CN114530863A - Excitation control method for improving power grid stability of double-shaft excitation phase modulator - Google Patents

Excitation control method for improving power grid stability of double-shaft excitation phase modulator Download PDF

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Publication number
CN114530863A
CN114530863A CN202210229190.9A CN202210229190A CN114530863A CN 114530863 A CN114530863 A CN 114530863A CN 202210229190 A CN202210229190 A CN 202210229190A CN 114530863 A CN114530863 A CN 114530863A
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excitation
voltage
phase modulator
double
stability
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CN202210229190.9A
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Chinese (zh)
Inventor
付敏
刘振华
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Harbin University of Science and Technology
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Harbin University of Science and Technology
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/12—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load
    • H02J3/16—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load by adjustment of reactive power
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/18—Arrangements for adjusting, eliminating or compensating reactive power in networks
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/24—Arrangements for preventing or reducing oscillations of power in networks
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
    • H02J3/50—Controlling the sharing of the out-of-phase component
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P21/00—Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
    • H02P21/0003—Control strategies in general, e.g. linear type, e.g. P, PI, PID, using robust control
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
    • Y02E40/30—Reactive power compensation

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Control Of Eletrric Generators (AREA)

Abstract

The invention discloses an excitation control method for improving the stability of a power grid by a double-shaft excitation phase modulator, which introduces system side voltage as feedback input quantity on the basis of a reactive-voltage coordination control strategy. In a steady state, the reactive power is taken as a control target to realize slow regulation and meet the requirement of a system on the reactive power; and in the transient state, the voltage at the side of the system is taken as a control target, so that the rapid response is realized, and the system is forced to be excited rapidly when large disturbance or short-time fault occurs in the system, so that the voltage stability at the side of the system is maintained. In addition, a PID correction circuit is introduced before an amplification link, so that the stability of an excitation system and the rising speed of the excitation voltage during forced excitation are improved. The excitation control method of the double-shaft excitation phase modulator starts from two aspects of the input quantity of the excitation control system and the excitation system, improves the stability of the excitation system and the rising speed of the excitation voltage during strong excitation, meets the requirement of a power grid on reactive power, and improves the voltage stability of the power grid.

