CN112467753B - Reactive power replacement method and device - Google Patents
Reactive power replacement method and device Download PDFInfo
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- CN112467753B CN112467753B CN202011379336.5A CN202011379336A CN112467753B CN 112467753 B CN112467753 B CN 112467753B CN 202011379336 A CN202011379336 A CN 202011379336A CN 112467753 B CN112467753 B CN 112467753B
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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
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- 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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Abstract
The invention discloses a reactive power replacement method and a reactive power replacement device. The reactive power replacement method comprises the following steps: when the running working point of the dynamic reactive power compensation equipment is not at the normal working point, calculating reactive power displacement of the dynamic reactive power compensation equipment; calculating the estimated bus voltage obtained by compensation according to the reactive displacement; judging whether the estimated bus voltage is out of limit; and if not, compensating the dynamic reactive power compensation equipment through a capacitor or a reactor according to the reactive power displacement. The invention can improve the margin of the dynamic reactive compensation equipment and quickly respond to the reactive regulation requirement of the power grid.
Description
Technical Field
The embodiment of the invention relates to the technical field of power regulation, in particular to a reactive power replacement method and device.
Background
At present, the reactive voltage operation problem of the regional distribution network is seriously urgent, and the phenomenon of higher voltage and lower voltage exist simultaneously in a large quantity. The high water yield period is greatly and electrically full of small water, so that the line voltage is higher, and the operation safety is threatened. During the load peak period, part of the low-voltage area generates the problem of low terminal voltage, and part of the area generates the problem of higher voltage during the load valley. The regional power distribution network is relatively weak, and the power distribution network lacks voltage regulation means, so that the problem of local low (high) voltage caused by power generation and load dynamic change cannot be solved.
Existing power system scheduling is implemented by the automatic voltage control (Automatic Voltage Control, AVC) system. The AVC system is constructed on the power grid energy management system, can scientifically determine an optimal reactive voltage adjustment scheme from the perspective of global optimization of the power grid by utilizing real-time operation data of the power grid, and automatically transmits the optimal reactive voltage adjustment scheme to a power plant, a transformer substation and a lower power grid dispatching mechanism for execution. The AVC system regulates and controls by taking the transformer substation as a unit, and the voltage distribution condition of the line and the transformer area is not considered. Therefore, the existing dispatching method has the problems of low margin of reactive compensation equipment and slow response.
Disclosure of Invention
The embodiment of the invention provides a reactive power replacement method and a reactive power replacement device, which are used for improving the margin of dynamic reactive power compensation equipment and rapidly responding to reactive power regulation requirements of a power grid.
In a first aspect, an embodiment of the present invention provides a reactive replacement method, including the steps of:
when the operation working point of the dynamic reactive power compensation equipment in the transformer substation is not at the normal working point, calculating the reactive power displacement of the dynamic reactive power compensation equipment;
calculating the estimated bus voltage obtained by compensation according to the reactive displacement;
judging whether the estimated bus voltage is out of limit;
and if not, compensating the dynamic reactive power compensation equipment through static reactive power compensation equipment in the transformer substation according to the reactive power displacement.
Optionally, the compensating the dynamic reactive power compensation device by the static reactive power compensation device in the transformer substation according to the reactive power displacement amount includes:
if the reactive replacement amount is larger than zero, adding capacitive reactive power for compensation by adding a capacitor or cutting off a reactor;
and if the reactive replacement amount is smaller than zero, switching inductive reactive power into the capacitor or the reactor for compensation.
Optionally, calculating the reactive displacement amount of the dynamic reactive compensation device includes:
calculating reactive power demand of the dynamic reactive power compensation equipment according to the operation working point and the normal working point;
judging whether the reactive power demand reaches the reactive power adjustment step length of the dynamic reactive power compensation equipment; if yes, setting the reactive displacement as the reactive adjustment step length; otherwise, the compensation is ended.
Optionally, after the determining whether the estimated bus voltage is out of limit, the method further includes:
if yes, judging whether a standby reactive power exists in the system; if yes, the standby reactive power is used for adjusting the voltage of the initial bus.
