CN101504135A - Steam pressure equalization controller for boiler-turbine unit - Google Patents

Abstract

The invention discloses a steam pressure equalization controller of a boiler-steam turbine unit, which belongs to the technical field of power generation equipment control. It consists of two parts: differential pressure compensator and pressure set point optimizer: the differential pressure compensator dynamically adjusts the rate and direction of load command change according to the magnitude of the steam pressure deviation signal _PE to generate the actual load target value _NR ; Driven by the steam pressure deviation signal _PE , the fixed-point optimizer dynamically adjusts the set value of the steam pressure to generate the actual steam pressure target value P _TR . The difference between _NR and P _TR and the actual load signal N and the actual steam pressure deviation signal _PT is used as the input of the boiler-boiler coordination controller to realize the steam pressure equalization control of the boiler-turbine unit. The application of the present invention adds a steam pressure equalization controller on the basis of the conventional machine-boiler coordinated control, which conveniently and effectively solves the problem of frequent steam pressure exceeding the limit when the output power of the unit changes in a large range, realizes the balanced control of the steam pressure, and improves the operation of the unit. level.

Description

Steam Pressure Equalization Controller for Boiler-Turbine Unit

technical field

The invention belongs to the technical field of equipment control, in particular to a steam pressure equalization controller of a boiler-steam turbine unit. Specifically, it is an optimization controller driven by a steam pressure deviation signal, composed of a pressure difference compensator and a pressure set point optimizer, and aimed at ensuring a stable and balanced steam pressure.

Background technique

Boiler-turbine unit has become the most popular and commonly used generator set in China. Its typical features are: a single boiler (subcritical, supercritical, circulating fluidized bed, biomass boiler, etc.) prepares steam and supplies a single A steam turbine, and then the steam turbine drives a generator to generate electricity. A boiler, a steam turbine, a generator and related auxiliary equipment together constitute a unit generator set.

Boiler-turbine units have proven to be the most efficient and economical form of fossil fuel-fired power generation plants. Nevertheless, there are still some inherent contradictions affecting the operating quality of the unit in the entire production process of the boiler-turbine unit, such as:

It takes a long time for the fuel to be added to the boiler furnace to generate high-temperature and high-pressure steam, and the demand N of the power grid for the output power of the unit is changing all the time. In order to increase the steam output speed of the boiler side, the opening of the main steam regulating valve μ _T is often As an adjustment method, when the load command N _sp increases, by increasing the opening of the main steam regulating valve, the heat storage in the metal material of the boiler is overdrawn to quickly prepare steam, thereby responding to the load demand of the power grid, and at the same time, correspondingly increase The amount of fuel B into the furnace is used to balance the supply and demand relationship of energy; however, the change of the opening of the main steam regulating valve will inevitably affect the steam pressure _PT at the outlet of the steam pipe (before the main steam regulating valve) (called the main steam pressure ), making it fluctuate in a large range, and the main steam pressure is the most important process parameter in the operation of the boiler-turbine unit, and its stability will directly affect the safe and economical operation of the unit.

To sum up, there is a contradiction between the load-following speed of the boiler-turbine unit and the steam pressure stability. The existing control method (especially the control method of the unit connected to the automatic generation control system AGC) emphasizes the rapidity of load response, and tolerates or ignores the frequent fluctuation of steam pressure to a certain extent, but in the frequently changing power grid load demand Under the excitation of the steam pressure, the fluctuation of the steam pressure sometimes tends to deteriorate, which will cause the cracking or even shutdown of the automatic system.

How to improve the stability of the steam pressure without affecting the load response speed of the boiler-turbine unit, that is, how to realize the pressure equalization control under various working conditions is an urgent problem to be solved.

