CN102946224B - Thermal power unit power prediction control system for ensuring safety and stability of sending-end electric grid - Google Patents
Thermal power unit power prediction control system for ensuring safety and stability of sending-end electric grid Download PDFInfo
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- CN102946224B CN102946224B CN201210536379.9A CN201210536379A CN102946224B CN 102946224 B CN102946224 B CN 102946224B CN 201210536379 A CN201210536379 A CN 201210536379A CN 102946224 B CN102946224 B CN 102946224B
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Abstract
The invention discloses a thermal power unit power prediction control system for ensuring the safety and stability of a sending-end electric grid. The thermal power unit power prediction control system comprises a high-frequency emergency state and prediction unit (1), a speed regulator prediction control unit (2) and a boiler prediction control unit (3), wherein the high-frequency emergency state and prediction unit (1) is electrically connected with the speed regulator prediction control unit (2) and the boiler prediction control unit (3); the speed regulator prediction control unit (2) is electrically connected with a servo of a speed regulating mechanism; and the boiler prediction control unit (3) is electrically connected with a boiler and an auxiliary machinery. According to the invention, when the sending-end electric grid is split, the power naturally distributed to a unit by the sending-end electric grid is measured, unit prediction power setting for keeping isolated grid balance and equitable distribution is obtained through conversion, fast and accurate control regulation is carried out through a unit prediction control method on a steam turbine and the boiler, so that the dynamic energy balance among the boiler, the steam turbine and the sending-end electric grid is effectively ensured, the problem of oscillation of OPC (Overspeed Protection Control) is solved, and the high-frequency stable level of the sending-end electric grid and the safety of the unit are greatly enhanced.
Description
Technical field
The present invention relates to Power system security control field and turbo generator set heating power control field, refer more particularly to a kind of fired power generating unit power prediction control system ensureing sending end electricity net safety stable.
Background technology
The generated output of the turbo generator set in sending end electrical network is sent to receiving end electrical network by electrical network, if charge circuit trips under sending end electrical network and receiving end electric network fault off-the-line or lonely net state, turbine generator acc power has exceeded load, mains frequency and generating unit speed will be caused to rise, if the uneven degree of grid power is larger, too high rotating speed, with regard to the safety of entail dangers to turbine blade, causes cutting machine, thus causes power grid high-frequency unstability.
Under power grid high-frequency state, turbo generator set overspeed protection (OPC) meeting action, steam off valve reduces unit output fast, mains frequency fast return can be made to normal, to ensure Turbine Safety.But when OPC release, the control of valve rotates back into again primary frequency modulation and the power control of speed regulator, speed regulator now loses correct control setting, still power setting before off-the-line, that exceed lonely net load level is to a great extent remained on, make unit start again increase to exert oneself, electrical network turns back to high frequency state once more, thus causes OPC action again.The circulation of this process repeatedly, causes mains frequency and the power of the assembling unit to be periodic zigzag fluctuation, finally causes lonely net large area dead electricity.This situation, repeatedly occurs in sending end grid disconnection accident at home.
Research finds, under the technical conditions of current standard, code and regulatory documents defined, the high-frequency stabilization nargin of fired power generating unit governing system is very low, if fired power generating unit power overloads the 12%(of power and unbalanced power supply rate during off-the-line) left and right, lonely net frequency would not be stablized.Especially the sending end electrical network that the little net of large machine is formed, electricity net safety stable controlling system and high-frequency cutting machine automatics are difficult to lonely net unbalance factor to control within 12%, high-frequency stabilization can not access guarantee, has had a strong impact on the safety and stability reliability service of sending end electrical network and unit.
Energy adjusting process due to boiler is slower than the power adjustment procedure of steam turbine, and the power adjustment procedure of steam turbine is slower than the electromechanical transient process of electrical network.When sending end grid disconnection, the power adjustment procedure of steam turbine slow, causes rotating speed too high, causes turbine blade safety problem; The energy adjusting process of boiler slow, causes main vapour pressure too high, causes emergency exit action, easily cause unit to cut machine.Therefore, accelerating the adjustment process of steam turbine and boiler, is the key of high-frequency stabilization problem when solving sending end grid disconnection.
Summary of the invention
The technical problem to be solved in the present invention: a kind of fired power generating unit power prediction control system ensureing sending end electricity net safety stable is provided, to solve when sending end grid disconnection, the power adjustment procedure of steam turbine slow, causes rotating speed too high, causes turbine blade safety problem; The energy adjusting process of boiler slow, causes main vapour pressure too high, causes emergency exit action, easily cause unit to cut the problems such as machine.
Technical solution of the present invention:
Ensure the fired power generating unit power prediction control system of sending end electricity net safety stable, it comprises:
The high frequency state of emergency and predicting unit, the high frequency state of emergency whether is according to input signal distinguishing electrical network, when the high frequency state of emergency, output fast power returns and falls signal, power control target, power of the assembling unit setting and power variation rate, is electrically connected with speed regulator PREDICTIVE CONTROL unit and boiler PREDICTIVE CONTROL unit; Described input signal comprises the power of the assembling unit, rotating speed and overspeed protection actuating signal.
