production-cycle for mining or construction. Other application areas are road construction and structural construction.

[0003] Traditionally, mining and / or construction machines have been driven by combustion engines. However, in recent years, growing environmental concerns have driven the mining industry to reducing or phasing out the traditional combustion engines to reduce and eventually stop the emission of greenhouse gases from fossil fuels.

[0004] In the mining industry the solution is focused on electrification of the machines. Electrification has some challenges, mainly in the capacity of today’s electric batteries, especially in a rock drilling rig, where the demands for power and energy are high during rock drilling. This is solved by making the rock drilling rig connectable to an external electrical network when performing its rock drilling work cycle.

[0005] Mining is power consuming and electricity grids in mines are often of limited capacity and varying power quality. The mining environment causes both technical and economical limitations that need to be considered when an electricity grid is constructed to a mine.

[0006] A further characteristic with mines is that they may be in a remote location, causing problems with the quality of the electrical power at the mining site. Weak grid with variable load and electrical distances to the location of electrical mining and / or construction machines connected to the power grid will have significant interactions with grid synchronizations and outer control loop of the grid converter of the mining machine.Summary of invention

[0007] An object of the present invention is to provide a method of stabilizing the electrical power of an electrical power grid.

[0008] The invention is based on the insight that the power control in the mining and / or construction machine can adapt to grid conditions and thereby ensure stable operation.

[0009] According to a first aspect of the invention, a method of stabilizing electrical operation of an electrical mining and / or construction machine is provided, wherein the electrical mining or construction machine is connected to a local electric power grid of a mine via a first point of connection, wherein the local electric power grid is connected to an electric power source via a second point of connection, the electrical mining and / or construction machine comprising a controller adapted to control at least one electrical load of the electrical mining and / or construction machine by means of a power converter, the method by means of controller comprising the following steps: based on determined voltage of the local electric power grid and based on a distance between the first point of connection and the second point of connection, measuring an electrical strength of the local electrical power grid, determining that measured strength of the local electrical power grid fails to meet a grid strength threshold criterion; and in response to said determination that the measured strength of the local electrical power grid fails to meet said grid strength threshold criterion, controlling at least one power reference parameter and / or control parameter of the electrical mining and / or construction machine by means of the power converter. By operating an electrical mining and / or construction machine in accordance with this method, thepower distribution control in the electrical mining and / or construction machine will adapt to the grid conditions and ensure stable operation.

[0010] In a preferred embodiment, the measured electrical strength of the electrical power grid comprises any of the following parameters: short circuit ratio, equivalent short circuit ratio and impedance ratio of the electrical line.

[0011] In a preferred embodiment, the method of stabilizing electrical operation of an electrical mining and / or construction machine comprises detecting resonance between the power converter (102) and the electrical power grid (10) supplying power to at least one electrical load (110, 120), wherein said resonance indicates low electrical strength of the local electrical power grid (10) compare to the electrical strength of the local electrical power grid (10) without resonance between the power converter (102) and the electrical power grid (10) supplying power to at least one electrical load (110, 120). By identifying resonant conditions, unstable electrical operation may be avoided.

[0012] In a preferred embodiment, an additional step of calculating gains and time constant for grid synchronization unit is performed based on the determined strength of the local electrical power grid. This will improve the accuracy of the control of power reference parameters and control parameters.

[0013] In a preferred embodiment, the at least one power reference parameter comprises: target active power flow, target reactive power flow, target voltage drop, target AC voltage of the power converter, target DC bus voltage of an internal DC bus of the electrical mining and / or construction machine, and target load of the electrical load.

[0014] In a preferred embodiment, the at least one control parameter comprises: gains of synchronization loop, damping factors, and gains of power or voltage control loops.

[0015] In a preferred embodiment, the step of controlling at least one power reference parameter and / or control parameter comprises calculating a damping component for the reference quantities, based on calculated grid strength andadditional measurements, preferably a power component to be added with the power reference.

[0016] In a preferred embodiment, the method comprises transmitting said measured strength to at least one additional electrical mining and / or construction machine connected to the electrical power grid.