After searching the existing academic and technical literature, no research specifically aimed at the problem of steam pressure equalization was found. The research on boiler-turbine unit control mostly focuses on the trial and simulation comparison of various advanced control algorithms, such as:

Gao Fuyan and others published the article "Research on Fuzzy Neural Network Controller Used in Main Steam Pressure Control of Power Station" in "Energy Engineering" (2004, No. 6, Page 12-15), according to the controlled object of main steam pressure Dynamic characteristics, a fuzzy neural network adaptive control system is designed, the system refers to the fuzzy Gaussian function neural network structure, and uses the improved learning algorithm based on variable scale optimization learning, and the simulation experiment proves the effectiveness of the method. However, from the perspective of engineering application, there are two problems in this study: first, the main steam pressure is regarded as an isolated system for control system design, and the coupling relationship between steam pressure and unit output power is not fully considered , the steam pressure is controlled only by adjusting the amount of fuel entering the furnace, and there is no limit to the opening of the main steam regulating valve. If the load demand of the power grid changes in a large range, this method will be difficult to ensure the stability of the steam pressure; second, The neural network structure based on the control system in this paper is complex, with many unknown parameters and unclear physical meanings. There are a large number of parameters that need to be determined by means of optimization. Therefore, this method is difficult to realize in the industrial control system, and the practical value is not high.

Contents of the invention

The object of the present invention is to propose a steam pressure equalization controller for boiler-turbine unit in view of the deficiencies in the prior art. The controller has a simple structure, is close to actual operation conditions, and is easy to realize in engineering.

The technical solution of the present invention is: the vapor pressure equalization controller is composed of a differential pressure compensator and a pressure set point optimizer, and the outputs _NR and P _TR of the two are respectively connected with the actual load signal N and the actual steam pressure signal P _T After calculating the difference, it can be used as the input of the boiler-boiler coordination controller to realize the steam pressure balance control of the boiler-steam turbine unit.

_NR and P _TR are jointly determined by the steam pressure deviation signal _PE , the expected target load N _sp , the expected steam pressure P _Tsp , the output rules of the differential pressure compensator and the pressure set point optimizer. Among them, P _E is the conditional variable, which drives the conversion between different rules and the establishment of input/output mapping relationship; N _sp and P _Tsp are the target variables, and after the system reaches the steady state, _NR and P _TR are finally maintained with N _sp and P _Tsp Consistent; the output rules of the differential pressure compensator and the pressure set point optimizer are set according to the operating conditions of the unit and the degree to which the steam pressure deviates from the expected value.

The specific implementation steps are as follows:

1) Establish the output rules of the differential pressure compensator:

According to the extent to which the steam pressure deviates from the expected value, that is, the magnitude of the deviation signal _PE , the output rules of the pressure difference compensator are established according to the following five situations.

①The steam pressure deviation signal P _E is within the allowable range, such as P _E |≤|0.03P _Tsp |, and the change rate of the target load expectation value N _sp is within the set range, then the output rule using the discrete expression is:

N _R (k)＝N _sp (k), when |P _E (k)|≤|0.03P _Tsp (k) and $f_N\text{<}\frac{N_{\mathrm{sp}}\left(k\right)-N_R(k-1)}{t\left(k\right)-t(k-1)}<R_N,$

Among them, _NR (k) and _NR (k-1) are the actual load target values at the current sampling time and the previous sampling time respectively, N _sp (k) is the target load expectation at the current sampling time, _PE (k) is the steam pressure deviation signal at the current sampling time, P _Tsp (k) is the expected value of the steam pressure at the current sampling time, t(k) and t(k-1) are the time of the current sampling time and the previous sampling time respectively, F _N and R _N are the falling rate and rising rate of the preset (modifiable) actual load target value _NR , respectively. The error boundary of |0.03P _Tsp | can be modified according to actual needs.

②The steam pressure deviation signal P _E is within the allowable range, but the rising rate of the target load expectation value N _sp exceeds the set rate R _N , then the output rule using the discrete expression is:

_NR (k)＝R _N [t(k)-t(k-1)]+ _NR (k-1), when |P _E (k)|≤|0.03P _Tsp (k)| and $\frac{N_{\mathrm{sp}}\left(k\right)-N_R(k-1)}{t\left(k\right)-t(k-1)}>R_N,$

③The steam pressure deviation signal P _E is within the allowable range, but the rate of decline of the target load expectation value N _sp exceeds the set rate F _N , then the output rule using discrete expressions is:

_NR (k)＝F _N [t(k)-t(k-1)]+ _NR (k-1), when |P _E (k)|≤|0.03P _Tsp (k)| and $\frac{N_{\mathrm{sp}}\left(k\right)-N_R(k-1)}{t\left(k\right)-t(k-1)}<f_N,$

④The steam pressure deviation signal P _E exceeds the allowable range but is still within the safe range. At this time, it is necessary to temporarily stop the change of the actual load target value _NR and wait for P _E to return to the allowable range. The output rule of the discrete expression is: _NR (k)＝ _NR (k-1), when |0.03P _Tsp (k)|<|P _E (k)|≤|0.05P _Tsp (k)|

This rule has hysteresis characteristics when the pressure deviation signal P _E changes within the range of [-0.05P _Tsp (k), -0.03P _Tsp (k)) and (0.03P _Tsp (k), 0.05P _Tsp (k)] , which can prevent frequent switching of the actual load target value _NR at the boundary point.

⑤The steam pressure deviation signal P _E exceeds the safe range. At this time, the actual load target value N _R should be adjusted in reverse to make P _E return to the safe range. The output rule of the discrete expression is:

$N_R\left(k\right)=N_R(k-1)-\mathrm{\&alpha;}\frac{{\mathrm{\&tau;}}_1\mathrm{the\; s}+1}{{\mathrm{\&tau;}}_2\mathrm{the\; s}+1}{P}_{\mathrm{E.}}\left(k\right),$ When |P _E (k)|>|0.05P _Tsp (k)

是为了动态地增强反调强度、快速消除压力偏差，一般情况下应取τ₁>τ₂，也可取τ₁＝τ₂，此时反调项就变为比例环节。in this rule The term is the reverse adjustment of _NR , so as to affect the opening μ _T of the main steam regulating valve, so as to actively reduce the deviation of steam pressure. α is the anti-modulation coefficient, which generally takes a value between 10 and 20; the lead-lag link

It is to dynamically enhance the anti-adjustment intensity and quickly eliminate the pressure deviation. Generally, τ ₁ >τ ₂ should be taken, and τ ₁ =τ ₂ can also be taken. At this time, the anti-adjustment item becomes a proportional link.

In summary, the output rule of the differential pressure compensator can be described by a set of equations:

2) Establish the output rules of the pressure set point optimizer

According to the magnitude of the steam pressure deviation signal _PE , the output rules of the pressure set point optimizer are established according to the following six situations.

①The steam pressure deviation signal P _E is within the allowable range, such as |P _E |≤|0.03P _Tsp |, and the change rate of the steam pressure expectation value P _Tsp is within the set range, then the output rule using the discrete expression is:

P _TR (k)＝P _Tsp (k), when |P _E (k)|≤|0.03P _Tsp (k)| and $f_P\text{<}\frac{P_{\mathrm{Tsp}}\left(k\right)-P_{\mathrm{TR}}(k-1)}{t\left(k\right)-t(k-1)}<R_P$

Among them, P _TR (k) and P _TR (k-1) are the actual steam pressure target values at the current sampling time and the last sampling time respectively, and F _P and R _P are the preset (modifiable) actual steam pressures respectively The rate of decrease and rate of increase of the target value P _TR . The error boundary of |0.03P _Tsp | can be modified according to actual needs.

②The steam pressure deviation signal PE is within the allowable range, but the rising rate of the steam pressure expectation value P _Tsp exceeds the set rate R _P , then the output rule using the discrete expression is:

P _TR (k)＝ _RP [t(k)-t(k-1)]+P _TR (k-1), when |P _E (k)|≤|0.03P _Tsp (k)| and $\frac{P_{\mathrm{Tsp}}\left(k\right)-P_{\mathrm{TR}}(k-1)}{t\left(k\right)-t(k-1)}>R_P,$

③The steam pressure deviation signal P _E is within the allowable range, but the decline rate of the steam pressure expectation value P _Tsp exceeds the set rate F _P , then the output rule using the discrete expression is:

_{P TR} (k)＝FP [t(k)-t(k-1)]+P _TR (k-1), when |P _E (k)|≤|0.03P _Tsp (k)| and $\frac{P_{\mathrm{Tsp}}\left(k\right)-P_{\mathrm{TR}}(k-1)}{t\left(k\right)-t(k-1)}<f_P,$

