Method of improving power quality in a mining environment

Abstract

A method of improving the quality of an electrical power grid (10) in a mining environment is provided, wherein an electrical mining and / or construction machine (2) is connected to the electrical power grid (10). The method comprises the following steps: detecting, by means of an electrical power detection device (20), a power quality of the electrical power grid (10) at a connection point (11); based on the detected power quality, requesting a mobile power compensation device (30) to connect to the electrical power grid (10); connecting the mobile power compensation device (30) to the electrical power grid (10); calculating a power compensation based on the detected power quality; and providing the calculated power compensation in the electrical power grid (10) by means of the mobile power compensation device (30). This provides for a flexible and efficient way of improving the power quality. An electrical mining and / or construction machine and a system are also provided.

Description

P24101WQ011METHOD OF IMPROVING POWER QUALITY IN A MINING ENVIRONMENTTechnical field

[0001] The present invention relates generally to improving the quality of an electrical power grid in a mining environment. It relates particularly to a method of improving power quality in an electrical grid in a mining environment 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 machine park. 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 in that the rock drilling rig can be connected 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.P24101WO012

[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, such as voltage drops in the cables making up the electrical power grid, requiring reactive power compensation.

[0007] Maintaining the power quality in a power system is also an essential assignment due to increase in wide variety of non-linear loads.

[0008] There is therefore a need for a solution mitigating or eliminating the problems of grid stability.Summary of invention

[0009] An object of the present invention is to provide an improved performance in electrical power grids in a mining environment.

[0010] The invention is based on the insight that an electrical power detection device at the location of an electrical mining and / or construction machine can detect and request electrical power compensation from a mobile electrical compensation device.

[0011] According to a first aspect of the invention, there is provided a method of improving the quality of an electrical power grid in a mining environment, wherein an electrical mining and / or construction machine is connected to the electrical power grid, the method comprising the following steps: detecting, by means of an electrical power detection device, a power quality of the electrical power grid at a connection point; based on the detected power quality, requesting a mobile power compensation device to connect to the electrical power grid; connecting the mobile power compensation device to the electrical power grid; calculating a power compensation based on the detected power quality; and providing the calculated power compensation in the electrical power grid by means of the mobile power compensation device.P24101WO013

[0012] In one embodiment, the electrical power detection device is provided at the connection point and the detected power quality is communicated to the electrical mining and / or construction machine, preferably wirelessly. The step of requesting a mobile power compensation device to connect to the electrical power grid is then preferably carried out before the electrical mining and / or construction machine is connected to the electrical power grid.

[0013] In an alternative embodiment, the electrical power detection device is provided in the electrical mining and / or construction machine.

[0014] In one embodiment, the electrical power detection device is provided remote from the connection point to which the electrical mining and / or construction machine is connected to the electrical power grid.

[0015] In one embodiment, the mobile power compensation device is connected directly to the electrical power grid at the connection point. Alternatively, the mobile power compensation device is connected to the electrical power grid via the electrical mining and / or construction machine.

[0016] In one embodiment, there is an additional step of connecting a charging station and / or an external energy source, preferably a battery energy storage system, to the connection point.

[0017] In one embodiment, when the electrical mining and / or construction machine is provided with an internal energy source, there is a separate input for the mobile power compensation device.

[0018] In one embodiment, the step of detecting a power quality of the electrical power grid at a connection point is carried out before the electrical mining and / or construction machine is connected to the electrical power grid.

[0019] In one embodiment, the step of requesting a mobile power compensation device to connect to the electrical power grid is performed by a controller internal to the electrical mining and / or construction machine. Alternatively, the step ofP24101WO014requesting a mobile power compensation device to connect to the electrical power grid is performed by a controller external to the electrical mining and / or construction machine, preferably a controller provided in the mobile power compensation device.

[0020] In one embodiment, the step of calculating a power compensation is performed by means of a controller provided in the mobile power compensation device.

[0021] In one embodiment, there is a step of providing a plurality of power compensation devices, wherein the step of calculating a power compensation is performed by means of a controller provided in the electrical mining and / or construction machine, and the step of providing the calculated power compensation in the electrical power grid comprises distributing the calculated power compensation among the plurality of mobile power compensation devices.

[0022] In one embodiment, the step of providing a plurality of power compensation devices comprising providing a mobile power compensation device and a fixed power compensation device and / or a power compensation device provided in the electrical mining and / or construction machine.

[0023] In one embodiment, the power compensation is any of the following: reactive compensation and / or harmonic compensation.

[0024] In one embodiment, the power compensation is additionally calculated based on mine operation planning.

[0025] In one embodiment, a plurality of electrical mining and / or construction machines is provided to a respective connection point of the electrical power grid, wherein the step of calculating a power compensation based on the detected power quality involves the detected power quality of all connection points.

[0026] According to a second aspect of the invention, an electrically powered mining and / or construction machine connectable to an electric power grid andP24101WO015comprising a controller is provided, wherein the controller is adapted to perform steps of the method according to the invention.

