CN112165116B - Handling method and device for small hydropower system with unplanned island effect - Google Patents

Handling method and device for small hydropower system with unplanned island effect Download PDF

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CN112165116B
CN112165116B CN202010988923.8A CN202010988923A CN112165116B CN 112165116 B CN112165116 B CN 112165116B CN 202010988923 A CN202010988923 A CN 202010988923A CN 112165116 B CN112165116 B CN 112165116B
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power
small hydropower
hydropower system
exchange
small
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CN112165116A (en
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欧阳本凯
阙胜和
黄伟
黄玉琛
庄泽宏
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Shaoguan Power Supply Bureau Guangdong Power Grid Co Ltd
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Shaoguan Power Supply Bureau Guangdong Power Grid Co Ltd
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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
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/388—Islanding, i.e. disconnection of local power supply from the network
    • 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
    • H02J3/48—Controlling the sharing of the in-phase component
    • 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
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
    • H02J2300/20—The dispersed energy generation being of renewable origin

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  • Power Engineering (AREA)
  • Control Of Eletrric Generators (AREA)

Abstract

The invention discloses a method and a device for handling a small hydropower system with an unplanned island effect. The method comprises the following steps: after a fault of a main power grid is monitored, a circuit breaker on the high-voltage side of a main transformer between a small hydropower system and the main power grid is controlled to be disconnected, exchange power between the small hydropower system and the main power grid is measured and obtained, the absolute value of the exchange power is determined to be smaller than or equal to the regulation limit active power of an electromechanical group in the small hydropower system, reactive exchange power between the small hydropower system and the main power grid is determined to be smaller than or equal to the regulation limit reactive power of the electromechanical group in the small hydropower system, the frequency change out-of-limit time of the exchange power is obtained, the frequency change out-of-limit time is determined to be smaller than the regulation time of the electromechanical group in the small hydropower system, and the output power of the electromechanical group of the small hydropower system is regulated according to the conversion power, so that the small hydropower system can stably run, the unplanned islanding effect in the small hydropower system can be eliminated, and normal power supply of the small hydropower system to loads is maintained.

Description

Handling method and device for small hydropower system with unplanned island effect
Technical Field
The embodiment of the invention relates to the technical field of micro-grids, in particular to a method and a device for handling a small hydropower system with an unplanned islanding effect.
Background
The small hydropower devices are large in quantity and wide in distribution in China, because the installed capacity is small, the full development and utilization of hydropower resources are accelerated, the small hydropower devices are built and low in cost, but unplanned conditions such as faults and the like can occur in a main network sometimes, the unplanned island effect at the moment affects the small hydropower grid part, usually, the frequency and power of the small hydropower grid system are not timely adjusted, the influence is eliminated by directly splitting the small hydropower devices, and the power supply efficiency of the small hydropower grid is greatly affected.
The method for eliminating the influence of the unplanned island effect only separates small hydropower devices at present, but the load in the power grid has power failure, the power supply quality can be deteriorated due to frequent sudden power failure, the service life of the load is shortened, the product quality is reduced, the electronic and automatic equipment fails, the daily work and rest of a user are influenced, the reliability of power utilization of the user is reduced, the waste of water resources can be caused, the efficiency of the small hydropower devices is reduced, if the recovery time of a main network is too long, the re-networking time of the small hydropower devices is too long, and the long-time power failure phenomenon of the user is caused.
Disclosure of Invention
The invention provides a small hydropower system coping processing method and device for an unplanned islanding effect, which are used for realizing the stable operation of a small hydropower system and eliminating the unplanned islanding effect in the small hydropower system.
