WO2015044803A1 - Procédé de connexion de sous-systèmes d'un système d'alimentation électrique et dispositif électronique intelligent associé - Google Patents

Procédé de connexion de sous-systèmes d'un système d'alimentation électrique et dispositif électronique intelligent associé Download PDF

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Publication number
WO2015044803A1
WO2015044803A1 PCT/IB2014/063966 IB2014063966W WO2015044803A1 WO 2015044803 A1 WO2015044803 A1 WO 2015044803A1 IB 2014063966 W IB2014063966 W IB 2014063966W WO 2015044803 A1 WO2015044803 A1 WO 2015044803A1
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WO
WIPO (PCT)
Prior art keywords
subsystem
voltage
electronic device
angle
instantaneous
Prior art date
Application number
PCT/IB2014/063966
Other languages
English (en)
Inventor
Sethuraman Ganesan
Arinjai Gupta
Amit Kumar
Original Assignee
Abb Technology
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Abb Technology filed Critical Abb Technology
Publication of WO2015044803A1 publication Critical patent/WO2015044803A1/fr

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Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/40—Synchronising a generator for connection to a network or to another generator
    • H02J3/42—Synchronising a generator for connection to a network or to another generator with automatic parallel connection when synchronisation is achieved
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/04—Circuit arrangements for ac mains or ac distribution networks for connecting networks of the same frequency but supplied from different sources
    • H02J3/08—Synchronising of networks
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/40—Synchronising a generator for connection to a network or to another generator