④ The steam pressure deviation signal P _E exceeds the allowable range but is still within the safe range. At this time, the change of the actual steam pressure target value P _TR should be temporarily stopped, and wait for P _E to return to the allowable range. The output rule of the discrete expression is :

P _TR (k)＝P _TR (k-1), when |0.03P _Tsp (k)|<|P _E (k)|≤|0.05P _Tsp (k)|,

This rule has hysteresis characteristics when the pressure deviation signal P _E changes within the range of [-0.05P _Tsp (k), -0.03P _Tsp (k)) and (0.03P _Tsp (k), 0.05P _Tsp (k)] , which can prevent frequent switching of the actual steam pressure target value P _TR at the boundary point.

⑤The steam pressure deviation signal P _E is greater than the upper limit of the safety range + 0.05P _Tsp . At this time, the actual steam pressure target value P _TR should be taken as a negative step, and the distance between P _TR and _PT should be actively shortened to alleviate the power change and steam pressure. The contradiction of pressure stability prompts the system to return to the steady state as soon as possible, then the output rule using the discrete expression is:

P _TR (k)＝0.98P _TR (k-1), when P _E (k)>+0.05P _Tsp (k)

⑥The steam pressure deviation signal P _E is less than the lower limit of the safety range -0.05P _Tsp . At this time, the actual steam pressure target value P _TR should be taken as a positive step, and the distance between P _TR and _PT should be actively shortened to alleviate the power change and steam The contradiction of pressure stability prompts the system to return to the steady state as soon as possible, then the output rule using the discrete expression is:

P _TR (k)＝1.02P _TR (k-1), when P _E (k)<-0.05P _Tsp (k)

In summary, the output rules of the pressure setpoint optimizer can be described by a set of equations:

3) The steam pressure equalization controller realizes the way of steam pressure equalization control

The above rules (1) and (2) are implemented in the way of applying software configuration in the distributed control system DCS, or combining the way of applying hardware circuit and software programming.

It is most convenient to implement the steam pressure equalization controller in DCS, just apply the configuration method to formulate the rules according to (1) and (2), and then use the output _NR of the pressure difference compensator and the output P of the pressure set point optimizer _TR can be used as the given input of the furnace coordination controller.

If the storage capacity or calculation load of the DCS is limited, it is necessary to use a combination of hardware circuit and software programming to realize steam pressure equalization control. In addition to the central processing unit, the hardware circuit also includes an I/O interface, a communication interface, a synchronization circuit, a real-time clock, EPROM, RAM, a fault detection circuit, a power-down detection circuit, and the like. Among them, the I/O interface is used to connect the keyboard and display; the communication interface is used for data communication with DCS; the synchronization circuit and real-time clock are used for time synchronization in data acquisition and transmission; EPROM is used to store the differential pressure compensator compiled by software and the output rules of the pressure set point optimizer; RAM is used to store real-time data from the DCS; the fault detection circuit is used to automatically reset the program when the operation fails; the power failure detection circuit is used to protect the power supply when the voltage drops or instantaneous power failure Status information in the CPU. _The circuit obtains the steam pressure deviation signal P _E , the target load expected value N _sp and the steam pressure expected value P _Tsp from the DCS through the communication interface; The output P _TR is sent back to the DCS as the actual target value of the coordinating controller of the machine furnace, so that the balanced control of the steam pressure can be realized.

Considering the complexity of the actual system, in engineering applications, the pressure control boundary points (|0.03P _Tsp | and |0.05P _Tsp |) selected in the above rules also need to be adjusted and reset appropriately in combination with field tests.

The beneficial effect of the present invention is that by using the method proposed by the invention, engineers and technicians can add a steam pressure equalization controller on the basis of conventional boiler-boiler coordinated control for various types of boiler-steam turbine units, so as to conveniently and effectively solve the problem of unit output. When the power changes in a large range, the steam pressure frequently exceeds the limit, so as to realize the balanced control of the steam pressure and improve the operation level of the unit.

