CN105207271A - Method for realizing seamless switching between isolated-network mode and grid-connected mode in CCHP (combined cooling, heating and power) system - Google Patents
Method for realizing seamless switching between isolated-network mode and grid-connected mode in CCHP (combined cooling, heating and power) system Download PDFInfo
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Abstract
The invention discloses a method for realizing seamless switching between an isolated-network mode and a grid-connected mode in a CCHP (combined cooling, heating and power) system. The method for switching the isolated-network mode into the grid-connected mode comprises the following steps: a synchronizing device is added with a mode switching function; when a CCHP mode controller receives a request instruction for switching the isolated-network mode into the grid-connected mode and a power grid runs in a normal state, the synchronizing device is started to adjust the frequency and voltage of a generator; when the frequency and voltage of the generator meet synchronous connection requirement, and the absolute value of phase difference of the generator and network voltage is smaller than a fixed value 1, an action instruction for switching the isolated-network mode into the grid-connected mode is output; the CCHP mode controller changes from frequency regulation and voltage regulation control to power control; when the frequency and voltage of the generator meet synchronous connection requirement, and the absolute value of phase difference of the generator and network is smaller than a fixed value 2, a generator grid connection instruction is output; and the isolated-network mode is switched into the grid-connected mode. Therefore, the problems of power failure in the switching process and overlarge disturbance and the like of the mode switching process in the CCHP system due to stop of output power of the generator are solved.
Description
Technical field
The invention belongs to comprehensive utilization of energy field, particularly relate to a kind of method of lonely net and grid-connect mode seamless switching in cold, heat and power triple supply system.
Background technology
Cold, heat and electricity triple supply, i.e. CCHP(CombinedCooling, HeatingandPower), refer to natural gas to be that main fuel drives the fuel gas generation equipment such as gas engine, miniature combustion engine or internal combustion engine to run, the electricity needs of supply of electric power user produced, the waste heat of discharging after systems generate electricity by waste heat recovery utilizing equipment (waste heat boiler, refrigeration machine etc.) to user's heat supply, cooling.Greatly improve the primary energy ratio of whole system in this way, achieve the cascade utilization of the energy.Grid-connected electric power can also be provided to do energy complementation, and economic well-being of workers and staff and the efficiency of whole system are higher.
There are two kinds of mode of operations in cold, heat and power triple supply system: lonely net pattern and grid-connect mode.Under lonely net pattern, the control mode of cold, heat and electricity triple supply mode controller is that frequency modulation and voltage modulation controls, and the control mode under grid-connect mode is that power controls.When two kinds of patterns switch, seamless switching be realized, large impact can not be produced to load or electrical network.Two kinds of mode handover procedure relate to the selector switch of pattern and the switching of grid-connected switch in the prior art.Will consider first switching controls mode or grid-connected switch in handoff procedure, different sequencings can cause load or the different shock effect of electrical network.In prior art, this cold, heat and power triple supply system Problems existing is: cold, heat and power triple supply system is when being transformed into lonely net pattern from grid-connect mode, generator needs to stop power output, and load will have the dead electricity process of similar 10s; When from lonely net patten transformation to grid-connect mode, generator also needs to stop power output, and load also will have the dead electricity process being less than 10s.The disturbance of cold, heat and power triple supply system mode handover procedure is excessive.
Summary of the invention
The technical problem to be solved in the present invention: a kind of method that lonely net and grid-connect mode seamless switching in cold, heat and power triple supply system are provided, to solve in prior art cold, heat and power triple supply system when being transformed into lonely net pattern from grid-connect mode or from lonely net patten transformation to grid-connect mode, generator needs to stop power output causing having a power failure in handoff procedure and the technical problem such as the disturbance of cold, heat and power triple supply system mode handover procedure is excessive.