Optionally, the conditions for predicting bus voltage out-of-limit include: the estimated bus voltage is larger than an upper operation limit parameter value or smaller than a lower operation limit parameter value;
the adjusting the initial bus voltage using the backup reactive power includes:
if the estimated bus voltage is larger than the operation upper limit parameter value, judging whether the reducible work load exists in the system or not; if yes, reducing reactive power to reduce the initial bus voltage;
or if the estimated bus voltage is smaller than the operation lower limit parameter value, judging whether the system has the variable work or not; if yes, reactive power is increased to increase the initial bus voltage.
Optionally, the reducing reactive power includes: judging whether the low-voltage side non-work amount of the main transformer in the system is larger than zero; if yes, cutting off the low-voltage side capacitor; otherwise, putting into a low-voltage side reactor;
the increasing reactive power includes: judging whether the low-voltage side non-work amount of the main transformer in the system is less than zero; if yes, cutting off the low-voltage side reactor; otherwise, a low-side capacitor is put in.
Optionally, before calculating the reactive displacement amount of the dynamic reactive compensation device, the method further comprises:
measuring an initial bus voltage;
judging whether the initial bus voltage is out of limit, if so, ending compensation; otherwise, judging whether the running working point of the dynamic reactive compensation equipment is a normal working point.
Optionally, before calculating the reactive displacement amount of the dynamic reactive compensation device, the method further comprises:
acquiring an operation working point and a normal working point of the dynamic reactive power compensation equipment, and acquiring reactive voltage sensitivity of the dynamic reactive power compensation equipment to a bus; the reactive voltage sensitivity is used for calculating the estimated bus voltage.
In a second aspect, an embodiment of the present invention provides a reactive replacement device, including:
the reactive displacement amount calculating module is used for calculating reactive displacement amount of the dynamic reactive compensation equipment when the operation working point of the dynamic reactive compensation equipment in the transformer substation is not at a normal working point;
the estimated bus voltage calculation module is used for calculating the estimated bus voltage obtained by compensating according to the reactive displacement;
the out-of-limit judging module is used for judging whether the estimated bus voltage is out-of-limit or not;
and the compensation module is used for compensating the dynamic reactive power compensation equipment through the static reactive power compensation equipment in the transformer substation according to the reactive power displacement when the estimated bus voltage is not beyond the limit.
Optionally, the reactive replacement device further comprises:
the initial bus voltage adjusting module is used for judging whether the pre-estimated bus voltage is out of limit or not, and judging whether standby reactive power exists in the system or not if the pre-estimated bus voltage is out of limit; and if the standby reactive power exists in the system, the standby reactive power is used for adjusting the voltage of the initial bus.
According to the reactive power replacement method provided by the embodiment of the invention, when the operation working point of the dynamic reactive power compensation equipment is not at the normal working point and the estimated bus voltage obtained by compensation according to the reactive power replacement amount is not out of limit, the dynamic reactive power compensation equipment is compensated through the static reactive power compensation equipment in the transformer substation according to the reactive power replacement amount, and the dynamic reactive power compensation equipment in the transformer substation can be ensured to work near the normal working point through the compensation of the static reactive power compensation equipment, so that the reactive power margin of the dynamic reactive power compensation equipment is ensured, the timely response of the reactive power compensation equipment to voltage fluctuation is ensured, and the bus voltage is fully regulated. And moreover, the dynamic reactive compensation equipment is compensated when the estimated bus voltage is not out of limit, so that the bus voltage out of limit caused by compensating the dynamic reactive compensation equipment can be prevented from causing impact on a power grid and even causing faults. Therefore, compared with the prior art, the method and the device can improve the margin of the dynamic reactive power compensation equipment and quickly respond to the reactive power regulation requirement of the power grid.
Drawings
Fig. 1 is a schematic flow chart of a reactive replacement method according to an embodiment of the present invention;
FIG. 2 is a schematic flow chart of another reactive replacement method according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of a reactive power replacement device according to an embodiment of the present invention.