Description of drawings

Figure 1 is a schematic diagram of the composition structure of the boiler-turbine unit steam pressure equalization controller and its connection with the boiler-boiler coordination control system.

Fig. 2 The hardware circuit structure diagram of the boiler-turbine unit steam pressure equalization controller.

Figure 3 shows a nonlinear model diagram of a 500MW boiler-turbine unit in a power plant.

Fig. 4 is a response curve diagram of the performance test of the steam pressure equalization controller in the constant pressure operation mode in the embodiment.

Figure 5 is the sliding pressure operation curve of a 500MW boiler-turbine unit in a power plant.

Fig. 6 is the response curve of the steam pressure equalization control performance test in the sliding pressure operation mode in the embodiment.

Detailed ways

The present invention proposes a steam pressure equalization controller for a boiler-steam turbine unit. The technical solution of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

As shown in FIG. 1 , the vapor pressure equalization controller 1 is composed of two parts: a differential pressure compensator 2 and a pressure set point optimizer 3 . The difference between the output _NR of the differential pressure compensator 2 and the output P _TR of the set point optimizer 3 and the actual load signal N and the actual steam pressure signal _PT are calculated as the input of the furnace coordination controller 4 to realize Steam pressure equalization control for boiler-turbine unit 5.

Fig. 2 shows the steam pressure equalization controller 1 using a combination of hardware circuit and software programming. In addition to the central processing unit, the hardware circuit also includes an I/O interface, a communication interface, a synchronization circuit, a real-time clock, EPROM, RAM, a fault detection circuit, a power-down detection circuit, and the like. Among them, the I/O interface is used to connect the keyboard and display; the communication interface is used for data communication with DCS; the synchronization circuit and real-time clock are used for time synchronization in data acquisition and transmission; EPROM is used to store the differential pressure compensator compiled by software and the output rules of the pressure set point optimizer; RAM is used to store real-time data from the DCS; the fault detection circuit is used to automatically reset the program when the operation fails; the power failure detection circuit is used to protect the power supply when the voltage drops or instantaneous power failure Status information in the CPU. _The circuit obtains the steam pressure deviation signal P _E , the target load expected value N _sp and the steam pressure expected value P _Tsp from the DCS through the communication interface; The output P _TR is sent back to the DCS as the actual target value of the coordinating controller of the machine furnace, so that the balanced control of the steam pressure can be realized.

Embodiment: Figure 3 shows a nonlinear model of a 500MW boiler-turbine unit in a power plant. The rated parameters of the unit are: main steam pressure 16.18Mpa, drum pressure 18.97Mpa, main steam flow 1650t/h, output power 500MW. The fuel quantity B% and the opening degree of the main steam regulating valve μ% satisfy the speed and amplitude limits respectively: |dB/dt|≤1.0/s, 0.0≤B≤100.0 and 0.0≤μ≤100.0. Based on above-mentioned model, apply the method that the present invention provides to realize the steam pressure equalization control of boiler-steam turbine unit, concrete implementation steps are as follows:

1) First, design the machine-furnace coordination controller of this model according to the linear decoupling control theory:

$\left[\begin{array}{c}\mathrm{<span\; class="notranslate">\; B</span>}\\ {\mathrm{<span\; class="notranslate">\; \&mu;</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}\end{array}\right]<span\; class="notranslate">\; =</span>\left[\begin{array}{cc}\mathrm{<span\; class="notranslate">\; 6.91</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 760</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}& \mathrm{<span\; class="notranslate">\; 0.1298</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 0.001</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; the\; s</span>}\\ <span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 0.0625</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; the\; s</span>}& \mathrm{<span\; class="notranslate">\; 0.001</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; the\; s</span>}\end{array}\right]\left[\begin{array}{cc}\mathrm{<span\; class="notranslate">\; 0.01</span>}& \mathrm{<span\; class="notranslate">\; 0</span>}\\ \mathrm{<span\; class="notranslate">\; 0</span>}& \mathrm{<span\; class="notranslate">\; 0.018</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 0.4</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}\end{array}\right]\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; E.</span>}}\\ {\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; E.</span>}}\end{array}\right]$

2) Then, realize the differential pressure compensator and the pressure set point optimizer in the form of formula (1) and formula (2) by software programming, and the two form the vapor pressure equalization controller. Among them, the pressure control boundary point is selected as (|0.03P _Tsp | and |0.05P _Tsp |), anti-adjustment coefficient α=18, time constant τ ₁ =τ ₂ ;

3) Then, according to the form in Figure 1, connect the steam pressure equalization controller and the boiler-boiler coordination controller to realize the pressure equalization control of the boiler-turbine unit model.