Technical solution of the present invention:
A method for lonely net and grid-connect mode seamless switching in cold, heat and power triple supply system, it comprises lonely net pattern and switches to grid-connect mode and grid-connect mode to switch to the method for lonely net pattern, and described lonely net pattern switches to the method for grid-connect mode to comprise:
Step 1, in synchronous device, increase mode switch function;
Step 2, cold, heat and electricity triple supply mode controller receive lonely net pattern switch to grid-connect mode request instruction and operation of power networks state is normal time, start synchronous device, by synchronous device regulator generator frequency and voltage;
Step 3, when generator frequency and voltage meet simultaneous interconnecting requirement and generator and electric network voltage phase difference absolute value be less than definite value 1 time, synchronous device exports lonely net pattern and switches to grid-connect mode action command;
Step 4, cold, heat and electricity triple supply mode controller receive after lonely net pattern switches to grid-connect mode action command, are converted to power control mode by frequency modulation and voltage modulation control mode, and the electrical power arrived using current detection is as power control set point;
Step 5, when generator frequency and voltage meet simultaneous interconnecting requirement and generator and grid phase difference absolute value be less than definite value 2 time, the grid-connected instruction of synchronous device output generator;
Step 6, generator connecting in parallel with system detected after, cold, heat and electricity triple supply mode controller switches to grid-connect mode by lonely net pattern.
Mode switch function described in step 1, refers to that synchronous device switches leading time according to mode switch and calculates phase difference, in conjunction with current phase difference, the order of deterministic model switching over send the moment, calculating the formula of phase difference is:
In formula:
for mode switch switches leading time both sides voltage phase difference;
for generator and electrical network both sides difference on the frequency;
for frequency difference rate of change;
for mode switch switches leading time.
Operation of power networks state described in step 2 normally refers to grid-connected switch and is in gate-dividing state, line voltage
in range of nominal tension 90%Ue-110%Ue and mains frequency
in rated frequency range 49.5Hz-50.5Hz, Ue is electrical network rated voltage.
Generator frequency described in step 3 and voltage meet simultaneous interconnecting requirement and refer to generator and electrical network both sides frequency-splitting
absolute value be less than 0.3Hz, generator and electrical network both sides voltage difference
absolute value be less than 0.05
, generator and electric network voltage phase difference absolute value are less than definite value 1 and refer to mode switch and switch leading time both sides voltage phase difference
absolute value is less than 5 °.
Generator frequency described in step 5 and voltage meet simultaneous interconnecting requirement and refer to generator and electrical network both sides frequency-splitting
absolute value be less than 0.3Hz, generator and electrical network both sides voltage difference
absolute value be less than 0.05
; Finger print formula switching over leading time both sides voltage phase difference when generator and electric network voltage phase difference absolute value are less than definite value 2
absolute value is less than 1 °.
Described grid-connect mode switches to the method for lonely net pattern to comprise:
Step 1, grid-connect mode power control in Chirp module;
Step 2, when Chirp module action cold, heat and electricity triple supply mode controller control mode by power control be converted to power control add Chirp control mode;
Step 3, frequency fluctuation after stable are less than definite value and after time delay n second, the control mode of cold, heat and electricity triple supply mode controller controls to add Chirp control mode by power and is converted to frequency modulation and voltage modulation control mode, and the frequency and voltage arrived using current detection is as the set point of frequency modulation and pressure regulation, and output generator off-the-line instruction;
After step 4, generator off-the-line, cold, heat and electricity triple supply mode controller switches to lonely net pattern by grid-connect mode, and frequency modulation and voltage modulation set point is 0.5Hz/min to 3Hz/min from currency by frequency modulation set point change speed, pressure regulation set point change speed is that 0.001Ue/s to 0.01Ue/s changes to default lonely net pattern lower frequency and voltage setting value, frequency modulation set point change speed is 0.5Hz/min to 3Hz/min, pressure regulation set point change speed is 0.001Ue/s to 0.01Ue/s, wherein: Ue is electrical network rated voltage.
