DK201470628A1 - Utilization of capability of generators - Google Patents
Utilization of capability of generators Download PDFInfo
- Publication number
- DK201470628A1 DK201470628A1 DKPA201470628A DKPA201470628A DK201470628A1 DK 201470628 A1 DK201470628 A1 DK 201470628A1 DK PA201470628 A DKPA201470628 A DK PA201470628A DK PA201470628 A DKPA201470628 A DK PA201470628A DK 201470628 A1 DK201470628 A1 DK 201470628A1
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- Denmark
- Prior art keywords
- generator
- alternator
- grid
- voltage
- controller
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- Control Of Eletrric Generators (AREA)
Abstract
This disclosure relates to a generator controller configured to control an alternator with an active load and a reactive load of a generator that is configured to be connected power, which generator controller is configured to measure and process a power factor of the grid, where the generator is configured to operate in a grid voltage support mode with a target voltage , which generator controller is configured to adjust the reactive load of the alternator as a function of the measured grid voltage and the target voltage when the grid voltage support mode is enabled.
Description
Utilization of Capability of Generators Field of the Invention
The present invention relates to a generator controller or alternator generator controller configured to control an alternator with an active load and a reactive load of a generator that is configured to be connected to a and is capable of producing active and reactive power, which generator controller is configured to measure and process a power factor of the grid, where the generator is configured to operate in a grid voltage support mode with a target voltage , which generator controller is configured to adjust the reactive load of the alternator as a function of the measured grid voltage and the target voltage when the grid voltage support mode is enabled.
Also disclosed is a method of supporting a voltage of a grid by a connected generator with an alternator and a generator controller.
Background of the Invention A stable power grid or simply a stable grid is important. In particular a grid with more power generators supplying power does demand stable power generators and grid connections.
To obtain a stable grid, operators of the grid provide and require adherence to so-called grid codes that describes conditions and generator behaviour of a generator to be connected to the grid.
Adhering to such grid codes has prompted generators and connections to the grid to focus on specifically fulfilling the narrow power factor and voltage requirements and then optimise operation of generators to fulfil, more or less, just those specific or narrow requirements.
One problem with such approach is that the grid may become unstable if or when a generator for some reason cannot adhere to the grid code requirements.
Another problem is that generators may be required to disconnect from the grid due say voltage requirements of the grid codes or other specific events.
As such current generator design and control may result in a fragile, inflexible and not so robust grid.
Objective of the Invention
It is an objective of the disclosure to provide solutions to the outlined problems or shortcomings of the prior art.
It is a further object of the pending patent application to maximize reactive power production at all active power levels of generators in accordance to their capability to fulfil requirements from the grid for reducing the phase difference between voltage and current at the grid.
It is a further object of the pending patent application to measuring voltage and reacts in case it is dropping. Q production is increased in the attempt to re-raise the voltage of the grid and improving the phase difference of the grid.
Description of the Invention
An objective is achieved by a generator controller configured to control an alternator with an active load and a reactive load of a generator that is configured to be connected to a and is capable of producing active and reactive power, which generator controller is configured to measure and process a power factor of the grid, where the generator is configured to operate in a grid voltage support mode with a target voltage , which generator controller is configured to adjust the reactive load of the alternator as a function of the measured grid voltage and the target voltage when the grid voltage support mode is enabled.
Thereby the grid may remain stable. Another advantage is that the grid becomes more robust since the margin of operation before grid code levels or thresholds increases. Thus such generator controller will pre-empt a situation where the generator would otherwise have had to be disconnected from the grid.
Moreover, the generator controller allows a generator to be connected for longer periods of operation and at lower risk of faulty operation of the generator.
The capability of the alternator is referred to as generator operating chart or capability curve throughout the document.
This allows maximizing reactive power production at all active power levels of generators in accordance to their capability to fulfil requirements from the grid for reducing the phase difference between voltage and current at the grid.
This disclosure also allows measuring voltage and to react in case the voltage is dropping. Reactive power production is increased in an attempt to re-raise the voltage of the grid and to improve the phase difference of the grid.
According to an aspect, the generator controller may be configured to reduce excitation of the alternator when the measured grid voltage is higher than the target voltage. The generator controller may further be configured to increase excitation of the alternator when the measured grid voltage is lower than the target voltage.
Thereby the controller enables the generator to remain connected to the grid and to at least contribute to the stability of the net in an adaptive way.
According to an aspect, the generator controller may be configured to store and process an operating characteristic of the alternator of the generator and configured to operate the generator within the limits of the operating characteristic.
The operation characteristic may be the capability curve of the alternator. The characteristic or curve may be supplied as tabulated values, as a function or as any other representation.
