WO2009153657A1

WO2009153657A1 - Power system

Info

Publication number: WO2009153657A1
Application number: PCT/IB2009/006021
Authority: WO
Inventors: Andries Hercules Putter
Original assignee: Desert Star 226 (Pty) Ltd
Priority date: 2008-06-18
Filing date: 2009-06-18
Publication date: 2009-12-23

Abstract

According to a first aspect of the invention there is provided a power system comprising at least one power switch matrix comprising a plurality of connector columns and a plurality of connector rows, with the connector rows being connectable to a plurality of power sources and the connector columns being connectable to additional circuitry. The system further comprises a plurality of switches to connect each connector row of the matrix to each connector column of the matrix. In an embodiment, the plurality of power sources comprises an AC mains power supply and at least one diesel generator. In an embodiment, the system includes a controller to control the switching of the switches within the matrix. In an embodiment, the switches are either AC switches or DC switches.

Description

POWER SYSTEM

FIELD OF THE INVENTION

This invention relates to a power system.

BACKGROUND OF THE INVENTION

There exists a requirement to provide electrical power to an electrical grid from various power sources. This requirement has traditionally been there to provide back-up power in the event of a failure of a primary power source. The standard method used today is to connect the electrical grid to be supplied to the primary power source and in parallel have a diesel generator connected as well, as shown in Figure 1 of the drawings. Figure 1 shows a typical low voltage (LV) distribution network 100 comprising 3 basic groups of loads, namely AC loads with no battery back-up 102, AC loads with battery back-up 104, 106 and DC loads with battery back-up 108. DC loads are not normally operated without battery back-up, although this is an option if there is such a requirement.

The loads are supplied from a single AC voltage source V1. In the event that this source should fail, power can be supplied from a diesel generator DG1. However, during the transfer of power to and from DG1 , there will be a momentary power black-out to the loads without battery back-up. Normally these are not critical loads, and such power interruptions can be tolerated. However, some loads draw very high inrush currents when started, and so this short power dip would require such loads to re-start, leading to very high current surges. Thus, where possible, these loads must be sequenced to ensure that they do not all come back on line at the same time. Unless scheduling is implemented, the diesel generator DG1 has to be oversized to cope with this surge in demand. Typical loads that can cause such a surge are air conditioners. The diesel generator DG1 has to be rated to provide the peak power required by the load. Some of the demand peaks can be smoothed by the batteries B1 - Bq and BB1 - BBw, but this is seldom done. The batteries are stand-by batteries, capable of deep discharge but only for a low number of cycles. The batteries are normally not suited for daily use, which would involve deep discharge and then rapid charging.

This type of distribution network 100 is not a high performance network. In particular, it is not fault tolerant, with failure of any one of the major components resulting in either a total system failure or at best a particular load being left without power. The system is not concurrently maintainable, with power to the load having to be interrupted to replace any of the upstream circuit components.

Turning now to Figure 2, an improved LV distribution network 120 is shown, again with respect to AC loads with no battery back-up 122, AC loads with battery back-up 124, 126 and DC loads with battery back-up 128. This network 120 is particularly aimed to make DC loads more fault tolerant. This requirement is often found in the telecommunications industry, where the DC loads comprise critical equipment operating from 48Vdc.

In order to make the supply to the DC components more fault tolerant, a single DC load is fed from two separate reticulation paths, referred to as DC Feed "A" and DC Feed "B". This dual feed is easily implemented using rectifiers E1 - En to provide a DC supply. A simple series diode 130, 132 implementing an "OR" function would ensure that the load always takes power from the feed with the highest DC voltage. The upshot is that the DC load is now operating from a more fault tolerant supply network. To achieve the same for the AC loads, the situation is a bit more complex, and requires the use of solid state switches that can switch rapidly to transfer the load to either one of the feeds. The switches SCR1 and SCR2 are bi- directional solid state switches that can transfer supply of power from either one of the two paths (AC Feed "A" and AC Feed "B") with battery back-up. This makes this part of the system fault tolerant, so that should any of the components in either one of the feeds fail, operation is secured from the remaining path.

In some cases it may be required to add a third switch, SCR3, to transfer the supply of power directly to the grid supply. This makes this part of the system concurrently maintainable. Normally the implementation with SCR1 , SCR2 and SCR3 requires the use of additional electronic control circuitry, with any combination of these switches being used to make the system 120 more fault tolerant and concurrently maintainable.