Detailed Description
The invention is described in further detail below with reference to the drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting thereof. It should be further noted that, for convenience of description, only some, but not all of the structures related to the present invention are shown in the drawings.
In the prior art, the voltage control strategy for the power transmission network mainly comprises two types of reactive power control strategies for all generators of a power plant and reactive power equipment control strategies for a transformer substation. Wherein, reactive power control strategy to each generator of power plant is: after reactive power adjustment quantity of each generator set of the power plant is obtained through reactive power optimization calculation by the AVC master station system of the dispatching center, the reactive power adjustment quantity is sent to an AVC substation system of the power plant through a data communication channel, and after the AVC substation of the power plant receives the reactive power adjustment quantity of the generator, reactive power sent by the generator is adjusted in a stepping mode according to the running state of each generator in the current power plant until the reactive power adjustment quantity issued by the AVC master station is reached. The reactive power equipment control strategy of the transformer substation is a switching instruction of reactive power compensation equipment, wherein the reactive power equipment mainly comprises a capacitor and a reactor, and when the capacitor is switched in or the reactor is cut off, the bus voltage is increased; when the capacitor is cut off or the reactor is put in, the bus voltage decreases. The AVC master station issues an instruction for switching in or switching off the reactive equipment, and an automatic monitoring system in the transformer substation finds a breaker connected with the reactive equipment according to the received instruction and switches on or off the breaker so as to complete switching in or switching off of the reactive equipment.
However, the grid frame of the regional distribution network is weak, the reactive voltage operation problem of the regional distribution network is seriously urgent, and the phenomenon of higher voltage and lower voltage exist simultaneously in a large quantity. The high water yield period is greatly and electrically full of small water, so that the line voltage is higher, and the operation safety is threatened. During the load peak period, part of the low-voltage area generates the problem of low terminal voltage, and part of the area generates the problem of higher voltage during the load valley. Because reactive power cannot be balanced in situ, reactive current increases line loss and reduces the running economy of the distribution network. The distribution network lacks a voltage regulation means, the problem of local low (high) voltage caused by power generation and dynamic load change cannot be solved, and the existing transformer substation, line and transformer area reactive power regulation devices independently operate and lack global coordination. AVC regulates and controls by taking a transformer substation as a unit, and does not consider the voltage distribution condition of a line and a transformer area; autonomous operation and scheduling of small hydropower stations, distributed photovoltaics and the like cannot be automatically adjusted remotely, so that high voltage occurs during power generation and low voltage occurs during power failure; the transformer area capacitor bank is automatically switched only according to the voltage of the head end of the transformer area, and cannot be adjusted cooperatively according to the voltage requirements of lines and users.
In conclusion, the existing reactive power adjustment method has the problems of small margin and slow response of dynamic reactive power compensation equipment.
In order to solve the problems, the embodiment of the invention provides a reactive power replacement method which can be realized based on a reactive power replacement device, and the method can be suitable for adjusting the coordination between reactive power regulation equipment in regional power grid substations. Fig. 1 is a schematic flow chart of a reactive replacement method according to an embodiment of the present invention. Referring to fig. 1, the reactive replacement method includes the steps of:
s110, when the operation working point of the dynamic reactive power compensation equipment in the transformer substation is not at the normal working point, calculating the reactive power displacement of the dynamic reactive power compensation equipment.
