Patent Application
20160238282
This disclosure relates generally to the power and communication delivery system for heliostats having reflectors for use in redirecting sun light to a target or receiver. In particular, the invention relates to a heliostat field having wiring loops and network topology to facilitate a system with multiple stages of redundancy.
In Concentrating Solar Power (CSP) plants, arrangements of heliostats reflect sunlight toward a receiver mounted atop a tower containing a working fluid. One type of receiver transfers incident radiant energy to the working fluid to produce high-pressure, high-temperature steam through the means of a heat exchanger or a phase change of the working fluid itself. The working fluid can be water, air, or a salt material heated to a molten state. The output steam can facilitate a variety of applications, such as electrical power generation, enhanced oil recovery, and desalination. Heliostats are generally mounted on the ground in an area about the tower. Each heliostat has a rigid reflective surface, such as a mirror, capable of sun-tracking, wherein the reflective surface takes on orientations throughout the day so as to optimally redirect sun light from the sun toward the receiver. Arrays of heliostats may be arranged into a plurality of subgroups comprising a field. The subgroups may be configured to provide a preferred orientation that facilitates efficient land usage, optimizes the amount of flux delivered to the receiver, and minimizes the blocking of outer heliostats by inner heliostats.
One approach to constructing a heliostat field is to utilize a small amount of comparatively large heliostats (e.g., greater than between about 50 and 150 m2). In such a power plant, the fewer number of heliostats can make it economical to manufacture very precise, and thus very expensive, components for the positioning of the reflective surfaces. Another approach, however, is to use a large amount of comparatively small heliostats (e.g., between about 1 and 10 m2), such as with reflective surfaces that measure between about 1 meter and 3 meters on each side. Such an approach may be more efficient at redirecting sun light because there are more individually adjustable reflective surfaces. In addition, smaller heliostats are easier to assemble, thereby decreasing installation time and the amount of requisite labor
Heliostats may be controlled by a drive comprising a one or two-axis tracker that tracks the sun and reflects sunlight onto a target. Heliostats may comprise drive control boards that accept commands from a controller and operate one or more actuators, such as motors. A heliostat may have a data and a power connection in order to direct the drive to a desired orientation. The power connection provides an energy path to the actuators and control boards of the heliostat drive. The data connection provides a communication pathway to the heliostat drive from a central or distributed controller. Power and communication connections may be provided using field cabling wired from central power distribution units and networking hubs, respectively, to individual heliostats in the field.
The routing of field cabling to thousands of actuating devices presents unique challenges and opportunities for improvement. Rows or subgroups of heliostats may receive power from a single bus while drive control boards may be connected in series to establish a communications network. Heliostats may have their data and communication delivery cables chained together, such that the same transmission line supplies power and facilitates data throughput to multiple units in a single subgroup. Such a configuration presents the possibility of cutting power and communication to an entire subgroup or a substantial portion thereof in the event a single component in the chain malfunctions. Components that could fail during the lifetime of the plant include, but are not limited to: connector wires, data and power transmission cables, power supplies, transceivers, and network switches. There exists a need to reduce the vulnerability of heliostat electronics topology to single point failures by incorporating redundant data and communication transmission pathways.
A system for powering and controlling a heliostat field is described herein, wherein the system comprises a power and communication network topology having multiple transmission pathways looped between adjacent heliostat subgroups. The system is thereby configured to advantageously reduce the impact of single point failures on plant operation.
The power and communication distribution network comprises both electronics hardware and controller software configured to operate said hardware. Heliostats in a field may be positioned into subgroups oriented to reflect sunlight onto one of a plurality of solar receivers and may be deployed in rows or other suitable arrangements. Each heliostat comprises a reflector and a controller. The controllers in adjacent heliostats in a row may be connected to each other via inter-drive cable, wherein an inter-drive cable facilitates both communication and power-delivery via constituent wiring.
A single heliostat in each row may be connected to a Communication Interface Module (CIM), the CIM being capable of interfacing in this manner with up to four heliostat rows simultaneously. This single heliostat may be the heliostat in the row that is closest to the CIM or closest to the end of the row. Each communication interface module is configured to pass along power and data communication to each connected heliostat in a row. The CIM may be further connected by way of field-routed cables to an Intelligent Power Distribution Unit (IPDU) housed in a Field Electrical Cabinet (FEC). Each IPDU may comprise a plurality of Intelligent Power Distribution Cards (IPDCs). Each CIM may be connected to a plurality of IPDCs; in this manner a single IPDU can deliver data and power to multiple CIMs. In a particular embodiment of the present invention, a CIM may be connected to adjacent IPDCs housed in the same IPDU. In an alternative embodiment, a CIM may be connected to IPDCs in different IPDUs. IPDCs in an IPDU may have network connections to each other, for instance adjacent IPDCs in an IPDU may be connected. Each IPDC in an IPDU may have a further connection by way of data-transmission cabling to a port of one of a plurality of network switches, the network switches being connected to each other in series via auxiliary data connectors and also to a plant network. The plant network may comprise additional communication pathways to a master power plant controller as well as monitoring systems. Commands issued to individual heliostats may originate from a control system within the plant network and may be delivered via the communication distribution topology described herein.