Speed regulator PREDICTIVE CONTROL unit, under the high frequency state of emergency, the control of PID power is carried out according to the power of the assembling unit setting that the high frequency state of emergency and predicting unit are sent, period is sent in overspeed protection OPC actuating signal, integration output state is readjusted the power setting into prediction, return at fast power and fall signal and send period, cancel or reduce the restriction of regulating command speed limit link, the high pressure valve instruction of output is sent to the server of speed adjusting gear, is electrically connected with the server of speed adjusting gear;
Boiler PREDICTIVE CONTROL unit, under the high frequency state of emergency, the fast power sent according to the high frequency state of emergency and predicting unit returns and falls signal, automatically analog control system MCS control mode is converted to boiler follow BF mode, cuts coal pulverizer according to power variation rate connection, accelerate the response of fuel supply process, fast power return fall signal send time, open and close controlling is carried out to electronic pressure relieving valve PCV, according to power variation rate, bypass BP is controlled, be electrically connected with boiler and subsidiary engine;
The high frequency state of emergency and predicting unit comprise:
High frequency state of emergency discrimination module, carries out logical operation according to overspeed protection OPC actuating signal, tach signal and unit off-grid signal, judges whether system is in the high frequency state of emergency, be electrically connected with state of emergency broadening module;
State of emergency broadening module, according to the high frequency state of emergency signal that high frequency state of emergency discrimination module is sent into, carry out broadening by the time of setting, export and fall power signal for returning fast, be electrically connected with power variation rate memory, power setting memory and supervisory control system;
Generator power, frequency and voltage acquisition module, gather generator power, frequency and voltage, is electrically connected with power, frequency and voltage factor correcting module;
Power, frequency and voltage factor correcting module, according to frequency and the voltage factor correction generator power of network load, make the generator power measured during OPC action, with load balancing in total amount, output one tunnel of power, frequency and voltage factor correcting module is electrically connected with power variation rate memory after delayer, one tunnel is directly electrically connected with power variation rate memory, and a road is electrically connected with power setting memory;
Power variation rate memory, triggers by returning fast the rising edge falling power signal FB, the ratio of generator power before generator power and off-the-line when calculating off-the-line, and Writing power rate of change memory also keeps;
Power setting memory, when state of emergency broadening module exports rising edge, the power of the assembling unit write memory measured in this moment, keeps and exports as power of the assembling unit setting during state of emergency broadening, in the state of emergency, power setting feram memory will keep always.
Speed regulator PREDICTIVE CONTROL unit comprises integral element module that state can reset and state of emergency speed limit exits module, and the integral element module that state can reset exits model calling by the 3rd adder and state of emergency speed limit.
Boiler PREDICTIVE CONTROL unit comprises:
" power is followed " control mode modular converter: fall signal according to returning fast of sending of the high frequency state of emergency and predicting unit, the control mode of analog control system MCS is set to " boiler follow " mode, be electrically connected with the first routing switch;
" boiler follow " controller output tracking module, in analog control system control mode, " boiler follow " controller is made to form a closed loop of following the tracks of stop-valve pressure, keep the correct output state of PID, when avoiding being switched to " boiler follow " control mode under the high frequency state of emergency, the generation transition of output state, is electrically connected with the first adder-subtracter;
Coal pulverizer excision and fuel distribution module, according to power variation rate, at the initial time of high frequency state of emergency amount, trigger and start coal pulverizer excision logic, excise the corresponding coal pulverizer quantity closest to power variation rate, accelerate the control response speed of fuel, alleviate the slow problem causing main vapour pressure high of fuel adjustment.
Described a kind ofly ensure that the fired power generating unit power prediction control system of sending end electricity net safety stable is when overspeed protection (OPC) action; measure generator active power; active power, after corrected Calculation, as the power of the assembling unit setting of prediction, controls the power of the assembling unit.
Period is sent in overspeed protection (OPC) actuating signal; the output state of integral element during the power P ID of speed regulator PREDICTIVE CONTROL unit is controlled; be adjusted to the conversion numerical value of predicted power setting; the conversion numerical value of the power setting of described prediction is the generator active power measured at OPC action initial time; through revising and converting, be re-used as the displacement numerical value of the output state of integral element.
Beneficial effect of the present invention:
The present invention is after sending end grid disconnection, lonely net trend can change immediately, in lonely net, the power of each power plant will be redistributed naturally, utilize the power of distribution naturally of initial time under the high frequency state of emergency, as the power setting of prediction after the correction of the frequency and voltage factor, this is the feature had of the present invention.This feature has ensured that in electrical network, each power plant is to disperse independently control mode, when sending end grid disconnection, coordinates reasonably to distribute adjustment task, makes electrical network reach power-balance, reduce the stable state frequency difference that classical control system exists; And ensured system of the present invention and stablely cut machine control system, without writing to each other, can control independently, keeping natively coordinating.
The present invention adopts Prediction and Control Technology, when sending end grid disconnection, lonely net load rejection and the load rejection of unit off-grid, achieve five coordinations, effectively improve sending end electrical network and unit safety stability, particularly:
Achieve the coordination of Opc primary frequency modulation, power control; While effective guarantee turbine blade safety, improve the stability of governing system and electrical network.
Achieve between governing system and boiler implosion and coordinate, namely coordinate between power and fuel vapor pressure-controlled, overcome the conflict produced because speed is different between steam turbine and boiler implosion, effectively prevent that vapour pressure is too high causes emergency exit action, improve unit safety reliability.