In a first aspect, an embodiment of the present invention provides a method for handling a small hydropower system with an unintended islanding effect, where the method includes:
after a fault of a main power grid is monitored, a circuit breaker on the high-voltage side of a main transformer between the small hydropower system and the main power grid is controlled to be disconnected;
measuring and obtaining the exchange power between the small hydropower system and the main power grid;
determining that the absolute value of the exchange power is smaller than or equal to the regulation limit active power of the electromechanical group in the small hydropower system, and the reactive exchange power between the small hydropower system and the main power grid is smaller than or equal to the regulation limit reactive power of the electromechanical group in the small hydropower system, and then acquiring the out-of-limit time of the frequency change of the exchange power;
and determining that the out-of-limit time of the frequency change is less than the electromechanical set adjusting time of the small hydropower system, and adjusting the electromechanical set output power of the small hydropower system according to the converted power so as to realize the stable operation of the small hydropower system.
Optionally, according to the exchange power, adjusting the output power of the electromechanical assembly of the small hydropower system to realize stable operation of the small hydropower system comprises:
if the output power is larger than 0, reducing the output power of the electromechanical group of the small hydro-electric system;
and if the output power is less than 0, increasing the output power of the electromechanical group of the small hydropower system.
Optionally, after the power exchange between the small hydropower system and the main power grid is obtained through measurement, the method further comprises the following steps;
and determining that the absolute value of the exchange power is greater than the regulation limit active power of the electromechanical group in the small hydropower system, and the reactive exchange power between the small hydropower system and the main power grid is greater than the regulation limit reactive power of the electromechanical group in the small hydropower system, so that the small hydropower grid system is disconnected.
Optionally, the limit power of the small hydropower system is 40% -50% of the rated power of the small hydropower generator set.
Optionally, obtaining the out-of-limit time of the frequency change of the exchange power includes:
calculating the change rate of the out-of-limit time corresponding to the exchange power;
and calculating to obtain the out-of-limit time according to the change rate and a difference calculation formula of the change rate and the working frequency of the main power grid.
Optionally, a calculation formula of a difference between the change rate and the working frequency of the main power grid is:
Figure BDA0002690187070000031
wherein Δ f is the exchangeThe difference between the change rate of the out-of-limit time corresponding to the power and the working frequency of the main power grid, f is the frequency of the small hydropower system, TcFor the out-of-limit time of the frequency change of said exchange power, f1 is the operating frequency of the main grid,
Figure BDA0002690187070000032
the change rate of the exchange power and the power of the small hydroelectric hydraulic turbine set is represented by derivation of frequency.
Optionally, after the measurement of the exchange power between the small hydropower system and the main power grid, the method further includes:
and determining that the out-of-limit time of the frequency change is less than the electromechanical group adjusting time of the small hydropower system, and disconnecting the small hydropower system.
In a second aspect, an embodiment of the present invention further provides a treatment device for a small hydropower system with an unintended islanding effect, the device including:
the monitoring control module is used for controlling a circuit breaker on the high-voltage side of a main transformer between the small hydropower system and the main power grid to be disconnected after the fault of the main power grid is monitored;
the power measurement module is used for measuring and obtaining the exchange power between the small hydropower system and the main power grid;
The power comparison module is used for determining that the absolute value of the exchange power is smaller than or equal to the regulation limit active power of the electromechanical group in the small hydropower system, and the reactive exchange power between the small hydropower system and the main power grid is smaller than or equal to the regulation limit reactive power of the electromechanical group in the small hydropower system, so that the out-of-limit time of the frequency change of the exchange power is obtained;
and the time comparison module is used for determining that the out-of-limit time of the frequency change is less than the electromechanical set adjusting time of the small hydropower system, and adjusting the electromechanical set output power of the small hydropower system according to the conversion power so as to realize the stable operation of the small hydropower system.
Optionally, the time comparison module includes:
the power reducing unit is used for reducing the output power of the electromechanical set of the small hydro-electric system when the output power is greater than 0;
and the power increasing unit is used for increasing the output power of the electromechanical group of the small hydropower system when the output power is less than 0.
Optionally, the power comparison module includes:
the time obtaining unit is used for calculating the change rate of the out-of-limit time corresponding to the exchange power;
and the time calculation unit is used for calculating and obtaining the out-of-limit time according to the change rate and a difference calculation formula of the change rate and the working frequency of the main power grid.