Finally, more than 1 diesel generator, in this case DG1 and DG2, may be used to make the overall system 120 even more fault tolerant.

The networks in Figures 1 and 2 show the extent of most systems found in industry today, with there being a certain measure of fault tolerance and system maintainability. However, significantly, the cabling or distribution paths are seldom duplicated except close to the load. In Figures 1 and 2, for example, the main cable feeder is a single feed from the primary source V1 as well as from the diesel generators DG1 , DG2.

To build LV distribution networks that are far more fault tolerant and concurrently maintainable, it is necessary to improve the situation dramatically. To make any distribution network more fault tolerant and concurrently maintainable, it is necessary to add more redundancy in terms of all the system components, including the cabling, with, in particular, multiple paths having to be added to the distribution network. Such networks are required in the telecommunications environment, data centres and alternative energy power systems. Alternative energy power systems, for example, make use of sources such as photo-voltaic panels, wind turbines and fuel cells that require a very high level of fault tolerance and concurrent maintainability to be able to provide the level of reliability required of distribution networks in general.

OBJECT OF THE INVENTION

It is therefore an object of the present invention to provide a low-cost power system that can be scaled, provides a high level of reliability and maintainability, and that can integrate various power sources, including primary, secondary and auxiliary power sources, such as wind and/or solar electrical power generators.

SUMMARY OF THE INVENTION

According to a first aspect of the invention there is provided a power system comprising:

at least one power switch matrix comprising a plurality of connector columns and a plurality of connector rows, with the connector rows being connectable to a plurality of power sources and the connector columns being connectable to additional circuitry; and

a plurality of switches to connect each connector row of the matrix to each connector column of the matrix.

In an embodiment, the plurality of power sources comprises an AC mains power supply and at least one AC power source, such as a diesel generator, provided that all of these sources are of the same voltage and frequency and in phase. In an embodiment, the system includes a controller to control the switching of the switches within the matrix.

In an embodiment, the switches are either AC switches or DC switches.

In an embodiment, first and second power switch matrices are connected side by side so that the connector rows of both matrices are connected together, with the rows of the first power switch matrix being connectable to the plurality of power sources and the columns of the adjacent second power switch matrix being connectable to a plurality of AC loads having no battery backup.

Alternatively, the AC loads can be connected directly to the rows of the first power switch matrix, provided that the number of such AC loads are equal to the number of columns in the first power switch matrix.

In an embodiment, the system includes a third power switch matrix, the columns of which are connected to the columns of the first power switch matrix, and the rows of which are connected to a plurality of rectifiers for providing DC current to a fourth power switch matrix.

In an embodiment, the rows of the fourth power switch matrix are connected to the rectifiers, and the columns of the fourth matrix are connected to a plurality of batteries.

In an embodiment, the rows of the fourth power switch matrix are also connected to a plurality of inverters, optionally via a fifth power switch matrix, and then ultimately connected, optionally via a sixth power switch matrix, to AC loads with battery backup.

In an embodiment, the columns of the third power switch matrix are also connected to the columns of a seventh power switch matrix, the rows of which can in turn be connected the rows of an eighth power switch matrix via a plurality of rectifiers, the rows of the eighth power switch matrix ultimately providing power to DC loads with battery backup via a ninth power switch matrix.

According to a second aspect of the invention there is provided a power system comprising:

an input to receive power from a mains power supply;

a first connector arrangement to connect the mains power supply to at least one non-critical load, the first connector arrangement being connectable to at least one auxiliary electrical generator to provide electricity to the at least one non-critical load in the event of the power from the mains power supply being interrupted;

a second connector arrangement to connect the mains power supply to at least one critical load, the second connector arrangement comprising:

a rectifier bank comprising at least one rectifier to rectify electrical current from the mains power supply; and

an inverter bank to invert the rectified electrical current for supply to the at least one critical load.

In an embodiment, the second connector arrangement comprises a battery connector arrangement connectable to a bank of batteries for providing DC power to the inverter bank in the event of the power from the mains power supply being interrupted.

In an embodiment, the second connector arrangement is connectable to the at least one auxiliary electrical generator to provide electricity to the rectifier bank in the event of the power from the mains power supply being interrupted. In an embodiment, the second connector arrangement comprises a solar panel connector arrangement connectable to a bank of solar panels for providing DC power to the inverter bank in the event of the power from the mains power supply being interrupted.