[0017] In a preferred embodiment, the method comprises: receiving measured strength from at least one additional electrical mining and / or construction machine connected to the electrical power grid; and determining that said received measured strength of the local electrical power grid fails to meet a grid strength threshold criterion; and controlling at least one power reference parameter and / or control parameter of the electrical mining and / or construction machine by means of the power converter.

[0018] In a preferred embodiment, when the electrical mining and / or construction machine comprises a local energy storage, the step of controlling at least one power reference and / or control parameter comprises controlling power to and / or from the local energy storage.

[0019] In a preferred embodiment, the step of measuring the electrical strength of the local electrical power grid is repeated when the electrical mining and / or construction machine reconnects to a different part of the electrical power grid.

[0020] In a preferred embodiment, the local electrical power grid is an AC power network.

[0021] According to a second aspect of the invention, an electrically powered mining and / or construction machine is provided comprising a power converter, an input of which is connectable to an external power source, a controller adapted to control the operation of the power converter, and at least one electrical load, wherein the controller is adapted to perform the above described method according to the invention.

[0022] According to a third aspect of the invention, a non-transitory computer-readable storage medium is provided that stores a program configured to execute the method according to the invention in an electrically powered mining and / or construction machine according to the invention.

[0023] According to a fourth aspect of the invention, a computer program product is provided comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method according to the invention in an electrically powered mining and / or construction machine according to the invention.Brief description of drawings

[0024] The invention is now described, by way of example, with reference to the accompanying drawings, in which:Fig. 1 shows a schematic view of a mining and / or construction machine in the form of a surface drilling rig that is electrified and has the possibility of connecting to an electrical network;Fig. 2 is an overall diagram showing an electrical mining and / or construction machine connected to an electrical network;Fig. 3 is a diagram showing the main components of an electric system of an electrical mining and / or construction machine;Fig. 4 is a diagram showing the main components of an alternative embodiment of an electric system of an electrical mining and / or construction machine wherein an internal energy storage is provided;Fig. 5 is a generic structure of a controller provided in a mining and / or construction machine according to the invention.Fig. 6 is a diagram illustrating a single electrical mining and / or construction machine connected to a power grid;Fig. 7 is a diagram illustrating two electrical mining and / or construction machines connected to a power grid, both determining the strength of the power grid and controlling the consumed power in dependence of the determined strengths;Fig. 8 is a diagram illustrating two electrical mining and / or construction machines connected to a power grid, wherein a first machine determines the strength of the power grid, and a second machine controls the consumed power in dependence of the determined strength;Fig. 9 is a diagram illustrating two electrical mining and / or construction machines connected to a power grid, wherein a first machine changes connection point;Fig. 10 is a flow chart of the main steps of the method according to the invention; andFig. 11 is a flow chart illustrating decisions made in the method according to the invention.Description of embodiments

[0025] In the following, a detailed description of a method of stabilizing electrical operation of an electrical mining and / or construction machine as well as an electrically powered mining and / or construction machine operating according to the method.

[0026] The term “electrical operation” should in this context be interpreted as the operation of all electrical components of an electrical mining and / or construction machine, including inverters, motors / generators and electrical loads.

[0027] The term “mining and / or construction machine” should in the context of this application be construed broadly and include drilling rigs, particularly rock drilling rigs, but also production, exploration, excavation, and construction mining rigs for surface and underground applications.

[0028] When reference is made to a “power source”, it should be understood that reference is made to a source of electrical power, unless explicitly stated otherwise.

[0029] In the drawing figures, like reference numerals designate identical or corresponding elements throughout the several figures. It will be appreciated that these figures are for illustration only and do not in any way restrict the scope of the present invention.

[0030] Fig. 1 shows a schematic representation of a mining and / or construction machine represented by a mining machine in the form of a rock drilling rig, generally designated 2. The rock drilling rig 2 comprises a carriage 4 and a rock drilling machine 6 attached to the front of the carriage 4. The rock drilling machine 6 is arranged on and connected to the carriage 4 by means of a boom 8, so that the rock drilling machine 6 can be arranged in different positions in relation to the carriage 4 and to the rock to be drilled. Together, the carriage 4, the rock drilling machine 6 and the boom 8 form the main part of the rock drilling rig 2. The carriage 4 is further provided with propulsion means 9, such as wheels or continuous track and propulsion equipment.