In order to check the performance of the vapor pressure equalization controller proposed by the present invention, carry out two groups of simulation tests respectively:

①Performance test of steam pressure equalization controller under constant pressure operation mode

Set the unit to work in the constant pressure operation mode (the set value of the main steam pressure does not change with the output power of the unit), and the load lifting rate is not limited (that is, F _N = -∞, R _N = +∞), and the test starts from t = 50s, the target load expectation value N _sp drops from 500MW to 400MW, and the output power response curve is shown in the upper curve of Fig. 4 . The dotted line in the figure——is the actual load target value _NR and the actual steam pressure target value P _TR ; the dotted line——is the expected value N _sp and the expected value of steam pressure P _Tsp ; the dotted line——is the steam pressure not added The output power of the unit when the balance controller is used; the steam pressure curve is shown in the lower curve of Figure 4; the solid line is the output power and steam pressure curve of the unit after adding the steam pressure balance controller. It can be seen from the test curve that due to the addition of the steam pressure equalization controller, the actual load target value N _R and the actual steam pressure target value P _TR have obvious changes compared with the target load expected value N _sp and the steam pressure expected value P _Tsp . Under this effect, the pressure stability of the unit is significantly improved, and at the same time, the original ability of the unit to follow the load demand of the power grid is maintained.

②Performance test of steam pressure equalization controller under sliding pressure operation mode

Set the unit to work in the sliding pressure operation mode (the fixed value of the main steam pressure changes with the fixed value of the output power of the group, and the corresponding relationship curve is shown in Figure 5). The load lifting rate and steam pressure changing rate are set as F _N =-15MW/min, R _N =+15MW/min, F _P =-0.3MPa/min, R _P =+0.3MPa/min. The test starts at t=50s, and the target load expectation value N _sp increases from 300MW to 400MW at a rate of 12MW/min. The response curve of the steam pressure expectation value P _Tsp according to the sliding pressure curve is shown in Figure 6. It can be seen from the test curve that even in the sliding pressure operation mode, the addition of the steam pressure equalization controller can obviously improve the pressure stability of the unit while maintaining a good load following ability. What has been described above is the excellent control effect shown by an embodiment of the present invention. It should be pointed out that the present invention is not limited to the above-mentioned embodiments, and can adapt to various types of boiler-steam turbines by appropriately deforming it without departing from the basic spirit of the present invention and not exceeding the scope involved in the essence of the present invention. unit.

Claims (4)

1. the vapour pressure balance controller of boiler-steam turbine unit is characterized in that:

The vapour pressure balance controller of boiler-steam turbine unit is made up of differential pressure compensator and pressure set-point optimizer two parts: differential pressure compensator is according to rule, according to vapour pressure deviation signal P _ESize dynamically adjust speed and the direction that the load instruction changes, produce actual load desired value N _RThe pressure set-point optimizer is according to operating condition, at vapour pressure deviation signal P _EDriving under, dynamically adjust the setting value of steam pressure according to rule, produce actual vapour pressure desired value P _TRWith N _RAnd P _TRRespectively with actual load signal N and actual vapour pressure deviation signal P _TAsk of the input of difference back, thereby realize the balanced control of vapour pressure boiler-steam turbine unit as the boiler-turbine coordinated controller.