Step 5, when Chirp module is not operating, cold, heat and electricity triple supply mode controller receives grid-connect mode and switches to the instruction of lonely net mode request, cold, heat and electricity triple supply mode controller is converted to frequency modulation and voltage modulation control mode by power control mode, and the frequency and voltage arrived using current detection is as frequency modulation and pressure regulation set point, the then instruction of output generator off-the-line;
After step 6, generator off-the-line, cold, heat and electricity triple supply mode controller switches to lonely net pattern by grid-connect mode, and frequency modulation and voltage modulation set point is 0.5Hz/min to 3Hz/min from currency by frequency modulation set point change speed, and pressure regulation set point change speed is that 0.001Ue/s to 0.01Ue/s changes to default lonely net pattern lower frequency and voltage setting value.
Step 7, when Chirp module not operating, cold, heat and electricity triple supply mode controller does not receive grid-connect mode and switches to the instruction of lonely net mode request, when cold, heat and electricity triple supply mode controller detects generator off-the-line, cold, heat and electricity triple supply mode controller switches to lonely net pattern by grid-connect mode, control mode controls to be converted to frequency modulation and voltage modulation by power and controls, and frequency modulation and voltage modulation set point is default lonely net pattern lower frequency and voltage setting value;
Step 8, when Chirp module is not operating, cold, heat and electricity triple supply mode controller does not receive grid-connect mode and switches to the instruction of lonely net mode request, when cold, heat and electricity triple supply mode controller does not detect generator off-the-line, return step 2 and wait for that logic performs next time.
Chirp module described in step 1 refers to the power correction signal superposing a FM module output on the power control set point of grid-connect mode, and described power correction signal is proportional to the deviation of frequency and rated value, and its algorithm is:
In formula:
for the power correction signal that Chirp module exports;
for the specified active power of generator;
for momentary speed variation;
for generator rated speed;
the deviate after dead band limits for electrical network rated frequency and generator frequency.
Chirp module action described in step 2 is the deviate after dead band limits by electrical network rated frequency and generator frequency
judge, when
time, Chirp module does not have action; When
time, Chirp module action.
Frequency fluctuation described in step 3 after stable is less than definite value and after time delay n second, limits be+0.1Hz extremely+0.5Hz, and delay time n is 0.2s-5s.
The lonely net pattern lower frequency preset described in step 4, step 6, step 7 and voltage setting value, frequency setting value is+49.5Hz to+50.5Hz, and voltage setting value is+0.9Ue to+1.1Ue, wherein: Ue is electrical network rated voltage.
Beneficial effect of the present invention:
Hinge structure of the present invention has following innovative point:
In lonely net pattern in grid-connect mode handoff procedure, utilize the high-speed sampling of synchronous device and quick computing function, in synchronous device, increase cold, heat and electricity triple supply mode changeover condition judgement and instruction export, enable the selector switch of synchronous device control model and grid-connected switch, so just can shorten mode selection switch as far as possible and switch interval time between grid-connected both switching overs, thus reduce cold, heat and power triple supply system disturbance to load and electrical network when pattern switches;
At grid-connect mode in lonely net mode handover procedure, Chirp module in the power of grid-connect mode controls.When at grid collapses, cold, heat and power triple supply system does not also detect electric network fault, the power control mode of cold, heat and electricity triple supply only according to electrical power instruction regulation output, and makes frequency departure rated value increasing.By increasing the frequency change that Chirp module can make cold, heat and power triple supply system cause according to electric network fault, adjust output of a generator in time, Accident prevention expands.This Chirp module exports and the proportional relation of frequency departure, and direction is contrary, can play the function of timely electric power grid frequency stabilization during electric network fault.After cold, heat and power triple supply system equifrequent modification stability, then carry out grid-connect mode and switch to lonely net pattern, thus reduce the disturbance to load and electrical network when pattern switches.
