Adaptive adjustment system and method for difference adjustment characteristic of expansion unit wiring unit

Abstract

The invention provides a self-adaptive adjustment system and method for difference adjustment characteristics of an expansion unit wiring unit, and the method comprises the steps: introducing terminal reactive current feedback in a virtual impedance form into an excitation regulator, adding a sampling calculation unit, collecting key parameters, such as terminal voltage and current, in real time, calculating the reactive power unbalance of two machines according to the information of adjacent units, and achieving the self-adaptive adjustment of the difference adjustment characteristics of the unit wiring unit. And solving an optimal feedback parameter which aims at adjusting the unbalance amount of the reactive power to zero by using an optimization algorithm, and changing the reactive power of the machine end by changing the exciting current, thereby realizing the balanced distribution of the reactive power and slowing down the reactive scrambling phenomenon.

Description

Technical Field

[0001] This invention relates to the field of power system operation and control technology, specifically to an adaptive adjustment system and method for the differential characteristics of extended unit connection units. Background Technology

[0002] Extended unit connection involves connecting two generating units in parallel to the system via a single main transformer. In actual operation, parameter variations can lead to an imbalance in reactive power distribution between the two units. Furthermore, due to the difference in response time between the two units, they may compete for reactive power, meaning one unit generates additional reactive power while the other absorbs it.

[0003] The relative rate of change of generator voltage when the reactive current of a generator increases from zero to its rated value is usually defined as the droop coefficient. For a generator in operation, its excitation regulator has already set the droop coefficient value based on information such as the unit capacity and the short-circuit voltage of the main transformer, so as to achieve a reasonable distribution of reactive power among generator units operating in parallel. Summary of the Invention

[0004] To address the problems of existing technologies, the purpose of this invention is to provide an adaptive adjustment system and method for expanding the differential characteristics of unit-connected generator sets. This method adds a reactive current feedback to the excitation regulator based on the existing excitation system, ensuring reasonable allocation of reactive power according to information from neighboring units and preventing the phenomenon of competing for reactive power.

[0005] To achieve the above-mentioned technical features, the present invention aims to provide an adaptive adjustment system for the differential characteristics of a unit with extended connection, comprising two parallel generator sets and their excitation systems. The generator sets are connected to a high-voltage bus via a main transformer. Measuring elements are installed at the generator terminals of each generator set, and the collected voltage and current data are sent to a sampling and calculation unit via the measuring elements. The sampling and calculation unit then sends the required data to the generator set and neighboring generator sets.

[0006] Preferably, it also includes a virtual impedance module for connecting to the sampling calculation unit; The output of the virtual impedance module is simultaneously connected to the reference voltage module, the measuring element, and the droop coefficient module, and is also connected to the amplifier module. The amplifier module is connected to the trigger module, the trigger module is connected to the excitation power unit, and the excitation power unit is connected to the generator.

[0007] Preferably, the measuring element includes a voltage measuring device and a current measuring device.

[0008] Preferably, the reference voltage module is used to set the reference voltage value.

[0009] The present invention, in another aspect, provides an adaptive adjustment method for the droop characteristics of an expanded unit wiring unit, the method being implemented using the aforementioned adaptive adjustment system for the droop characteristics of an expanded unit wiring unit, comprising: By introducing virtual impedance reactive current feedback at the generator terminal into the excitation regulator and adding a sampling and calculation unit, the key parameters of generator terminal voltage and current are collected in real time. The reactive power imbalance between the two generators is calculated based on information from neighboring generators. An optimization algorithm is used to find the optimal feedback parameters with the goal of adjusting the reactive power imbalance to zero. By changing the excitation current, the reactive power at the generator terminal is changed, thereby achieving a balanced distribution of reactive power and mitigating the occurrence of reactive power contention.