The technical scheme provided by the embodiment of the invention comprises the steps of controlling a breaker on the high-voltage side of a main transformer between a small hydropower system and a main power grid to be disconnected after a fault of the main power grid is monitored by a small hydropower grid-connected breaker power measuring instrument, measuring to obtain the exchange power between the small hydropower system and the main power grid, determining that the absolute value of the exchange power is less than or equal to the regulation limit active power of an electromechanical group in the small hydropower system, determining that the reactive exchange power between the small hydropower system and the main power grid is less than or equal to the regulation limit reactive power of the electromechanical group in the small hydropower system, acquiring the frequency change out-of-limit time of the exchange power, determining that the frequency change out-of-limit time is less than the regulation time of the electromechanical group in the small hydropower system, regulating the output power of the electromechanical group of the small hydropower system according to the exchange power, ensuring that the working frequency of the small hydropower system is consistent with the working frequency of the main power grid, and realizing the stable operation of the small hydropower system, the method can eliminate the unplanned island effect in the small hydropower system and maintain the normal power supply of the small hydropower system to the load.
Drawings
Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments thereof, made with reference to the following drawings:
Fig. 1 is a flowchart of a handling method for a small hydropower system with an unplanned islanding effect according to an embodiment of the present invention;
fig. 2 is a flowchart of acquiring a frequency change out-of-limit time of exchange power according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of a handling device of a small hydropower system for handling unintended islanding provided by an embodiment of the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, specific embodiments of the present invention are described in further detail below with reference to the accompanying drawings. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention.
It should be further noted that, for the convenience of description, only some but not all of the relevant aspects of the present invention are shown in the drawings. Before discussing exemplary embodiments in more detail, it should be noted that some exemplary embodiments are described as processes or methods depicted as flowcharts. Although a flowchart may describe the operations (or steps) as a sequential process, many of the operations can be performed in parallel, concurrently or simultaneously. In addition, the order of the operations may be re-arranged. The process may be terminated when its operations are completed, but may have additional steps not included in the figure. The processes may correspond to methods, functions, procedures, subroutines, and the like.
Example one
Fig. 1 is a flowchart of a handling method for a small hydropower system with an unplanned islanding effect according to an embodiment of the present invention. The handling method for the small hydropower system with the unplanned islanding can be executed by a handling device for the small hydropower system with the unplanned islanding, which can be implemented in the form of software and/or hardware. As shown in fig. 1, the method may specifically include the following:
and S110, after the fault of the main power grid is monitored, controlling a circuit breaker on the high-voltage side of the main transformer between the small hydropower system and the main power grid to be disconnected.
When the power grid supplies power, the main power grid sometimes breaks down, for example, the voltage frequency of the main power grid changes due to the fact that a main power grid circuit is broken, a main power grid short circuit and the like, the fault effects can affect a small hydropower system, and the main power grid needs to be monitored by a small hydropower grid-connected circuit breaker power measuring instrument at any time.
Specifically, the small hydropower station grid-connected circuit breaker power measuring instrument is a common instrument for industrially measuring power transmission and distribution power, mainly monitors the power of a main transformer in real time, controls a circuit breaker on the high-voltage side of the main transformer between a small hydropower system and a main grid to be disconnected after monitoring that a fault condition exists in the main grid, forms a small hydropower station island state, and further adjusts the small hydropower system in the island state to maintain the power supply of a normal load.
And S120, measuring and obtaining the exchange power between the small hydropower system and the main power grid.
Specifically, the exchange power between the small hydropower system and the main power grid is measured by the power measuring instrument of the small hydropower grid-connected circuit breaker in the steps, namely the voltage U and the current I on the low-voltage side of the main transformer are monitored and measured, and the exchange power can be obtained by PchangeIs shown to be
Figure BDA0002690187070000061
Therefore, the exchange power between the small hydropower system and the main power grid can be obtained through measurement, on the basis, whether the frequency of the small hydropower system can be stabilized through adjusting the power or not can be timely processed, and the power supply efficiency of the small hydropower system is improved.