In an embodiment, the second connector arrangement comprises a wind turbine connector arrangement connectable to a bank of wind turbines for providing DC power to the inverter bank in the event of the power from the mains power supply being interrupted.

In an embodiment, the first connector arrangement and the second connector arrangement overlap in a first auxiliary generator switching matrix so as to provide electricity from the mains power supply and the plurality of auxiliary generators to both the first and second connector arrangements.

In an embodiment, the first auxiliary generator switching matrix comprises:

connector rows extending from the mains power supply and the at least one auxiliary generator to the at least one non-critical load;

connector columns that are connected to the rectifier bank for rectifying the current provided by the at least one auxiliary generator and mains power supply; and

switches operable to connect each connector row to each connector column.

In an embodiment, the system includes a second auxiliary generator switching matrix comprising:

connector rows extending from the connector rows of the first auxiliary generator switching matrix; connector columns that are ultimately connectable to the at least one non-critical load; and

switches operable to connect each connector row to each connector column.

In an embodiment, the second connector arrangement comprises a second switching matrix comprising:

connector columns that are connected to the rectifier bank;

connector rows; and

switches operable to connect each connector row to each connector column.

In an embodiment, the battery connector arrangement comprises a battery switching matrix comprising:

connector columns that are connectable to the bank of batteries;

connector rows that are connectable to the connector rows of the second switching matrix; and

switches operable to connect each connector row to each connector column.

In an embodiment, the switches of the battery switching matrix are operable to switch direct current out of the system to the bank of batteries and for switching direct current into the system from the bank of batteries when needed. In an embodiment, the solar panel connector arrangement comprises a solar panel switching matrix comprising:

connector columns that are connectable to the bank of solar panels;

connector rows that are connectable to the connector rows of the battery switching matrix; and

switches operable to connect each connector row to each connector column.

In an embodiment, the wind turbine connector arrangement comprises a wind turbine switching matrix comprising:

connector columns that are connectable to the bank of wind turbines;

connector rows that are connectable to the connector rows of the solar panel switching matrix; and

switches operable to connect each connector row to each connector column.

In an embodiment, the system includes a controller for operating the switches.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows one version of a typical LV distribution system;

Figure 2 shows an improved version of a typical LV distribution system;

Figure 3 shows a first power switch matrix building block, according to an embodiment of the present invention; Figures 4 to 13 sequentially show additional power switch matrices and associated components being added to the first power switch matrix shown in Figure 3, to ultimately define a power system according to an embodiment of the invention to supply power to

AC loads with no battery back-up, AC loads with battery backup, and DC loads with battery back-up;

Figure 14 shows a system topology corresponding to the power system shown in Figure 13;

Figure 15 shows an alternate system topology according to a further embodiment of the present invention;

Figure 16 shows a system topology, according to yet a further embodiment of the present invention, for implementing the LV distribution system shown in Figure 1 ;

Figure 17 shows a schematic diagram of a system controller, according to an embodiment, for controlling the components of the power system of the present invention;

Figures 18 to 23 show various system topologies for particular use in telecommunications base station applications; and

Figure 24 shows a circuit diagram for a power system according to yet a further embodiment of the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

Referring first to Figure 3, a first power switch matrix 150 comprises m columns and n rows. The rows are connected to a plurality of power sources. For example, row 1 is connected to a single grid supply AC voltage source V1 , with subsequent rows each being connected to a diesel generator DG 1 - DGn. Thus, in this case, there are (n-1) generators.

Each column of the matrix 150 is connectable to each row with AC switches, the switches being controllable by a controller which will be described in more detail below with reference to Figure 18. Thus, row 1 comprises switches S11 to S1m, row 2 comprises switches S21 to S2m etc., with ultimate row n comprising switches Sn1 to Snm.

Each of the AC switches within the matrix 150 can be implemented electronically with a bi-directional thyristor arrangement 152. Alternatively, each AC switch may comprise a conventional electromechanical contactor 154. The thyristor version 152 advantageously offers rapid switching without interrupting the flow of power to the load, which as will be seen, can be ultimately connected to any of the rows or columns of the matrix 150. The electromechanical version 154 does not provide this advantage, and so would not be used for critical loads where the flow of power is critical.