The reactive power compensation method and the reactive power compensation device are suitable for reactive power replacement between dynamic reactive power compensation devices and static reactive power compensation devices in regional power grid substations, and therefore reactive power margin of the dynamic reactive power compensation devices is improved. The dynamic reactive power compensation device is also called a static reactive power compensator, and the compensation capacity of the dynamic reactive power compensation device can be adjusted arbitrarily. The dynamic reactive power compensation equipment can be a thyristor phase control reactor, a thyristor switching capacitor, a static reactive power generator and the like. Preferably, the dynamic reactive compensation device is a static synchronous compensator (Static synchronous compensator, STATCOM) to ensure fast response and to fulfill reactive power regulation tasks. The static synchronous compensator is a dynamic reactive power compensation device based on a voltage source converter, and is a reactive power dynamic compensation device for generating and absorbing reactive power by a self-commutated power semiconductor bridge converter. The system comprises an alternating current link and a direct current link, wherein the alternating current link is connected with the system, alternating current energy of the system is firstly converted into direct current through a converter and is stored in an energy accumulator at a direct current side, and meanwhile, voltage and current at the direct current side are changed into alternating current voltage and current through the converter and are transmitted to the system.
When the dynamic reactive power compensation equipment operates at a normal operating point, the compensation capacity is best, and the reactive power margin is highest. Therefore, when the dynamic reactive compensation device does not operate at the normal operating point (for example, in order to adjust the bus voltage, the dynamic reactive compensation device has already performed reactive compensation), other standby reactive devices (for example, static reactive compensation devices) need to be controlled to perform reactive replacement with the dynamic reactive compensation device, so that the operating point of the dynamic reactive compensation device returns to the vicinity of the normal operating point to ensure the reactive margin thereof.
Alternatively, the reactive displacement amount may be positive or negative; the reactive power compensation device can be determined according to the operation working point of the dynamic reactive power compensation device, for example, the difference between the operation working point and the normal working point is used as reactive power displacement; or the reactive replacement amount is determined by integrating the operation working point of the dynamic reactive compensation equipment and the standby reactive amount in the system. For example, when the reactive power replacement is performed by switching the capacitor, the capacity and the number of the capacitor may be considered, and the combination of the capacity and the number of the capacitor in the amount closest to the difference between the operating point and the normal operating point may be used as the reactive power replacement amount.
S120, calculating the estimated bus voltage obtained by compensation according to the reactive replacement quantity.
In the embodiment of the invention, after the reactive displacement is calculated, before the dynamic reactive compensation equipment is compensated, the state of the bus voltage (called estimated bus voltage) is calculated firstly on the basis of the current bus voltage if the reactive displacement is compensated. When the estimated bus voltage is within the normal operation range of the bus voltage, compensation can be performed according to the reactive displacement, so that impact on the system caused by out-of-limit bus voltage after compensation is prevented.
S130, judging whether the estimated bus voltage is out of limit; if not, S140 is performed.
Wherein, the bus voltage has normal operating range in which the bus voltage can operate, such as allowing voltage fluctuation to be +/-10%; or allow a voltage ripple of +10%, -5%, etc. The normal operating range is determined based on factors such as bus length, rated voltage class, and operating environment. In general, the higher the voltage level, the smaller the allowable voltage fluctuation range. And when the difference value between the estimated bus voltage and the rated voltage exceeds the range of the allowable voltage fluctuation, the estimated bus voltage is considered to be out of limit.
When the estimated bus voltage is over the limit, the dynamic reactive power compensation equipment can not be compensated; or adding constraint conditions that the estimated bus voltage is not out of limit, recalculating reactive displacement, and compensating according to the new reactive displacement; or, the current bus voltage is reversely adjusted to ensure that the bus voltage does not exceed the limit after the compensation according to the reactive replacement quantity. In a word, the dynamic reactive power compensation equipment is compensated on the basis that the estimated bus voltage is not out of limit, so that the dynamic reactive power compensation equipment returns to the vicinity of a normal working point.
And S140, compensating the dynamic reactive power compensation equipment through the static reactive power compensation equipment in the transformer substation according to the reactive power displacement.
The adjusting devices in the power grid system are often redundant, and standby allowance exists. The static var compensation devices may be capacitors and reactors. In compensating the dynamic reactive compensation device, the capacitive reactive power may alternatively be put in by putting in a capacitor or cutting off a reactor; or by cutting off the capacitor or putting in the reactor. The compensation mode can be selected according to actual requirements, and is not limited herein.