[0027] In one embodiment, a port is provided for connecting an electric power compensation device to the electrical power grid.

[0028] In one embodiment, an electric power compensation device is adapted to be connected to the electrical power grid.

[0029] According to a third aspect of the invention, a non-transitory computer-readable storage medium is provided that stores a program configured to execute steps of the method according to the invention in an electrically powered mining and / or construction machine according to the invention.

[0030] 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 steps of the method according to the invention in an electrically powered mining and / or construction machine according to the invention.

[0031] According to a fifth aspect of the invention, a system for improving the quality of an electrical power grid in a mining environment is provided, the system comprising an electrical mining and / or construction machine connected or connectable to the electrical power grid, an electrical power detection device for detecting a power quality of the electrical power grid at a connection point; a mobile power compensation device connectable to the electrical power grid at the connection point and adapted to provide power compensation to the electrical power grid at the connection point; means for calculating a power compensation based on a power quality detected by the electrical power detection device; and means for requesting the mobile power compensation device to connect to the electrical power grid based on the detected power quality.P24101WO016Brief description of drawings

[0032] 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 power grid;Fig. 2 is an overall diagram showing an electrical mining and / or construction machine connected to an electrical power grid, wherein a mobile power compensation device is available;Fig. 3 is an overall diagram similar to that of Fig. 2, wherein the mobile power compensation device has been connected to the electrical power grid;Fig. 4 is a diagram showing an electrical mining and / or construction machine with an electrical power quality detection device connected to an electrical power grid; Fig. 5 is a diagram showing an electrical mining and / or construction machine with an electrical power detection device connected to an electrical power grid, and additionally in communication with a mine operation planning service;Fig. 6 is a diagram showing an electrical power quality detection device connected to an electrical power grid and in communication with an electrical mining and / or construction machine.Figs. 7a-d show alternatives how a mobile power compensation device is connected to an electrical power grid;Fig. 8 is a diagram showing the design of a mobile power compensation device;Fig. 9 illustrates that a plurality of electrical power compensators can be provided in a mobile power compensation device;P24101WO017Fig. 10 is a more detailed diagram of an electric drive system in an electrical mining and / or construction machine connected to an electrical power grid together with an electrical power compensation device;Fig. 11 is a diagram similar to that of Fig. 10 but with the electrical power compensation device connected to the electrical power grid via the electrical mining and / or construction machine,Figs. 12 and 13 illustrate how a controller of an electrical mining and / or construction machine may interact with a controller of an electrical power compensation device;Fig. 14 illustrates how a controller of an electrical mining and / or construction machine may interact with a controller of a mobile electrical power compensation device and a controller of a fixed electrical power compensation device;Fig. 15 is a diagram illustrating the current distribution in a mobile power compensation device and an electrical mining and / or construction machine connected to an electrical power grid;Fig. 16 is an overall diagram similar to that of Fig. 2, wherein a plurality of mobile power compensation devices has been connected to an electrical power grid; Fig. 17 is a diagram similar to that of Fig. 11 but with an electrical power compensation device provided in the electrical mining and / or construction machine, andFig. 18 is a flow chart of the main steps of the method according to the invention.Description of embodiments

[0033] In the following, a detailed description of a method of improving the quality of an electrical power grid in a mining environment, wherein an electrical mining and / or construction machine is connected to an electrical power grid. TheP24101WO018system provided for enabling the method as well as the electrical mining and / or construction machine will also be described.

[0034] 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.

[0035] The rock drilling rig 2 further comprises an electric drive 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 / or an internal energy source comprised in the electric drive 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 or an internal energy source. A work cycle normally comprises a plurality of work tasks. The controller is further configured to selectively charge the internal energy source with energy from the external electrical source, as will be described below.

[0036] Reference will now be made to Figs. 2 and 3, wherein the general method according to the invention is illustrated. Turning first to Fig. 2, there is shown a block representing an electrical mining and / or construction machine 2, as described above with reference to Fig. 1. The electrical mining and / or construction machine 2 is connected to an electrical power grid 10 in a mining environment at a connection point 11 of the electrical power grid 2. The term “mining environment"P24101WO019should in this context be construed as any site where coal, metal or other materials are extracted from the earth. The term “electrical power grid” should in this context be construed as a grid of electrical cables and associated equipment, such as circuit breakers, connection points, charging stations etc., enabling the provision of electrical power to an electrical mining and / or construction machine 2 operating in a mining environment. Although only one connection point 11 is shown in the figure, it will be realized that there will be multiple connection points in the electrical power grid 11.

[0037] A mobile power compensation device 30 is provided somewhere in the mining environment. Power compensators are essential components of an electric power grid. The ability to provide reactive and / or harmonic power compensation has many benefits. Reactive compensation is the process of adding or injecting positive and / or negative VAr to a power system to essentially attain voltage control. Depending upon the application, reactive compensation can be achieved passively with capacitors and reactors or actively with power electronic solutions such as STATCOMS and Static VAr Generators (SVG’s) for distribution grid applications.