Thus the generator may be operated to its full potential rather than be operated at fixed or limited operational point determined by the grid or grid codes.
The use of the operation characteristic or the capability curve in the controller allows further improves the outlined advantages. At the same time it will maximize the power generated by the generator whilst stabilising the grid. Finally it will increase protection of the generator by avoiding operation in regimes that will develop critical tern- peratures in the windings, which may also be caused due to asymmetric operation of the generator.
In particular a generator has been operated at a fixed operation point to avoid coming close to a point of no return were insulation layers on generator windings alter or even bum through.
The controller may keep track of a current operation point in relation to the operating characteristics.
According to an aspect, the generator controller may be configured to update the operating characteristic of the alternator of the generator.
In an aspect the characteristic is uploaded to the controller automatically. The update may take into account changes in the physical configuration of the generator, changes in components or as a function of time taking wear and tear into account. In another aspect the update may be initiated based on operational experience obtained from similar generators and grid situations. In brief the characteristic is adapted to reflect the optimal possible operational range of the alternator.
According to an aspect, the generator controller may be configured to model and/or forecast the operating characteristic of the alternator of the generator as a function of detected operational conditions.
Thus the generator controller will be able to react dynamically to changes in conditions or parameters. This may in relation to varying temperatures may be advantageous.
According to an aspect, the generator controller may be configured to model and/or forecast the operating characteristic of the alternator of the generator based on operational data from similar generators.
Hence learning or operational experience obtained over time or to particular situations may be accounted for and shared. The alternator generator interaction may alter or change over time. This may result in a broadened operational space, which when shared will increase the operating range of the other generators. On the other hand experiences that will narrow the operational space may be equally valuable to reduce the risk of faulty operations.
According to an aspect, the generator controller may be configured to operate multiple generators attached to a common grid.
In an embodiment the generator controller may be configured to operate and adjust one generator at the time and keep track of the extra operational capacity of the other generators and thereby pre-empt sever grid failures.
Multiple generators each characterised by an operating characteristic made available to the generator controller will allow to stabilise the grid over broader range of operational conditions than hereto.
An objective may be achieved by a method of supporting a grid voltage by a connected generator with an alternator and a generator controller. Such method may comprise acts of measuring the power factor of the grid and operating the generator by adjusting the reactive load of the alternator as a function of the measured voltage of the grid and a target voltage.
Hereby a more stable grid is achieved, which stability is achieved over broader operating conditions than compared to prior art methods.
According to an aspect, the method of supporting a voltage of a grid may further comprise acts of reducing excitation of the alternator when the measured voltage of the grid is higher than the target voltage; and/or acts of increasing excitation of the alternator when the measured voltage of the grid is lower than the target voltage.
According to an aspect, the method of supporting a voltage of a grid may further comprise acts of storing and/or processing an operating characteristic of the alternator of the generator and operating the generator within the limits of the operating characteristic of the alternator of the generator.
Thereby the generator is enabled to remain connected to the grid and to at least contribute to the stability of the net in an adaptive way. Thus the generator may be operated to its full potential rather than be operated at fixed or limited operational point determined by the grid or grid codes.
According to an aspect, the method of supporting a voltage of a grid may further comprise acts of updating the operating characteristic of the alternator of the generator.
The act of updating may comprise one or more acts of modelling and/or forecasting the operating characteristic of the alternator of the generator as a function of sensed operational conditions.
The act of updating may comprise one or more acts modelling and/or forecasting the operating characteristic of the alternator of the generator based on operational data from similar generator.
According to an aspect, the method of supporting a voltage of a grid may further comprise the acts of using multiple generators and operating the multiple generators by the same controller.
A person skilled in the art will appreciate the equivalences of the systems and methods disclosed herein.
Descriptionn of the Drawings
The invention is described by example only and with reference to the drawings, whereon:
Fig. 1 illustrates a generator configuration in connection with a grid and a characteristic curve of an alternator of a generator;
Fig. 2 illustrates an operating characteristic curve of an alternator;
Fig. 3, 4 illustrate generator control based on an operating characteristic curve;
Fig. 5 illustrates generator control based on an operating characteristic curve;
Fig. 6 illustrates a method of supporting a grid voltage; and
Fig. 7,8 illustrate methods of supporting a grid voltage and additional actions of updating the operating characteristics.
In the following text, the figures will be described one by one and the different parts and positions seen in the figures will be numbered with the same numbers in the different figures. Not all parts and positions indicated in a specific figure will necessarily be discussed together with that figure.
Fig. 1 illustrates a generator configuration in connection with a grid and a characteristic curve of an alternator of a generator.