Turning now to Figure 4, a second power switch matrix 160 may be added to the first matrix 150 as shown. The second matrix 160 thus comprises n rows and p columns, each of the p columns being connected or associated with an AC load group 162 having no battery backup. As with the first matrix 150, each column of the matrix 160 is connectable to each row with AC switches. Thus, the second matrix 160 is added to connect p AC loads to the (n-1) feeds supplied by the (n-1) diesel generators DG1 - DGn and mains voltage source V1. In this embodiment, the second matrix 160 is required to allow the n to p connection, with n not being equal to p, and to provide a multipath connection from each AC load 162 to the diesel generators DG1 - DGn and mains power source V1. A given AC load 162 can thus be connected to any one of the mains voltage source V1 and diesel generators DG1 - DGn. With the addition of the second matrix 160 to the first matrix 150, the power supply network to the AC loads 162 is completely concurrently maintainable and fault tolerant. There are now a number of feed paths to each AC load 162, with only one active feed at any one time, thus providing maximum compliance with the requirement to be concurrently maintainable. In addition, fault tolerance is provided in terms of the cabling and the diesel generators. There are more generators than required, with there being multiple cables to feed any load.

With reference now also to Figure 5, it should be appreciated that in one version, the second matrix is not required. Thus, in this version, the AC loads 162 are connected directly to the n feeds from the AC power supply sources, namely the (n-1) diesel generators and mains power supply V1 , provided that there are n AC loads as well. The arrangement shown in Figure 5 thus offers a limited implementation of the power supply of the present invention. Clearly, there are no redundant paths to each load, with each load being connected to a single AC power supply source. This version is shown to illustrate the flexibility of the power supply of the invention, in that it allows certain loads to be connected in the normal way, namely a single AC source to a single AC load 162. For example, in a particular application, it may not be necessary to provide a fully tolerant, concurrently maintainable distribution system for the AC loads 162, with the arrangement shown in Figure 5 illustrating one version of achieving this.

Turning now to Figure 6, a third power switch matrix 170 may be added to the first matrix 150 as shown. The third matrix 170 thus comprises m columns and q rows, the q rows being connected or associated with rectifiers A1 - Aq 181 , the use of which will become apparent further on below. Again, each column of the matrix 170 is connectable to each row with AC switches.

Turning now to Figure 7, a fourth power switch matrix 180 may be added to the third matrix 170 as shown. The fourth matrix 180 thus comprises q rows and r columns so as to connect the q rectifiers A1 - Aq 181 to r batteries 182. This arrangement allows for the individual charging of the r batteries 182, with a given rectifier 181 being used to charge a given battery without any further connection to that battery. Advantageously, this allows the rectifier 181 to control the voltage and current supplied to the load to match the required charge profile of the battery, without the voltage or current being disturbed by the requirements of a load connected to the same battery.

Although not shown in this figure, but as will be explained in more detail further below, additional sources of DC power may be added to the batteries 182. These may include photo voltaic cells as well as wind turbines, with each of these sources typically having its own switching matrix to switch these sources into circuit.

Again, each column of the matrix 180 is connectable to each row with AC switches. In this case, however, the fourth matrix 180 defines a DC matrix, with each DC switch taking the form shown by arrow 184. This arrangement is required because power has to be transferred between batteries with differing voltages - if this arrangement is not used, a short circuit would result with very high current pulses. To disconnect a battery, the switch 186 in parallel with diode 188 is open, with the battery that has to be connected then being connected by closing top switch 190. Then for the battery being disconnected, switch 186 is opened, and then finally the same switch 186 is closed for the battery being connected.

With reference now to Figure 8, in one version of the invention, the q rows of fourth matrix 180 may be connected to q inverters INV1 - INVq 184. Thus, if the number of rectifiers equals the number of inverters, a direct connection can be made. This connection, however, does not offer a fault tolerant connection between the rectifiers and the inverters, since there is only a single connection between each rectifier and inverter. In addition, concurrent maintenance is also not possible and so, for example, to replace an inverter, the connection between the inverter has to be deactivated. Turning now to Figure 9, a preferred alternative to the arrangement shown in Figure 8 includes a fifth power switch matrix 200 added to the fourth matrix 180. The fifth matrix comprises q rows and s columns, so as to connect s inverters INV1 - INVs 202 to r batteries 182 and q rectifiers 181. This provides a fully fault tolerant and concurrently maintainable distribution path to inverters 202. Thus, a given inverter can only be connected to a particular battery, with another inverter only be connectable to another particular battery. In other words, battery charging can be achieved from a given rectifier without having to connect an inverter to that particular battery. Advantageously, this allows for warranty compliant battery charging.