According to the reactive power replacement method provided by the embodiment of the invention, when the operation working point of the dynamic reactive power compensation equipment is not at the normal working point and the estimated bus voltage obtained by compensation according to the reactive power replacement amount is not out of limit, the dynamic reactive power compensation equipment is compensated through the static reactive power compensation equipment in the transformer substation according to the reactive power replacement amount, and the dynamic reactive power compensation equipment in the transformer substation can be ensured to work near the normal working point through the compensation of the static reactive power compensation equipment, so that the reactive power margin of the dynamic reactive power compensation equipment is ensured, the timely response of the reactive power compensation equipment to voltage fluctuation is ensured, and the bus voltage is fully regulated. And moreover, the dynamic reactive compensation equipment is compensated when the estimated bus voltage is not out of limit, so that the bus voltage out of limit caused by compensating the dynamic reactive compensation equipment can be prevented from causing impact on a power grid and even causing faults. The embodiment of the invention defines the replacement logic among different reactive power equipment and improves the reactive power reserve of the dynamic reactive power compensation equipment, thereby reducing the voltage fluctuation of the regional power grid and improving the static voltage stability margin of the regional power grid. Therefore, the embodiment of the invention can improve the margin of the dynamic reactive power compensation equipment and quickly respond to the reactive power regulation requirement of the power grid.
With continued reference to fig. 1, optionally, with the reactive replacement method, after determining whether the estimated bus voltage is out of limit (S130), the method further includes:
if the estimated bus voltage is out of limit, executing S150;
s150, judging whether a standby reactive power exists in the system; if yes, executing S160; if not, S170 is performed.
After it is determined that reactive power compensation is performed on the dynamic reactive power compensation device according to the reactive power displacement, the estimated bus voltage is over-limited, and first, the initial bus voltage (i.e., the current uncompensated bus voltage) is reversely adjusted, so that the adjusted bus voltage is not over-limited after the reactive power displacement is compensated.
And S160, adjusting the voltage of the initial bus by using the standby reactive power.
Illustratively, the standby reactive may be a reactive device (such as a capacitor or reactor) that is redundantly located in the system; but also a redundant part of the dynamic reactive compensation device that is not powered. The adjustment of the initial bus voltage includes: when the estimated bus voltage exceeds the upper limit, the initial bus voltage is adjusted downwards; and when the estimated bus voltage is lower than the lower limit, the initial bus voltage is adjusted upwards. The adjustment amount of the initial bus voltage can be set according to the condition that the estimated bus voltage is out of limit. For example, the setting adjustment amount is proportional to the amount of the overshoot.
S170, finishing compensation.
If no spare reactive power exists in the system, that is, the initial bus voltage cannot be adjusted first, and then the dynamic reactive power compensation equipment is compensated. In this case, the compensation may be ended; or recalculating the reactive replacement amount by limiting the estimated bus voltage not to exceed the limit.
In this embodiment, by adding a judgment as to whether there is a standby reactive in the system, the conditions and steps of reactive replacement are further clarified.
On the basis of the above embodiments, the embodiments of the present invention will be further described with respect to a manner of compensating the dynamic reactive power compensation device. Optionally, according to the reactive replacement amount, compensating the dynamic reactive compensation device by the static reactive compensation device in the transformer substation, including the following steps:
if the reactive replacement amount is greater than zero, the capacitive reactive power is input by inputting a capacitor or cutting off a reactor to compensate.
If the reactive replacement amount is smaller than zero, inductive reactive power is input for compensation by cutting off the capacitor or inputting the reactor.
The reactive power of the electric line is not consumed, the inductive device (reactor) can only generate inductive reactive power (voltage lead current), the capacitor can only generate capacitive reactive power (current lead voltage), and the inductive device (reactor) and the capacitor can compensate each other by 180 degrees in phase. When the reactive displacement is greater than zero, the system lacks capacitive reactive power; when the reactive displacement is less than zero, the reactive of the system content is excessive, and inductive reactive is needed to be input for compensation. The reactive replacement can be performed according to the system requirement by the arrangement of the embodiment, and in each case, the capacitor or the reactor or the combination of the capacitor and the reactor can be selected for compensation, so that more flexible compensation can be realized, and a better replacement effect can be achieved.