S130, determining that the absolute value of the exchange power is smaller than or equal to the regulation limit active power of the electromechanical group in the small hydropower system, and the reactive exchange power between the small hydropower system and the main power grid is smaller than or equal to the regulation limit reactive power of the electromechanical group in the small hydropower system, and then obtaining the frequency change out-of-limit time of the exchange power.
Wherein, confirm that the absolute value of exchange power is less than or equal to the regulation limit active power of electromechanical group in the little water and electricity system, be in order to guarantee the circuit breaker disconnection of the main transformer high pressure side between little water and electricity system and main electric network, after forming little water and electricity island state, little water and electricity system self possesses sufficient regulating power, can guarantee that the island operation can not be in the island operation The small hydropower station is unstable, and whether the small hydropower station has enough regulation capacity is judged, namely, the range of the adjustable frequency of the small hydropower station when the small hydropower station unit stably runs is utilized, and the exchange power P between the small hydropower station and the main power grid is utilizedchangeComparing the active power with the limit regulation active power of the electromechanical group in the small hydropower system, wherein the limit regulation active power of the electromechanical group in the small hydropower system can be PTMTo indicate. In addition, the reactive exchange power between the small hydropower system and the main power grid is ensured to be less than or equal to the regulation limit reactive power of the electromechanical group in the small hydropower system, so that the auxiliary comparison of the electric energy operation quality of the small hydropower system is ensured, the reactive power of the small hydropower system is ensured to be supplied and required and can be transmitted to the main power grid, and the electric energy loss is reduced mainly. When the small hydropower system operates stably, the frequency and the voltage of the small hydropower system must be kept stable, the effect of stabilizing the frequency can be achieved by adjusting the active power, and the effect of stabilizing the voltage can be achieved by adjusting the reactive power, wherein the reactive exchange power between the small hydropower system and the main power grid can be achieved by using the absolute value QchangeExpressed by | Q, the regulation limit reactive power of the electromechanical group in the small hydropower system can be expressed by | QchangeIn the expression of |,
specifically, on the basis of the previous step, the exchange power P between the small hydropower system and the main power grid is measured changeBy means of exchange power PchangeAdjusting limit active power P with electromechanical group in small hydropower systemTMComparing to determine the exchange power PchangeIs less than or equal to the active power P of the regulation limit of the electromechanical group in the small hydropower systemTMAnd reactive exchange power | Q between the small hydropower system and the main power gridchangeThe | is less than or equal to the regulation limit reactive power | Q of the electromechanical group in the small hydropower systemchangeIf, then the exchange power P is statedchangeWithin the adjustable limit when the small hydropower system unit stably operates, the out-of-limit time of the frequency change of the exchange power can be obtained.
It should be noted that the reactive exchange power | Q between the small hydropower system and the main gridchangeAdjusting limit reactive power | Q of electromechanical group in | and small hydropower systemchangeIs formed by reactive power and active powerThe power ratio is obtained by the tangent angle, and the relation can be expressed as
Figure BDA0002690187070000081
S140, determining that the out-of-limit time of the frequency change is smaller than the electromechanical set adjusting time of the small hydropower system, and adjusting the electromechanical set output power of the small hydropower system according to the converted power so as to realize the stable operation of the small hydropower system.
Wherein the power P is exchangedchangeThe out-of-limit time of frequency change refers to the exchange power P for stably adjusting and monitoring the power measuring instrument of the small hydropower grid-connected circuit breaker changeThe corresponding time is required, it being understood that the time-out is the exchange of the power PchangeAdjusting the level position of a power transmission balance point before the island power grid and the main power grid, wherein the island power grid and the main power grid can independently drive the time required by respective systems, and the exchange power PchangeThe out-of-limit time of the frequency change may be TCTo indicate.