Realize the coordination between each Power Plant in lonely net, power after machine reasonable set shares lonely net load rejection in lonely net adjusts task, unit is undertaken regulating by setting separately, and the power that can not occur to cause because machine unit characteristic is different with parameter is grabbed and conflict, avoids the vibration formed thus.
Achieve the power of the assembling unit and control the balance and coordination with lonely net load, the power setting summation that in lonely net, unit is predicted separately is equal with lonely net load, and after each self-regulation of unit, mains frequency can turn back to rated frequency.
Achieve the coordination that unit allocation and electricity net safety stable cut machine measure, unit allocation and electricity net safety stable cut machine measure can without communicating to connect and cooperating, each self-adjusting and action, and both cooperation keeps natural harmonious.
The present invention is that unit carries out disperseing independent control with unit, and between unit, unit and stable machine of cutting link without communication, automatically mutually coordinates.This distributed coordination control technology, for the sending end grid disconnection that unpredictable character fault causes, for the lonely net high-frequency stabilization under hazardous condition, possesses very strong adaptability,
The present invention significantly can improve sending end power grid high-frequency maintenance level, improves the anti-disaster ability of electrical network under electrical network robustness under Unpredictability fault and hazardous condition, improves unit safety, have significant social benefit
The present invention is with the control technology of low cost, the frequency security stable problem of the little net of the large machine of effective solution, after eliminating these restraining factors, Large-scale machine set just can be accessed 220kV regional power grid when planning by electrical network, dissolve and get in touch with change by 500kV after load and send, eliminate the roundabout of load current, the electric energy loss of the power transmission network greatly reduced, be a kind of less investment, energy-saving and emission-reduction measure that effect is large.
The invention solves Large-scale machine set access 220kV regional power grid key issue, after Large-scale machine set access 220kV regional power grid, generated output is dissolved 220kV regional power grid load, send into 500kV grid power to reduce in a large number, the corresponding capacity decreasing 500kV power transformating and supplying facility, can the huge investment of corresponding saving 500kV electrical network primary equipment, there is significant economic benefit.
The present invention utilizes the natural partition characteristic of the power of the assembling unit after sending end grid disconnection, do not need to build Centralized Control System, control with decentralized control, there is enforcement technology simple, feature with low cost, and, the present invention and domestic current relevant criterion, specification and specify not clash, be beneficial to and develop on prior art and transform, be beneficial to popularization, solve when sending end grid disconnection, the power adjustment procedure of steam turbine slow, cause rotating speed too high, cause turbine blade safety problem; The energy adjusting process of boiler slow, causes main vapour pressure too high, causes emergency exit action, easily cause unit to cut the problems such as machine.
accompanying drawing illustrates:
Fig. 1 is each control unit composition frame chart of the present invention;
Fig. 2 is the high frequency state of emergency of the present invention and predicting unit modular structure schematic diagram;
Fig. 3 is speed regulator PREDICTIVE CONTROL unit module structural representation of the present invention;
Fig. 4 is boiler PREDICTIVE CONTROL unit module structural representation of the present invention;
Fig. 5 is the analogous diagram of conventional governing system when electrical network throws away 40% load;
Fig. 6 is the analogous diagram of control system of the present invention when throwing away 40% unit output.
embodiment:
The principle that during sending end grid disconnection, the lonely net power of the assembling unit is distributed and character:
When sending end grid disconnection, lonely net trend changes immediately, unit generation power is redistributed, theoretical foundation of the present invention, on the character being based upon unit generation power division after lonely net off-the-line, because electrical network electromechanical process is complicated, its character of must deriving in the ideal situation, then analyzes actual electric network and desirable departing from property of electrical network.
When sending end grid disconnection, in lonely net, the electromagnetism synchronous torque of each generator is mutually led and is drawn, and each unit in electrical network can keep synchronous, the rotating speed rate of climb is basically identical, the moment arriving OPC action (3090rpm) is substantially identical, therefore, can suppose that in lonely net, generating unit speed is consistent.After grid disconnection with OPC action before this period, because of the time delay of valve servo, pipeline and cylinder, can suppose that the mechanical output of prime mover is before OPC action, power does not change; After the voltage ignoring load and frequency effect, the character of unit power division when can obtain sending end grid disconnection under supposition state.
Keep the principle of balance at synchronization according to electric network swim, after grid disconnection, unit is identical in the moment of OPC action, now inscribes each self-metering generated output of unit that lonely net is all, equal with lonely net load, is called character 1.
Character 1 shows, all units in electrical network, and at the unit generation power that the moment of OPC action measures, the power setting as governing system carries out each self-adjusting, and grid generation power can be made equal with load, and mains frequency can turn back to specified.
[0001] there is m platform generating set in lonely net, following standardization formula can be derived according to electro-mechanical principle
Wherein,
it is generated output before interior i-th the unit solution of lonely net
with power after off-the-line
difference,
for this unit generation capacity,
for this turbine generator inertia time constant.
it is the difference of lonely net load power after lonely net off-the-line front generate electricity gross power and off-the-line.
<2> formula shows: after off-the-line, when OPC action, measures the power of the assembling unit setting of unit generated output as prediction
, when each unit regulates by predicted power setting, the uneven gross power of lonely net
adjustment task be that this character is called character 2 by the pro rate of the product of each unit capacity and turbine generator inertia time constant to each unit in netting.