On the basis of the above embodiments, alternatively, an automatic control period (denoted as T c ) The AVC system controls the period T automatically c The dynamic reactive power compensation equipment is automatically monitored in real time, and when reactive power replacement is needed, the dynamic reactive power compensation equipment is automatically compensated, so that the real-time performance and the automaticity of the replacement process are ensured. Wherein the period T is automatically controlled c Can be set according to actual requirements, such as automatic control period T when the electricity consumption is complex c The setting area is short; access in a systemWith less distributed subnetworks of greater uncertainty, the period T will be automatically controlled c Longer setting, etc. One time, for each automatic control period T c The steps of the reactive replacement method are described.
Fig. 2 is a schematic flow chart of another reactive replacement method according to an embodiment of the present invention. Referring to fig. 2, the steps of reactive replacement are further supplemented in this embodiment, so that the whole replacement logic is more definite, and the system is beneficial to quickly and accurately responding to reactive replacement requirements. Optionally, the reactive replacement method comprises the steps of:
s210, acquiring an operation working point and a normal working point of the dynamic reactive power compensation equipment, and acquiring reactive voltage sensitivity of the dynamic reactive power compensation equipment to a bus.
Wherein, in each automatic control period T c When coming, the operation working points (real-time reactive power measurement value Q) of dynamic reactive power compensation equipment (such as a static synchronous compensator) in regional power grid substations are respectively read from a power grid automatic voltage control system r-s ) Normal operating point (reactive normal operating point parameter Q nom-s ) Reactive power replacement threshold parameter (denoted as Q max Upper limit value for reactive power substitution) and reactive power adjustment step length Q step And the reactive voltage sensitivity (marked as C) of the static synchronous compensator in the regional power grid substation to the bus (such as 220kV bus) of the regional power grid substation is read s-m ). The sensitivity of the dynamic reactive power compensation equipment to each bus can be the same or different. Reactive voltage sensitivity C s-m The method for calculating the estimated bus voltage is described in the following steps.
S220, judging whether the initial bus voltage is out of limit; if yes, finishing compensation; if not, S230 is performed.
In this case, the initial busbar voltage is first measured, for example, the voltage measurement of the busbar in the regional power substation is read from the power grid dispatching system (denoted V m I.e. the initial bus voltage), the upper operating limit parameter value (noted as V) of the bus is read from the grid automatic voltage control system m-max ) And a lower run limit parameter value (denoted as V m-min ) For initial bus voltage V m And (3) judging: when the initial bus voltage V m Satisfy V m-min <V m <V m-max At the time, consider the initial bus voltage V m Not out of limit; when the initial bus voltage V m Is in accordance with V m-min >V m Or V m >V m-max In one of them, the initial bus voltage V is determined m Out of limit. When the initial bus voltage V m When exceeding the limit, the initial bus voltage V should be immediately applied m And processing is carried out to prevent accidents from happening, and compensation of the dynamic reactive power compensation equipment is not carried out any more.
The order given in the embodiments of the present invention is only one example of reactive replacement method and is not intended to limit the present application. The order of the steps can be adjusted or combined according to the actual situation.
S230, judging whether the operation working point of the dynamic reactive compensation equipment is a normal working point; if yes, finishing compensation; if not, S240 is performed.
S240, calculating reactive power demand of the dynamic reactive power compensation equipment according to the operation working point and the normal working point.
The reactive displacement (referred to as DeltaQ) s ) Is further illustrated. Alternatively, the operating point Q may be used r-s Subtracting the normal operating point Q nom-s The absolute value of the reactive difference obtained is taken as the reactive demand (denoted as deltaq) of the dynamic reactive compensation device.
S250, judging whether the reactive power demand reaches the reactive power adjustment step length of the dynamic reactive power compensation equipment; if yes, executing S260; if not, the compensation is ended.