[0038] Current drawn by nonlinear loads, such as inverters provided in electric mining and / or construction machines, are non-sinusoidal and therefore contains harmonics. Therefore, it becomes necessary to compensate these unwanted harmonics for better performance of the system. There are three main types of harmonic power compensation devices: passive filters, active filters, and hybrid systems. Passive filters are composed of capacitors, inductors, and resistors that create a low-impedance path for harmonic currents to flow. Active filters are electronic devices that inject counter-harmonic currents to cancel out the harmonic currents in the system. Hybrid systems are combinations of passive and active filters that offer the benefits of both.

[0039] When determining the power compensation to be provided by a power compensation device, harmonic limits and objectives for the electrical power grid 10 should be taken into account. The relevant standards and regulations, such asP24101WO0110IEEE 519, IEC 61000, or EN 50160, should be followed. These standards define the maximum allowable harmonic distortion levels for different voltage levels and system types. Specific requirements and expectations of an electrical power grid 10 in a mining environment should also be taken into account.

[0040] In the present disclosure, the term “mobile” device should be interpreted broadly and to cover all devices which can be relocated within the mining site without undue burden. The term “mobile” excludes devices which are permanently connected to the electrical power grid 10. Thus, a mobile power compensation device within the context of this disclosure encompasses manually movable devices, devices provided on a transport vehicle, such as lorries, self-propellered devices, including wheeled and tracked vehicles, and even devices provided in or on an electrical mining and / or construction machine.

[0041] The mobile power compensation device in the present disclosure can also be to various degrees autonomous. In one end of this spectrum, the mobile power compensation device is essentially manually operated, which means that it is relocated to a connection point under the supervision of an operator. The power compensation provided by the mobile power compensation device 30 is controlled by means of a user interface. In the opposite end of this spectrum, the mobile power compensation device 30 is fully autonomous, meaning that it relocates to a connection point by means of internal software, possibly supported by Al, without the involvement of an operator.General method

[0042] A method of improving the quality of the electrical power grid 10 in a mining environment, wherein an electrical mining and / or construction machine 2 is connected to electrical power grid 10 will now be described in detail. It should be noted that the electrical mining and / or construction machine 2 can be connected to the electrical power grid 10 at various times, as will be described below with reference to different examples.P24101WO0111

[0043] Current drawn by non-linear loads are non-sinusoidal and therefore contains harmonics. Therefore, it becomes necessary to compensate these unwanted harmonics for better performance of the system. One basic step of the method is therefore to detect a power quality of the electrical power grid 10 at a connection point 11. This can be done by conducting a harmonic study or survey, which involves measuring and analyzing the harmonic currents and voltages at different points in the electrical power grid 10 by means of an electrical power detection device. Specialized instruments such as power analyzers, harmonic meters, or oscilloscopes can be used for this purpose. Additionally, data on the load profiles, generator ratings, and system configuration could be collected, to supplement the data obtained from the measuring.

[0044] The electrical power detection device used in the method could be provided in different places, such as in the electrical mining and / or construction machine 2, in the power compensation device 30, or as a separate unit, as will be described below.

[0045] Based on the detected power quality, a mobile power compensation device 30 is requested to connect to the electrical power grid 10. This request can be issued by the electrical mining and / or construction machine 2, but it is also possible to have a separate controller make this request.

[0046] After the request for a mobile power compensation device 30 to connect to the electrical power grid 10 has been issued, the mobile power compensation device 30 connects to the electrical power grid 10. This usually requires that the mobile power compensation device 30 moves from one location in the mining environment to another, as indicated by the arrow in Fig. 3. The mobile power compensation device 30 preferably connects to the electrical power grid 10 at a connection point 11 to which the electrical mining and / or construction machine 2 is connected or will be connected.

[0047] A power compensation required for obtaining an improved quality of the electrical power grid 10 is calculated based on the detected power quality, asP24101WO0112described above. This calculation is preferably performed by a controller provided in the mobile power compensation device 30 or the electrical mining and / or construction machine 2, as will be described below. However, the calculation can also be performed by a standalone computer device provided in the mining environment.

[0048] The required power compensation may include harmonic compensation, reactive compensation, or a combination of harmonic compensation and reactive compensation.

[0049] Communication between the different devices in the mining environment is preferably performed wirelessly. However, also wired connections can be used for communication. For example, a mobile power compensation device 30 can be connected to an electrical mining and / or construction machine 2 and this connection may include a communication interface.

[0050] When the required power compensation has been calculated, it is the task of the mobile power compensation device 30 to provide the required power compensation in the electrical power grid 10.