[0010] Preferably, the procedure specifically includes the following steps: Step 1, from the reference voltage value U REF The measured terminal voltage value U G Subtraction yields the voltage difference U de The expression is: ; In the formula, k 3 is a differential pressure system; Step 2: The sampling and calculation unit collects the unit's voltage and current signals in real time through measuring elements, and calculates the reactive power imbalance of the unit based on the unit's capacity ratio and the computer unit's reactive power imbalance, expressed as: ; ; In the formula, , These represent the capacities of the two generator sets, k This indicates the capacity multiple of unit 1 compared to unit 2. This indicates the amount of reactive power imbalance. This indicates the reactive power output of unit 1. This indicates the reactive power generated by unit 2; Step 3: Introduce virtual impedance compensation based on reactive current at the generator terminals. Using zero reactive power imbalance as the objective function, solve for the compensation parameters using an optimization algorithm. k 1. k The optimal solution for 2 is expressed as: ; ; In the formula, R This represents the resistance value in the virtual impedance. X This represents the reactance value in the virtual impedance; Step 4, based on virtual impedance and droop coefficient D The voltage difference is corrected and compensated using the following expression: ; In the formula, This represents the voltage difference after correction and compensation. Indicates the reactive current of the generator unit. j Represents the imaginary unit; Step 5, based on the voltage output The excitation power unit is given a trigger signal through the amplifier module and the trigger module, the excitation current is adjusted, the reactive power of the unit is changed, the reactive power is rationally distributed, and the phenomenon of competition for reactive power between units is reduced.

[0011] Preferably, the optimization algorithm in step 3 adopts the particle swarm optimization algorithm.

[0012] Preferably, in the measurement and comparison stage of the excitation regulator, the reference voltage value is... U REF Increase the reactive current at the generator terminals in the form of virtual impedance I Q The feedback, expressed as: ; In the formula, This indicates the corrected reference voltage value.

[0013] Preferably, in step 3, the optimal parameter value is solved by an optimization algorithm, that is, the virtual impedance value is related to the reactive power imbalance.

[0014] Preferably, in step 5, the output of the excitation regulator and the excitation current are changed, thereby changing the reactive power of the unit and achieving the purpose of rational allocation of reactive power.

[0015] The present invention has the following beneficial effects: This invention addresses the problem that existing extended unit wiring structures used in power plants, which improve the reliability and flexibility of power plant operation by connecting two generating units in parallel to a single main transformer, may lead to problems such as unreasonable reactive power distribution or reactive power contention during operation. This invention introduces reactive current feedback in the form of virtual impedance into the excitation regulator to compensate for the reactive power imbalance between the two parallel generating units. Attached Figure Description

[0016] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0017] Figure 1 This is a schematic diagram of the wiring structure of an adaptive adjustment method for the differential characteristics of an expanded unit wiring unit as described in this invention.

[0018] Figure 2 This is a block diagram of the excitation structure of an adaptive adjustment method for the differential characteristics of an expanded unit wiring unit as described in this invention. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Example 1: See Figure 1 An adaptive adjustment system for the droop characteristics of a parallel generator unit is disclosed, comprising two parallel generator sets and their excitation systems. The generator sets are connected to a high-voltage bus via main transformers. Measuring elements are installed at the terminals of each generator set, and the collected voltage and current data are sent to a sampling and calculation unit. The sampling and calculation unit then sends the required data to the generator set and neighboring generator sets. The system also includes a virtual impedance module connected to the sampling and calculation unit. The output of the virtual impedance module is simultaneously connected to a reference voltage module, the measuring elements, and a droop coefficient module, and further connected to an amplifier module. The amplifier module is connected to a trigger module, which is connected to an excitation power unit, which is connected to the generator. By introducing reactive current feedback in the form of virtual impedance into the excitation regulator, the reactive power imbalance between the two parallel generator sets is compensated.

[0021] Furthermore, the measuring element includes a voltage measuring device and a current measuring device. These voltage and current measuring devices can be used to measure terminal voltage and current.

[0022] Furthermore, the reference voltage module is used to set a reference voltage value. The voltage difference is obtained by subtracting the reference voltage value from the measured terminal voltage value.