Notice, the moment of inertia time constant difference of Large Hydropower Station and fired power generating unit is little, the uneven gross power of lonely net
substantially be according to the pro rate of unit capacity size to each unit.The character of naturally distributing by generated output after this grid disconnection regulates unit original machine power, is fair and reasonable.
Character 2 shows all units in electrical network, and at the unit generation power that the moment of OPC action measures, the power setting as governing system controls adjustment separately, and it is rational that each unit adjustment amount distributes.Character 1 and character 2 show jointly, without writing to each other, under power grid high-frequency state, can realize cooperation control between unit unit.
Load rejection power
, moment of inertia time constant
, rotating speed
and raising speed
can derive as follows with the relational expression of OPC t operate time:
<3>
In formula, all variablees are perunit value
The operate time that OPC is rising to 3090rpm is:
The moment of inertia time constant of 300MW and above fired power generating unit is greater than 8.4 seconds, under unit generation power all throws away situation, namely
=1, can calculate OPC operate time is 0.27 second.
And whole group of operate time of electricity net safety stable controlling system control of section is less than or equal to 0.2 second, be therefore less than fired power generating unit OPC operate time whole group of operate time of electricity net safety stable controlling system.
If safety stabilization control system is with deficient Qie Celveqie machine after off-the-line, stable cut machine after the lonely net power of the assembling unit again naturally distribute, after being assigned, OPC is action subsequently, this unit generation power measured constantly, still retention properties 1 and character 1.Therefore, no matter whether security stability control system cuts machine, and the generated output measured during OPC action is as the power setting of speed regulator, always correct, and this character is called character 1.
Character 3 shows, between safety stabilization control system and power of the assembling unit control system, without writing to each other, can disperse regulable control separately, mutually keeps coordinating.
Above-mentioned character is derived according to supposition, and in actual electric network, situation can depart to some extent with above-mentioned character, and according to simulation calculation, the character of actual electric network is as follows:
The lonely net that unit or single factory homotype unit are formed is at the various fault disconnection of generation, and the power of the assembling unit can not fluctuate, and the power setting of prediction meets three character, and departure degree is very little.
The lonely net fault-free trip off-the-line of the unit formation that many factories are dissimilar, power of the assembling unit fluctuation is minimum, and the power setting of prediction meets three character, and departure degree is very little.
Many factories form sending end electrical network generation three-phase ground, alternate, single-phase permanent fault and off-the-line, lonely net unit can fluctuate mutually, if lonely net load rejection rate (unbalance factor) is greater than 50%, in limited instances, the power setting of prediction departs from character 2, occur that unit regulates task matching non-uniform phenomenon, but power of the assembling unit setting is balance with lonely net load, the degree departing from character 1 is very little, control system can ensure high-frequency stabilization, just unit regulates the distribution slightly unjust phenomenon of task, in actual electric network is run, this situation is very rare, electrical network just considers power-balance problem when planning and run, substantially there is not load rejection rate and be greater than the lonely net of factory more than 50%.
Embodiment of the present invention
A kind of fired power generating unit power prediction control system ensureing sending end electricity net safety stable it comprise (see figure 1):
The high frequency state of emergency and predicting unit 1, the high frequency state of emergency whether is according to input signal distinguishing electrical network, when the high frequency state of emergency, output fast power returns and falls signal, power control target, power of the assembling unit setting and power variation rate, be connected with speed regulator PREDICTIVE CONTROL unit 2 and boiler PREDICTIVE CONTROL unit 3 signal of telecommunication, the high frequency state of emergency and predicting unit 1 to be connected with automatic power generation system (AGC) by supervisory control system carries out information interaction.
The function of the high frequency state of emergency and predicting unit 1 is, fast, accurately, reliably dope and keep the power of the assembling unit balanced to set with lonely net load, the rapid adjustment for vapour pressure, fuel, air quantity provides PREDICTIVE CONTROL amount accurately.According to the signal comprising overspeed protection (OPC) actuating signal, it differentiates whether electrical network is in the high frequency state of emergency, carries out time explanation to the state of emergency, output fast power returns and falls signal; Utilize in the naturally distribution of off-the-line initial stage electrical network to the power of the assembling unit, in overspeed protection (OPC) the action moment, measure the power of the assembling unit as the power of the assembling unit after grid disconnection, after the correction of LOAD FREQUENCY Summing Factor voltage factor, output to speed regulator PREDICTIVE CONTROL unit as the power setting predicted under the high frequency state of emergency; The regulated quantitys such as the rated output rate of change export boiler PREDICTIVE CONTROL unit.
The high frequency state of emergency and predicting unit comprise (see figure 2):
High frequency state of emergency discrimination module, carries out logical operation according to overspeed protection OPC actuating signal, tach signal and unit off-grid signal, judges whether system is in the high frequency state of emergency, be connected with state of emergency broadening module by signal; Basic handling logic is: the actuating signal sent according to overspeed protection OPC, the out-of-limit signal of rotating speed (output after tach signal and rotary speed setting signal ω set comparison operation) and the logic NOT signal of unit off-grid carry out logical AND operation, the criterion of high frequency state is in as unit, the out-of-limit signal of rotating speed plays and prevents misoperation from using, the high frequency state of emergency differentiates that basic logic can determine two kinds of high frequency fault forms that may occur: a. sending end grid disconnection, and unit is among the orphan's net under high frequency state; B. the unit in lonely net, large charge circuit tripping operation.This module only comprises basic logic, but the invention is not restricted to utilize other signals to carry out logical combination, as: under considering sliding pressure operation state, unit does not participate in high frequency adjustment, sliding pressure status signal can be got " non-" and access this module afterwards.