[0051] In summary, the method according to the invention of improving the quality of an electrical power grid 10 in a mining environment, wherein an electrical mining and / or construction machine 2 is connected to electrical power grid 10 comprises a number of steps, as illustrated in Fig. 18. In one step 202, a power quality of the electrical power grid 10 is detected at a connection point by means of an electrical power detection device 20. In another step 204, a mobile power compensation device 30 is requested to connect to the electrical power grid 10 based on the detected power quality. In another step 206, the mobile power compensation device 30 is connected to the electrical power grid 10. In another step 208, a power compensation is calculated based on the detected power quality. In another step 210, the calculated power compensation is provided in the electrical power grid 10 by means of the mobile power compensation device 30.P24101WO0113

[0052] Electrical mining and / or construction machines often has an inverter interface to the electrical power grid at the mining site. The power ratings of these inverters are too small for them to have any impact on the system frequency but their power rating can be sufficient to contribute to local voltage control through reactive power exchange both in terms of magnitude and power quality.

[0053] Fig. 4 is a diagram showing an electrical mining and / or construction machine 2 with an electrical power detection device 20 connected to an electrical power grid 10. Thus, in this embodiment, the electrical power detection device 20 is provided in the electrical mining and / or construction machine 2. A probe or corresponding measuring arrangement 22 is connected to one or more cables of the electrical power grid 10 at or close to a connection point 11. The probe is in the figure shown as being connected by wire to the electrical power detection device 20, but this connection could as well be wireless. Alternatively, the electrical power detection device 20 can be part of a circuit already provided in the electrical mining and / or construction machine 2 for measuring incoming power, as indicated with dashed lines in the figure.

[0054] The information gathered by the measuring arrangement 22 is used to determine the quality of the electrical power grid 10 at or close to the connection point 11 to which the electrical mining and / or construction machine 2 is connected or will be connected. With the term “at or close to” is meant a very short distance, such as less than 50 meters, preferably less than 30 meters. Another definition is that a device connected to the same substation, preferably the same secondary substation, as the connection point 11 is “at or close to” that connection point. The information, possibly together with other relevant data, is used either by a controller in the electrical mining and / or construction machine 2 or in the mobile power compensation device 30 to determine whether to request the mobile power compensation device 30 to connect to the electrical power grid 10 or not. In case the decision is made in the electrical mining and / or construction machine 2, a request is transmitted, preferably wirelessly, to the mobile power compensation device 30, which acts accordingly by moving to the connection point 11 and thereP24101WO0114connecting to the electrical power grid 10. Alternatively, if the information about the quality of the electrical power grid 10 is processed in the mobile power compensation device 30, the decision is made in the mobile power compensation device 30.

[0055] Fig. 5 illustrates that information is exchanged with a mining operations network 50. In the figure, the network 50 is illustrated as a cloud-based network, but it could also be a network comprising physical servers. Both the electrical mining and / or construction machine 2 and the mobile power compensation device 30 then exchange information with the mining operations network 50 and may use relevant information, such as from a mine operations planning tool, in the decision whether to request power compensation or not.

[0056] A mine operations planning tool is used for determining the distribution of change in power consumption between the plurality of electrical mining and / or construction machines 2. This schedule planning tool may include the creation and execution of mine plans, taking into account variables like ore quality, safety, and efficiency. Short term planning is the detailed mine design, mine activity scheduling and mitigation of constraints through the detailed scheduling of necessary actions and the debottlenecking of activity constraints to ultimately achieve the production targets.

[0057] As an example, if the use of a stone crusher or other machine drawing high power levels, is in a mine plan, this could be taken into account when requesting power compensation. In other words, the future need for power compensation can be a parameter when requesting power compensation.

[0058] Fig 6 illustrates the case where an electric power detection device 20 is provided at or near the connection point 11. This electric power detection device 20 may be a standalone device or be integrated in equipment provided at or near the connection point 11, such as in a charging station (not shown). In this scenario, there is no need for the electrical mining and / or construction machine 2 to be at or close to the connection point 11 when the request for power compen-P24101WO0115sation is made. For example, it could be tramming, with a next drill position in the vicinity of the connection point 11. Instead of having to wait with a request for a mobile power compensation device 30 to connect at the connection point 11, the request can be made as soon as it has been determined that the quality of the electrical power grid 10 should be improved by means of power compensation.

[0059] The general method steps are the same as in the previous cases, but instead of having an electrical power detection device 20 in the electrical mining and / or construction machine 2 or the mobile power compensation device 30, the step of detecting a power quality of the electrical power grid 10 at the connection point 11 is made by means of an electrical power detection device 20 already at the connection point 11.

[0060] It has been described that the electrical power detection device 20 is provided at the connection point 11 to which the electrical mining and / or construction machine 2 is connected to the electrical power grid 10. However, it will be realized that the electrical power detection device 20 can be provided remote from the connection point 11 to which the electrical mining and / or construction machine 2 is connected to the electrical power grid 10. The mobile power compensation device 30 can be connected to the electrical power grid 10 in different ways, as will now be described with reference to Figs. 7a-d. Fig. 7a illustrates the simplest way of connecting the mobile power compensation device 30, namely to simply connect it to the connection point 11 in the same way as the electrical mining and / or construction machine 2 is connected thereto. The connection point 11 comprises a plurality of electrical connectors adapted to the electrical connectors of the different mining machines, mobile power compensation devices 30 and other equipment at the mining site. These connectors could comprise male and female connectors adapted to be interconnected, thereby conducting electrical power between the electrical power grid 10 and devices and machines connected thereto. This will also be described below with reference to Fig. 10.P24101WO0116

[0061] Fig. 7b shows an alternative way of connecting the mobile power compensation device 30 to the electrical power grid 10, namely via the electrical mining and / or construction machine 2. In this case, the electrical mining and / or construction machine 2 is provided with a port or connector to which the mobile power compensation device 30 can connect. The electrical mining and / or construction machine 2 is internally designed so that the mobile power compensation device 30 is connected to the electrical power grid 10, which will be described in detail below with reference to Fig. 11.