[0031] The rock drilling rig 2 further comprises an electric system 100, which is connectable to an external grid via a cable interface 12. The rock drilling rig 2 is provided with operative power from an external energy source, not shown in Fig.1, via the cable interface 12, and optionally an internal energy source comprised in the electric system 100, such as an electric battery, a super capacitor, or a fuel cell, or a combination thereof. Operative power is power that either powers the propulsion means 9 and / or the rock drilling machine 6. When the rock drilling rig 2 is operated, a controller of the electric drive system 100 is configured to selectively control operating power from the external energy source and / or, if present, an internal energy source.

[0032] Fig. 2 is a schematic view of an electrical mining and / or construction machine 2, the electric system 100 of which is connected to a local electric power grid 10 at a first connection 14. The local electric power grid 10 is connected to anelectric power source 16 via a second point of connection 18. This electric power source 16 may be an alternating current (AC) generator or other source of electricity, such as a mains network to which the local electric power grid 10 is connected via a power station.

[0033] An overall diagram of an embodiment of the electric system 100 of the electrical mining and / or construction machine 2 of Fig. 1 is shown in Fig. 3. The electric drive system comprises a power converter 102, the input of which is connectable to an external power source 10, such as a main grid supply in the form of an electrical network, via the cable interface 12. The output of the power converter 102 is connected to a bus 104 adapted to provide electric power to one or more electrical power consuming devices or loads in the form of electric motor units 110, 120 of the electrical mining and / or construction machine 2. This bus 104 can be either a DC bus or an AC bus. In the present example, a first electric drive unit 110 comprises a first electric motor 114 adapted to drive a load in the form of a compressor 116. For controlling the operation of the first electric motor 114, a first motor drive 112 is provided between the bus 104 and the first electric motor 114. Correspondingly, a second electric drive unit 120 comprises a second electric motor 124 adapted to drive a load in the form of one or more hydraulic pumps 126. For controlling the operation of the second electric motor 124, a second motor drive 122 is provided between the bus 104 and the second electric motor 124.

[0034] This general description of the electric system 100 is applicable both for AC application and DC application, and the different parts thereof are designed accordingly. For example, in the preferred embodiment that the external power source 10 is an AC network and the bus 104 is a DC bus, the power converter 102 is designed as an AC / DC converter.

[0035] Finally, a controller 106 is connected to the power converter 102 for controlling the operation thereof and being configured to perform some or all of the method steps as described below. The controller 106 communicates with the electric drive units 110, 120 for controlling the operation thereof, preferably by means of separate controllers for the electric drive units 110, 120. If the BMS 132is provided, see Fig. 4, then it is preferred that it is connected to the controller 106. The controller 106 is also in communication with the network control unit at grid side, preferably by means of a wireless communication channel.

[0036] A non-transitory computer-readable storage medium is provided that stores a program configured to execute a method of stabilizing electrical operation of an electrical mining and / or construction machine as described below. Thus, a computer program product comprising instructions which, when the program is executed by a computer, such as the controller 106, cause the computer to carry out the above-mentioned method of stabilizing electrical operation of an electrical mining and / or construction machine.

[0037] In an alternative embodiment, see Fig. 4, a local energy storage in the form of an internal power source 130 is provided for powering the motor drives 112, 122. The internal power source 130 is electrically connected to the bus 104 and via this bus to the electric drive units 110, 120. The internal power source can be any kind of electric power storage, such as a battery, a capacitor, a super capacitor etc. It is preferred that a Battery Management System (BMS) 132 is provided for managing the internal power source 130.

[0038] The method of stabilizing electrical operation of an electrical mining and / or construction machine according to the invention will now be described with reference to Fig. 5, which shows a generic structure of a controller provided in a mining and / or construction machine according to the invention.

[0039] Initially, an electrical strength of the local electrical power grid 10 is determined, preferably measured. The term “electrical strength” could mean for example short circuit ratio, equivalent short circuit ratio, or impedance ratio of the electrical line.