In fig. 1A a generator controller 10 is configured to control an alternator 20 having an active load 22 and a reactive load 24 of a generator 30. The generator 30 is configured to be connected to a grid 40 and is capable of producing active 32 and reactive 34 power. The generator controller 10 is configured to sense, measure and process a power factor 42 of the grid 40. Furthermore the generator controller 10 is configured to operate in a grid voltage support mode 50 with a target voltage 52 or a set voltage.
The generator controller 10 is configured to adjust the reactive load 22 of the alternator 20 as a function of the power factor or the measured grid voltage 44 and the target voltage 52. This may be part of the operation when the grid voltage support mode 50 is enabled. It is understood that the controller may control the generator 30 according to a grid code provided by the grid operator when the generator controller grid voltage support mode 50 is not enabled.
Fig. IB illustrates an alternator 20 of a generator 30 and a power curve of the generator and in particular the operating characteristics 60 as exemplified by a capability curve 62 of the alternator. It is understood that the operating characteristic 60 defines operational limits 64 or simply limits 64 of the power generation capabilities of the generator.
During operation a system as shown at fig. 1 will be able to supply power to the grid 40. As disclosed generator controller 10 calculates the voltage by measuring conditions on the grid 40. The generator controller 10 adjusts the generator 30 so that the generator 30 starts generating reactive power in order to compensate the grid conditions. In some situations it is necessary to reduce the production of active power 32 in order to increase reactive power 34. By a generator controller 10 that automatically adjusts the reactive power at the grid 40, it is possible to perform an effective compensation of reactive power of a grid and thus result in a high degree of stability of the grid 40.
Thus voltage support 50 is enabled the reactive load 24 of the alternator 30 will adjust according to the measured grid voltage 44. If the grid voltage 44 is high the excitation of the alternator 20 is reduced and when the grid voltage 44 is low the excitation is increased thereby stabilizing the grid 40.
Fig. 2 illustrates an embodiment of a part of an operating characteristic 60. The operating characteristic 60 is obtained as a capability curve 62 of the alternator 20 (not shown).
The X-axis indicates reactive load, as per unit Q, and the Y-axis indicates active load as per unit P. Further the line indicates the generator limits 66. Furthermore, power factor 42 lines are indicated such as 0.95, 0.8, 0.6, 0.4, 0.3, and 0.2. The generator 30 (not shown) has operational limits 64 and generator limits 66 and must be operated within those limits.
The operation may be limited due to various reasons outside the limits 64. To the left of the capability curve 64 pole slip instability may be dominant. Outside the limit 64 to the right the rotor may be damaged. In the area between the generator limit 66 and the capability curve 62 engine overload may be dominant and above that the stator may be damaged.
Fig. 3 and 4 illustrates generator control based on an operating characteristic curve and generator limit and shows the operating characteristic 60 in terms of a capability curve 62 of the alternator 20 (not shown) and the generator limit 66.
In this embodiment it is seen (Fig. 4) that at a particular operating point 68, it is possible to produce power with different power factors 42, but as soon as the power factor 42 is smaller than 0.8, the generator has to reduce its active load in order to achieve higher reactive load.
The generator controller 10 or alternator generator controller will control the generator 30 within its limits 64.
According to prior art systems and primarily due to grid standards the operating point 68 will normally be adjusted to a power factor 42 of 0.8i to 1.0 (unity) because the nominal power rating of the alternator is given at a power factor = 0.8L
On the operating chart as seen in fig. 4 it looks like this: the full load capability of the alternator as given by Alternator kVA multiplied by the power factor 0.8.
Thus as an example: if the alternator 20 is 2500 kVA, then the full load capability will be 0.8*2500 = 2000 kW. If the same alternator 20 is used on other networks or types of jobs, the engine power is reduced. This means that the alternator 20 will be over dimensioned for most jobs.
Fig. 5 illustrates generator control based on an operating characteristic where the limitation 64 and generator limits 66 are indicated.
Also indicated are two operation situations with limited load of active power. The operating point 68A has a power factor 0.8 and a reduced production of active power, but still some production of reactive power.
It is possible by this production of active power further to increase the production of reactive power, which is indicated by the operating point 68B. In this case it is seen that the reactive load is increased compared with what is described in fig. 3.
As an example: a continuous power generator that operates at 1400 kW will normally be driven like a 1750 kVA alternator (maximum 0.8i). On the operating chart it is seen for 1400 kW there is a large overhead up to 2325 kVA which shows that using a power factor of about 0.6 yields about the active power of 1400 kW.