Hinge structure of the present invention has following remarkable advantage: the seamless switching achieving cold, heat and power triple supply system two kinds of mode of operations, avoids generator to stop power output, thus avoids the dead electricity of load; Decrease the impact of cold, heat and power triple supply system two kinds of work-mode switching process to load and electrical network, achieve comparatively level and smooth switching.To the invention solves in prior art cold, heat and power triple supply system when being transformed into lonely net pattern from grid-connect mode or from lonely net patten transformation to grid-connect mode, generator needs to stop power output causing having a power failure in handoff procedure and the technical problem such as the disturbance of cold, heat and power triple supply system mode handover procedure is excessive.
Embodiment
The basic thought of the inventive method is by transforming synchronous device and cold, heat and power triple supply system mode controller, make the parameter such as generator output voltage, frequency, power of cold, heat and power triple supply system before and after pattern switches close as far as possible, thus avoid needing generator to stop the situation of power output because generator parameter deviation is too large before and after pattern switching, achieve lonely net and grid-connect mode seamless switching in cold, heat and power triple supply system.
The inventive method in grid-connect mode handoff procedure, adopts following method in lonely net pattern:
Step 1, synchronous device increase mode switch function, enable synchronous device control the selector switch of cold, heat and power triple supply system control model and grid-connected switch.Utilize the high-speed sampling function of synchronous device, shorten the interval time between mode selection switch switching with grid-connected both switching overs as far as possible, thus reduce the disturbance to load and electrical network.
Described mode switch function, refers to that synchronous device switches leading time according to mode switch and calculates phase difference, in conjunction with current phase difference, the order of deterministic model switching over send the moment, calculating the formula of phase difference is:
In formula:
for mode switch switches leading time both sides voltage phase difference;
for generator and electrical network both sides difference on the frequency;
for frequency difference rate of change;
for mode switch switches leading time.
Step 2, switch to grid-connect mode request instruction when cold, heat and electricity triple supply mode controller receives lonely net pattern, and when operation of power networks state is normal, start synchronous device, by synchronous device regulator generator frequency and voltage; Operation of power networks state normally refers to grid-connected switch and is in gate-dividing state, line voltage
in range of nominal tension 90%Ue-110%Ue and mains frequency
in rated frequency range 49.5Hz-50.5Hz.Wherein: be electrical network rated voltage.
Step 3, when generator frequency and voltage meet simultaneous interconnecting requirement and generator and grid phase difference absolute value be less than definite value 1 time, synchronous device exports lonely net pattern and switches to grid-connect mode action command; Generator frequency and voltage meet simultaneous interconnecting requirement and refer to generator and electrical network both sides frequency-splitting
absolute value be less than 0.3Hz, generator and electrical network both sides voltage difference
absolute value be less than 0.05Ue, generator and electric network voltage phase difference absolute value are less than definite value 1 and refer to mode switch and switch leading time both sides voltage phase difference
absolute value is less than 5 °.
Step 4, cold, heat and electricity triple supply mode controller receive after lonely net pattern switches to grid-connect mode action command, are converted to power control mode by frequency modulation and voltage modulation control mode, and the electrical power arrived using current detection is as power control set point;
Why adopting electrical power that current detection arrives as power control set point, is in order to lonely net pattern switches to grid-connect mode to take over seamlessly as far as possible.Under lonely net pattern, cold, heat and electricity triple supply mode controller with the frequency and voltage set as set point regulates generator, after switching to grid-connect mode, cold, heat and electricity triple supply mode controller with the power set as set point regulates generator, if pattern has switched that moment, there is deviation in set value of the power and power actual sample value, cold, heat and electricity triple supply mode controller will be caused to regulate action, impact disturbance to load.When the electrical power detected after switching in mode is as power control set point, set value of the power and power actual sample value are consistent, cold, heat and electricity triple supply mode controller exports and remains unchanged, thus achieves lonely net pattern and switch to taking over seamlessly of mode switch in grid-connect mode.