In particular, on the basis of the previous step, the exchange power P is determinedchangeAfter the small hydropower system unit operates stably within the adjustable limit, the exchange power P is further comparedchangeOut-of-limit time T of frequency changeCAnd the electromechanical group adjusting time of the small hydropower system, wherein the electromechanical group adjusting time of the small hydropower system is the actual time which can be adjusted in time when the small hydropower system unit stably operates after the main power grid fails, and can be T-shapedMTo indicate that the switching power P is determinedchangeOut-of-limit time T of frequency changeCElectromechanical set adjusting time T smaller than small hydropower systemMThen, the regulation of the switching power P is describedchangeOut-of-limit time T of frequency changeCIn the regulating time of small hydroelectric system unit, the exchange power P is enabledchangeAdjusted to a state of system stability and can be based on the power PchangeAnd the stable operation of the small hydropower system can be realized by adjusting the output power of the electromechanical set of the small hydropower system.
Optionally, according to the exchange power, adjust the electromechanical group output power of little hydroelectric system to realize the steady operation of little hydroelectric system includes: if the output power is larger than 0, the output power of the electromechanical group of the small hydroelectric system is reduced, and if the output power is smaller than 0, the output power of the electromechanical group of the small hydroelectric system is increased.
Specifically, when the small hydropower grid-connected circuit breaker power measuring instrument monitors that a fault condition exists in a main power grid, the circuit breaker on the high-voltage side of a main transformer between a small hydropower system and the main power grid is controlled to be disconnected, after a small hydropower island state is formed, if the power of the small hydropower system is increased, the small hydropower system transmits power to the main power grid system, namely, the output power of an electromechanical group of the small hydropower system is reduced, and if the power of the small hydropower system is reduced, the main power grid system transmits power to the small hydropower system, namely, the output power of the electromechanical group of the small hydropower system is increased, so that the stable operation of the small hydropower system is ensured.
For example, if the power of the small hydropower system is increased, the small hydropower system transmits power to the main power grid system, that is, the output power of the electromechanical group of the hydropower system is reduced, and the power can be transmitted to the small hydropower system by slowing down the drainage speed, increasing the load, increasing the energy storage of the small hydropower system, and the like.
Optionally, after the power exchange between the small hydropower system and the main power grid is obtained through measurement, the method further includes: and determining that the absolute value of the exchange power is greater than the regulation limit active power of the electromechanical group in the small hydropower system, and the reactive exchange power between the small hydropower system and the main power grid is greater than the regulation limit reactive power of the electromechanical group in the small hydropower system, so that the small hydropower grid systems are disconnected.
Specifically, the exchange power P between the small hydropower system and the main power grid is measuredchangeBy means of exchange power PchangeAdjusting limit active power P with electromechanical group in small hydropower systemTMBy making a comparison, the exchange power P can also be determinedchangeThe absolute value of the power is larger than the active power of the regulation limit of the electromechanical group in the small hydropower systemRate PTMAnd reactive exchange power | Q between the small hydropower system and the main power gridchangeI is greater than regulating limit reactive power Q of electromechanical group in small hydropower systemchangeIf, then the exchange power P is statedchangeAnd exceeding the adjustable limit of the stable operation of the small hydropower system unit, and separating the small hydropower system at the moment.
Optionally, the limit power of the small hydropower system is 40% -50% of the rated power of the small hydropower generator.
Specifically, in order to ensure that the small hydropower system unit stably operates within the adjustable frequency range, the power P is exchanged changeAdjusting limit active power P with electromechanical group in small hydropower systemTMA comparison is made wherein the limit active power P is regulated by the electromechanical group in the small hydropower systemTMIn relation to the regulating capacity of the turbine, in the prior art, the ultimate active power PTMThe power value is the self-adjustable power value of the small hydroelectric generating set, and a large number of experiments prove that the power value is generally 40% -50% of rated power.