The benefit or advantage of the disclosed system and method is for utilising the full capability of the alternator. This can be seen by the following example.
The reactive Q production at a power factor can be found by QA2 = SA2 - PA2, where Q is the reactive power, P the active power and S the apparent power.
QA2 = 1750A2 - 1400A2 which yields: Q = 1050 kVAr
Using prior art whereas using the disclosed system or method allows for a reactive power utilising the full limit: QA2 = 2325A2 - 1400A2, which yields: Q = 1856 kVAr.
A person skilled in the art will furthermore take current specifics of a plant into account. As an illustrative example: if a 3000 V/5 A current transformer is installed, the current transformer would have an apparent power of: S = V3*0.400*3000 = 2078 kVA, and thus a maximum of reactive power of:
Qmax = V(2078A2-1400A2), which yields Qmax= 1536 kVAr.
Fig. 6 illustrates another example of generator control based on an operating characteristic curve. In the previous example the generator was kept at 1400 kW. However, as illustrated in fig. 5, it is also possible to decrease the output power, which gives a larger regulation area for the reactive load. Compared to the previous example, decreasing production of active power will allow increasing production of reactive power.
With reference to the numbers from the previous example, decreasing the power to say 1000 kW allows for a power factor of 0.44 with 2250 kVAr. For the same reference, a plant with a 3000 V/5 A current transformer installed would have an apparent power of:
S = V3*0.400*3000 = 2078 kVA
And thus a maximum of reactive power of:
Qm.ax = V(2078A2-1000Λ2), which yields Qmax= 1821 kVAr
Fig. 7 illustrates a method 100 of supporting a grid voltage 40 by a connected generator 30 with an alternator 20 and a generator controller 10 such as those disclosed and with references to previously disclosed features. The method may comprise acts of measuring 110 the power factor 42 of the grid 40 and by operating 120 the generator 30 by adjusting the reactive load 24 of the alternator 20 as a function of the measured grid voltage 44 and a target voltage 52.
The method 100 of supporting a grid voltage 44 may further comprise acts of decreasing 130 excitation of the alternator 20 when the measured grid voltage 44 is higher than the target voltage 52 and/or increasing 140 excitation of the alternator 20 when the measured grid voltage 44 is lower than the target voltage 52.
The method 100 of supporting a grid voltage 44 may further comprise acts of storing 150 and/or processing 155 an operating characteristic 60 of the alternator 20 of the generator 30 and operating the generator 30 within the limits 64 of the operating characteristic 60 of the alternator 20 of the generator 30.
Fig. 8 illustrates a method of supporting a grid voltage and additional actions of updating the operating characteristics.
The method 100 of supporting a grid voltage 44 may further comprise acts of updating 160 the operating characteristic 60 of the alternator 20 of the generator 30. Such acts of updating 160 may comprise one or more acts of modelling 162 and/or forecasting 164 the operating characteristic 60 of the alternator 20 of the generator 30 as a function of sensed operational conditions.
Acts of modelling 162 and/or forecasting 164 the operating characteristic 60 of the alternator 20 of the generator 30 may also be based on operational data from similar generators to the generator controlled. That is by using operational learning or experience from one generator to another generator.
The invention is not limited to the embodiments described herein, and may be modified or adapted without departing from the scope of the present invention as described in the patent claims below.
Claims (13)
1. A generator controller (10) configured to control an alternator (20) with an active load (22) and a reactive load (24) of a generator (30) that is configured to be connected to a grid (40) and is capable of producing active (32) and reactive (34) power, which generator controller (10) is configured to measure and process a power factor (42) of the grid (40), where the generator controller (10) is configured to operate in a grid voltage support mode (50) with a target voltage (52), which generator controller (10) is configured to adjust the reactive load (22) of the alternator (20) as a function of the measured grid voltage (44) and the target voltage (52) when the grid voltage support mode (50) is enabled.
2. A generator controller (10) according to claim 1 configured to reduce excitation of the alternator (20) when the measured grid voltage (44) is higher than the target voltage (52).
3. A generator controller (10) according to claim 1 or 2 configured to increase excitation of the alternator (20) when the measured grid voltage (44) is lower than the target voltage (52).
4. A generator controller (10) according to any of claim 1 to 3 configured to store and process an operating characteristic (60) of the alternator (20) of the generator (30) and configured to operate the generator (30) within the limits (64) of the operating characteristic (60).
5. A generator controller (10) according to claim 4 configured to update the operating characteristic (60) of the alternator (20) of the generator (30).
6. A generator controller (10) according to any of claim 4 to 5 configured to model and/or forecast the operating characteristic (60) of the alternator (20) of the generator (30) as a function of detected operational conditions.