Step 5, when generator frequency and voltage meet simultaneous interconnecting requirement and generator and grid phase difference absolute value be less than definite value 2 time, synchronous device exports grid-connected instruction; Generator frequency and voltage meet simultaneous interconnecting requirement and refer to generator and electrical network both sides frequency-splitting
absolute value be less than 0.3Hz, generator and electrical network both sides voltage difference
absolute value be less than 0.05Ue; Finger print formula switching over leading time both sides voltage phase difference when generator and electric network voltage phase difference absolute value are less than definite value 2
absolute value is less than 1 °.
Step 6, generator connecting in parallel with system detected after, cold, heat and electricity triple supply mode controller switches to grid-connect mode by lonely net pattern.
The inventive method at grid-connect mode in lonely net mode handover procedure, grid-connect mode power control in Chirp module.When at grid collapses, cold, heat and power triple supply system does not also detect electric network fault, the change that Chirp module occurs according to generator frequency, timely adjustment output of a generator, carry out grid-connect mode after equifrequent modification stability again to switch to lonely net pattern, thus reduce the disturbance to load and electrical network.
Grid-connect mode switches to the concrete steps method of lonely net pattern to comprise:
Step 1, grid-connect mode power control in Chirp module; Described Chirp module refers to the power correction signal superposing a FM module output on the power control set point of grid-connect mode, and described power correction signal is proportional to the deviation of frequency and rated value, and its algorithm is:
In formula:
for the power correction signal that Chirp module exports;
for the specified active power of generator;
for momentary speed variation, value 5%;
for generator rated speed, value 3000;
the deviate after dead band limits for electrical network rated frequency and generator frequency.
Right in FM module
set certain dead band, dead band value 0.034Hz, that is:
When
time,
;
When
time,
;
When
time,
;
Wherein:
for electrical network rated frequency, value 50Hz;
for generator frequency;
Step 2, when Chirp module action cold, heat and electricity triple supply mode controller control mode by power control be converted to power control add Chirp control mode;
Chirp module action is the deviate after dead band limits by electrical network rated frequency and generator frequency
judge, when
time, Chirp module does not have action; When
time, Chirp module action.
It is act on set value of the power that Chirp controls, and the difference according to ongoing frequency and rated frequency carrys out corrected output set point, thus power adjustments is regulated on the direction of maintenance electrical network rated frequency.
Step 3, frequency fluctuation after stable are less than definite value and after time delay n second, the control mode of cold, heat and electricity triple supply mode controller controls to add Chirp control mode by power and is converted to frequency modulation and voltage modulation control mode, and the frequency and voltage arrived using current detection is as the set point of frequency modulation and pressure regulation, and output generator off-the-line instruction;
Described frequency fluctuation after stable is less than definite value and after time delay n second, limits be that extremely+0.5Hz, delay time n are 0.2s-5s to+0.1Hz.Now can think the frequency fluctuation temporary stabilization that electric network fault causes, Chirp module exports temporarily can not there is large change.
Step 3, adopting the frequency and voltage that arrives of current detection respectively as the set point of frequency modulation and pressure regulation, is in order to grid-connect mode switches to lonely net pattern to take over seamlessly as far as possible.Under grid-connect mode, cold, heat and electricity triple supply mode controller with the power set as set point regulates generator, after switching to lonely net pattern, cold, heat and electricity triple supply mode controller with the frequency and voltage set as set point regulates generator, if pattern has switched that moment, there is deviation in frequency setting value and frequency actual sample value, cold, heat and electricity triple supply mode controller will be caused to regulate action, impact disturbance to load.
When the frequency detected after switching in mode is as FREQUENCY CONTROL set point, frequency setting value and frequency actual sample value are consistent, cold, heat and electricity triple supply mode controller exports and remains unchanged, thus achieves grid-connect mode and switch to taking over seamlessly of mode switch in lonely net pattern.