[0062] Yet an alternative way of connecting the mobile power compensation device 30 to the electrical power grid 10 is illustrated in Fig. 7c, showing a charging station 14 connected to the connection point 11. The mobile power compensation device 30 is there connected to the connection point 11 in parallel with the charging station 14. Alternatively, as indicated in dashed line, the mobile power compensation device 30 can be connected to the electrical power grid 10 via the charging station 14.

[0063] A last example of how an mobile power compensation device 30 could be connected to the electrical power grid 10 is in parallel with an energy storage 16, such as a battery energy storage system (BESS). Alternatively, as indicated in dashed line, the mobile power compensation device 30 can be connected to the electrical power grid 10 via the BESS 16.

[0064] Fig. 8 illustrates an embodiment of a mobile power compensation device 30 with a number of internal components. Electrical power compensators are known perse in the art and the skilled person can design a mobile power compensation device 30 for different situations. In the shown embodiment, the mobile power compensation device 30 has a port 31 which is connectable to a connection point 11 of an electrical power grid 10 for conducting electrical power between the mobile power compensation device 30 and the electrical power grid 10. The port may also comprise an interface for wired data transmission.Alternatively or additionally, a wireless transmitter / receiver 30a is provided forP24101WO0117wireless communication with an electrical mining and / or construction machine 2, a wireless mining network or the like.

[0065] The mobile power compensation device 30 also comprises an active compensator 30b and / or a passive compensator 30c. An active compensator is a device semiconductor circuit controlled by a controller while a passive compensator is a filter with fixed components, such as resistors, inductors and / or capacitors, designed to provide a power compensation.

[0066] The mobile power compensation device 30 may optionally comprise a capacitor 30d for reactive power compensation.

[0067] Optionally, a battery energy storage 30e is provided for reactive power compensation as well as harmonic compensation.

[0068] The operation of the mobile power compensation device 30 is controlled by means of a power compensator controller 34.

[0069] Fig. 9 illustrates an mobile power compensation device 30 which comprises a plurality of, in the embodiment shown in the figure two, electrical compensation sub-devices 30’, 30”, each preferably provided with an associated controller 34’, 34”. The provision of different sub-devices makes it possible to design an mobile power compensation device 30 suitable for both reactive and harmonic compensation in a simple way. Also, one of the sub-devices may be an active device and the other be a passive device.

[0070] For better understanding of the invention, the electric drive system 100 of an electrical mining and / or construction machine 2 will now be described with reference to Figs. 10 and 11. In Fig. 10, the electric drive system 100, provided in the electrical mining and / or construction machine 2, is connected to a connection point 11 of an electrical power grid 10 via a cable interface 12 of the electrical mining and / or construction machine 2. An mobile power compensation device 30 is connected to the same connection point 11 in parallel with the electric drive system 100. Thus, this configuration corresponds to that of Fig. 7a.P24101WO0118

[0071] The electric drive system 100 comprises a bus 104 adapted to provide electrical power to an electric drive unit 110 of the mining machine. This bus 104 can be either a DC bus or an AC bus. The term “bus” should in this context be construed broadly and encompass any kind of device adapted to conduct electrical current, irrespective of the number of devices connected thereto.

[0072] The electric drive unit 110 may comprise an electric motor adapted to drive a load device in the form of a compressor, for example. A second electric motor may be provided to drive a load in the form of one or more hydraulic pumps, for example. One or more electric motor drives are provided for controlling the operation of the electric motors provided in the electric drive unit 110. An electric drive unit controller 110a is provided for controlling the operation of the electric drive unit 110.

[0073] The electric drive system 100 also comprises a power converter 102, the input of which is connectable to the electrical power grid 10, via the cable interface 12. The output of the power converter 102 is connected to the bus 104 adapted to provide electrical power to the electric drive unit 110 of the mining machine. The operation of the power converter 102 is controlled by means of a power converter controller 102a, connected thereto. The power converter 102, being connected to an AC electrical power grid 10, can be either an AC / AC converter or an AC / DC converter, depending on whether the bus 104 is an AC bus or a DC bus.

[0074] The power converter 102 is preferably designed as an inverter, which in itself may improve the quality of the electrical power grid 10 by exchanging reactive power with the electrical power grid.