Figure 9A is substantially similar to Figure 9, except that s AC loads 204 may be connected to the s inverters INV1 - INVs 202.

Turning now to Figure 10, a sixth power switch matrix 210 may be added to the fifth matrix 200 as shown. The sixth matrix 210 thus comprises s columns connected to the s inverters 202 and t rows connected to t AC loads 212 requiring battery backup power, so as to connect the s inverters 202 to the t AC loads 212. Again, each column of the matrix 170 is connectable to each row with AC switches. This connection now completes a second part of the distribution system, namely AC loads with battery backup. Thus the arrangement shown in Figure 10 can supply power to normal AC loads 162 that do not require battery backup (i.e. non-critical loads) and AC loads 212 that do require battery backup (i.e. critical loads). In both cases, the distribution network is fully fault tolerant and concurrently maintainable.

Turning now to Figure 11 , a seventh power switch matrix 220 may be added to the third matrix 170 as shown. The seventh matrix 220 thus comprises m columns and u rows, the u rows being connected or associated with rectifiers A1 - Au 222, the use of which will become apparent further on below. Again, each column of the matrix 220 is connectable to each row with AC switches. Turning now to Figure 12, an eighth power switch DC matrix 230 may be added to the seventh matrix 220 as shown. The eighth matrix 230 thus comprises u rows and v columns so as to connect the u rectifiers A1 - Au 222 to v batteries 232. As indicated, this arrangement allows for the individual charging of the v batteries 232, with a given rectifier 222 being used to charge a given battery without any further connection to that battery.

Again, although not shown in this figure, additional sources of DC power may be added to the batteries 232, with each of these sources typically having its own switching matrix to switch these sources into circuit.

Turning now to Figure 13, a ninth power switch matrix 240 may be added to the eighth matrix 230 as shown. The ninth matrix 240 thus comprises v rows and w columns so as to connect w DC loads without battery backup 242 to the v batteries 232 and u rectifiers 222. This provides a fully fault tolerant and concurrently maintainable distribution network to these loads 242.

Figure 14 shows a system topology corresponding to the power system shown in Figure 13, the components of which have been numbered similarly and thus need not be explained in any further detail.

Figure 15 shows an alternate system topology according to a further embodiment of the present invention. The components that are the same as those shown and described with respect to Figure 13 have been numbered similarly, and will thus not be explained in any further detail. The difference relates to the AC loads with battery backup 212, in which the rectifier 181 , battery 182 and inverter arrangement 202 are all combined into a UPS device 250 comprising a built in battery.

Figure 16 simply shows how the matrices of the present invention may be used to implement the prior art LV distribution system shown in Figure 1. Again, identical components as those described above have been numbered the same. A number of changes need to be made, for example, new matrices 252, 254, 256, 258, 260, 262, 264 and 266.

Figure 17 shows a schematic diagram of a system controller 280, according to an embodiment, for controlling the components of the power system of the present invention. The system controller 280 comprises an AC power switch controller 282 to control the AC switches in the AC matrices 150, 160, 170, 210 and 220. In addition, the system controller 280 comprises a DC power switch controller 284 to control the DC switches in the DC matrices 180, 200 and 230.

In particular, the AC power switch controller 282 comprises a switch interface 286 to control the switches within the AC matrices and a plurality of peripheral interfaces 288 to control switching to peripheral devices such as the diesel generators, the inverters, the rectifiers and AC metering devices.

Similarly, the DC power switch controller 284 comprises a switch interface 290 to control the switches within the DC matrices and a plurality of peripheral interfaces 292 to control switching to peripheral devices such as battery monitors, the inverters, the rectifiers, DC metering devices and a photo voltaic regulator.

Various system topologies for particular use in telecommunications base station applications will now be described with reference to Figures 18 to 23. Again, for the sake of brevity, similar components to those described above will be labeled similarly and not described in any further detail.

Figure 18, for example, shows the second matrix 160 providing power to an AC load not requiring backup, such as air conditioners. Seventh, eighth and ninth matrices 220, 230 and 240 are also provided in this embodiment to provide power to DC loads with battery backup. Figure 19 is substantially similar to Figure 18, except that instead of providing a grid supply AC voltage source and (n-1) generators, the grid supply AC voltage source is omitted and so there would then be n generators in place.