When the voltage detected after switching in mode is as voltage control set point, voltage setting value and voltage actual sample value are consistent, cold, heat and electricity triple supply mode controller exports and remains unchanged, thus achieves grid-connect mode and switch to taking over seamlessly of mode switch in lonely net pattern.
After step 4, generator off-the-line, cold, heat and electricity triple supply mode controller switches to lonely net pattern by grid-connect mode, and frequency modulation and voltage modulation set point is changed to default lonely net pattern lower frequency and voltage setting value from currency by given pace;
Described default lonely net pattern lower frequency and voltage setting value, frequency setting value is+49.5Hz to+50.5Hz, and voltage setting value is+0.9Ue to+1.1Ue, and optimized frequency set point is 50Hz, and voltage setting value is+1.0Ue.
Adopt frequency modulation and voltage modulation set point from currency by given pace be changed to default lonely net pattern lower frequency and voltage setting value refer to pattern switch before the disturbance that causes of electric network fault make frequency and voltage deviate from rated value, so to need after pattern switches smooth adjustment to default lonely net pattern lower frequency set point and voltage setting value.
Step 5, when Chirp module is not operating, cold, heat and electricity triple supply mode controller receives grid-connect mode and switches to the instruction of lonely net mode request, cold, heat and electricity triple supply mode controller is converted to frequency modulation and voltage modulation control mode by power control mode, and the frequency and voltage arrived using current detection is as frequency modulation and pressure regulation set point, the then instruction of output generator off-the-line;
After step 6, generator off-the-line, cold, heat and electricity triple supply mode controller switches to lonely net pattern by grid-connect mode, and frequency modulation and voltage modulation set point is changed to default lonely net pattern lower frequency and voltage setting value from currency by given pace;
Described default lonely net pattern lower frequency and voltage setting value, frequency setting value is+49.5Hz to+50.5Hz, and voltage setting value is+0.9Ue to+1.1Ue, and optimized frequency set point is 50Hz, and voltage setting value is+1.0Ue.
Described frequency modulation and voltage modulation set point changes from currency by given pace, frequency modulation set point change speed is 0.5Hz/min to 3Hz/min, pressure regulation set point change speed is 0.001Ue/s to 0.01Ue/s, preferred frequency modulation set point change speed is 1Hz/min, and pressure regulation set point change speed is 0.006Ue/s.Wherein: Ue is electrical network rated voltage.
Frequency modulation and voltage modulation set point is changed to default lonely net pattern lower frequency and voltage setting value from currency by given pace and refers to that grid-connect mode may be different from the frequency and voltage set point lonely net pattern, so to need after pattern switches smooth adjustment to default lonely net pattern lower frequency set point and voltage setting value.
Step 7, when Chirp module is not operating, cold, heat and electricity triple supply mode controller does not receive grid-connect mode and switches to the instruction of lonely net mode request, when cold, heat and electricity triple supply mode controller detects generator off-the-line, cold, heat and electricity triple supply mode controller switches to lonely net pattern by grid-connect mode, control mode controls to be converted to frequency modulation and voltage modulation by power and controls, and frequency modulation and voltage modulation set point is default lonely net pattern lower frequency and voltage setting value;
Described default lonely net pattern lower frequency and voltage setting value, frequency setting value is+49.5Hz to+50.5Hz, and voltage setting value is+0.9Ue to+1.1Ue, and optimized frequency set point is 50Hz, and voltage setting value is+1.0Ue.
Step 8, when Chirp module is not operating, cold, heat and electricity triple supply mode controller does not receive grid-connect mode and switches to the instruction of lonely net mode request, when cold, heat and electricity triple supply mode controller does not detect generator off-the-line, return step 2 and wait for that logic performs next time.
Described frequency modulation and voltage modulation set point changes from currency by given pace, frequency modulation set point change speed is 0.5Hz/min to 3Hz/min, pressure regulation set point change speed is 0.001Ue/s to 0.01Ue/s, preferred frequency modulation set point change speed is 1Hz/min, and pressure regulation set point change speed is 0.006Ue/s.Wherein: Ue is electrical network rated voltage.