[0075] An internal power unit 130 is optionally provided for, in addition to the power provided by the power converter 102, powering the electric drive unit 110. The internal power unit 130 is connected to the bus 104 and via this bus to the electric drive unit 110. The power unit 130 may comprise any kind of electrical power source, such as a battery, a capacitor, a super capacitor etc., or a combination thereof. It is preferred that a battery management system (BMS) 130aP24101WO0119is provided for the oversight of the power unit 130. The functions of the BMS 130a may include, but is not limited, to monitoring and protecting the electrical power sources, estimating the operational state and continually optimizing battery performance, and reporting operational status.

[0076] A control unit 106 is provided for controlling the operation of the electric drive system 100. This control unit 106 is preferably connected to the power converter controller 102a, the electric drive unit controller 110a, and the BMS 130a. In case the electric drive system 100 is connected to a charger (not shown), the control unit 106 is preferably connected thereto. By being connected to the different controllers / BMS of the electric drive system 100, the control unit 106 can control the operation thereof. Alternatively, one or more of the power converter controller 102a, the electric drive unit controller 110a, and the BMS 130a can be omitted. If that is the case, the different units of the electric drive system 100 are controlled directly by the control unit 106.

[0077] In one embodiment, the step of requesting a mobile power compensation device 30 to connect to the electrical power grid 10 is performed by the control unit 106 internal to the electrical mining and / or construction machine 2. Alternatively or additionally, the control unit 106 calculates the required power compensation based on the detected power quality at the connection point 11.

[0078] Finally, an electrical power detection device 20 is provided so that it can detect the quality of the electrical power provided by the electrical power grid 10 to the power converter 102. In other words, probes or other measuring devices are arranged to detect the electrical power, such as voltage, current, and phase of incoming electrical power supplied to the power converter 102. This information is supplied to the electrical power detection device 20 and this information is further supplied to the control unit 106. Note that this embodiment corresponds to those of Figs 4 and 5. In other embodiments, such as the one corresponding to Fig. 6, the electrical power detection device 20 internal of the electrical mining and / or construction machine 2 is omitted.P24101WO0120

[0079] A non-transitory computer-readable storage medium is provided, preferably in the control unit 106, that stores a program configured to execute one or more steps of a method controlling the operation of an electrical power unit in a mining machine as described below. Thus, a computer program product comprising instructions which, when the program is executed by a computer, such as the control unit 106, cause the computer to carry out the above-mentioned method of controlling the operation of an electrical power unit in a mining machine.

[0080] Fig 11 illustrates a design wherein the electric drive system 100 is provided with a port 38 for a mobile power compensation device 30. Thus, this configuration corresponds to that of Fig. 7b. In this way, when the mobile power compensation device 30 is connected to the electrical mining and / or construction machine 2 via port 38 and the electrical mining and / or construction machine 2 is connected to the electrical power grid 10 via the cable interface 12, then the mobile power compensation device 30 is connected to the electrical power grid 10.

[0081] Different ways of requesting a mobile power compensation device 30 to connect to the electrical power grid 10 and calculating a required power compensation will now be described with reference to Figs. 12-14.

[0082] In Fig. 12, it is illustrated that an electrical power detection device 20 provided in an electrical mining and / or construction machine 2 is used for detecting a power quality of the electrical power grid 10 at a connection point 11. The information about the power quality of the electrical power grid 10 is forwarded to a controller 106 provided in the electrical mining and / or construction machine 2. This controller evaluates the detected power quality and if it is determined that electrical power compensation is required at the connection point 11, then a mobile power compensation device 30 is requested to connect to the electrical power grid 10. The mobile power compensation device 30 connects to the connection point 11 and the controller 34 of the mobile power compensation device 30 calculates a required power compensation based on the detected power quality. After having connected to the connection point 11, the mobile powerP24101WO0121compensation device 30 provides the calculated power compensation to the electrical power grid 10.

[0083] In Fig. 13, a scenario similar to that of Fig. 12 is illustrated, wherein an electrical power detection device 20 provided in an electrical mining and / or construction machine 2 is used for detecting a power quality of the electrical power grid 10 at a connection point 11. The information about the power quality of the electrical power grid 10 is forwarded to a controller 106 provided in the electrical mining and / or construction machine 2. However, in this embodiment, if it is determined that electrical power compensation is required at the connection point 11, then a plurality of mobile power compensation device 30, in this example two mobile power compensation devices 30, are requested to connect to the electrical power grid 10. In this case, the mobile power compensation devices 30 connect to the connection point 11 and the controller 106 of the electrical mining and / or construction machine 2 distributes the required power compensation between the mobile power compensation devices 30.