Definitions

  • the invention relates generally to the field of power management systems, and more specifically to a method of synchronizing subsystems for fast bus transfer in a power system.
  • connection between the standby source and the load is achieved by a circuit breaker, when the voltage, frequency and phase angle differences across the breaker poles of the circuit breaker are within synchronization limits.
  • the synchronization limits ensure that there is minimal mechanical shock to motors and other electromechanical equipment present in the load. This is called 'fast' transfer.
  • the invention describes a method for connecting a first subsystem of a multi-phase electrical power system with a second subsystem of the multi-phase electrical power system.
  • the second subsystem includes a voltage of time-varying frequency.
  • the method includes calculating, by an Intelligent Electronic Device, an instantaneous angle of separation between a voltage of the first subsystem and the voltage of the second subsystem using instantaneous voltage magnitude of the voltage of the first subsystem and instantaneous voltage magnitude of the voltage of the second subsystem, determining, by the Intelligent Electronic Device, a synchronization time using the calculated instantaneous angle of separation, and operating, by the Intelligent Electronic Device, at least one switching device for connecting the first subsystem with the second subsystem based on the synchronization time. Determining the synchronization time comprises compensating for the time- varying frequency of the voltage of the second subsystem.
  • calculating the instantaneous angle of separation includes calculating instantaneous voltage magnitude of the second subsystem using a two or more phase-phase voltages.
  • determining the synchronization time includes estimating an advance angle based on a converging function of the calculated instantaneous angle of separation.
  • the method further includes calculating, by the Intelligent Electronic Device, a second instantaneous angle of separation, upon connecting the first subsystem with the second subsystem of the multi-phase electrical power system.
  • the method further includes calculating, by the Intelligent Electronic Device, an estimation error based on the estimated advance angle and the second instantaneous angle of separation.
  • the invention describes an Intelligent Electronic Device for connecting a first subsystem of a multiphase electrical power system with a second subsystem of the multiphase electrical power system.
  • the second subsystem includes a voltage of time- varying frequency.
  • the Intelligent Electronic Device includes one or more processors, and a memory module communicatively coupled to the one or more processors.
  • the one or more processors are configured to receive measurements from one or more voltage measuring means, calculate an instantaneous voltage magnitude of a voltage of the first subsystem and instantaneous voltage magnitude of the voltage of the second subsystem, calculate an instantaneous angle of separation using instantaneous voltage magnitude of the voltage of the first subsystem and instantaneous voltage magnitude of the voltage of the second subsystem, determine a synchronization time using the calculated instantaneous angle of separation, and operate the at least one switching device for connecting the first subsystem with the second subsystem based on the synchronization time.
  • the one or more processors are further configured to compensate the synchronization time due to the time-varying frequency of the voltage of the second subsystem. In an embodiment, the one or more processors are configured to calculate a converging function of the instantaneous angle of separation for estimating an advance angle.
  • the one or more voltage measuring means includes a voltage transformer.
  • the first subsystem includes at least one power generation system and the second subsystem includes a motor load.
  • Figure 1 illustrates a multi-phase electrical power system, in accordance with various embodiments of the invention
  • Figure 2 illustrates phasor representations of three individual phase voltages and phase to phase voltages of an subsystem, in accordance with various embodiments of the invention
  • Figure 3 is a graph showing wave forms of phase to phase voltages of a second subsystem, in accordance with various embodiments of the invention.
  • Figure 4 illustrates angle of separation between the waveforms of phase to phase voltage of a first subsystem and a second subsystem, in accordance with various embodiments of the invention
  • Figure 5 is a graph showing estimated error between an estimated advance angle and a second angle of separation, in accordance with various embodiments of the invention.
  • Figure 6 is a graph showing relationship between an estimated advance angle and a second angle of separation, in accordance with various embodiments of the invention.
  • Figure 7 is a flowchart of a method for connecting a first subsystem with a second subsystem, in accordance with various embodiments of the invention.
  • the invention provides a method for connecting a first subsystem of a multi-phase electrical power system with a second subsystem of the multi-phase electrical power system.
  • the second subsystem includes a voltage of time-varying frequency.
  • the method is used to provide an accurate and efficient mode of synchronizing multi-phase systems by using an Intelligent Electronic Device (IED).An overview of a scenario where the invention is applicable is provided with the help of Figure 1.
  • IED Intelligent Electronic Device
  • FIG. 1 illustrates a multi-phase electrical power system 100.
  • the multi-phase electrical power system 100 includes a motor load bus 110 for supplying power to one or more motors 115 of an industrial plant via load-side circuit breakers 116.
  • the motor load bus 110 is connected with two independent multiphase power sources: a main power source 120 (shown in the figure as generator 120) and a standby power source (not shown in figure), through Unit Auxiliary Transformer (UAT) 123 and station transformer 133 respectively.
  • UAT Unit Auxiliary Transformer
  • the standby power source along with the station transformer 133 is collectively referred to as a first subsystem in the multiphase electrical power system 100.
  • the motor load bus 110 along with the motors 115 and the load side circuit breakers 116 are collectively referred to as a second subsystem in the multiphase electrical power system 100.
  • a switching device 126 such as a circuit breaker
  • a switching device 136 such as a circuit breaker
  • a high speed bus transfer Intelligent Electronic Device 140 is provided to transfer load (shown in the figure as motors 115) on the motor load bus 110 from the main power source 120 to standby power source upon tripping of the main source 120.
  • the IED 140 includes one or more processors (not shown in figure) and a memory module (not shown in figure) communicatively coupled to the one or more processors (not shown in figure).
  • a plurality of current transformers (shown in the figure as current transformer 143 and current transformer 146 and a plurality of voltage transformers (shown in the figure as voltage transformer 153, voltage transformer 156 and voltage transformer 159) are communicatively coupled to the IED 140.
  • the motor load bus 110 gets energy from the station transformer 133 Once the generator is brought up to full speed, the motor load bus 110 gets transferred to the Unit Auxiliary Transformer 123. This is accomplished by closing the switching device 126, momentarily paralleling the two sources and then tripping the switching device 136. The operation of the switching devices 126 and 136 are managed by the IED 140. During steady generating conditions, the switching device 126 remains closed and the switching device 136 remain open.