2. the vapour pressure balance controller of a kind of boiler according to claim 1-steam turbine unit is characterized in that described differential pressure compensator is according to vapour pressure deviation signal P _ESize produce actual load desired value N _RInstitute's foundation regular as follows:

In the formula, N _R(k) and N _R(k-1) be respectively the actual load desired value of a current sampling instant and a last sampling instant, N _Sp(k) be the target load desired value of current sampling instant, P _E(k) be the vapour pressure deviation signal of current sampling instant, P _Tsp(k) be the steam pressure desired value of current sampling instant, t (k) and t (k-1) are respectively the time of a current sampling instant and a last sampling instant, F _NAnd R _NBe respectively actual load desired value N given in advance _RFall off rate and climbing speed,

Item is to N _RAnti-accent, influence the aperture μ of main steam control valve with this _TThereby, initiatively reducing the deviation of steam pressure, α is the anti-coefficient of transferring, generally value between 10～20 is leading-delay component

Be in order dynamically to strengthen anti-accent intensity, to eliminate pressure divergence fast, should getting τ generally speaking ₁τ ₂, also desirable τ ₁=τ ₂, this moment, the anti-item of transferring just became proportional component.

In the rule, vapour pressure deviation signal P _EAt [0.05P _Tsp(k) ,-0.03P _TspAnd (0.03P (k)) _Tsp(k), 0.05P _TspHave hysteresis characteristic when (k)] changing in the scope, can prevent actual load desired value N _RFrequent switching at boundary point.| 0.03P _Tsp| and | 0.05P _Tsp| error boundary can make amendment according to actual needs.

3. the vapour pressure balance controller of a kind of boiler according to claim 1-steam turbine unit is characterized in that described set-point optimization device is according to vapour pressure deviation signal P _ESize produce actual vapour pressure desired value P _TRInstitute's foundation regular as follows:

In the formula, P _TR(k) and P _TR(k-1) be respectively the actual vapour pressure desired value of a current sampling instant and a last sampling instant, F _PAnd R _PBe respectively actual vapour pressure desired value P given in advance _TRDecline and climbing speed.

In the rule, vapour pressure deviation signal P _EGreater than the safe range upper limit+0.05P _TspThe time will be with actual vapour pressure desired value P _TRDoing an amplitude is 0.02P _TR(k-1) negative sense step, P initiatively furthers _TRWith P _TDistance, alleviate power and change and the stable contradiction of steam pressure, impel system to get back to stable state as early as possible.In like manner, vapour pressure deviation signal P _ELess than safe range lower limit-0.05P _TspThe time will be with actual vapour pressure desired value P _TRDoing an amplitude is 0.02P _TR(k-1) positive step is alleviated power and is changed and the stable contradiction of steam pressure.

In the rule, pressure divergence signal P _EAt [0.05P _Tsp(k) ,-0.03P _TspAnd (0.03P (k)) _Tsp(k), 0.05P _TspHave hysteresis characteristic when (k)] changing in the scope, can prevent actual vapour pressure desired value P _TRFrequent switching at boundary point.| 0.03P _Tsp| and | 0.05P _Tsp| error boundary can make amendment according to actual needs.

4. the vapour pressure balance controller of a kind of boiler according to claim 1-steam turbine unit, it is characterized in that, the mode of application software configuration in scattered control system DCS is adopted in the balanced control of described vapour pressure, or the mode that the application hardware circuit combines with software programming is realized; Except that comprising central processing unit, also comprise I/O interface, communication interface, synchronous circuit, real-time clock, EPROM, RAM, failure detector circuit and power-fail detection circuit in the hardware circuit; Wherein the I/O interface is used to connect keyboard and display; Communication interface is used for carrying out data communication with DCS; Synchronous circuit and real-time clock are used for data acquisition and the time synchronized of transmitting; EPROM is used to store the output rule by the differential pressure compensator and the pressure set-point optimizer of software programming; RAM is used to store the real time data from DCS; Failure detector circuit is used for the program that automatically resets when computing is failed; Power-fail detection circuit is used for the status information of protection central processing unit when voltage die or instant cut-off; This circuit obtains vapour pressure deviation signal P by communication interface from DCS _E, target load desired value N _SpWith steam pressure desired value P _TspAgain with the output N of the differential pressure compensator that produces after the computing _ROutput P with the pressure set-point optimizer _TRSend back among the DCS realistic objective value as the boiler-turbine coordinated controller.

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