According to the technical scheme provided by the embodiment, after a fault of a main power grid is monitored by a small hydropower grid-connected circuit breaker power measuring instrument, a circuit breaker on the high-voltage side of a main transformer between a small hydropower system and the main power grid is controlled to be disconnected, the exchange power between the small hydropower system and the main power grid is measured and obtained, the absolute value of the exchange power is determined to be smaller than or equal to the regulation limit active power of an electromechanical group in the small hydropower system, the reactive exchange power between the small hydropower system and the main power grid is smaller than or equal to the regulation limit reactive power of the electromechanical group in the small hydropower system, the frequency change out-of-limit time of the exchange power is obtained, the frequency change out-of-limit time is determined to be smaller than the regulation time of the electromechanical group in the small hydropower system, the output power of the electromechanical group in the small hydropower system is regulated according to the conversion power, the working frequency of the small hydropower system is ensured to be consistent with the working frequency of the main power grid, and the stable operation of the small hydropower system is realized, the normal electricity supply of the small hydroelectric system to the load is maintained, and the service efficiency of the small hydroelectric system is improved.
Example two
On the basis of the foregoing embodiment, this embodiment further optimizes the time for acquiring the out-of-limit time of the frequency change of the exchange power, and specifically, fig. 2 is a flowchart for acquiring the out-of-limit time of the frequency change of the exchange power provided in the embodiment of the present invention, where the step of acquiring the out-of-limit time of the frequency change of the exchange power may specifically include the following steps:
s210, calculating the change rate of the out-of-limit time corresponding to the exchange power.
Specifically, on the basis of the above-mentioned embodiment, the power P is exchangedchangeAdjusting limit active power P with electromechanical group in small hydropower systemTMMaking a comparison to ensure the exchange power PchangeWithin the adjustable limit when the small hydropower system unit operates stably, the exchange power P can be further obtainedchangeFrequency change off-limit time TCFirst, the exchange power P is calculatedchangeCorresponding out-of-limit time TCThe rate of change of the power and the power of the small hydropower system water turbine set can be represented by derivation of the frequency, and the rate of change can be represented as fCThen, then
Figure BDA0002690187070000111
Wherein the rate of change may be fCThe method is mainly obtained from a water turbine unit of an island, H is a water turbine inertia time constant in a hydroelectric power generation system, S is the capacity of a small hydropower system unit, f is the frequency of the small hydropower system, and the exchange power P between the small hydropower system and a main power grid is obtained by combining measurement changeBy using the above formula, the exchange power P can be obtainedchangeCorresponding out-of-limit time TCRate of change fC。
And S220, calculating to obtain out-of-limit time according to the change rate and a difference calculation formula of the change rate and the working frequency of the main power grid.
Specifically, the working frequency of the main grid is usually 50Hz, and the change rate f obtained in the previous step is combinedCFurther, the rate of change f can be obtainedCThe difference from the operating frequency of the main network, denoted by Δ f, is based on the rate of change fCAnd rate of change fCFormula and meter for calculating difference value delta f between working frequency of main power gridCalculating to obtain the out-of-limit time TC。
Illustratively, in the present embodiment, the power P is exchanged according to the abovechangeCorresponding out-of-limit time TCRate of change fCAnd rate of change fCThe difference value calculation formula between the working frequency of the main power grid can obtain the change rate fCDifference from main network operating frequency and exchange power PchangeIn connection with, by regulating the exchange power PchangeThe rate of change f can be adjustedCThe difference delta f between the working frequency of the small hydropower system and the working frequency of the main power grid is close to 0 as far as possible, so that the working frequency of the small hydropower system is consistent with the working frequency of the main power grid, and the stable operation of the small hydropower system is further ensured.
Optionally, the calculation formula of the difference between the variable rate and the working frequency of the main power grid is:
Figure BDA0002690187070000121
Where Δ f is the exchange power PchangeCorresponding rate of change f of off-limit timeCDifference from the operating frequency f1 of the main grid, f being the frequency of the small hydropower system, TCTo exchange power PchangeThe out-of-limit time of the frequency variation, f1 is the operating frequency of the main grid,
Figure BDA0002690187070000122
the derivative of the passing frequency represents the change rate of the exchange power and the power of the small hydroelectric hydraulic turbine set.