7. A generator controller (10) according to any of claim 4 to 6 configured to model and/or forecast the operating characteristic (60) of the alternator (20) of the generator (30) based on operational data from similar generators (30’).
8. A generator controller (10) according to any of claims 1 to 7 configured to operate multiple generators (72) attached to a common grid (40).
9. A method (100) of supporting a grid voltage (40) by a connected generator (30) with an alternator (20) and a generator controller (10), which method comprises acts of: a) measuring (110) the power factor (42) of the grid (40); b) operating (120) the generator (30) by adjusting the reactive load (24) of the alternator (20) as a function of the measured grid voltage (44) and a target voltage (52).
10. A method (100) of supporting a grid voltage (44) according to claim 9 further comprising acts of: c) decreasing (130) excitation of the alternator (20) when the measured grid voltage (44) is higher than the target voltage (52); and/or d) increasing (140) excitation of the alternator (20) when the measured grid voltage (44) is lower than the target voltage (52).
11. A method (100) of supporting a grid voltage (44) according to claim 9 or 10 further comprising an act of: e) storing (150) and/or processing (155) an operating characteristic (60) of the alternator (20) of the generator (30) and operating the generator (30) within the limits (64) of the operating characteristic (60) of the alternator (20) of the generator (30).
12. A method (100) of supporting a grid voltage (44) according to claim 11 further comprising acts of: f) updating (160) the operating characteristic (60) of the alternator (20) of the generator (30), which act of: updating (160) comprises one or more acts chosen amongst: i) modelling (162) and/or forecasting (164) the operating characteristic (60) of the alternator (20) of the generator (30) as a function of sensed operational conditions; ii) modelling (162) and/or forecasting (164) the operating characteristic (60) of the alternator (20) of the generator (30) based on operational data from similar generators (30’).
13. A method (100) of supporting a grid voltage (44) according to any of claim 9 to 12 comprising the acts of: g) using multiple generators (72) and h) operating the multiple generators (72) by the same controller (10).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DKPA201470628A DK201470628A1 (en) | 2014-10-10 | 2014-10-10 | Utilization of capability of generators |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DKPA201470628A DK201470628A1 (en) | 2014-10-10 | 2014-10-10 | Utilization of capability of generators |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| DK201470628A1 true DK201470628A1 (en) | 2016-04-18 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| DKPA201470628A DK201470628A1 (en) | 2014-10-10 | 2014-10-10 | Utilization of capability of generators |
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| Country | Link |
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| DK (1) | DK201470628A1 (en) |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4245182A (en) * | 1977-03-30 | 1981-01-13 | Hitachi, Ltd. | Excitation control apparatus for a generator |
| US5321308A (en) * | 1993-07-14 | 1994-06-14 | Tri-Sen Systems Inc. | Control method and apparatus for a turbine generator |
| US20050040655A1 (en) * | 2003-08-18 | 2005-02-24 | Wilkins Thomas A. | Continuous reactive power support for wind turbine generators |
| US20080074810A1 (en) * | 2006-09-22 | 2008-03-27 | Armando Guzman-Casillas | Apparatus and method for providing protection for a synchronous electrical generator in a power system |
| US20100025994A1 (en) * | 2008-07-29 | 2010-02-04 | General Electric Company | Intra-area master reactive controller for tightly coupled windfarms |
| US20120101640A1 (en) * | 2009-01-30 | 2012-04-26 | Dewind Co. | Adaptive voltage control for wind turbines |
-
2014
- 2014-10-10 DK DKPA201470628A patent/DK201470628A1/en not_active Application Discontinuation
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4245182A (en) * | 1977-03-30 | 1981-01-13 | Hitachi, Ltd. | Excitation control apparatus for a generator |
| US5321308A (en) * | 1993-07-14 | 1994-06-14 | Tri-Sen Systems Inc. | Control method and apparatus for a turbine generator |
| US20050040655A1 (en) * | 2003-08-18 | 2005-02-24 | Wilkins Thomas A. | Continuous reactive power support for wind turbine generators |
| US20080074810A1 (en) * | 2006-09-22 | 2008-03-27 | Armando Guzman-Casillas | Apparatus and method for providing protection for a synchronous electrical generator in a power system |
| US20100025994A1 (en) * | 2008-07-29 | 2010-02-04 | General Electric Company | Intra-area master reactive controller for tightly coupled windfarms |
| US20120101640A1 (en) * | 2009-01-30 | 2012-04-26 | Dewind Co. | Adaptive voltage control for wind turbines |
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| PHB | Application deemed withdrawn due to non-payment or other reasons |
Effective date: 20170309 |