[0023] Example 2: On the other hand, an adaptive adjustment method for the droop characteristics of extended unit-connected generator sets is provided. The method is implemented using the aforementioned adaptive adjustment system for the droop characteristics of extended unit-connected generator sets. It includes: introducing virtual impedance form of reactive current feedback at the generator terminals in the excitation regulator, adding a sampling calculation unit, collecting key parameters of generator terminal voltage and current in real time, calculating the reactive power imbalance between the two generators based on information from neighboring generator sets, and using an optimization algorithm to solve for the optimal feedback parameters with the goal of adjusting the reactive power imbalance to zero. By changing the excitation current, the reactive power at the generator terminals is changed, thereby achieving a balanced distribution of reactive power and mitigating the occurrence of reactive power contention.

[0024] Example 3: An adaptive adjustment method for the differential control characteristics of extended unit wiring units specifically includes the following steps: Step 1, from the reference voltage value U REF The measured terminal voltage value U G Subtraction yields the voltage difference U de The expression is: ; In the formula, k 3 is a differential pressure system; Step 2: The sampling and calculation unit collects the unit's voltage and current signals in real time through measuring elements, and calculates the reactive power imbalance of the unit based on the unit's capacity ratio and the computer unit's reactive power imbalance, expressed as: ; ; In the formula, , These represent the capacities of the two generator sets, k This indicates the capacity multiple of unit 1 compared to unit 2. This indicates the amount of reactive power imbalance. This indicates the reactive power output of unit 1. This indicates the reactive power generated by unit 2; Step 3: Introduce virtual impedance compensation based on reactive current at the generator terminals. Using zero reactive power imbalance as the objective function, solve for the compensation parameters using an optimization algorithm. k 1. k The optimal solution for 2 is expressed as: ; ; In the formula, R This represents the resistance value in the virtual impedance. X This represents the reactance value in the virtual impedance; Step 4, based on virtual impedance and droop coefficient D The voltage difference is corrected and compensated using the following expression: ; In the formula, This represents the voltage difference after correction and compensation. Indicates the reactive current of the generator unit. j Represents the imaginary unit; Step 5, based on the voltage output The excitation power unit is given a trigger signal through the amplifier module and the trigger module, the excitation current is adjusted, the reactive power of the unit is changed, the reactive power is rationally distributed, and the phenomenon of competition for reactive power between units is reduced.

[0025] Furthermore, the optimization algorithm in step 3 adopts the particle swarm optimization algorithm.

[0026] Furthermore, in the measurement and comparison stage of the excitation regulator, the reference voltage value is... U REF Increase the reactive current at the generator terminals in the form of virtual impedance I Q The feedback, expressed as: ; In the formula, This indicates the corrected reference voltage value.

[0027] Furthermore, in step 3, the optimal parameter value is solved by an optimization algorithm, that is, the virtual impedance value is related to the reactive power imbalance.

[0028] Furthermore, in step 5, the output of the excitation regulator and the excitation current are changed, thereby changing the reactive power of the unit and achieving the purpose of rational allocation of reactive power.

[0029] Example 4: Referring to the extended unit wiring system of the Gezhouba Hydropower Station, without virtual impedance compensation, the reactive power imbalance between the two generating units is... This is 15% of the output reactive power. When virtual impedance compensation is present, the reactive power imbalance is... The reactive power output is 2%, which shows that the reactive power imbalance has been significantly reduced.

[0030] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An adaptive adjustment system for the differential control characteristics of an expanded unit wiring unit, characterized in that, It includes two parallel generator sets and their excitation systems. The generator sets are connected to the high-voltage bus via a main transformer. Measuring elements are installed at the generator terminals of each generator set. The voltage and current data collected by the measuring elements are sent to a sampling and calculation unit. The sampling and calculation unit then sends the required data to the generator set and neighboring generator sets.

2. The adaptive adjustment system for differential pressure characteristics of an expanded unit wiring unit according to claim 1, characterized in that, It also includes a virtual impedance module for connecting to the sampling calculation unit; The output of the virtual impedance module is simultaneously connected to the reference voltage module, the measuring element, and the droop coefficient module, and is also connected to the amplifier module. The amplifier module is connected to the trigger module, the trigger module is connected to the excitation power unit, and the excitation power unit is connected to the generator.

