AU2012371202A1

AU2012371202A1 - Variable speed gas turbine generation system and method

Info

Publication number: AU2012371202A1
Application number: AU2012371202A
Authority: AU
Inventors: Velayudhan Nayar Chemmangot
Original assignee: Regen Technologies Pty Ltd
Current assignee: Regen Technologies Pty Ltd
Priority date: 2012-02-20
Filing date: 2012-02-20
Publication date: 2014-10-09
Also published as: US20150108759A1; WO2013123546A1

Abstract

A power generation system comprises a heat collector, a turbine generator system having a turbine and at least one doubly fed induction generator, a heat exchanger, a gas holding tank, an energy storage unit and a load. The heat collector is coupled to and in fluid communication with the heat exchanger, which is in turn coupled to the turbine of the turbine generator system. The turbine is coupled to the doubly fed induction generator, which is then coupled to the load. A controller is communicatively coupled to the at least one doubly fed induction generator for maintaining a constant electrical output and frequency. Depending upon the electrical output load, the doubly fed induction generator can operate in varying speeds to achieve efficiency. To enhance the expansion of the gas, the turbine generator system can further include a pre-heater for preheating the gas to be heated and expanded by the heat exchanger.

Description

WO 2013/123546 PCT/AU2012/000153 VARIABLE SPEED GAS TURBINE GENERATION SYSTEM AND METHOD TECHNICAL FIELD 5 [0001] The present disclosure relates to efficient power generation systems and method. The power generation system and method of this disclosure are tailored to achieve power efficiency. By using at least one doubly fed induction generator driven by a turbine of a turbine generator system, power is generated at varying speeds, which increases efficiency of the power generation system. 10 BACKGROUND [0002] Power generation is achieved by use of generators which supply alternating current (AC) power. In most configurations of power generation systems, two or more generators 15 are used to meet the power demand. The AC power is converted to direct current (DC) power by way of a bank of rectifiers. Additionally, these rectifiers charge a bank of energy storage units that is used to bridge the switching from one generator to another generator so as to ensure a smooth supply of energy. The generators used in power generation systems are varied based upon the fuel used to operate the generators. Some examples of generators include nuclear 20 powered generators, diesel powered generators and those dependent upon fossil fuels as the energy source. [0003] In many applications of electrical generator systems, steady state load demand is usually low relative to generator power capacity. However, generators for use in power 25 generation are selected based upon their peak performance and this leads to an 'over-sized' generator most of the time. This in turn leads to excessive usage of fuel which may have adverse effects on the environment. Although there are solar energy based generators which utilizes solar energy to generate power, these are not reliable as the lack of adequate solar energy can result in the generators operating at a lower efficiency. 30 WO 2013/123546 PCT/AU2012/000153 [0004] Therefore, there is a need for power generation systems which are reliable and at the same time, reduce adverse environmental effects. 5 SUMMARY [0005] One of the objects of certain exemplary aspects of the present disclosure is to address the aforementioned exemplary problems and/or to overcome the exemplary deficiencies commonly associated with power generation systems as described herein. Accordingly, provided 10 and described herein are certain exemplary embodiments of exemplary power generation systems and methods for improving power generation efficiency. [0006] According to one aspect of this disclosure, there is provided a power generation system comprising a heat collector for receiving heat energy to heat up a fluid. The heat energy 15 is generated by at least one of a heat source. The power generation system further includes a turbine generator system comprising a turbine and at least one doubly fed induction generator and a heat exchanger configured to receive the heated fluid for heating and expanding gas contained therein. The expanded gas is communicated to the turbine for converting the expanded gas into displacement motion for driving the at least one doubly fed induction generator for 20 generating power therefrom. [0007] In another aspect of this disclosure, there is disclosed a method of managing a power system. The method comprising: receiving heat energy to heat up fluid in a heat collector; and channeling the heated fluid to a heat exchanger. The heat exchanger configured to receive 25 the heated fluid for heating and expanding a gas contained therein. The expanded gas communicated to a turbine for converting the expanded gas into displacement motion for driving at least one of a doubly fed induction generator for generating power therefrom. The at least one doubly fed induction generator for managing power provided to a load. 30 [0008] In another aspect of this disclosure, the power generation system further includes 2 WO 2013/123546 PCT/AU2012/000153 a controller communicatively coupled to the at least one doubly fed induction generator for maintaining the at least one doubly fed induction generator at a constant electrical output and frequency. Such an arrangement allows the at least one doubly fed induction generator to manage the power provided to the load based on the power requirement of the load at the 5 constant electrical output voltage and frequency. In this way, the turbine may advantageously run freely at speeds governed by the heat transferred to the gas and the demand from the load at the aforementioned constant electrical output voltage and frequency. 