CN105024601A - Power generator excitation low excitation limit method and device - Google Patents

Abstract

The invention provides a power generator excitation low excitation limit method and device. The method comprises the steps that gain of low excitation limit is adjusted according to a power generator power angle; and excitation low excitation limiting is performed on a power generator according to the adjusted gain. The technical problems in the prior art that system oscillation is liable to occur in actual work due to the fact that low excitation limiting is performed by adopting manufacturer default parameters can be solved so that the technical effects of reducing system oscillation and enhancing system stability can be achieved.

Description

Generator excitation low excitation limiting method and device

technical field

The invention relates to the technical field of generators, in particular to a method and device for limiting excitation low excitation of generators.

Background technique

With the advancement of excitation control technology, the excitation control system of modern large-scale units generally has multiple auxiliary functions. The main function of the Under Excitation Limiter (UEL) is to avoid the overheating of the winding caused by the excessive stator current of the generator. And avoid the problem that the static stability of the generator is destroyed when the generator is running under excitation. For large-capacity long-distance power transmission systems, when the load is light at night, the system has excess capacitive reactive power, and the generator sets need to be operated in phase advance, which may even cause the UEL of the excitation system to operate. However, if the UEL parameter setting is unreasonable, it will have adverse effects on the stability of the excitation system.

Since the generator is running under excitation, the electromotive force in the generator decreases, the power angle of the generator increases, the static stability of the unit decreases, and the damping also decreases, which is more likely to cause oscillation instability, so the low excitation limit is particularly important. important. At present, the parameters of the low-excitation limiting link mostly adopt the default fixed parameters of the manufacturer. If the manufacturer's low-excitation parameter setting is improper, or the overall structure design of the control system is unreasonable, or even the parameters of the low-excitation limiting link are different from the actual variable operating conditions. Any mismatch will lead to system oscillation after the low excitation limit is actually put into work.

Contents of the invention

Embodiments of the present invention provide a method and device for limiting excitation low excitation of a generator, so as to reduce system oscillation and improve system stability.

An embodiment of the present invention provides a method for limiting the low excitation excitation of a generator to achieve the purpose of reducing system oscillation and improving system stability. The method includes: adjusting the gain of low excitation limitation according to the power angle of the generator; The gain limits the field underexcitation of the generator.

In one embodiment, adjusting the gain of the low excitation limit according to the power angle of the generator includes:

The gain decreases as the generator power angle increases, and the gain increases as the generator power angle decreases.

In one embodiment, the gain of the low excitation limit is adjusted according to the following formula:

${\mathrm{<span\; class="notranslate">\; \&Delta;V</span>}}_{\mathrm{<span\; class="notranslate">\; UEL</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; UEL</span>}}\frac{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; UEL</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; UEL</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; \&Delta;z</span>}$

Among them, ΔV _UEL represents the adjusted gain of low excitation limit, K _UEL represents the proportional gain of low excitation limit, T _UEL1 represents the lead time constant of low excitation limit, T _UEL2 represents the lag time constant of low excitation limit, δ represents the power angle of the generator, and s represents the complex frequency.

In one embodiment, before adjusting the low-excitation-limited gain according to the power angle of the generator, the method further includes: calculating the reactive power of the generator according to the active power of the generator and the terminal voltage of the generator;

Limiting the under-excitation of the generator according to the adjusted gain includes: performing under-excitation limitation on the generator when the reactive power is greater than a predetermined threshold.

In one embodiment, the reactive power of the generator is calculated according to the following formula:

Q _t ＝ K _U P _t + pU _t ²

Among them, P _t represents the active power of the generator, U _t represents the terminal voltage of the generator, Q _t represents the reactive power of the generator, K _U represents the proportional coefficient, and p represents the voltage correction coefficient.

The embodiment of the present invention also provides an excitation low-excitation limiting device of a generator to achieve the purpose of reducing system oscillation and improving system stability. The device includes:

A gain adjustment module is used to adjust the gain of the low excitation limit according to the power angle of the generator;

The low excitation limiting module is used to limit the excitation low excitation of the generator according to the adjusted gain.