State of emergency broadening module, according to the high frequency state of emergency signal that high frequency state of emergency discrimination module is sent into, broadening is carried out by the time of setting, export and fall power signal for returning fast, with power variation rate memory, power setting memory is connected with supervisory control system wire, the high frequency state of emergency signal that it is sent into according to high frequency state of emergency discrimination module, broadening is carried out by the time of setting, export and fall power signal FB(Fast Back for returning fast), represent the emergency pulling back to setting power fast of machine furnace control system, this be one with RB(Run Back) and FCB(Fast Cut Back) have the event signal of larger difference.FB and RB difference is, it is not according to adjusting power or energy under given pace or time sequencing, but by the signal rapid adjustment unit output once predicted; It and FCB difference are, FCB throws away the whole loads to mains supply, and FB is that the setting power of unit rapid downward regulation to prediction is to mains supply.The high frequency state of emergency (namely returning fast the process of falling in the time broadening of power signal FB) refer to lonely net frequency from high frequency to stable state dynamic process, time broadening is set at 200 ~ 300s, for fired power generating unit, this period includes the rotating speed of steam turbine and the dynamic process of power adjustment, includes boiler pressure critical first time fluctuation adjustment process;
Generator power, frequency and voltage acquisition module, generator power, frequency and voltage are gathered, be connected with power, frequency and voltage factor correcting module signal, the power of Generator end is sampled the generator power obtained, take the delayer time delay mode of 5 ~ 10 seconds, obtain the power of generator before off-the-line;
Power, frequency and voltage factor correcting module, according to frequency and the voltage factor correction generator power of network load, make the generator power measured during OPC action, with load balancing in total amount, output one tunnel of said module is connected with power variation rate memory signals and exports power P before off-the-line after delayer
-N, a road is directly connected power P when exporting off-the-line with power variation rate memory signals, and a road is connected power P (promptly) when exporting off-the-line with power setting memory signals;
Power variation rate memory, triggers by returning fast the rising edge falling power signal FB, generator power P before generator power P and off-the-line when calculating off-the-line
-Nratio, write memory also keeps;
Power setting memory, when state of emergency broadening module exports rising edge, the power of the assembling unit P write memory of " promptly " state moment measurement will be somebody's turn to do, keep during state of emergency broadening and export as power of the assembling unit setting, in the state of emergency, memory will keep always, it exports the moment (i.e. OPC action moment) of rising edge in state of emergency broadening module, the power of the assembling unit write memory of " promptly " moment measurement will be somebody's turn to do, keep during state of emergency broadening and export as power of the assembling unit setting, state that if supervisory control system is not removed " promptly ", memory will keep always.If " state of emergency " is removed in monitoring, then the power of the assembling unit that write supervisory control system is sent sets by memory.It may be that automatic power generation system (AGC) is sent that power setting is sent in monitoring, has the power setting of " remote control " character, also may be that power plant operations staff operates write, have the power setting of " this locality " character.
Speed regulator PREDICTIVE CONTROL unit 2(is shown in Fig. 3):
Under the high frequency state of emergency, the control of PID power is carried out according to the power setting that the high frequency state of emergency and predicting unit 1 are sent, period is sent in overspeed protection OPC actuating signal, integration output state is readjusted the power setting into prediction, fast power return fall signal send period, cancel or reduce the restriction of regulating command speed limit link, the high pressure valve instruction of output is sent to the server of speed adjusting gear, is connected with the server wire of speed adjusting gear; Speed regulator PREDICTIVE CONTROL unit 2 comprises integral element module 3.1 that state can reset and state of emergency speed limit exits module 3.2, and the integral element module 3.1 that state can reset exits module 3.2 by the 3rd adder 3.5 and state of emergency speed limit and is connected.