[0084] In Fig. 14 it is illustrated that an electrical power detection device 20 provided in an electrical mining and / or construction machine 2 is used for detecting a power quality of the electrical power grid 10 at a connection point 11. The information about the power quality of the electrical power grid 10 is forwarded to a controller 106 provided in the electrical mining and / or construction machine 2. In this embodiment, if it is determined that electrical power compensation is required at the connection point 11, then a mobile power compensation device 30 and an power compensation device 36 internal of the electrical mining and / or construction machine 2, preferably with a fixed power compensation, are requested to connect to the electrical power grid 10. In this case, the mobile power compensation device 30 connects to the connection point 11 and the controller 106 of the electrical mining and / or construction machine 2 distributes the required power compensation between the mobile power compensation devices 30 and the internal power compensation device 36.P24101WO0122

[0085] The current distribution from the electrical power grid 10 and the mobile power compensation devices 30 will now be described with reference to Fig. 15, showing a simplified diagram of the electric drive system 100 connected to an electrical power grid 10 and a mobile power compensation device 30. The electric drive system 100 comprises a power converter 102 and an internal power unit 130, both connected to a DC bus 104. Also connected to the DC bus 104 is an electric drive unit 110, comprising for example electric motors driving hydraulic pumps or motors.

[0086] The electrical power grid 10 supplies active current iFand reactive current irminus power compensation reactive current irc, i.e., partial reactive current as follows:IIgrid= IF+ Ir- Irc

[0087] The current i* from the mobile power compensation device 30 can be represented as the sum of harmonic current ihand reactive current irc.Ic= ih+ irc

[0088] The current imsupplied to the electrical mining and / or construction machine 2 can be represented as the sum of active current iF, reactive current irand harmonic current ih.im= iF+ ih+ ir

[0089] The current inside the machine at DC bus 104, which will be supplied to the electric drive unit 110, is the combined current idcfrom the power converter 102 and the current ibattery from the internal power unit 130.

[0090] An example of an implementation is given below, in which the following equations are used:PL= vs· iLP24101WO0123qL= vsX iL=PcVs! qc*Xvsvs.vsvs.vsPL = PL + PLQL - L + QLwhereinpL, qL, are instantaneous active and reactive power based on positive sequence fundamental andpl, q are instantaneous active and reactive power based on negative sequence and harmonics.Additionally,PL = PL2W + PLhQL—QL2W T QL / IwhereinPL2W, C[L2Wareinstantaneous active and reactive power based on negative sequence fundamental, andPL / I, QL / Iareinstantaneous harmonic active and reactive power.Different scenarios are set out in Table 1 below.Scenarios Compensator Compensator Compensator current reference active power reactive reference power reference Compensate only qc*XvsPc = 0 Qc—QL oscillating reactivelcvs.vspowerP24101WO0124Compensate full=q*XvsPc = 0 Qc - QL + QL reactive powerlcvs.vsCompensate.*=PcVs! qc*XvsPc = PL QC = QL + QL oscillating activecvs.vsvs.vspower and fullreactive powerTable 1

[0091] The first row is the case where the compensator is used only for oscillating reactive power, wherein the active power reference is zero and reactive power reference is just the oscillating part (third and fourth column) and so the current reference for the compensator is calculated based on the reactive power only as shown in second column.

[0092] Fig. 16 illustrates the situation where a plurality of mobile power compensation devices 30, in the example shown two mobile power compensation devices 30, is provided. In this situation, the required power compensation in the electrical power grid is distributed among the plurality of mobile power compensation devices 30.

[0093] The illustration of Fig.16 also comprises a plurality of electrical mining and / or construction machines 2, in the example shown two electrical mining and / or construction machines 2. With a plurality of electrical mining and / or construction machines 2, it is preferred that the requests for a mobile power compensation device 30 to connect to the electrical power grid 10 take into account the quality of the electrical power grid 10 at all connection points 11 and the needs of all electrical mining and / or construction machines 2. Particularly when a mine operations planning tool is used, see the description of Fig. 5, the electrical mining and / or construction machines 2 can be given different priorities and the mobileP24101WO0125power compensation device 30 be requested to connect to the electrical power grid 10 accordingly. In other words, a connection point 11 to which an electrical mining and / or construction machines 2 with higher priority is connected will be provided with power compensation before a connection point 11 to which an electrical mining and / or construction machines 2 with lower priority is connected.

[0094] Fig. 17 is a diagram of an electric drive system 100 similar to those of Figs. 10 and 11. However, in this embodiment, an internal electric power compensation device 36 is provided, as described above with reference to Fig. 14. This internal electric power compensation device 36 is preferably a fixed compensator which, together with a mobile power compensation device 30, provides the required power compensation. In all other aspects, this electric drive system 100 operates as the ones described above with reference to Fig. 10 and 11.

[0095] Preferred embodiments of a method of improving the quality of an electrical power grid in a mining environment, wherein an electrical mining and / or construction machine is connected to electrical power grid, and an electrical mining and / or construction machine and a system have been described. It will be realized that these embodiments may be varied within the scope of the appended claims without departing from the inventive idea.

Claims

P24101WO0126CLAIMS1. A method of improving the quality of an electrical power grid (10) in a mining environment, wherein an electrical mining and / or construction machine (2) is connected to the electrical power grid (10), the method comprising the following steps:a) detecting, by means of an electrical power detection device (20), a power quality of the electrical power grid (10) at a connection point (11 );b) based on the detected power quality, requesting a mobile power compensation device (30) to connect to the electrical power grid (10); c) connecting the mobile power compensation device (30) to the electrical power grid (10);d) calculating a power compensation based on the detected power quality; ande) providing the calculated power compensation in the electrical power grid (10) by means of the mobile power compensation device (30).