In one embodiment, the gain decreases as the generator power angle increases, and the gain increases as the generator power angle decreases.

In one embodiment, the gain adjustment module is used to adjust the gain of the low excitation limit according to the following formula:

${\mathrm{<span\; class="notranslate">\; \&Delta;V</span>}}_{\mathrm{<span\; class="notranslate">\; UEL</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; UEL</span>}}\frac{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; UEL</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; UEL</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; \&Delta;z</span>}$

Among them, ΔV _UEL represents the adjusted gain of low excitation limit, K _UEL represents the proportional gain of low excitation limit, T _UEL1 represents the lead time constant of low excitation limit, T _UEL2 represents the lag time constant of low excitation limit, δ represents the power angle of the generator, and s represents the complex frequency.

In one embodiment, the above device further includes a power determination module, which is used to calculate the reactive power of the generator according to the active power of the generator and the terminal voltage of the generator before adjusting the gain of the low excitation limit according to the power angle of the generator ;

The low excitation limiting module is specifically configured to limit the excitation low excitation of the generator when the reactive power is greater than a predetermined threshold.

In one embodiment, the power determination module is specifically configured to calculate the reactive power of the generator according to the following formula:

Q _t ＝ K _U P _t + pU _t ²

Among them, P _t represents the active power of the generator, U _t represents the terminal voltage of the generator, Q _t represents the reactive power of the generator, K _U represents the proportional coefficient, and p represents the voltage correction coefficient.

In the embodiment of the present invention, the gain of low excitation limitation is adjusted according to the power angle of the generator, and the excitation low excitation limitation of the generator is performed according to the adjusted gain. During the process of performing low excitation limitation, the gain is The power angle of the machine changes dynamically, thus solving the technical problem that the system oscillation is easy to occur after the actual operation is caused by using the default parameters of the manufacturer to limit the low excitation in the existing technology, and achieves the reduction of system oscillation and the improvement of system stability. technical effect.

Description of drawings

The drawings described here are used to provide further understanding of the present invention, constitute a part of the application, and do not limit the present invention. In the attached picture:

Figure 1 is a schematic diagram of the conventional generator's excitation low excitation limit control mode;

Fig. 2 is a flow chart of a method for limiting excitation under excitation of a generator according to an embodiment of the present invention;

Fig. 3 is a structural block diagram of an excitation low excitation limiting device of a generator according to an embodiment of the present invention;

Fig. 4 is a schematic diagram of the excitation low excitation limit control mode of the generator according to the embodiment of the present invention;

Fig. 5 is a specific schematic diagram of the low-excitation limit control mode of the generator according to the embodiment of the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be described in further detail below in conjunction with the embodiments and accompanying drawings. Here, the exemplary embodiments and descriptions of the present invention are used to explain the present invention, but not to limit the present invention.

The inventors found that the low-excitation limitation of the excitation regulator can be performed by using the constant voltage method of the PID method as shown in Figure 1, where P _t represents the active power of the generator, U _t represents the terminal voltage of the generator, and Q _t Represents the reactive power of the generator, K _U represents the proportional coefficient, K _UEL represents the low excitation limit proportional gain, T _UEL1 represents the low excitation limit lead time constant, T _UEL2 represents the low excitation limit lag time constant, ΔS represents the reactive power control deviation .

The overall transfer function is:

${\mathrm{<span\; class="notranslate">\; \&Delta;V</span>}}_{\mathrm{<span\; class="notranslate">\; UEL</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; UEL</span>}}\frac{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; UEL</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; UEL</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; \&Delta;z</span>}$

However, in the method shown in Figure 1, each gain parameter is also set by the manufacturer, and the low excitation control according to this parameter will easily lead to system oscillation when it is actually put into production. In this regard, the inventor proposed a low-excitation limitation method in which the total gain of the excitation regulator's low-excitation limitation dynamically changes according to the size of the generator power angle, thereby solving the problem of using the default parameters of the manufacturer's generator low-excitation limitation in the prior art. Adapt to the problem of changing field operating conditions, so that the low excitation limit can obtain fast and stable ideal characteristics in various operating modes of the generator.