In particular, based on the calculated exchange power PchangeCorresponding out-of-limit time TCRate of change fCAnd the above rate of change fCCalculating the out-of-limit time T by using a difference value calculation formula with the working frequency of the main power gridC。
Optionally, after the measurement obtains the exchange power between the small hydropower system and the main power grid, the method further includes: and determining that the out-of-limit time of the frequency change is less than the adjusting time of the electromechanical group of the small hydropower system, and disconnecting the small hydropower system.
In particular, on the basis of the above-described embodiments, the switching power P is determinedchangeAfter the small hydropower system unit operates stably within the controllable limit, the exchange power P is further comparedchangeOut-of-limit time T of frequency changeCAdjusting time with electromechanical group of small hydropower system, and determining out-of-limit time T of frequency changeCThe adjustment time of the electromechanical group is shorter than that of the small hydroelectric system, the adjustment of the exchange power P is illustrated changeOut-of-limit time T of frequency changeCAnd (4) exceeding the adjusting time of the small hydropower system unit, and separating the small hydropower system.
According to the technical scheme provided by the embodiment, the out-of-limit time of the change of the frequency of the exchange power is obtained through calculation by calculating the change rate of the out-of-limit time corresponding to the exchange power and according to the change rate and a difference calculation formula of the change rate and the working frequency of the main power grid, whether the out-of-limit time for adjusting the exchange power is within the adjustment time of the small hydropower system or not can be processed in time, the output power of an electromechanical set of the small hydropower system is adjusted, and the small hydropower system can be ensured to operate stably.
EXAMPLE III
Fig. 3 is a schematic structural diagram of a handling device of a small hydropower system with an unintended islanding effect according to an embodiment of the invention. As shown in fig. 3, the apparatus may include:
and the monitoring control module 310 is used for controlling the circuit breaker on the high-voltage side of the main transformer between the small hydropower system and the main power grid to be disconnected after the fault of the main power grid is monitored.
And the power measurement module 320 is used for measuring and obtaining the exchange power between the small hydropower system and the main power grid.
And the power comparison module 330 is configured to determine that the absolute value of the exchange power is less than or equal to the regulation limit active power of the electromechanical group in the small hydropower system, and the reactive exchange power between the small hydropower system and the main power grid is less than or equal to the regulation limit reactive power of the electromechanical group in the small hydropower system, so as to obtain the out-of-limit time of the frequency change of the exchange power.
And the time comparison module 340 is used for determining that the out-of-limit time of the frequency change is less than the electromechanical set adjusting time of the small hydropower system, and adjusting the electromechanical set output power of the small hydropower system according to the converted power so as to realize the stable operation of the small hydropower system.
Optionally, the time comparison module includes: the power increasing unit is used for increasing the output power of the electromechanical set of the small hydroelectric system when the output power is less than 0.
Optionally, the power comparing module includes: and the time calculation unit is used for calculating and obtaining the out-of-limit time according to the change rate and a difference calculation formula of the change rate and the working frequency of the main power grid.
The coping processing method provided by any embodiment of the coping processing method for the small hydropower system with the unplanned islanding, which is provided by the embodiment and is used by the coping processing device for the small hydropower system with the unplanned islanding, has the corresponding functional modules and beneficial effects of the execution method, and is not described herein again.
It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious modifications, rearrangements, combinations and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims (8)

1. A small hydropower system coping processing method for unplanned islanding is characterized by comprising the following steps:
after a fault of a main power grid is monitored, a circuit breaker on the high-voltage side of a main transformer between the small hydropower system and the main power grid is controlled to be disconnected;
measuring and obtaining the exchange power between the small hydropower system and the main power grid;
determining that the absolute value of the exchange power is less than or equal to the regulation limit active power of the electromechanical group in the small hydropower system, and the reactive exchange power between the small hydropower system and the main power grid is less than or equal to the regulation limit reactive power of the electromechanical group in the small hydropower system, and then acquiring the frequency change out-of-limit time of the exchange power;
determining that the out-of-limit time of the frequency change is less than the electromechanical set adjusting time of the small hydropower system, and adjusting the electromechanical set output power of the small hydropower system according to the exchange power so as to realize the stable operation of the small hydropower system;
acquiring the out-of-limit time of the frequency change of the exchange power, comprising the following steps:
calculating the change rate of the out-of-limit time corresponding to the exchange power;
and calculating to obtain the out-of-limit time according to the change rate and a difference calculation formula of the change rate and the working frequency of the main power grid.