[0040] The electrical strength is determined based on determined voltage of the local electric power grid 10. The voltage is preferably measured at the first point of connection 14, i.e. where the electrical mining and / or construction machine 2 is connected to the local electrical power grid 10. The voltage can also be measuredat other places in the local electrical power grid 10, preferably at the second connection point 18. By measuring the voltage at different positions in the local electrical power grid 10, the voltage drop therein can be calculated.

[0041] The electrical strength is determined also based on the distance between the first point of connection 14 and the second point of connection 18, see Fig. 2 -“the electric distance”.

[0042] In one embodiment, measuring the electrical strength of the local electrical power grid 10 comprises identifying electrical resonance between the power converter (102) and the local electrical power grid 10.

[0043] By means of the information relating to voltage and electrical distance, it is then determined whether the measured strength of the local electrical power grid 10 meets a grid strength threshold criterion or not. Generally, grid strength is a measure of an electrical power system that evaluates the change in voltage and operating conditions, following a disturbance in the power system. The grid strength criterion is value indicating the grid strength. This criterion can be that a short circuit ratio (SRC) value below 3 is considered as lower than the threshold, and the grid is considered as weak grid.

[0044] Additionally, gains and time constant for grid synchronization unit (phase lock loop) based on the determined strength of the local electrical power grid 10 can be calculated.

[0045] If it is determined the measured strength of the local electrical power grid 10 fails to meet the grid strength threshold criterion, at least one power reference parameter and / or control parameter of the electrical mining and / or construction machine 2 is controlled. The power reference parameters may refer to both active and reactive power, and it could also be voltage reference. In the electrical mining and / or construction machine 2, this is done by controlling the power converter 102, which acts as an electric interface between the local electrical power grid 10 and the loads 110, 120.

[0046] In one embodiment, power reference parameters may comprise target active power flow, target reactive power flow, target voltage drop, target AC voltage of the power converter 102, target DC bus voltage of an internal DC bus 104 of the electrical mining and / or construction machine 10, and target load of the at least one electrical load 110, 120.

[0047] In one embodiment, control parameters may comprise gains of synchronization loop, damping coefficients, and gains of power or voltage control loops.

[0048] It is preferred that controlling power reference parameters comprises calculating power reference component to be added with the power reference and / or controlling control parameters comprises calculating a damping component for the reference quantities, based on calculated grid strength.

[0049] When the electrical mining and / or construction machine 2 comprises a local energy storage 130, see the embodiment of Fig. 4, controlling power references and / or control parameters preferably comprises controlling power to and / or from the local energy storage 130.

[0050] Fig. 6 shows schematically a local electrical power grid 10. The grid comprises a loop of cables with a plurality of connection points, shown as circles. An electrical mining and / or construction machine 2 is connected to a connection point designated 14. The end connection points 18, 18’ are connected to a respective electric power source 16, 16’. This is a more elaborate representation of a local electric power grid than the one shown in Fig. 2, but the implementation of the method according to the invention is the same.

[0051] The location of the electrical mining and / or construction machine 2 may be determined, for example by means of GPS. The information about the location may be used for calculating the electrical distance. For example, if you know the location of another connection point at a distance from the electrical mining and / or construction machine 2, the electrical distance used in the method according to the invention can be calculated.

[0052] In an alternative embodiment, see Fig. 7, at least one additional electrical mining and / or construction machine 2’ is connected to the local electrical power grid 10. While the first machine 2 is connected to the local electrical power grid 10 at a first connection point 14, the second machine 2’ is connected to the local electrical power grid 10 at another connection point 14’.

[0053] In this figure, there are two machines 2, 2’ shown, but it will be realized that more than this number is possible. The fact that there is more than one machine 2 connected to the local electrical power grid 10 can be used in several ways. One alternative is to use both machines 2, 2’ for measuring the electrical strength of the local electrical power grid 10 in more than one location. In other words, an electrical strength of the local electrical power grid 10 is determined, preferably measured, in a plurality of locations, wherein power reference parameters and / or control parameters of the electrical mining and / or construction machines 2, 2’ are controlled simultaneously. It is preferred that the two machines 2, 2’ use two different grid strength calculations from two different locations of the local electrical power grid 10. Thus, in the example shown in Fig. 7, the first machine 2 calculates the grid strength based on the determined voltage at the connection point 14 to which the first machine 2 is connected and on the distance between this connection point 14 and a connection point 18 at the electric power source 16. The second machine 2’ calculates the grid strength based on the determined voltage at the connection point 14’ to which the second machine 2’ is connected and on the distance between this connection point 14’ and a different connection point 14”.