10 BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING [0009] Embodiments of the disclosure are described hereinafter with reference to the following drawings, in which: 15 [0010] FIG. 1 is a schematic block diagram of a power generation system of this disclosure showing the heat collector, a turbine generator system comprising a turbine and one doubly fed induction generator, a heat exchanger, a controller, an energy storage unit, a holding tank, a preheater and a load. 20 [0011] FIG. 2 is a flow diagram showing a process of power generation in accordance to the various embodiments of this disclosure. DETAILED DESCRIPTION 25 [0012] Representative embodiments of the disclosure for addressing one or more of the foregoing problems associated with conventional power generation systems are described hereafter with reference to figs. I and 2. For purposes of brevity and clarity, the description herein is primarily directed to systems, devices, and techniques for efficient power generation. 30 This, however, does not preclude various embodiments of the disclosure from other applications 3 WO 2013/123546 PCT/AU2012/000153 where fundamental principles prevalent among the various embodiments of the disclosure such as operational, functional, or performance characteristics are required. In the description that follows, like or analogous reference numerals indicate like or analogous elements. 5 [0013] Embodiments of this disclosure relate to power generation systems and/or methods for use in conjunction with electrical grids. In particular, the power generation systems and/or methods can be utilised in a telecommunication base station, remote mining camp sites or one or more pumpjacks. The power generation system 10 comprises a heat collector 100, a heat exchanger 300 and a turbine generator system 200 comprising a turbine 220 and at least one 10 doubly fed induction generator 240. The heat collector 100 is for receiving heat energy to heat up a fluid. The heat energy is generated by a heat source. In many embodiments, the heat exchanger 300 is configured to receive the heated fluid for heating and expanding gas contained in the heat exchanger 300. The expanded gas is then communicated to the turbine 220 for converting the expanded gas into displacement motion for driving the at least one doubly fed induction 15 generator 240 for generating power therefrom. [0014] The power generation system further includes a controller 280 for maintaining the at least one doubly fed induction generator 240 at a constant electrical output and frequency. Such an arrangement allows the at least one doubly fed induction generator 240 to manage the 20 power provided to the load 400 based on the power requirement of the load 400 at the constant electrical output voltage and frequency. In this way, the turbine 220 may advantageously run freely at speeds governed by the heat transferred to the gas and the demand from the load 400 at the constant electrical output voltage and frequency. 25 [0015] The turbine 220 that drives the doubly fed induction generator 240 further uses a low temperature expending gas that operates at a low pressure. This facilitates power to be generated by the at least one doubly fed induction generator 240 even at low solar thermal levels. Due to its low operating pressures, auxiliary infrastructure to manage any high temperature and high pressure is not required. Additionally, complicated gearing systems to drive the at least one 30 doubly fed induction generator are not required due to the low operating pressure such that the 4 WO 2013/123546 PCT/AU2012/000153 doubly fed induction generator may be directly coupled to the turbine. [00161 In many embodiments, the heat collector 100 comprises a solar collector system for receiving solar thermal energy. The solar collector system can comprise at least one solar 5 collector for converting the solar thermal energy into heat energy to heat up the fluid. Depending upon embodiment details, the at least one solar collector is a concentrated solar power system. [0017] Although the description of this disclosure is directed to use of a turbine for converting gas into displacement motion for driving the at least one doubly fed induction 10 generator, it should be understood by a person of ordinary skill in the art that other types of turbines, such as a steam turbine can be used. Any alterations and further modifications in the following described embodiments, and any further applications of the principles of the invention as described herein are contemplated as would normally occur to one of ordinary skill in the art to which the disclosure relates. 