Description

Excitation control method for improving power grid stability of double-shaft excitation phase modulator
Technical Field
The invention relates to an excitation control method for improving the stability of a power grid by a double-shaft excitation phase modulator, in particular to an excitation control method for maintaining the transient stability of a power system after the double-shaft excitation phase modulator is connected with the power grid.
Background
With the development of new energy power generation technology and high-voltage direct-current transmission technology, the voltage of a transmitting-end power grid for new energy power generation changes dramatically when faults such as direct-current system line faults, receiving-end commutation failure, direct-current blocking and the like face, even the grid can be disconnected, and the voltage stability of the power grid is seriously influenced. Compared with the traditional large phase modulation machine built on the main network side, the distributed phase modulation machine built near the new energy plant station not only can play a role of dynamic reactive power storage of a system, but also can provide voltage support for a new energy power station in a whole process of sub-transient state, transient state and steady state.
In addition, the traditional synchronous phase modulator adopts single-shaft excitation, is influenced by motor parameters, has poor phase-in capability and poor phase-delay capability, and cannot effectively inhibit transient overvoltage. The traditional reactive power-voltage coordination control strategy aims at maintaining the voltage at the generator end to be stable, when the voltage at the system side drops, the phase modulator sends out reactive power to adjust, at the moment, the voltage at the generator end is stable, and the voltage at the system side drops. Namely, when the terminal voltage is used as the control target, the system voltage stability cannot be ensured.
Disclosure of Invention
In order to solve the above problems, the present invention provides an excitation control method for improving power grid stability of a dual-axis excitation phase modulator, comprising:
1. the double-shaft excitation phase modulator is characterized in that two-phase excitation windings which are perpendicular to each other are distributed on a rotor, and the structural parameters and the excitation conditions of the two-phase excitation windings are the same. The size of the exciting current can be flexibly adjusted, and the exciting state of the phase modulator is changed. When the motor is excited by force, the exciting current is increased to make the synthesized exciting electromotive force greater than the terminal voltage, and the phase modulator emits reactive power. When under excitation, reducing exciting current to make the synthesized exciting electromotive force smaller than the terminal voltage, and absorbing reactive power by the phase modulator;
2. the method comprises the following steps of (1) integrating a double-shaft excitation phase modulator into a power grid, and measuring terminal voltage, reactive power and system side voltage of the phase modulator;
3. calculating the difference between the actual value and the reference value of the terminal voltage of the phase modulator, and acting on a PID correction circuit to realize quick forced excitation and maintain the terminal voltage to be stable;
4. calculating the difference between the actual value and the reference value of the reactive power of the phase modulator, and acting on a PID correction circuit through an integral link to realize the fine adjustment of the exciting current and meet the requirement of a system on the reactive power;
5. calculating the difference between the actual value and the reference value of the system side voltage, and acting on a PID correction circuit through links of amplification, phase compensation and amplitude limiting so as to improve the voltage stability of the system;
6. further, the double-shaft exciting current is the same in size, and the included angle between the synthesized exciting current and the d-axis satisfies the following conditions: θ is 45 °;
7. furthermore, when the active loss of the phase modulator is not counted, the direction of the synthesized excitation electromotive force is the same as or opposite to that of the terminal voltage;
8. further, when the total input amount of the PID correction circuit is equal to zero, the excitation is normal. When the total input quantity of the PID correction circuit is larger than zero, d-axis and q-axis exciting currents are reduced, and the phase modulator operates in a phase-in mode and absorbs reactive power. When the total input quantity of the PID correction circuit is less than zero, the d-axis exciting current and the q-axis exciting current are increased, and the phase modulator operates in a delayed phase mode and shows that reactive power is emitted;
9. further, when the error change rate inputted to the PID correction circuit is larger than zero, the d-axis and q-axis exciting currents are reduced. When the error change rate input to the PID correction circuit is less than zero, increasing d-axis and q-axis exciting currents;
10. further, the output quantity of the PID correction circuit is amplified, limited, triggered in a phase-shifting mode and rectified to obtain exciting electromotive force.
As described above, the excitation control method for improving the power grid stability of the dual-axis excitation phase modulator provided by the invention has the following effects:
the two-phase exciting currents of the double-shaft excitation phase modulator are the same in magnitude, so that the heating of a rotor can be reduced; the two-phase excitation winding adopts the same excitation control strategy, and supplies power to the two-phase excitation winding through a set of excitation system, so that the operation is easy, and the cost is saved; compared with the traditional synchronous phase modulator, the double-shaft excitation phase modulator breaks through the limit that the minimum excitation current is zero, can obtain the short-time phase-advancing capability equivalent to the slow-phase capability through reverse forced excitation, and can meet the requirement of a system on reactive power; the system voltage is introduced as a feedback quantity, so that the voltage stability of the power grid can be improved; the PID correction circuit is introduced to improve the stability of the excitation system and the rising speed of the excitation voltage during forced excitation.
Drawings
FIG. 1 is a flow chart of a method of the present invention;
fig. 2 is an excitation system function model of the present invention.
Detailed Description
While the following description sets forth numerous specific details to provide a thorough understanding of the present invention, it will be appreciated that the described embodiments are merely exemplary of the invention, which may be embodied or used in various other specific forms. Various details in this description may also be modified or changed in various respects, all without departing from the spirit of the invention, based on different perspectives and applications. The invention is therefore not limited to the specific implementations disclosed below.
As shown in fig. 1, the excitation control method for improving the stability of a power grid of a dual-axis excitation phase modulator provided by the invention comprises the following steps:
1. a50 Mvar non-salient pole type distributed phase modulator is selected, excitation windings are arranged on d and q axes of a rotor, the two-phase excitation windings are perpendicular to each other, and parameters are the same.
2. The same excitation control strategy is adopted for the two-phase excitation windings, so that the excitation voltage and the excitation current of the two-phase excitation windings are ensured to be the same, namely ufd＝ufq、ifd＝ifq。
3. The double-shaft excitation phase modulator is connected into a power grid through a step-up transformer, the voltage, the current and the system side voltage of the phase modulator terminal are measured, and the reactive power emitted by the phase modulator is calculated. Terminal voltage, reactive power and system side voltage, i.e. U in FIG. 2g、Q、Us。
4. Calculating actual value U of terminal voltage of phase modulatorgAnd a reference value UrefThe difference is directly inputted to the PID correction circuit. Calculating actual value Q and reference value Q of reactive power of phase modulatorrefThe difference is input to a PID correction circuit through an integration link. Calculating the actual value U of the system voltagesAnd a reference value UsrefThe difference is input to a PID correction circuit through amplification, phase compensation and amplitude limiting links. The 3 input quantities are added to obtain the total input deviation quantity.
PID correction circuit adopts parallel proportional-integral-derivative correction circuit with expression as
Figure BDA0003537493220000031
And 6, finally outputting the exciting electromotive force by the output quantity of the PID correction circuit through amplification, amplitude limiting, phase-shifting triggering and a rectification circuit. Wherein the amplifying circuit
Figure BDA0003537493220000032
Magnification k inA50, time constant TA0.1 s. The amplitude limiting link is provided with a maximum excitation voltage and a minimum excitation voltage, so that the phase modulator is prevented from being out of step due to overheating of an excitation winding or under excitation caused by over excitation. Rectifying circuit
Figure BDA0003537493220000033
Magnification k inz1, time constant
Figure BDA0003537493220000034
The foregoing descriptions of embodiments of the present invention have been presented for purposes of illustration and description. The present invention is capable of other embodiments and its several details are capable of modifications in various obvious respects, all without departing from the spirit and scope of the present invention. It is, therefore, to be understood that the invention is intended to cover all modifications and the like within the scope of the following claims.