Claims (10)
1. the method for lonely net and grid-connect mode seamless switching in a cold, heat and power triple supply system, it comprises lonely net pattern and switches to grid-connect mode and grid-connect mode to switch to the method for lonely net pattern, it is characterized in that: described lonely net pattern switches to the method for grid-connect mode to comprise:
Step 1, in synchronous device, increase mode switch function;
Step 2, cold, heat and electricity triple supply mode controller receive lonely net pattern switch to grid-connect mode request instruction and operation of power networks state is normal time, start synchronous device, by synchronous device regulator generator frequency and voltage;
Step 3, when generator frequency and voltage meet simultaneous interconnecting requirement and generator and electric network voltage phase difference absolute value be less than definite value 1 time, synchronous device exports lonely net pattern and switches to grid-connect mode action command;
Step 4, cold, heat and electricity triple supply mode controller receive after lonely net pattern switches to grid-connect mode action command, are converted to power control mode by frequency modulation and voltage modulation control mode, and the electrical power arrived using current detection is as power control set point;
Step 5, when generator frequency and voltage meet simultaneous interconnecting requirement and generator and grid phase difference absolute value be less than definite value 2 time, the grid-connected instruction of synchronous device output generator;
Step 6, generator connecting in parallel with system detected after, cold, heat and electricity triple supply mode controller switches to grid-connect mode by lonely net pattern.
2. the method for lonely net and grid-connect mode seamless switching in a kind of cold, heat and power triple supply system according to claim 1, it is characterized in that: mode switch function described in step 1, refer to that synchronous device switches leading time according to mode switch and calculates phase difference, in conjunction with current phase difference, the order of deterministic model switching over send the moment, calculating the formula of phase difference is:
In formula:
for mode switch switches leading time both sides voltage phase difference;
for generator and electrical network both sides difference on the frequency;
for frequency difference rate of change;
for mode switch switches leading time.
3. the method for lonely net and grid-connect mode seamless switching in a kind of cold, heat and power triple supply system according to claim 1, is characterized in that: operation of power networks state described in step 2 normally refers to grid-connected switch and is in gate-dividing state, line voltage
in range of nominal tension 90%Ue-110%Ue and mains frequency
in rated frequency range 49.5Hz-50.5Hz, Ue is electrical network rated voltage.
4. the method for lonely net and grid-connect mode seamless switching in a kind of cold, heat and power triple supply system according to claim 1, is characterized in that: generator frequency described in step 3 and voltage meet simultaneous interconnecting requirement and refers to generator and electrical network both sides frequency-splitting
absolute value be less than 0.3Hz, generator and electrical network both sides voltage difference
absolute value be less than 0.05Ue, generator and electric network voltage phase difference absolute value are less than definite value 1 and refer to mode switch and switch leading time both sides voltage phase difference
absolute value is less than 5 °.