The low excitation excitation method of the generator provided by the embodiment of the present invention is shown in Figure 2, and includes the following steps:

Step 201: Adjust the gain of the low excitation limit according to the power angle of the generator;

Step 202: Limit the excitation and low excitation of the generator according to the adjusted gain.

In the above embodiment, the gain of low excitation limitation is adjusted according to the power angle of the generator, and the excitation low excitation limitation of the generator is performed according to the adjusted gain. During the process of performing low excitation limitation, the gain follows the generator The dynamic change of the power angle solves the technical problem that the system oscillation is easy to occur after the actual operation is caused by using the default parameters of the manufacturer to limit the low excitation in the existing technology, and achieves the goal of reducing system oscillation and improving system stability. technical effect.

In order to ensure that the reactive power of the generator can be quickly limited within a reasonable range after the low-excitation limiting action, and at the same time, compared with the conventional constant low-excitation limiting gain, the dynamic stability of the unit can be improved. In this example, the gain increases with The generator power angle increases and decreases, and the gain increases as the generator power angle decreases.

Specifically, the gain of the low excitation limit can be determined according to the following formula:

${\mathrm{<span\; class="notranslate">\; \&Delta;V</span>}}_{\mathrm{<span\; class="notranslate">\; UEL</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; UEL</span>}}\frac{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; UEL</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; UEL</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; \&Delta;z</span>}$

Among them, ΔV _UEL represents the adjusted gain of low excitation limit, K _UEL represents the proportional gain of low excitation limit, T _UEL1 represents the lead time constant of low excitation limit, T _UEL2 represents the lag time constant of low excitation limit, δ represents the power angle of the generator, and s represents the complex frequency.

Excitation under-excitation limitation is carried out under the condition of excess capacitive reactive power in the system, so the process of determining reactive power can be carried out before proceeding, that is, before adjusting the gain of under-excitation limitation according to the motor power angle, the above method also It includes: calculating the reactive power of the generator according to the active power of the generator and the terminal voltage of the generator; only when the reactive power is greater than a predetermined threshold value, the generator is triggered to limit excitation and low excitation.

Specifically, the reactive power of the generator can be calculated according to the following formula:

Q _t ＝ K _U P _t + pU _t ²

Among them, P _t represents the active power of the generator, U _t represents the terminal voltage of the generator, Q _t represents the reactive power of the generator, K _U represents the proportional coefficient, and p represents the voltage correction coefficient.

Based on the same inventive concept, an embodiment of the present invention also provides a low-excitation limiting device for a generator, as described in the following embodiments. Since the problem-solving principle of the low-excitation limiting device of the generator is similar to the low-excitation limiting method of the generator, the implementation of the low-excitation limiting device of the generator can refer to the implementation of the low-excitation limiting method of the generator, and repeat I won't repeat them here. As used below, the term "unit" or "module" may be a combination of software and/or hardware that realizes a predetermined function. Although the devices described in the following embodiments are preferably implemented in software, implementations in hardware, or a combination of software and hardware are also possible and contemplated. Fig. 3 is a structural block diagram of an excitation low-excitation limiting device of a generator according to an embodiment of the present invention. As shown in Fig. 3 , it includes a gain adjustment module 301 and a low-excitation limiting module 302. The structure will be described below.

A gain adjustment module 301, configured to adjust the gain of the low excitation limit according to the power angle of the generator;

The low excitation limiting module 302 is configured to limit the excitation low excitation of the generator according to the adjusted gain.

In one embodiment, the gain decreases as the generator power angle increases, and the gain increases as the generator power angle decreases.