[0054] The two machines 2, 2’ are preferably in communication with each other, indicated by a dashed line in the figure, such as by means of a wireless local communication network. In this way, they can exchange information relevant to the stabilizing electrical operation of the machines 2, 2’. For example, they can transmit the measured strength of the local electrical power grid 10 to the other machine or to a central network controller (not shown).

[0055] In one embodiment with an additional machine 2’, see Fig. 8, one of the machines 2, 2’, in this example the additional machine 2’, measures the strength of the local electrical power grid 10. This information is sent to the first machine 2, which is also connected to the local electrical power grid 10. If it is determining that the received measured strength of the local electrical power grid 10 fails to meet a grid strength threshold criterion, then at least one power reference parameter and / or control parameter of the first electrical mining and / or construction machine 2 is controlled by means of the power converter of that first machine.

[0056] During operation of an electrical mining and / or construction machine 2, it sometimes changes location and thereby disconnects from one connection point to reconnect to the local electrical power grid 10 at another connection point. This is illustrated in Fig. 9 where an original position, shown in dashed lines, is replaced by a new position, wherein the electrical mining and / or construction machine 2 is connected to a new connection point 14. After such reconnection, the measuring of the electrical strength of the local electrical power grid 10 is repeated when the electrical mining and / or construction machine (2) has been reconnected to a different part of the local electrical power grid 10.

[0057] A method of stabilizing electrical operation of an electrical mining and / or construction machine 2, wherein the electrical mining or construction machine is connected to a local electric power grid 10 of a mine via a first point of connection 14, and the local electric power grid 10 is connected to an electric power source 16 via a second point of connection (18), can be summarized as follows, see Fig.10. In this method, the electrical mining and / or construction machine 2 comprises a controller 106 adapted to control at least one electrical load 110, 120 of the electrical mining and / or construction machine 2 by means of a power converter 102.

[0058] In a first step 202, based on determined voltage of the local electric power grid 10 and based on a distance between the first point of connection 14 and the second point of connection 18, an electrical strength of the local electrical power grid 10 is measured. In a second step 204, it is determined that measuredstrength of the local electrical power grid 10 fails to meet a grid strength threshold criterion. In a third step 206, in response to said determination that the measured strength of the local electrical power grid 10 fails to meet said grid strength threshold criterion, at least one power reference parameter and / or control parameter of the electrical mining and / or construction machine 2 is controlled by means of the power converter 102.

[0059] An implementation example will now be described. Assume that the grid strength threshold criterion is an SCR above 3. The control algorithm is that the gain of power control loop is 10 when the SCR is above the threshold, i.e., above 3, and that the gain is 5 when the SCR is below the threshold. In other words, when a low grid strength is detected, the gain moves from 10 to 5. When the grid strength later is improved, the gain reverts to 10.

[0060] This is illustrated in the flowchart of Fig. 11. If the grid strength threshold criterion is met, no changes will be made in the power reference and / or control parameters. The flow goes back to this question, possibly after some delay. However, if the grid strength threshold criterion is no met, there will be changes in the power reference and / or control parameters. In this example, the gain moves from 10 to 5. The new power reference and / or control parameters will be maintained until it is detected that the grid strength threshold criterion is met. Power reference and / or control parameters will then be restored to original, i.e., the gain will be restored to 10.

[0061] Preferred embodiments of a method and an electrical mining and / or construction machine have been described. It will be realized that these can be varied within the scope of the appended claims without departing from the inventive idea. For example, in the embodiments of Figs. 6-9, the local electrical power grid is shown as a loop system, looping through the mining or construction site area and returning either to the original point or a different point. It will be realized that also other configurations of the local electrical power grid are possible, such as a radial configuration.