Under the normal state of electrical network, this unit carries out conventional PID and regulates, under the high frequency state of emergency after off-the-line, and the power setting that its power setting is predicted after being switched to grid disconnection by the high frequency state of emergency and predicting unit 1.Period is sent in overspeed protection (OPC) actuating signal; namely high pressure valve control right transfer is to OPC; during speed regulator PREDICTIVE CONTROL unit loses high pressure valve control; speed regulator PREDICTIVE CONTROL unit utilizes this period to carry out the conversion of state; by the output state of integral element, be converted into the power setting of prediction.After overspeed protection (OPC) actuating signal terminates, when high pressure valve control transfers to again speed regulator PREDICTIVE CONTROL unit, the integral element output state of speed regulator PREDICTIVE CONTROL unit PID has been converted into the power setting of prediction.Return at fast power and fall signal and send period, speed regulator PREDICTIVE CONTROL unit by cancelling or reduce the restriction of regulating command speed limit link, to adapt to the significantly change of correct regulating command.The effect of this unit is solution overspeed protection (opc), speed regulator power controls and the conflict of primary frequency modulation; make to keep between three coordinating; solve the instability problem of OPC perseveration unit and grid power oscillation on large scale; make the power of the assembling unit and mains frequency turn back to rated frequency fast, steadily, ensure unit and power grid security.This unit is made up of primary frequency modulation, power P ID adjuster and speed limit amplitude limit link, build in (DEH) in digital electro-hydraulic governing system, be with conventional governors difference, the integral element module 3.1 that integral element in PID takes state to reset, state of emergency speed limit exits module 3.2.Particularly, the function declaration of each module is as follows:
The integral element module 3.1 that state can reset is by state Resetting Switching 3.1.1, discharge switch 3.1.2, and integrating state resets coefficient 3.1.3, pure integral element 3.1.4 and corresponding control loop and forms.When OPC action, state Resetting Switching 3.1.1 signal condition is " T ", the power setting signal that " Y " identifies is exported to the 4th adder-subtracter 3.1.6, now power setting has been the predicted power of unit after grid disconnection, the integral element module 3.1 that the discharge switch 3.1.2 state of getting can reset outputs signal, and forms inner feedback loop.Because integrating state resets coefficient 3.1.3 very greatly, the output of 3.2 can be adjusted to close to 0 by feedback loop in a step-length, and now pure integral element 3.1.4 exports the predicted power of just clamping down on as unit after grid disconnection.When OPC exits, state is " F ", and discharge switch 3.1.2 cuts off feedback loop, and it is 0 that state Resetting Switching 3.1.1 exports, and the output of the integral element 3.2 that state can reset is exactly the output of pure integral element, i.e. the predicted power of unit after grid disconnection.
The output signal that 3rd adder-subtracter gets the output signal and the second adder-subtracter 3.6 that integrating state resets coefficient 3.1.3 delivers to the 3rd adder-subtracter 3.1.5, after carrying out subtracting calculating, after carrying out integral and calculating by integral constant and integrated value 1/S 3.1.4, deliver to the 4th adder-subtracter 3.1.6.The 3rd adder 3.5 is outputed signal to by the 4th adder-subtracter 3.1.6, deliver to the second adder-subtracter 3.6 together with rotating speed sets with the power of the assembling unit with power of the assembling unit P after primary frequency modulation and carry out plus and minus calculation, output lead up to proportionality constant amplify after deliver to the 3rd adder 3.5, the 3rd adder 3.5 is delivered in one tunnel after derivative constant and derivative constant value S carry out differential calculation, 3rd adder 3.5 is after adding computing, export speed limit module 3.2.1 to, hold with the Y of the 3rd routing switch 3.2.2, speed limit module 3.2.1 exports the N end of the 3rd routing switch 3.2.2 to, 3rd routing switch 3.2.2 falls signal FB by quick time to be triggered, clipping module 3.3 is delivered in output, the output of clipping module 3.3 is delivered to the 4th adder and form valve command output after being added computing together with the output after primary frequency modulation.
Boiler PREDICTIVE CONTROL unit 3(is shown in Fig. 4)
Under the high frequency state of emergency, the fast power sent according to the high frequency state of emergency and predicting unit 1 returns and falls signal, automatically analog control system (MCS) control mode is converted to boiler follow (BF) mode, coal pulverizer is cut according to power variation rate connection, accelerate the response of fuel supply process, fast power return fall signal send time, open and close controlling is carried out to electronic pressure relieving valve (PCV), according to power variation rate, bypass (BP) is controlled, be electrically connected with boiler and subsidiary engine;
Boiler PREDICTIVE CONTROL unit 3 comprises (see figure 4): " power is followed " control mode modular converter 4.1: fall signal according to returning fast of sending of the high frequency state of emergency and predicting unit 1, the control mode of analog control system (MCS) is set to " boiler follow " mode;
" boiler follow " controller output tracking module 4.2, under analog control system control mode, " boiler follow " controller is made to form a closed loop of following the tracks of stop-valve pressure, keep the correct output state of PID, when avoiding being switched to " boiler follow " control mode under the high frequency state of emergency, the generation transition of output state; Coal pulverizer excision and fuel distribution module 4.3, according to power variation rate, at the initial time of high frequency state of emergency amount, trigger and start coal pulverizer excision logic, according to owing to cut principle, excise the corresponding coal pulverizer quantity closest to power variation rate, accelerate the control response speed of fuel, alleviate the slow problem causing main vapour pressure high of fuel adjustment.
The course of work: boiler PREDICTIVE CONTROL unit receives to return fast and falls signal FB, spray water flux, high pressure valve valve position signal, main vapour pressure setting TPs, the information such as power variation rate and main vapour pressure, spray water flux and high pressure valve valve position signal deliver to two inputs of first adder 4.7, after adding computing, Output rusults delivers to an input of second adder 4.8, main vapour pressure sets the input value of output as the first adder-subtracter of TPs and secondary route switch, after subtracting computing, deliver to vapour pressure and fuel Control PID module 4.6, an input of second adder 4.8 is delivered in the output of vapour pressure and fuel Control PID module 4.6, second adder 4.8 exports boiler follow and controls output signal, deliver to the N input of secondary route switch and the Y input of the first routing switch 4.4, stop-valve pressure is connected to secondary route switch Y input, the output of second adder 4.8 is connected to the N input of secondary route switch, the N of the first routing switch 4.4 inputs other control modes of termination and exports, the output boiler follow that Y inputs termination second adder 4.8 controls output signal, first routing switch 4.4 exports boiler master order to fuel controlling functions module 4.9, the coal pulverizer that outputs to of fuel controlling functions module 4.9 excises and fuel distribution module 4.3, coal pulverizer excision and the fuel distribution module 4.3 received power rate of change fall signal with returning fast, export coal pulverizer Resection in Treatment and fuel control command.