In one embodiment, the gain adjustment module 301 is configured to adjust the gain of the low excitation limit according to the following formula:

${\mathrm{<span\; class="notranslate">\; \&Delta;V</span>}}_{\mathrm{<span\; class="notranslate">\; UEL</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; UEL</span>}}\frac{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; UEL</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; UEL</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; \&Delta;z</span>}$

Among them, ΔV _UEL represents the adjusted gain of low excitation limit, K _UEL represents the proportional gain of low excitation limit, T _UEL1 represents the lead time constant of low excitation limit, T _UEL2 represents the lag time constant of low excitation limit, δ represents the power angle of the generator, and s represents the complex frequency.

In one embodiment, the above device further includes a power determination module, which is used to calculate the reactive power of the generator according to the active power of the generator and the terminal voltage of the generator before adjusting the gain of the low excitation limit according to the power angle of the generator The low-excitation limiting module 302 is specifically configured to limit the excitation low-excitation of the generator when the reactive power is greater than a predetermined threshold.

In one embodiment, the power determination module is specifically configured to calculate the reactive power of the generator according to the following formula:

Q _t ＝ K _U P _t + pU _t ²

Among them, P _t represents the active power of the generator, U _t represents the terminal voltage of the generator, Q _t represents the reactive power of the generator, K _U represents the proportional coefficient, and p represents the voltage correction coefficient.

The method for limiting the excitation low excitation of the above-mentioned generator will be specifically described below in conjunction with a specific embodiment. However, it should be noted that this specific embodiment is only for better describing the present invention, and does not constitute an improper limitation of the present invention.

In this example, it is proposed that the gain of the low excitation limit dynamically changes according to the current generator power angle, that is, as shown in Figure 4, a dynamic gain link is added after the lead-lag link shown in Figure 1. The specific implementation method of the adaptive gain adopted by the low-excitation excitation method of the generator of the present invention is shown in FIG. 5 .

In Figure 5, δ represents the generator power angle measured by the excitation regulator, and the specific calculation formula for the output of the adaptive module is as follows:

$\mathrm{<span\; class="notranslate">\; \&Delta;z</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; |</span>\mathrm{<span\; class="notranslate">\; \&delta;</span>}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&divide;</span>\frac{\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}$

Wherein, the output times of Δz are limited in the range of 0.1-1.

Through the dynamic change of the low-excitation limit gain according to the generator power angle proposed in this example, when the generator power angle is large, the low-excitation limit adopts a smaller gain coefficient, and when the generator power angle is small, a smaller gain coefficient is used. Large gain coefficient, which can not only ensure that the reactive power of the generator is quickly limited within a reasonable range after the low-excitation limiting action, but also improve the dynamic stability of the unit compared with the conventional constant low-excitation limiting gain, and also enhance the resistance. The ability to reverse interference such as tuning. The comparison test with the conventional fixed-gain low-excitation limiter under the same disturbance shows that the dynamic response of the low-excitation limiter with adaptive gain proposed in this example reaches a plateau quickly after 10 swings, while the dynamic response of the fixed-gain controller requires It took a long time for the oscillation to return to stability.

In another embodiment, software is also provided, and the software is used to implement the technical solutions described in the above embodiments and preferred implementation manners.

In another embodiment, there is also provided a storage medium, in which the software is stored, the storage medium includes but not limited to: optical discs, floppy disks, hard disks, rewritable memories, and the like.

From the above description, it can be seen that the embodiment of the present invention achieves the following technical effects: adjust the gain of low excitation limitation according to the power angle of the generator, and perform excitation low excitation limitation on the generator according to the adjusted gain. In the process of low excitation limitation, the gain is dynamically changed with the power angle of the generator, thus solving the problem of easy system oscillation after the actual operation due to the low excitation limitation using the default parameters of the manufacturer in the prior art Technical problems have achieved the technical effect of reducing system oscillation and improving system stability.