5 The versatility of the power supply system of the present invention has already been described, with Figure 20 confirming this by omitting the seventh matrix 220 found in Figure 19.

As already mentioned above, additional sources of DC power may be used to

I O provide power. For example, Figure 21 shows a photo voltaic cell 300 providing power via an eleventh DC matrix 302, a photo voltaic regulator 304 and a tenth DC matrix 306 into an eighth DC matrix 308 which is simultaneously also receiving power form matrix 150 via rectifier 222. The eighth DC matrix 308 may in turn be connected to battery 232 and a DC load

15 with battery backup 242 via ninth matrix 310.

A slight modification to the circuit shown in Figure 21 is shown in Figure 22, in which the sole source of energy is the photo voltaic cell 300. A slightly modified matrix 312 is required between the regulator 304 and the eighth 0 matrix 308, otherwise this circuit operates as described above.

A simplified version of the circuit shown in Figure 22 is shown in Figure 23 in which the photo voltaic cell 300 is connected straight into the eighth matrix 308 via regulator 304. The eighth matrix 308 may then be directly connected to the 5 DC load with battery backup.

One particular implementation of the power supply system of the present invention will now be described with reference to Figure 24. In this figure, a power system 410 comprises an input 412 to receive power from a mains AC 0 power supply 414. A first connector arrangement, indicated by block 416, connects the mains power supply 414 to a plurality of non-critical loads 418, 420, 422 and 424. The first connector arrangement 416 is also connectable to a plurality of auxiliary electrical generators 426, 428, 430 and 432, typically diesel generators, to provide electricity to the non-critical loads 418, 420, 422 and 424 in the event of the power from the mains power supply 414 being interrupted.

The non-critical loads 418, 420, 422 and 424 are loads that can operate with brief interruptions of power.

The system 410 further comprises a second connector arrangement, indicated by block 434 to connect the mains power supply 414 to a plurality of critical loads 436, 438, 440 and 442. The second connector arrangement 434 comprises a rectifier bank 444 comprising rectifiers 446, 448, 450 and 452 to rectify electrical current from the mains power supply 414.

The second connector arrangement 434 further comprises an inverter bank 454 with inverters 456, 458, 460 and 462 to invert the rectified electrical current for supply to the critical load 436, 438, 440 and 442.

The second connector arrangement 434 comprises a battery connector arrangement 464 connectable to a bank of batteries 466, 468, 470 and 472 for providing DC power to the inverter bank 454 in the event of the power from the mains power supply 414 being interrupted.

In an embodiment, the second connector arrangement 434 is connectable to the diesel generators 426, 428, 430 and 432 to provide electricity to the rectifier bank 444 in the event of the power from the mains power supply 414 being interrupted.

The second connector arrangement 434 may further comprise a solar panel connector arrangement 474 connectable to a bank of solar panels 476, 478 and 480 for providing DC power to the inverter bank 454 in the event of the power from the mains power supply 414 being interrupted. The second connector arrangement 434 may yet further comprise a wind turbine connector arrangement 482 connectable to a bank of wind turbines 484, 486 and 488 for providing DC power to the inverter bank 454 in the event of the power from the mains power supply 414 being interrupted.

As clearly shown in Figure 1 , the first connector arrangement 416 and the second connector arrangement 434 overlap in a first auxiliary generator switching matrix 490. This arrangement ensures that electricity from the mains power supply 414 and the diesel generators 426, 428, 430 and 432 can be provided to both the first and second connector arrangements 416, 434.

In an embodiment, the first auxiliary generator switching matrix 490 comprises connector rows extending from the mains power supply 414 and the diesel generators 426, 428, 430 and 432 to, ultimately, the non-critical loads 418, 420, 422 and 424. The matrix 490 further comprises connector columns that are connected to the rectifier bank 444 for rectifying the current provided by the generators 426, 428, 430 and 432 and the mains power supply 414. Switches are provided that are operable to connect each connector row to each connector column within this matrix 490.

The power system 410 may further comprise a second auxiliary generator switching matrix 492 comprising connector rows extending from the connector rows of the first auxiliary generator switching matrix 490, connector columns that are ultimately connectable to the non-critical loads 418, 420, 422 and 424, and swi tches operable to connect each connector row to each connector column.