When overspeed protection (OPC) action, measure generator active power, active power or after corrected Calculation, as the power of the assembling unit setting of prediction, the power of the assembling unit is controlled.
Period is sent in overspeed protection (OPC) actuating signal; the output state of integral element during the power P ID of speed regulator is controlled; be adjusted to the conversion numerical value of predicted power setting; the conversion numerical value of the power setting of described prediction is the generator active power measured at OPC action initial time; through revising and converting, be re-used as the displacement numerical value of the output state of integral element.
Integration mode:
The present invention is in turbo generator set Distributed Control System DCS, the high frequency state of emergency and predicting unit 1 and speed regulator PREDICTIVE CONTROL unit 2 are embedded into the digital electro-hydraulic control system (DEH) in DCS, boiler PREDICTIVE CONTROL unit 3 is embedded in analog control system (MCS).
The high frequency state of emergency and predicting unit, exploitation becomes hardware module new in numerical control screen cabinet in DEH, and its processing speed is identical with the overspeed protection module in DEH.
Speed regulator PREDICTIVE CONTROL unit, exploitation becomes new module and replaces speed regulating control module in former DEH, or is changed by the software of master mould member.
The development scheme of boiler PREDICTIVE CONTROL unit, by DCS signal and functional configuration mode, " power is followed " control mode modular converter in Fig. 4 4.1 and " boiler follow " controller output tracking module 4.2 are embedded in " boiler follow " mode control loop of MCS boiler master part; Fuel in fuel sub-system distributes control section, falls signal FB and power variation rate according to returning fast, implements prediction excision coal pulverizer function 4.3.
Data acquisition and communication mode, be input to the power signal of the high frequency state of emergency and predicting unit, tach signal and OPC actuating signal and should adopt mode of directly adopting and special optic fibre communication mode, ensure described signals collecting and the rapidity communicated and synchronism.All the other I/O signals are undertaken gathering and transmitting by the data acquisition of DCS and communication network.
Fig. 5 and Fig. 6 is: conventional governing system and Qi Zhong ⊿ ω-speed discrepancy (Hz) of the simulation comparison of control system of the present invention when throwing away 40% unit output, Pe-generated output (pu), Pm-mechanical output (pu),
OPC-OPC actuating signal (1 is action, and 0 for being failure to actuate).
Embodiment is described in this specification, but the present invention is not limited to the details that above-mentioned demonstration is implemented, when not departing from spirit of the present invention and essential characteristic, also available additive method realizes the present invention, therefore, should embodiment be regarded as exemplary, and it is nonrestrictive, scope of the present invention is limited by claims instead of above-mentioned explanation, therefore all changes be intended in the implication of the equivalency by dropping on claim and scope are included in the present invention, the any Reference numeral in claim should be considered as the claim involved by limiting.In addition, obviously " comprising " one word do not get rid of other unit or module, be also all subject to the protection of this patent.Parameter values described in embodiment is only example, parameter values should be considered as the claim involved by limiting.Multiple unit of stating in claim, module also can be realized by software or hardware by a unit or module or device.A unit of stating in claim, module also can be realized by software or hardware by multiple unit or module or device.
Claims (5)
1. ensure the fired power generating unit power prediction control system of sending end electricity net safety stable, it comprises:
The high frequency state of emergency and predicting unit (1), the high frequency state of emergency whether is according to input signal distinguishing electrical network, when the high frequency state of emergency, output fast power returns and falls signal, power control target, power of the assembling unit setting and power variation rate, is electrically connected with speed regulator PREDICTIVE CONTROL unit (2) and boiler PREDICTIVE CONTROL unit (3); Described input signal comprises the power of the assembling unit, rotating speed and overspeed protection actuating signal;
Speed regulator PREDICTIVE CONTROL unit (2), under the high frequency state of emergency, the control of PID power is carried out according to the power of the assembling unit setting that the high frequency state of emergency and predicting unit (1) are sent, period is sent in overspeed protection OPC actuating signal, integration output state is readjusted the power setting into prediction, fast power return fall signal send period, cancel or reduce the restriction of regulating command speed limit link, the high pressure valve instruction of output is sent to the server of speed adjusting gear, is electrically connected with the server of speed adjusting gear;
Boiler PREDICTIVE CONTROL unit (3), under the high frequency state of emergency, the fast power sent according to the high frequency state of emergency and predicting unit (1) returns and falls signal, automatically analog control system MCS control mode is converted to boiler follow BF mode, cuts coal pulverizer according to power variation rate connection, accelerate the response of fuel supply process, fast power return fall signal send time, open and close controlling is carried out to electronic pressure relieving valve PCV, according to power variation rate, bypass BP is controlled, be electrically connected with boiler and subsidiary engine;
The high frequency state of emergency and predicting unit comprise:
High frequency state of emergency discrimination module, carries out logical operation according to overspeed protection OPC actuating signal, tach signal and unit off-grid signal, judges whether system is in the high frequency state of emergency, be electrically connected with state of emergency broadening module;
State of emergency broadening module, according to the high frequency state of emergency signal that high frequency state of emergency discrimination module is sent into, carry out broadening by the time of setting, export and fall signal for fast power returns, be electrically connected with power variation rate memory, power setting memory and supervisory control system;
Generator power, frequency and voltage acquisition module, gather generator power, frequency and voltage, is electrically connected with power, frequency and voltage factor correcting module;
Power, frequency and voltage factor correcting module, according to frequency and the voltage factor correction generator power of network load, make the generator power measured during OPC action, with load balancing in total amount, output one tunnel of power, frequency and voltage factor correcting module is electrically connected with power variation rate memory after delayer, one tunnel is directly electrically connected with power variation rate memory, and a road is electrically connected with power setting memory;
Power variation rate memory, returns by fast power the rising edge falling signal and triggers, the ratio of generator power before generator power and off-the-line when calculating off-the-line, and Writing power rate of change memory also keeps;
Power setting memory, when state of emergency broadening module exports rising edge, the power of the assembling unit write memory measured in this moment, keeps and exports as power of the assembling unit setting during state of emergency broadening, in the state of emergency, power setting feram memory will keep always.