15 [0018] FIG. 1 shows a power generation system 10 according to embodiments of this disclosure. The power generation system 10 comprises a heat collector 100, a turbine generator system 200 comprising a turbine 220 and at least one doubly fed induction generator 240, a heat exchanger 300, a controller 280 and a load 400. The turbine 220 can be a gas turbine and/or a 20 steam turbine. Although this disclosure describes the use of one turbine 220, it should be understood by a person of ordinary skill in the art that more than one turbine 220 can be used. In applications where more than one turbine 200 is used, there can be a combination of gas and steam turbines. 25 [0019] The power generation system 10 can be a constituent of a power grid or a stand alone system to provide electrical energy. While the doubly fed induction generator 240 is the main source of power to charge up the load 400, the power generation system 10 of this disclosure is capable of operating in tandem with other generators such as a variable speed DC generator to provide/generate power. The doubly fed induction generator 240 is also able to 30 operate with other renewable energy sources to generate power. For instance, a wind turbine can 5 WO 2013/123546 PCT/AU2012/000153 be integrated into the power generation system 10 to generate energy to drive an engine to operate the doubly fed induction generator 240. Depending upon embodiment details, the power generation system 10 is capable of operating with other power generation systems where renewable energy sources can operate in tandem to charge up one or more energy storage units. 5 This can optimize charging of one or more energy storage units 250 in that the doubly fed induction generator 240 can operate to charge up the one or more energy storage units 250 when the renewable energy sources are not in operation. For instance, during windy conditions, a wind turbine can operate to charge up the one or more energy storage units 250 and during times when the wind conditions are not favourable, the doubly fed induction generator 240 can operate to 10 charge up the one or more energy storage units 250. [00201 To facilitate the operations of the power generation system 10, the heat collector 100 is coupled to and in fluid communication with the heat exchanger 300, which is in turn coupled to the turbine 220 of the turbine generator system 200. The turbine 220 is coupled 15 directly to the at least one doubly fed induction generator 240, which is then coupled to the load 400. The controller 280 may further be communicatively coupled to the at least one doubly fed induction generator 240. The load 400 can be a telecommunication base station, remote mining camp sites or one or more pumpjacks. Depending upon the electrical output load 400 such as the availability of a telecommunication base station and/or remote mining camp site, the at least one 20 doubly fed induction generator 240 can operate in varying speeds to achieve efficiency. In some embodiments, an energy storage unit 250 is coupled to the doubly fed induction generator 240 for storing energy before the energy is dissipated to the load 400. [0021] The power generation system 10 generates electrical power by collecting and/or 25 concentrating energy to operate the turbine 220 to drive the at least one doubly fed induction generator 240. Collection and/or concentration of energy can be by way of the heat collector 100. The heat collector 100 receives heat energy generated by at least one heat source to heat up a fluid contained therein. The at least one heat source can further comprise at least one of biogas, biomass, methane, waste heat or any other combustible material that is able to produce heat. To 30 increase intensity of the heat energy, the heat collector 100 can operate with a set of optics to 6 WO 2013/123546 PCT/AU2012/000153 converge the heat energy generated by the at least one heat source. In some embodiments, the heat collector 100 comprises a solar collector system such as solar collectors for receiving solar thermal energy. Further, the solar collector system comprises at least one solar collector for converting the solar thermal energy into heat energy to heat the fluid contained in the heat 5 collector 100. The solar collector system can be a concentrated solar power system. The fluid in the heat collector 100 is at least one of oil, water, ammonia and Freon. In many embodiments, the power generation system 10 further comprises one or more fluid holding tanks 260 for storing and supplying/channeling fluid to the heat collector 100. 10 [00221 The heat exchanger 300 is configured to receive the heated fluid for heating and expanding gas contained therein. The gas used is one that is easily expandable such as helium and/or hydrogen. The expanded gas is communicated to the turbine 220 for converting the expanded gas into displacement motion for driving the at least one doubly fed induction generator 240 for generating power therefrom. The at least one doubly fed induction generator 15 240 manages power provided to the load 400. In other words, the pressurized/heated gas expands and facilitates movement of the turbine 220 for driving the at least one doubly fed induction generator 240. To enhance the expansion of the gas, the turbine generator system 200 can further comprise a pre-heater 270 for preheating the gas to be heated and expanded by the heat exchanger 300. 