  • the switching device 126 Under faulty conditions such as when the main source 120 gets tripped or depowered, the switching device 126 trips and enters into open state. Since, the motor load bus 110 is without any active energy input from either of the sources, rapid decay occurs to residual bus voltage of the motor load bus 110. On tripping, the switching device 126 sends a trip signal to the IED 140. Upon receiving a trip signal from the switching device 126, the IED 140 monitors the back electromotive force (herein after referred to as EMF) generated by the disconnected motors 115 via the voltage transformer 159 to determine a instance in time or synchronization time where the back EMF is in synchronization with the voltage of the standby power source to ensure proper transfer or switching.
  • EMF back electromotive force
  • the back EMF will have a frequency that varies over time.
  • a generator not shown in figure
  • the frequency would increase.
  • the motors 115 will slow down causing the frequency to decrease.
  • the switching device 136 will take some time (also known as operating time) to connect the motor load bus 110 to the standby power source, the delay caused due to the operating time of the switching device 136 have to be taken into account while determining the synchronization time.
  • the IED 140 uses a methodology explained below.
  • the methodology allows for determination of peak of a sinusoidal voltage waveform with continuously varying frequency and magnitude of a three phase system from individual samples of input phase to phase voltages.
  • Phase C voltage vE c *sin(ot + 120°) (4)
  • ⁇ peak magnitude of individual phases in volts
  • ⁇ angular frequency of system E in degrees per second
  • t time in seconds.
  • the three phase voltages can be represented as phasors , 120 degrees apart as indicated in portion a of Figure 2. From the vF
  • VE AB VE A- VE B (5)
  • vE ⁇ VE*sin(«t)-VE*sin( «t-120°)
  • vE ⁇ V3*VE*sin( «t + 30°) (7 )
  • phase to phase voltage CB is derived as
  • VE CB vE c - VE B ( 8 )
  • vE CB VE*sin( «t + 120 o )-VE*sin( «t-120°)
  • vE CB V3*VE*sin(iot + 90°) (10)
  • the two phase to phase voltages are measured using voltage transformer 156 and transmitted to the IED 140.
  • the two phase to phase voltages are measured at equal intervals, for
  • phase to phase voltages are shown as phasors AB and VE
  • Aphasor XB perpendicular to m is derived using equation (11) as provided below: vF ' I—
  • the two phase to phase voltages are measured using voltage transformer 159 and transmitted to the IED 140.
  • FIG. 3 is a graph 300 showing wave forms of phase to phase voltages of the system F, in accordance with various embodiments of the invention.
  • Waveform 310 corresponds to the phase to phase voltage VF CB
  • waveform 320 corresponds to the phase to phase voltage vF AB - Since the system F is a motor load system, the frequency of the waveforms decreases with time.
  • VFAB' corresponding to motor load system F is derived as shown in equations (24) and (25): vF ⁇ V3 *VF * sin( « 't + 120° + «) (25)
  • equation (26) shows the peak value of the voltages of motor load system F .
  • FIG. 4 illustrates the waveforms of the corresponding phase to phase voltages of the system E and system F.
  • Waveform 410 corresponds to the phase to phase voltage of the system E and similarly, the waveform 420 corresponds to the phase to phase voltage of the system F. As seen from the figure, the waveforms 410 and 420 coincide in phase at certain intervals of time.
  • the angle ⁇ ( ⁇ ⁇ ⁇ ) + a ⁇ between two systems is measured instantaneously using real time samples of both the systems voltages.
  • Portion b of figure 4 illustrates the instantaneous values of angle (shown as waveform 430) between two systems over a period of time.
  • the IED 140 predicts exact phase coincidence between the voltages of the system E and system F, and the synchronization time, based on the angle of separation.
  • the IED 140 uses a converging function of the angle of separation for prediction of phase coincidence and synchronization time, thereby allowing for compensation of switching device operating time.
  • a converging power series function of the angle of separation is used.
  • the converging power series function is Taylor series expansion, limited to third order. Taylor's series expansion of the wave form 430 of the angle as shown in portion b of figure 4 is done as stated in equation (31). ° ⁇ is angle measured at instant 1 at which point the IED 140 is predicting the angle for a further time At . This can be written as equation (31).
  • At) a(t) + ⁇ At + 0.5 * ⁇ At 2 + 0.166 * ⁇ At 3 + ... (31)
  • the angle is estimated ahead of switching device operating time by adding the computed advanced angle in present angle measured as given in equation (34).
  • a'(t + t CB ) a(t) + a adv (t) (34)
  • FIG. 5 illustrates the relationship between the actual angle measured (shown as waveform 510) and the estimated advance angle (shown as waveform 520). The difference between the two waveforms 510 and 520 indicates the magnitude of error. Because of inherent errors, the instant of switching is not at exact phase co-incidence.
  • a methodology is provided for correction of the advanced angle using error from past estimation.
  • the IED 140 performs angle estimation from the moment initial advance angle estimation is performed.
  • a continuous process estimating the angle in advance time equal to the switching device operating time is performed and is compared with the actual angle difference after elapse of switching device operating time. Error in estimation is calculated and is utilized in next estimation of advanced angle.
  • Figure 6 illustrates the relationship between the actual angle measured (shown as waveform 610) and the estimated advance angle (shown as waveform 620). As shown in Figure
  • FIG. 7 is a flowchart 700 for a method of connecting the first subsystem with the second subsystem using the IED 140.
  • the method initiates upon the IED 140 receiving a command or input to initiate switching of the load of the motor load bus from either the master source or the standby power source to either the standby power source or the main source correspondingly.
  • the IED 140 calculates an instantaneous angle of separation using the instantaneous values of the voltages received from the voltage transformers 156 and 159 based on the methodology explained above.
  • the IED 140 determines the synchronization time when phase coincidence will occur based on the switching device operating time of the switching device 136 and the calculated angle of separation.
  • Step 720 includes a sub-step 725 where the IED 140 compensates for the time varying frequency of the voltage of the second subsystem.
  • the IED 140 issues the command to the switching device 136 to perform switching or connection of the first subsystem with the second subsystem.
  • the present invention can be utilized for connecting any two sub systems where both or any one system have frequencies varying over time. It is also to be noted by a person skilled in the art, that the present invention can be utilized for connecting any two sub system where both or any one system have voltages varying over time.
  • the second subsystem has been exemplarily shown as a motor load system, the second sub system could be a power generating system as well.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Control Of Ac Motors In General (AREA)
  • Control Of Multiple Motors (AREA)