5. the method for lonely net and grid-connect mode seamless switching in a kind of cold, heat and power triple supply system according to claim 1, is characterized in that: generator frequency described in step 5 and voltage meet simultaneous interconnecting requirement and refers to generator and electrical network both sides frequency-splitting
absolute value be less than 0.3Hz, generator and electrical network both sides voltage difference
absolute value be less than 0.05Ue; Finger print formula switching over leading time both sides voltage phase difference when generator and electric network voltage phase difference absolute value are less than definite value 2
absolute value is less than
1°。
6. the method for lonely net and grid-connect mode seamless switching in a kind of cold, heat and power triple supply system according to claim 1, is characterized in that: described grid-connect mode switches to the method for lonely net pattern to comprise:
Step 1, grid-connect mode power control in Chirp module;
Step 2, when Chirp module action cold, heat and electricity triple supply mode controller control mode by power control be converted to power control add Chirp control mode;
Step 3, frequency fluctuation after stable are less than definite value and after time delay n second, the control mode of cold, heat and electricity triple supply mode controller controls to add Chirp control mode by power and is converted to frequency modulation and voltage modulation control mode, and the frequency and voltage arrived using current detection is as the set point of frequency modulation and pressure regulation, and output generator off-the-line instruction;
After step 4, generator off-the-line, cold, heat and electricity triple supply mode controller switches to lonely net pattern by grid-connect mode, and frequency modulation and voltage modulation set point is 0.5Hz/min to 3Hz/min from currency by frequency modulation set point change speed, pressure regulation set point change speed is that 0.001Ue/s to 0.01Ue/s changes to default lonely net pattern lower frequency and voltage setting value, frequency modulation set point change speed is 0.5Hz/min to 3Hz/min, pressure regulation set point change speed is 0.001Ue/s to 0.01Ue/s, wherein: Ue is electrical network rated voltage;
Step 5, when Chirp module is not operating, cold, heat and electricity triple supply mode controller receives grid-connect mode and switches to the instruction of lonely net mode request, cold, heat and electricity triple supply mode controller is converted to frequency modulation and voltage modulation control mode by power control mode, and the frequency and voltage arrived using current detection is as frequency modulation and pressure regulation set point, the then instruction of output generator off-the-line;
After step 6, generator off-the-line, cold, heat and electricity triple supply mode controller switches to lonely net pattern by grid-connect mode, and frequency modulation and voltage modulation set point is 0.5Hz/min to 3Hz/min from currency by frequency modulation set point change speed, and pressure regulation set point change speed is that 0.001Ue/s to 0.01Ue/s changes to default lonely net pattern lower frequency and voltage setting value;
Step 7, when Chirp module not operating, cold, heat and electricity triple supply mode controller does not receive grid-connect mode and switches to the instruction of lonely net mode request, when cold, heat and electricity triple supply mode controller detects generator off-the-line, cold, heat and electricity triple supply mode controller switches to lonely net pattern by grid-connect mode, control mode controls to be converted to frequency modulation and voltage modulation by power and controls, and frequency modulation and voltage modulation set point is default lonely net pattern lower frequency and voltage setting value;
Step 8, when Chirp module is not operating, cold, heat and electricity triple supply mode controller does not receive grid-connect mode and switches to the instruction of lonely net mode request, when cold, heat and electricity triple supply mode controller does not detect generator off-the-line, return step 2 and wait for that logic performs next time.
7. the method for lonely net and grid-connect mode seamless switching in a kind of cold, heat and power triple supply system according to claim 6, it is characterized in that: Chirp module described in step 1 refers to the power correction signal superposing a FM module output on the power control set point of grid-connect mode, described power correction signal is proportional to the deviation of frequency and rated value, and its algorithm is:
In formula:
for the power correction signal that Chirp module exports;
for the specified active power of generator;
for momentary speed variation;
for generator rated speed;
the deviate after dead band limits for electrical network rated frequency and generator frequency.
8. the method for lonely net and grid-connect mode seamless switching in a kind of cold, heat and power triple supply system according to claim 6, is characterized in that: Chirp module action described in step 2 is the deviate after dead band limits by electrical network rated frequency and generator frequency
judge, when
time, Chirp module does not have action; When
time, Chirp module action.
9. the method for lonely net and grid-connect mode seamless switching in a kind of cold, heat and power triple supply system according to claim 6, it is characterized in that: the frequency fluctuation described in step 3 after stable is less than definite value and after time delay n second, limits is+0.1Hz is 0.2s-5s to+0.5Hz, delay time n.
10. the method for lonely net and grid-connect mode seamless switching in a kind of cold, heat and power triple supply system according to claim 6, it is characterized in that: the lonely net pattern lower frequency preset described in step 4, step 6, step 7 and voltage setting value, frequency setting value is+49.5Hz to+50.5Hz, voltage setting value is+0.9Ue to+1.1Ue, wherein: Ue is electrical network rated voltage.
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