In an embodiment, the second connector arrangement 434 comprises a second switching matrix 494 comprising connector columns that are connected to the rectifier bank 444, connector rows and switches operable to connect each connector row to each connector column. The battery connector arrangement 464 comprises a battery switching matrix comprising connector columns that are connectable to the bank of batteries 466, 468, 470 and 472, connector rows that are connectable to the connector rows of the second switching matrix 494 and switches operable to connect each connector row to each connector column. In use, the switches of the battery switching matrix are operable to switch direct current out of the system 410 to the bank of batteries 466, 468, 470 and 472 and for switching direct current into the system 410 from the bank of batteries 466, 468, 470 and 472 when needed.

It will be noted that the batteries 466, 468 and 470 are connectable to each row within the battery switching matrix, thus allowing it to provide DC current to any of the rows, and thus ultimately to any of the inverters in the inverter bank 454.

The solar panel connector arrangement 474 comprises a solar panel switching matrix comprising connector columns that are connectable to the bank of solar panels 476, 478 and 480, connector rows that are connectable to the connector rows of the battery switching matrix, and switches operable to connect each connector row to each connector column.

Similarly, the wind turbine connector arrangement 482 comprises a wind turbine switching matrix comprising connector columns that are connectable to the bank of wind turbines 484, 486 and 488, connector rows that are connectable to the connector rows of the solar panel switching matrix, and switches operable to connect each connector row to each connector column.

Since the bank of batteries 466, 468, 470 and 472 may be directly switched into circuit, it is possible to ensure that the power supplied to the critical loads 436, 438, 440 and 442 is never interrupted. While the diesel generators 426, 428, 430 and 432 may take some time to start-up and supply power in the event of a mains 414 power failure, the power supplied via rows of the second connector arrangement 434 is continuously available and will ensure that the critical loads 436, 438, 440 and 442 are always supplied with power.

The presence of additional sources of power, namely solar panels 476, 478 and 480 and wind turbines 484, 486 and 488 provide redundancy.

The overall system 410 has an extremely high level of availability and reliability, with it being possible to disconnect any of the elements from the overall system 410 without interrupting the overall supply.

Another advantage is that the system capabilities can be expanded without interruption of power to the existing loads. Using the switch matrix arrangement, another number of diesel generators can be connected and tested without interrupting the power supply to the loads. The same applies to the batteries, solar panels and wind generators. More loads can also be connected in the same way.

Another advantage is that the system costs less than a system of comparable size using large single or double generators. In this regard, an example costing was done for a 2MW system. The first design used the traditional system where two generators rated at 2MW were specified. When the matrix system was used, using a multiplicity of smaller units, the overall installed power was increased to 8MW at a third of the cost. Also, the reliability figure for the matrix system is much higher that for the dual installation using low cost small units. For example, if the reliability of a single 2MW diesel generator is 90% per generator, this means that, statistically speaking, 10 out of 100 times when required to start, the generator would fail to start. If a second generator is installed of the same power to provide power if the first fails to start, it would mean that the probability of a failure would be halved, thus ensuring that the failure is reduced to 5 times out of a 100 starts. In many applications the reliability is of utmost importance, often requiring figures of 1 in 100 failures. Generators capable of this level of performance are very expensive. However, in the example stated, the matrix system provided 8MW of installed power for a requirement of 2MW. This meant that power to the load would be compromised if more than 75% of the generators failed to start. Or put in another way, if any one generator failed to start, there were three more to take its place. This means that the reliability figure for each individual generator could be reduced. Because the probability of a failure is the product of the individual failure probabilities, this means that if the matrix system is used with at four times the required power requirement, each generator could have a failure rate of 10 out of a hundred and the overall failure rate of the system would be 0.1 x 0.1 x 0.1 x 0.1 = 0.00001 , and this is a figure that require 2MW generators with a failure rate of 0.001 , or 1 failures out of 1000 starts. These would be very expensive generators. Or another alternative to compare with would be to use 4 x 2MW generators with a failure per generator of 0.01 , still an expensive prospect.

By designing a power system in a matrix configuration, the present invention provides scalability and increased reliability due to the high number of redundant units.

Claims

1. A power system comprising:

2. The power system of claim 1 , wherein the plurality of power sources comprises an AC mains power supply and at least one diesel generator.