2. the fired power generating unit power prediction control system of guarantee sending end electricity net safety stable according to claim 1, it is characterized in that: speed regulator PREDICTIVE CONTROL unit (2) comprises integral element module (3.1) that state can reset and state of emergency speed limit exits module (3.2), and the integral element module (3.1) that state can reset exits module (3.2) by the 3rd adder (3.5) and state of emergency speed limit and is connected.
3. the fired power generating unit power prediction control system of guarantee sending end electricity net safety stable according to claim 1, is characterized in that: boiler PREDICTIVE CONTROL unit (3) comprising:
" power is followed " control mode modular converter (4.1): the fast power sent according to the high frequency state of emergency and predicting unit (1) returns and falls signal, the control mode of analog control system MCS is set to " boiler follow " mode, is electrically connected with the first routing switch (4.4);
" boiler follow " controller output tracking module (4.2), under analog control system control mode, " boiler follow " controller is made to form a closed loop of following the tracks of stop-valve pressure, keep the correct output state of PID, when avoiding being switched to " boiler follow " control mode under the high frequency state of emergency, the generation transition of output state, is electrically connected with the first adder-subtracter (4.5);
Coal pulverizer excision and fuel distribution module (4.3), according to power variation rate, at the initial time of high frequency state of emergency amount, trigger and start coal pulverizer excision logic, excise the corresponding coal pulverizer quantity closest to power variation rate, accelerate the control response speed of fuel, alleviate the slow problem causing main vapour pressure high of fuel adjustment.
4. the fired power generating unit power prediction control system of guarantee sending end electricity net safety stable according to claim 1; it is characterized in that: the fired power generating unit power prediction control system of described guarantee sending end electricity net safety stable is when overspeed protection OPC action; measure generator active power; active power is after corrected Calculation; as the power of the assembling unit setting of prediction, the power of the assembling unit is controlled.
5. the fired power generating unit power prediction control system of guarantee sending end electricity net safety stable according to claim 1; it is characterized in that: send period in overspeed protection OPC actuating signal; the output state of integral element during the power P ID of speed regulator PREDICTIVE CONTROL unit is controlled; be adjusted to the conversion numerical value of predicted power setting; the conversion numerical value of the power setting of described prediction is the generator active power measured at OPC action initial time; through revising and converting, be re-used as the displacement numerical value of the output state of integral element.
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| CN103501145B (en) * | 2013-09-16 | 2016-05-11 | 贵州电网公司电网规划研究中心 | Power grid high-frequency stability forecast control method based on lonely net trend principle of transfer |
| CN104267594A (en) * | 2014-09-11 | 2015-01-07 | 国家电网公司 | Improved load calculation loop method for gas and steam combined cycle unit |
| CN107046289B (en) * | 2016-11-08 | 2020-05-19 | 国电南瑞科技股份有限公司 | Power grid steady-state frequency estimation method considering security control strategy and primary frequency modulation characteristic |
| CN108879791B (en) * | 2017-05-12 | 2021-03-05 | 中国石油化工股份有限公司 | Isolated grid steam-electricity balancing method |
| CN108565854B (en) * | 2018-04-20 | 2024-01-23 | 华北电力科学研究院有限责任公司 | Simulation method and system for reproducing frequency characteristics of power system |
| CN109098788B (en) * | 2018-07-12 | 2021-04-13 | 广西电网有限责任公司电力科学研究院 | Pressurized water reactor nuclear power unit overspeed protection control optimization system and optimization control method |
| CN111525608A (en) * | 2020-04-17 | 2020-08-11 | 广西电网有限责任公司电力科学研究院 | Method and device for realizing power regulation of thermal power generating unit based on rapid load shedding |
| CN113031565B (en) * | 2021-03-08 | 2022-06-21 | 国网湖南省电力有限公司 | Method and system for predicting primary frequency modulation power response performance of thermal power generating unit |
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