Obviously, those skilled in the art should understand that each module or each step of the above-mentioned embodiments of the present invention can be implemented by a general-purpose computing device, and they can be concentrated on a single computing device, or distributed among multiple computing devices. Optionally, they may be implemented in program code executable by a computing device, thereby, they may be stored in a storage device to be executed by a computing device, and in some cases, may be implemented in a code different from that described herein The steps shown or described are executed in sequence, or they are fabricated into individual integrated circuit modules, or multiple modules or steps among them are fabricated into a single integrated circuit module for implementation. Thus, embodiments of the invention are not limited to any specific combination of hardware and software.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, various modifications and changes may be made to the embodiments of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. the excitation of generator is low encourages a method for limiting, it is characterized in that, comprising:

According to the low gain of encouraging restriction of generator's power and angle adjustment;

According to the gain after adjustment described generator carried out to excitation is low encourages restriction.

2. the method for claim 1, is characterized in that, according to the low gain of encouraging restriction of generator's power and angle adjustment, comprising:

Gain increases along with generator's power and angle and reduces, and gain reduces along with generator's power and angle and increases.

3. method as claimed in claim 2, is characterized in that, according to the low gain of encouraging restriction of following formula adjustment:

${\mathrm{\&Delta;V}}_{\mathrm{UEL}}=K_{\mathrm{UEL}}\frac{T_{\mathrm{UEL}1}s+1}{T_{\mathrm{UEL}2}s+1}\&times;\mathrm{\&Delta;z}$

Wherein, Δ V _uELrepresent the low gain of encouraging restriction after adjustment, K _uELrepresent low proportional gain of encouraging restriction, T _uEL1represent low and encourage limit advance time constant, T _uEL2represent low and encourage limit retardation time constant, δ represents generator's power and angle, and s represents complex frequency.

4. method as claimed any one in claims 1 to 3, is characterized in that:

According to generator's power and angle adjustment is low encourage the gain of restriction before, described method also comprises: according to the reactive power of the active power of generator and the set end voltage calculating generator of generator;

According to the gain after adjustment described generator carried out to excitation is low encourages restriction, comprising: when reactive power is greater than predetermined threshold, described generator is carried out to excitation is low encourages restriction.

5. method as claimed in claim 4, is characterized in that, the reactive power according to following formulae discovery generator:

Q _t＝K _UP _t+pU _t ²

Wherein, P _trepresent the active power of generator, U _trepresent the set end voltage of generator, Q _trepresent the reactive power of generator, K _urepresent proportionality coefficient, p represents voltage correction factor.

6. the excitation of generator is low encourages a restraint device, it is characterized in that, comprising:

Gain regulation module, for adjusting low gain of encouraging restriction according to generator's power and angle;

Lowly encourage limiting module, for carrying out described generator according to the gain after adjustment, excitation is low encourages restriction.

7. device as claimed in claim 6, is characterized in that, gain increases along with generator's power and angle and reduces, and gain reduces along with generator's power and angle and increases.

8. device as claimed in claim 7, is characterized in that, described gain regulation module is used for according to the low gain of encouraging restriction of following formula adjustment:

${\mathrm{\&Delta;V}}_{\mathrm{UEL}}=K_{\mathrm{UEL}}\frac{T_{\mathrm{UEL}1}s+1}{T_{\mathrm{UEL}2}s+1}\&times;\mathrm{\&Delta;z}$

Wherein, Δ V _uELrepresent the low gain of encouraging restriction after adjustment, K _uELrepresent low proportional gain of encouraging restriction, T _uEL1represent low and encourage limit advance time constant, T _uEL2represent low and encourage limit retardation time constant, δ represents generator's power and angle, and s represents complex frequency.

9. the device according to any one of claim 6 to 8, is characterized in that:

Also comprise power determination module, for according to generator's power and angle adjustment is low encourage the gain of restriction before, according to the reactive power of the active power of generator and the set end voltage calculating generator of generator;

Describedly lowly encourage limiting module, specifically for when reactive power is greater than predetermined threshold, described generator is carried out to excitation is low encourages restriction.

10. device as claimed in claim 9, is characterized in that:

Described power determination module is specifically for the reactive power according to following formulae discovery generator:

Q _t＝K _UP _t+pU _t ²

Wherein, P _trepresent the active power of generator, U _trepresent the set end voltage of generator, Q _trepresent the reactive power of generator, K _urepresent proportionality coefficient, p represents voltage correction factor.