As described previously, a centralized power and data distribution network for controlling thousands of individual heliostats is vulnerable to single point component failures. In order to increase the reliability of the system, power and communication loops may be created to provide redundant pathways for distribution in the event of aberrant breakdowns or power loss. One such redundancy may be created with the provision that no two adjacent IPDCs in an IPDU will be connected to the same network switch. If a connection between network switches fails, the IPDCs in an IPDU can still access the Plant Network through an auxiliary switch.
As described above, each CIM may supply power and data communication to up to four rows of heliostats by interfacing with the inter-drive cable from the heliostat at the proximate end of each row. DC power may be delivered from a DC power source in the plant electrical network to an IPDU, where it is then transmitted to the CIM and the Drive Control Boards (DCBs) in the heliostats. Heliostats in a pair of adjacent rows may be connected in parallel to form a power transmission loop. Data may be delivered to and from the plant network through the network switches to an IPDU, where it is then transmitted between the IPDCs and CIM and finally between the CIM and the DCBs in the heliostats.
In a preferred embodiment, the CIM may have one microcontroller per row to provide data communication (four microcontrollers in total). Each CIM microcontroller may provide a data communication pathway between a communication port on the IPDC (via field cable) and the first heliostat in a row (via inter-drive cable). The cables may be connected such that heliostats in adjacent rows connect to communication ports on different IPDCs. Additionally the outermost DCBs (furthest from the CIM) of two adjacent heliostat rows may be connected to each other via inter-drive cabling to create a power and communication transmission loop. In this manner data communication pathways are never interrupted by the failure of single component. In the event of a microcontroller failure, malfunctioning transceiver, or damaged microcontroller power supply, data may still be transmitted to the heliostats of all four rows. The result is an added element of redundancy to the system to mitigate the effects of component failures. In an alternative embodiment a single CIM may be used to facilitate data transfer to less than four heliostat rows.
Each IPDU 102 is a chassis for housing a plurality of modular IPDCs 103, wherein each IPDC comprises an electronics board for delivering power and data communication to four microcontrollers 110 in a CIM 109. Adjacent IPDCs within an IPDU may have network connections 120 to each other. The CIM acts as a “pass-through”, passing power and data to the DCBs 108 of heliostats in the heliostat field. Heliostats are mounted on structures 114 having an alternating tripod pattern, wherein the tripod configuration comprises members of two adjacent heliostat rows.
Power and data connections between the CIMs and the IPDCs are made via field cables 118. Power and data connections between the CIMs and heliostats, between adjacent heliostats in a heliostat row, and between heliostats in adjacent rows are made via inter-drive cables. Both field cables and inter-drive cables comprise communication delivery wires 111 and power delivery wires 112. The field cables comprise one set of power delivery wires and two sets of communication delivery wires. The inter-drive cables comprise one set of power delivery wires and one set of communication wires. Field cables and inter-drive cables may comprise different gauge wires. For instance, the field cables may have a higher gauge wire than the inter-drive cables. In field cables and inter-drive cables both types of wire may be sheathed to form a single cable. Inter-drive cables may comprise coupling connectors on at least one end that can attach to compatible coupling connectors connected to DCBs 108 installed in the heliostats. Communication delivery wires 111 may be twisted pair wires or single-ended wires and may be shielded, for example with plastic material. All data communication pathways are bi-directional, for example the DCBs may send data up to the Plant Network via the CIM and IPDCs.
As described previously, field cables 118 connect the IPDCs 103 to a plurality of CIMs 109. Each IPDC comprises an electronics board, a microcontroller, two data communication ports, and PCB connectors for connecting to power delivery wires and communication delivery wires in a field cable. An IPDC may have the additional functions of converting data communication signals to and from the plant network and of monitoring power distribution. Each data communication port on an IPDC connects to one of two sets of communication delivery wires in a field cable. Each CIM comprises an electronics board, microcontrollers 110, and PCB connectors 119 for passing through power and data communications from the IPDCs 103 to the DCBs 108. The CIMs facilitate the field termination of field cables from the IPDC and the inter-drive cables from the heliostats and may comprise resistors for minimizing signal reflection over long transmission distances. In a preferred embodiment, each CIM interfaces with four rows of heliostats by connecting to four separate DCBs via inter-drive cables. Communication delivery wires 111 in the inter-drive cables connect a microcontroller 110 in a CIM to the first heliostat of a row, wherein the first heliostat is the closest heliostat to the CIM of the heliostats in the row. The communication delivery wires 111 in the first field cable connect to the CIM microcontrollers for rows N and N+2. The communication delivery wires 111 in the second field cable connect to the CIM microcontrollers for rows N+1 and N+3.
In a preferred embodiment, the outermost DCBs 108 of two adjacent heliostat rows may be connected via inter-drive cabling to create a communication transmission loop 113 or 117. Adjacent DCBs in a heliostat row or between heliostat rows are connected to each other in a “daisy chain” for the purposes of data transmission. As visible in
In a preferred embodiment, the outermost DCBs 108 of two adjacent heliostat rows may be connected via inter-drive cabling to create a power transmission loop 115 or 116. Adjacent DCBs in a heliostat row or between heliostat rows may be connected to each other in a “daisy chain” for the purposes of power transmission. As visible in
The present application claims priority to and the benefit of U.S. Provisional Patent Application No. 61/976,906, filed on Apr. 8, 2014, the entire disclosure of which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61976906 | Apr 2014 | US |