3. The power system of either claim 1 or claim 2, which includes a controller to control the switching of the switches within the matrix.

4. The power system of any one of the preceding claims, wherein the switches are either AC switches or DC switches.

5. The power system of any one of the preceding claims, wherein first and second power switch matrices are connected side by side so that the connector rows of both matrices are connected together, with the rows of the first power switch matrix being connectable to the plurality of power sources and the columns of the adjacent second power switch matrix being connectable to a plurality of AC loads having no battery backup.

6. The power system of claim 5, which includes a third power switch matrix, the columns of which are connected to the columns of the first power switch matrix, and the rows of which are connected to a plurality of rectifiers for providing DC current to a fourth power switch matrix.

7. The power system of claim 6, wherein the rows of the fourth power switch matrix are connected to the rectifiers, and the columns of the fourth matrix are connected to a plurality of batteries.

8. The power system of claim 7, wherein the rows of the fourth power switch matrix are also connected to a plurality of inverters, optionally via a fifth power switch matrix, and then ultimately connected, optionally via a sixth power switch matrix, to AC loads with battery backup.

9. The power system of claim 8, wherein the columns of the third power switch matrix are also connected to the columns of a seventh power switch matrix, the rows of which can in turn be connected the rows of an eighth power switch matrix via a plurality of rectifiers, the rows of the eighth power switch matrix ultimately providing power to DC loads with battery backup via a ninth power switch matrix.

10. A power system comprising:

an input to receive power from a mains power supply;

a first connector arrangement to connect the mains power supply to at least one non-critical load, the first connector arrangement being connectable to at least one auxiliary electrical generator to provide electricity to the at least one non- critical load in the event of the power from the mains power supply being interrupted;

a second connector arrangement to connect the mains power supply to at least one critical load, the second connector arrangement comprising: a rectifier bank comprising at least one rectifier to rectify electrical current from the mains power supply; and

11. The power system of claim 10, wherein the second connector arrangement comprises a battery connector arrangement connectable to a bank of batteries for providing DC power to the inverter bank in the event of the power from the mains power supply being interrupted.

12. The power system of claim 11 , wherein the second connector arrangement is connectable to the at least one auxiliary electrical generator to provide electricity to the rectifier bank in the event of the power from the mains power supply being interrupted.

13. The power system of claim 12, wherein the second connector arrangement comprises a solar panel connector arrangement connectable to a bank of solar panels for providing DC power to the inverter bank in the event of the power from the mains power supply being interrupted.

14. The power system of claim 13, wherein the second connector arrangement comprises a wind turbine connector arrangement connectable to a bank of wind turbines for providing DC power to the inverter bank in the event of the power from the mains power supply being interrupted.

15. The power system of claim 14, wherein the first connector arrangement and the second connector arrangement overlap in a first auxiliary generator switching matrix so as to provide electricity from the mains power supply and the plurality of auxiliary generators to both the first and second connector arrangements.

16. The power system of claim 15, wherein the first auxiliary generator switching matrix comprises:

switches operable to connect each connector row to each connector column.

17. The power system of claim 16, which includes a second auxiliary generator switching matrix comprising:

connector rows extending from the connector rows of the first auxiliary generator switching matrix;

connector columns that are ultimately connectable to the at least one non-critical load; and

switches operable to connect each connector row to each connector column.

18. The power system of claim 17, wherein the second connector arrangement comprises a second switching matrix comprising:

connector columns that are connected to the rectifier bank; connector rows; and

switches operable to connect each connector row to each connector column.

19. The power system of claim 18, wherein the battery connector arrangement comprises a battery switching matrix comprising:

connector columns that are connectable to the bank of batteries;

switches operable to connect each connector row to each connector column.

20. The power system of claim 19, wherein the switches of the battery switching matrix are operable to switch direct current out of the system to the bank of batteries and for switching direct current into the system from the bank of batteries when needed.

21. The power system of claim 18, wherein the solar panel connector arrangement comprises a solar panel switching matrix comprising:

connector columns that are connectable to the bank of solar panels;

switches operable to connect each connector row to each connector column.

22. The power system of claim 21, wherein the wind turbine connector arrangement comprises a wind turbine switching matrix comprising:

connector columns that are connectable to the bank of wind turbines;

switches operable to connect each connector row to each connector column.

23. The power system of claim 22, which includes a controller for operating the switches.