Claims

CLAIMS1. A method of stabilizing electrical operation of an electrical mining and / or construction machine (2) , wherein the electrical mining or construction machine is connected to a local electric power grid (10) of a mine via a first point of connection (14), wherein the local electric power grid (10) is connected to an electric power source (16) via a second point of connection (18), the electrical mining and / or construction machine (2) comprising a controller (106) adapted to control at least one electrical load (110, 120) of the electrical mining and / or construction machine (2) by means of a power converter (102), the method by means of controller (106) comprising the following steps:- based on determined voltage of the local electric power grid (10) and based on a distance between the first point of connection (14) and the second point of connection (18), measuring an electrical strength of the local electrical power grid (10),- determining that measured electrical strength of the local electrical power grid (10) fails to meet a grid strength threshold criterion; and- in response to said determination that the measured strength of the local electrical power grid (10) fails to meet said grid strength threshold criterion, controlling at least one power reference parameter and / or control parameter of the electrical mining and / or construction machine (2) by means of the power converter (102).

2. The method according to claim 1 , wherein the measured electrical strength of the electrical power grid (10) comprises any of the following parameters: short circuit ratio, equivalent short circuit ratio and impedance ratio of the electrical line.

3. The method according to claim 1 , comprises detecting resonance between the power converter (102) and the electrical power grid (10) supplying power to at least one electrical load (110, 120), wherein said resonance indicateslow electrical strength of the local electrical power grid (10) compare to the electrical strength of the local electrical power grid (10) without resonance between the power converter (102) and the electrical power grid (10) supplying power to at least one electrical load (110, 120).

4. The method according to any one of claims 1-3, comprising the additional step of calculating gains and time constant for grid synchronization unit based on the determined strength of the local electrical power grid (10).

5. The method according to any one of claims 1-4, wherein said at least one power reference parameter comprises: , target active power flow, target reactive power flow, target voltage drop, target AC voltage of the power converter (102), target DC bus voltage of an internal DC bus (104) of the electrical mining and / or construction machine (10), and target load of the at least one electrical load (110, 120).

6. The method according to any one of claims 1-5, wherein said at least one control parameter comprises: gains of synchronization loop, damping factors, and gains of power or voltage control loops.

7. The method according to any one of claims 1-6, wherein the step of controlling at least one power reference parameter and / or control parameter comprises calculating a damping component for the reference quantities, based on calculated grid strength and additional measurements, preferably a power component to be added with the power reference.

8. The method according to any one of claims 1-7, wherein the method comprises transmitting said measured strength to at least one additional electrical mining and / or construction machine (2’) connected to the electrical power grid (10).

9. The method according to any one of claims 1-8, wherein the method comprises:receiving measured strength from at least one additional electrical mining and / or construction machine (2’) connected to the electrical power grid (10);determining that said received measured strength of the local electrical power grid (10) fails to meet a grid strength threshold criterion; andcontrolling at least one power reference parameter and / or control parameter of the electrical mining and / or construction machine (2) by means of the power converter (102).

10. The method according to any one of claims 1-9, wherein, when the electrical mining and / or construction machine (2) comprises a local energy storage (130), the step of controlling at least one power reference and / or control parameter comprises controlling power to and / or from the local energy storage (130).

11. The method according to any one of claims 1 -10, wherein the step of measuring the electrical strength of the local electrical power grid (10) is repeated when the electrical mining and / or construction machine (2) reconnects to a different part of the electrical power grid (10).

12. The method according to any one of claims 1-11, wherein the local electrical power grid (10) is an AC power network.

13. An electrically powered mining and / or construction machine (2) comprising a power converter (102), an input of which is connectable to an external power source (10), a controller (106) adapted to control the operation of the power converter (102), and at least one electrical load (110, 120), wherein the controller is adapted to perform the method according to any one of claims 1-12.

14. A non-transitory computer-readable storage medium that stores a program configured to execute the method of any one of claims 1 to 12 in an electrically powered mining and / or construction machine according to claim 13.

15. A computer program product comprising instructions which, when the program is executed by a computer, cause the computer to carry out the methodof any one of claims 1 to 12 in an electrically powered mining and / or construction machine according to claim 13.

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