20 [0023] In many embodiments, the doubly fed induction generator 240 is driven by the turbine 220 that uses a low temperature expanding gas that operates at low pressures. Due to its low operating pressures, auxiliary infrastructure to manage any high temperature and high pressure is not required. Additionally, complicated gearing systems to drive the at least one 25 doubly fed induction generator 240 are not required due to the low operating pressure such that the doubly fed induction generator 240 may be directly coupled to the turbine 220. [0024] The doubly fed induction generator 240 is capable of generating power at various speeds including very low speeds of approximately 1,500 to 7,000 revolutions per minute (rpm). 30 Being able to operate at low speeds suggest that the power generation system 10 of this 7 WO 2013/123546 PCT/AU2012/000153 disclosure is capable of operating under low solar thermal levels and low pressures. This increases efficiency of the power generation system 10. The power generation system 10 can further be hybridized with any other renewable energy resources enabling the whole hybrid system to be an ideal primary power generation system. 5 [0025] Process of efficient power generation [0026] FIG. 2 is a flow diagram showing a process of efficient power generation 500 in accordance to various embodiments of this disclosure. The process of efficient power generation 10 500 comprises the steps of storing gas in a holding tank 502, preheating the gas 504, receiving heat energy to heat a fluid in a heat collector 506, channeling the heated fluid to a heat exchanger 508, channeling the gas to the heat exchanger 510, heating up the gas in the heat exchanger 512, communicating the heated gas to a turbine for driving a doubly fed induction generator 514, maintaining the at least one doubly fed induction generator at a constant electrical output and 15 frequency 516, generating power 518, and delivering power to a load 520. [0027] The process of efficient power generation 500 described herein provides an efficient method of delivering power to the load 400. As described previously, the load 400 can be a telecommunication base station, remote mining camp sites or one or more pumpjacks. 20 [0028] The first process step 502 involves storing a gas in a holding tank 260 and in some embodiments; the gas can be preheated 504 in a pre-heater 270 before the gas is channeled to a heat exchanger 300. Thereafter, process step 506 involves receiving heat energy to heat up fluid in a heat collector 100. The fluid in the heat collector 100 is at least one of oil, water, 25 ammonia and Freon. As discussed previously, the heat collector 100 is coupled to and in fluid communication with a heat exchanger 300. The heat collector 100 receives heat energy generated by at least one heat source to heat up the fluid contained therein. The at least one heat source can comprise at least one of biogas, biomass, methane, waste heat or any other combustible material that is able to produce heat. In some embodiments, the heat collector 100 can comprise a solar 30 collector system and the solar collector system can be a concentrated solar power system. The 8 WO 2013/123546 PCT/AU2012/000153 solar collector system can comprise at least one solar collector for converting the solar thermal energy into heat energy to heat up the fluid. [0029] The heated fluid in the heat collector 100 is then channeled to the heat exchanger 5 300. The heat exchanger 300 is configured to receive the heated fluid for heating up and consequently expanding gas contained therein. This is shown in process step 508. Subsequently in process step 510, the expanded gas is communicated to a turbine 220 for converting the expanded gas into displacement motion for driving at least one doubly fed induction generator 240. The at least one doubly fed induction generator 240 generates power in process step 512 10 and subsequently, power is delivered to a load 400 in process step 514. Further, the at least one doubly fed induction generator 240 is communicatively coupled to a controller 280 for managing power provided to the load 400 at a constant electrical output and frequency. In this way, the turbine 220 may run freely at speeds which are governed by the heat transferred to the gas and the demand from the load at the constant electrical output and frequency. 15 [0030] Thus, there has been shown and discussed various embodiments of a power generation system and method which fulfils the objectives and advantages sought thereof. Many changes, modifications, variations, and other uses and applications of the subject disclosure will, however, become apparent to those skilled in the art after considering this specification together 20 with the accompanying figures and claims. The power generation system and/or method, together with ensuing benefits are also applicable to similar equipment in unrelated industries where such technology can be implemented. All such changes, modifications, variations and other uses and applications which do not depart from the spirit and scope of the detecting device of this disclosure are deemed to be covered by embodiments of this disclosure which is limited 25 only by the claims which follows. [0031] In the foregoing manner, various embodiments of the disclosure are described for addressing at least one of the foregoing disadvantages. Such embodiments are intended to be encompassed by the following claims, and are not to be limited to specific forms or arrangements 30 of parts so described and it will be apparent to one skilled in the art in view of this disclosure that 9 WO 2013/123546 PCT/AU2012/000153 numerous changes and/or modification can be made, which are also intended to be encompassed by the following claims. 10