2. The handling method for the small hydropower system with the unplanned islanding effect according to claim 1, wherein the adjusting of the electromechanical group output power of the small hydropower system according to the exchange power to achieve stable operation of the small hydropower system comprises:
if the exchange power is larger than 0, reducing the output power of the electromechanical group of the small hydro-electric system;
and if the exchange power is less than 0, increasing the output power of the electromechanical group of the small hydropower system.
3. The handling method for a small hydropower system with an unplanned islanding according to claim 1, wherein after the measurement of the exchange power between the small hydropower system and the main power grid, the handling method further comprises:
and determining that the absolute value of the exchange power is greater than the regulation limit active power of the electromechanical group in the small hydropower system, and the reactive exchange power between the small hydropower system and the main power grid is greater than the regulation limit reactive power of the electromechanical group in the small hydropower system, so that the small hydropower grid system is disconnected.
4. The handling method for the small hydropower system with the unplanned islanding effect according to claim 1, wherein the limit power of the small hydropower system is 40-50% of the rated power of a small hydropower station.
5. The method for handling the small hydropower system handling the unplanned islanding according to claim 1, wherein the difference between the change rate and the working frequency of the main power grid is calculated by the formula:
Figure FDA0003538419570000021
wherein Δ f is a difference between the change rate of the out-of-limit time corresponding to the exchange power and the working frequency of the main power grid, f is the frequency of the small hydropower system, and T is the frequency of the small hydropower systemcFor the out-of-limit time of the frequency change of said exchange power, f1 is the operating frequency of the main grid,
Figure FDA0003538419570000022
the change rate of the exchange power and the power of the small hydroelectric turbine set is represented by derivation of frequency.
6. The handling method for the handling of the small hydropower system with the unplanned islanding according to claim 1, wherein after the measurement of the exchange power between the small hydropower system and the main power grid, the handling method further comprises:
and determining that the out-of-limit time of the frequency change is less than the adjustment time of the electromechanical group of the small hydropower system, and disconnecting the small hydropower system.
7. A small hydropower system coping processing device for unintended islanding, comprising:
the monitoring control module is used for controlling a circuit breaker on the high-voltage side of a main transformer between the small hydropower system and the main power grid to be disconnected after monitoring the fault of the main power grid;
The power measurement module is used for measuring and obtaining the exchange power between the small hydropower system and the main power grid;
the power comparison module is used for determining that the absolute value of the exchange power is smaller than or equal to the regulation limit active power of the electromechanical group in the small hydropower system, and the reactive exchange power between the small hydropower system and the main power grid is smaller than or equal to the regulation limit reactive power of the electromechanical group in the small hydropower system, so that the out-of-limit time of the frequency change of the exchange power is obtained;
the time comparison module is used for determining that the out-of-limit time of the frequency change is less than the electromechanical group adjusting time of the small hydropower system, and adjusting the electromechanical group output power of the small hydropower system according to the exchange power so as to realize the stable operation of the small hydropower system;
the power comparison module includes:
the time obtaining unit is used for calculating the change rate of the out-of-limit time corresponding to the exchange power;
and the time calculation unit is used for calculating and obtaining the out-of-limit time according to the change rate and a difference calculation formula of the change rate and the working frequency of the main power grid.
8. A treatment plant for a small hydropower system coping with an unplanned islanding according to claim 7, wherein the time comparison module comprises:
The power reducing unit is used for reducing the output power of the electromechanical group of the small hydro-electric system when the exchange power is greater than 0;
and the power increasing unit is used for increasing the output power of the electromechanical group of the small hydropower system when the exchange power is less than 0.
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