Claims (4)

1. An excitation control method for improving power grid stability of a double-shaft excitation phase modulator comprises the following steps: excitation regulation of an excitation system acts on the two-phase excitation windings, so that the two-phase excitation currents are equal in magnitude, and rotor heating caused by excitation current imbalance is reduced; acquiring system side voltage, phase modulator terminal voltage and reactive power in real time; in a steady state, the reactive power control is taken as a target, and the actual value of the reactive power changes along with the reference value, so that the requirement of a system on the reactive power is met; in transient state, the voltage stabilization is taken as a target, the actual value of the terminal voltage of the double-shaft excitation phase modulator changes along with the reference value, the actual value of the system side voltage changes along with the reference value, and when the system generates large disturbance or short-time fault, the excitation system is quickly excited by force to maintain the stability of the system side voltage; the PID correction circuit compensates and corrects the input small deviation signal, so that the excitation system can stably run in a working range.
2. The excitation control method for improving the power grid stability of the double-shaft excitation phase modulator according to claim 1, is characterized in that: and introducing a reactive power control outer ring, and finely adjusting the exciting current by the difference value of the actual value of the reactive power and the reference value in the steady-state operation time of the system.
3. The excitation control method for improving the power grid stability of the double-shaft excitation phase modulator according to claim 1, is characterized in that: on the basis that the voltage at the leading-in terminal of an excitation system of the double-shaft excitation phase modulator is used as a feedback quantity, a system side voltage is added to be used as a feedback quantity, and when the voltage of a bus at the system side is greatly reduced, the voltage deviation quantity at the system side is introduced to be calculated, so that the reactive output of the double-shaft excitation phase modulator is improved, and the purpose of improving the voltage stability of the system is achieved.
4. The excitation control method for improving the power grid stability of the double-shaft excitation phase modulator according to claim 1, is characterized in that: the PID correction circuit is introduced, so that the stability of an excitation system and the rising speed of the excitation voltage during strong excitation can be improved, and the steady-state error can be reduced, thereby improving the static voltage regulation precision.
CN202210229190.9A 2022-03-09 2022-03-09 Excitation control method for improving power grid stability of double-shaft excitation phase modulator Pending CN114530863A (en)

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