Claims

1. A power generation system comprising: a turbine generator system comprising a turbine; 5 at least one doubly fed induction generator directly coupled to the turbine; a heat collector for receiving heat energy to produce a heated fluid, the heat energy generated by at least one of a heat source; a heat exchanger configured to receive the heated fluid for heating and expanding a gas contained therein, the expanded gas being communicated to the turbine for converting the 10 expanded gas into displacement motion for driving the at least one of a doubly fed induction generator for generating power therefrom; and a controller communicatively coupled to the at least one doubly fed induction generator for maintaining the at least one doubly fed induction generator at a constant electrical output and frequency; 15 wherein the at least one doubly fed induction generator manages power provided to a load by based on the power requirement of the load at the constant electrical output voltage and frequency; wherein the turbine runs freely at speeds governed by the heat transferred to the gas and the demand from the load at the constant electrical output voltage and frequency. 20

2. The power generation system of claim 1, wherein the heat collector comprises a solar collector system for receiving solar thermal energy.

3. The power generation system of claim 2, wherein the solar collector system comprises at 25 least one solar collector for converting the solar thermal energy into heat energy to heat up the fluid.

4. The power generation system of claim 2, wherein the solar collector system is a concentrated solar power (CSP) system. 30 11 WO 2013/123546 PCT/AU2012/000153

5. The power generation system of claim 1, wherein the fluid is at least one of oil, water, ammonia and Freon.

6. The power generation system of claim 1, wherein the at least one heat source comprises 5 at least one of biogas, biomass, natural gas, methane and waste heat.

7. The power generation system as in claim 1, the turbine generator system further comprising a pre-heater for preheating the gas to be heated and expanded by the heat exchanger. 10

8. The power generation system as in claim 1, further comprising a holding tank for containing the gas.

9. The power generation system as in claim 1 further comprising an energy storage unit. 15

10. The power generation system as in claim 1, wherein the doubly fed induction generator generates power at various speeds of approximately 1,500 to 7,000 revolutions per minute.

11. The power generation system as in claim 1, wherein the heated fluid operates at a temperature range of about 150"C to 3000C. 20

12. A method of managing a power system, the method comprising: heating a fluid in a heat collector; channeling the heated fluid to a heat exchanger, the heat exchanger configured to receive the heated fluid for heating up and expanding a gas contained therein; 25 communicating the expanded gas to a turbine for converting the expanded gas into displacement motion for driving at least one of a doubly fed induction generator for generating power therefrom; maintaining the at least one doubly fed induction generator at a constant electrical output and frequency by a controller; and 12 WO 2013/123546 PCT/AU2012/000153 wherein the at least one doubly fed induction generator manages power provided to a load based on the power requirement of the load at the constant electrical output voltage and frequency; wherein the turbine runs freely at speeds governed by the heat transferred to the gas and 5 the demand from the load at the constant electrical output voltage and frequency.

13. The method of claim 10 further comprising: storing the gas in a holding tank; preheating the gas; and 10 channeling the gas to the heat exchanger.

14. The method of claim 10, further providing the heat collector with a solar collector system for receiving solar thermal energy. 15 13. The method of claim 12, further providing the solar collector system with at least one solar collector for converting solar thermal energy into heat energy to heat up the fluid. 14. The method of claim 12, wherein the solar collector system is a concentrated solar power system. 20

15. The method of claim 10, wherein the fluid is at least one of oil, water, ammonia and Freon.

16. The method of claim 10, further providing an energy storage unit. 25

17. The method of claim 10, wherein the doubly fed induction generator generates power at speeds of approximately 1,500 to 7,000 revolutions per minute.

18. The method of claim 10, wherein the heated fluid operates at a temperature range of 30 about 150 0 C to 300 0 C. 13