Abstract

Selon certains aspects, la présente invention pourvoit à un procédé de connexion d'un premier sous-système d'un système d'alimentation électrique polyphasé à un second sous-système du système d'alimentation électrique polyphasé. Le second sous-système comprend une tension de fréquence variable dans le temps. Le procédé consiste à calculer, au moyen d'un dispositif électronique intelligent, un angle instantané de séparation entre une tension du premier sous-système et la tension du second sous-système, à déterminer, au moyen du dispositif électronique intelligent, un temps de synchronisation, et à commander, au moyen du dispositif électronique intelligent, au moins un dispositif de commutation en vue de connecter le premier sous-système au second sous-système sur la base du temps de synchronisation. La détermination du temps de synchronisation consiste à compenser la fréquence variable dans le temps de la tension du second sous-système.
PCT/IB2014/063966 2013-09-26 2014-08-19 Procédé de connexion de sous-systèmes d'un système d'alimentation électrique et dispositif électronique intelligent associé WO2015044803A1 (fr)

Applications Claiming Priority (2)

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IN4376/CHE/2013 2013-09-26
IN4376CH2013 IN2013CH04376A (fr) 2013-09-26 2014-08-19

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WO2015044803A1 true WO2015044803A1 (fr) 2015-04-02

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2018122631A1 (fr) * 2016-12-28 2018-07-05 Abb Schweiz Ag Procédé de délestage de charge pendant un transfert de bus et dispositif électronique intelligent associé
CN109861214A (zh) * 2019-02-28 2019-06-07 中国电力科学研究院有限公司 判断区域电网暂态功角稳定薄弱线路的方法、系统

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4310771A (en) * 1979-05-10 1982-01-12 Beckwith Electric Co., Inc. Method for transferring power in a synchronous mode to a motor bus
JPH11266541A (ja) * 1998-03-16 1999-09-28 Meidensha Corp 同期発電機の自動同期投入装置
US20080111507A1 (en) * 2006-11-14 2008-05-15 Yalla Murty V V S Digital system for motor bus transfer
US20110182091A1 (en) * 2010-01-25 2011-07-28 Origin Electric Company Limited Synchronization detecting circuit and automatic synchronous parallelization apparatus

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4310771A (en) * 1979-05-10 1982-01-12 Beckwith Electric Co., Inc. Method for transferring power in a synchronous mode to a motor bus
JPH11266541A (ja) * 1998-03-16 1999-09-28 Meidensha Corp 同期発電機の自動同期投入装置
US20080111507A1 (en) * 2006-11-14 2008-05-15 Yalla Murty V V S Digital system for motor bus transfer
US20110182091A1 (en) * 2010-01-25 2011-07-28 Origin Electric Company Limited Synchronization detecting circuit and automatic synchronous parallelization apparatus

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2018122631A1 (fr) * 2016-12-28 2018-07-05 Abb Schweiz Ag Procédé de délestage de charge pendant un transfert de bus et dispositif électronique intelligent associé
CN109861214A (zh) * 2019-02-28 2019-06-07 中国电力科学研究院有限公司 判断区域电网暂态功角稳定薄弱线路的方法、系统

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