3. The adaptive adjustment system for differential pressure characteristics of an expanded unit wiring unit according to claim 2, characterized in that, The measuring elements include a voltage measuring device and a current measuring device.

4. The adaptive adjustment system for differential pressure characteristics of an expanded unit wiring unit according to claim 2, characterized in that, The reference voltage module is used to set the reference voltage value.

5. A method for adaptive adjustment of differential control characteristics of extended unit wiring units, characterized in that, The method is implemented using an adaptive adjustment system for differential pressure characteristics of an expanded unit wiring unit as described in any one of claims 2-4, comprising: By introducing virtual impedance reactive current feedback at the generator terminal into the excitation regulator and adding a sampling and calculation unit, the key parameters of generator terminal voltage and current are collected in real time. The reactive power imbalance between the two generators is calculated based on information from neighboring generators. An optimization algorithm is used to find the optimal feedback parameters with the goal of adjusting the reactive power imbalance to zero. By changing the excitation current, the reactive power at the generator terminal is changed, thereby achieving a balanced distribution of reactive power and mitigating the occurrence of reactive power contention.

6. The adaptive adjustment method for differential pressure characteristics of an expanded unit wiring unit according to claim 5, characterized in that, Specifically, the following steps are included: Step 1, from the reference voltage value U REF The measured terminal voltage value U G Subtraction yields the voltage difference U de The expression is: ； In the formula, k 3 is a differential pressure system; Step 2: The sampling and calculation unit collects the unit's voltage and current signals in real time through measuring elements, and calculates the reactive power imbalance of the unit based on the unit's capacity ratio and the computer unit's reactive power imbalance, expressed as: ； ； In the formula, , These represent the capacities of the two generator sets, k This indicates the capacity multiple of unit 1 compared to unit 2. This indicates the amount of reactive power imbalance. This indicates the reactive power output of unit 1. This indicates the reactive power generated by unit 2; Step 3: Introduce virtual impedance compensation based on reactive current at the generator terminals. Using zero reactive power imbalance as the objective function, solve for the compensation parameters using an optimization algorithm. k 1. k The optimal solution for 2 is expressed as: ； ； In the formula, R This represents the resistance value in the virtual impedance. X This represents the reactance value in the virtual impedance; Step 4, based on virtual impedance and droop coefficient D The voltage difference is corrected and compensated using the following expression: ； In the formula, This represents the voltage difference after correction and compensation. Indicates the reactive current of the generator unit. j Represents the imaginary unit; Step 5, based on the voltage output The excitation power unit is given a trigger signal through the amplifier module and the trigger module, the excitation current is adjusted, the reactive power of the unit is changed, the reactive power is rationally distributed, and the phenomenon of competition for reactive power between units is reduced.

7. The adaptive adjustment method for differential pressure characteristics of an expanded unit wiring unit according to claim 5, characterized in that, The optimization algorithm in step 3 uses the particle swarm optimization algorithm.

8. The adaptive adjustment method for differential pressure characteristics of an expanded unit wiring unit according to claim 5, characterized in that, In the measurement and comparison stage of the excitation regulator, the reference voltage value is... U REF Increase the reactive current at the generator terminals in the form of virtual impedance I Q The feedback, expressed as: ； In the formula, This indicates the corrected reference voltage value.

9. The adaptive adjustment method for differential pressure characteristics of an expanded unit wiring unit according to claim 5, characterized in that, In step 3, the optimal parameter value is solved by the optimization algorithm, that is, the virtual impedance value is related to the reactive power imbalance.

10. The adaptive adjustment method for differential pressure characteristics of an expanded unit wiring unit according to claim 5, characterized in that, In step 5, the output of the excitation regulator and the excitation current are changed, thereby changing the reactive power of the unit and achieving the purpose of rational distribution of reactive power.

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