2. The method according to claim 1, wherein the electrical power detection device (20) is provided at the connection point (11 ) and the detected power quality is communicated to the electrical mining and / or construction machine (2), preferably wirelessly.

3. The method according to claim 2, wherein the step of requesting a mobile power compensation device (30) to connect to the electrical power grid is carried out before the electrical mining and / or construction machine (2) is connected to the electrical power grid (10).

4. The method according to claim 1, wherein the electrical power detection device (20) is provided in the electrical mining and / or construction machine (2).P24101WO01275. The method according to claim 1, wherein the electrical power detection device (20) is provided remote from the connection point (11 ) to which the electrical mining and / or construction machine (2) is connected to the electrical power grid (10).

6. The method according to any one of claims 1-5, wherein the mobile power compensation device (30) is connected directly to the electrical power grid (10) at the connection point (11 ).

7. The method according to any one of claims 1-5, wherein the mobile power compensation device (30) is connected to the electrical power grid (10) via the electrical mining and / or construction machine (2).

8. The method according to any one of claims 1-7, comprising the additional step of connecting a charging station (14) and / or an external energy source (16), preferably a battery energy storage system, to the connection point (11 ).

9. The method according to any one of claims 1-8, wherein the step of detecting a power quality of the electrical power grid (10) at a connection point (11) is carried out before the electrical mining and / or construction machine (2) is connected to the electrical power grid (10).

10. The method according to any one of claims 1-9, wherein the step of requesting a mobile power compensation device (30) to connect to the electrical power grid (10) is performed by a controller (106) internal to the electrical mining and / or construction machine (2).

11. The method according to any one of claims 1-9, wherein the step of requesting a mobile power compensation device (30) to connect to the electrical power grid (10) is performed by a controller (34) external to the electrical mining and / or construction machine (2), preferably a controller provided in the mobile power compensation device (30).P24101WO012812. The method according to any one of claims 1-11, wherein the step of calculating a power compensation is performed by means of a controller (34) provided in the mobile power compensation device (30). (Fig. 14)13. The method according to any one of claims 1-11, comprising the step of providing a plurality of power compensation devices (30, 32), wherein the step of calculating a power compensation is performed by means of a controller (106) provided in the electrical mining and / or construction machine (2), and the step of providing the calculated power compensation in the electrical power grid comprises distributing the calculated power compensation among the plurality of mobile power compensation devices (30).

14. The method according to claim 13, wherein the step of providing a plurality of power compensation devices comprising providing a mobile power compensation device (30) and a fixed power compensation device (32) and / or a power compensation device (34) provided in the electrical mining and / or construction machine (2).

15. The method according to any one of claims 1-14, wherein the power compensation is any of the following: reactive compensation and / or harmonic compensation.

16. The method according to any one of claims 1-15, wherein the power compensation is additionally calculated based on mine operation planning.

17. The method according to any one of claims 1-16, wherein a plurality of electrical mining and / or construction machines (2) is provided to a respective connection point (11 ) of the electrical power grid (10), wherein the step of calculating a power compensation based on the detected power quality involves the detected power quality of all connection points (11 ).

18. An electrically powered mining and / or construction machine (2) connectable to an electric power grid (10) and comprising a controller (106),P24101WO0129wherein the controller (106) is adapted to perform any of steps b) and d) of the method according to any one of claims 1-17.

19. The electrically powered mining and / or construction machine (2) according to claim 18, comprising a port (38) for connecting an electric power compensation device (30) to the electrical power grid (10).

20. The electrically powered mining and / or construction machine (2) according to claim 18, comprising an electric power compensation device (34) adapted to be connected to the electrical power grid (10).

21. A non-transitory computer-readable storage medium that stores a program configured to execute any of steps b) and d) of the method of any one of claims 1 to 17 in an electrically powered mining and / or construction machine according to any one of claims 18-20.

22. A computer program product comprising instructions which, when the program is executed by a computer, cause the computer to carry out any of steps b) and d) of the method of any one of claims 1 to 17 in an electrically powered mining and / or construction machine according to any one of claims 18-20.

23. A system for improving the quality of an electrical power grid (10) in a mining environment, comprising- an electrical mining and / or construction machine (2) connected or connectable to the electrical power grid (10),- an electrical power detection device (20) for detecting a power quality of the electrical power grid (10) at a connection point (11);- a mobile power compensation device (30) connectable to the electrical power grid (10) at the connection point (11) and adapted to provide power compensation to the electrical power grid (10) at the connection point (11);P24101WO0130- means (106) for calculating a power compensation based on a power quality detected by the electrical power detection device (20); and- means (106) for requesting the mobile power compensation device (30) to connect to the electrical power grid (10) based on the detected power quality.

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