Wherein when the reactive power demand quantity delta Q does not reach the reactive power regulation step length Q step When the dynamic reactive compensation equipment is operated at the normal operating point Q nom-s Nearby, there is no need to compensate for this.
And S260, setting the reactive displacement amount as a reactive adjustment step size.
Wherein when the reactive difference in the above steps is positive, the reactive displacement ΔQ is calculated s Setting positive adjustment step Q step The method comprises the steps of carrying out a first treatment on the surface of the When the reactive difference is negative, the reactive displacement quantity delta Q is calculated s Setting negative adjustment step-Q step 。
S270, calculating the estimated bus voltage obtained by compensation according to the reactive replacement amount.
According to the reactive voltage sensitivity C read in S210 s-m The estimated bus voltage (denoted as V) of the reactive power compensation device in the regional power grid transformer substation after being adjusted according to the reactive power displacement is calculated m '), the calculation formula is as follows: v (V) m ’＝V m +C s-m *ΔQ s 。
S280, judging whether the estimated bus voltage is out of limit; if yes, then execution S290; if not, S2C0 is executed.
The condition for predicting bus voltage out-of-limit comprises the following steps: the estimated bus voltage is greater than the upper operating limit parameter value (V m ’>V m-max ) Or the estimated bus voltage is smaller than the operation lower limit parameter value (V m-min >V m ’)。
S290, judging whether the estimated bus voltage is greater than an operation upper limit parameter value; if yes, executing S2A0; if not, S2B0 is executed.
Wherein, when the bus voltage V is estimated m ' greater than the upper operating limit parameter value V m-max At the time, the low-voltage side no-load (denoted as Q) of the main transformer in the transformer substation is read from the power grid dispatching system j ) And can reduce the amount of work (denoted as Q dec-j ). And judging whether the reducible no-work quantity Q exists in the system dec-j The method comprises the steps of carrying out a first treatment on the surface of the If yes, reactive power is reduced to reduce the initial bus voltage V m The method comprises the steps of carrying out a first treatment on the surface of the Otherwise, due to no reducible dead quantity Q dec-j To reduce the initial bus voltage V m Will lead to the following reactive displacement quantity delta Q s After compensation, bus voltage is out of limit, which causes impact to the power grid, so that no reducible no work quantity Q dec-j Or can reduce the amount of work Q dec-j When the compensation is insufficient, the compensation is ended.
When the bus voltage V is estimated m ' less than the lower operating limit parameter value V m-min Reading low-voltage side no-load Q of main transformer in transformer substation from power grid dispatching system j And can increase the amount of work (denoted as Q add-j ). And judging whether the system has the variable work quantity Q add-j The method comprises the steps of carrying out a first treatment on the surface of the If yes, reactive power is increased to increase the initial bus voltage V m . Otherwise, the compensation is ended.
S2A0, reducing reactive power to reduce the initial bus voltage.
Wherein reducing reactive power comprises: judging the low-voltage side non-work Q of main transformer in system j Whether greater than zero; if yes, cutting off the low-voltage side capacitor; otherwise, the low-voltage side reactor is put into operation.
S2B0, reactive power is increased to increase the initial bus voltage.
Wherein increasing reactive power comprises: judging the low-voltage side non-work Q of main transformer in system j Whether or not it is less than zero; if yes, cutting off the low-voltage side reactor; otherwise, a low-side capacitor is put in.
And S2C0, compensating the dynamic reactive power compensation equipment through a capacitor or a reactor according to the reactive power displacement.
Wherein, when the reactive displacement quantity DeltaQ s >When 0, the inductive reactive power is input into the dynamic reactive power compensation equipment through a capacitor or a reactor; when reactive displacement quantity DeltaQ s <When 0, the inductive reactive power is input into the dynamic reactive power compensation equipment through a capacitor or a reactor; the reactive value of the dynamic reactive compensation equipment in the regional power grid transformer substation is the reactive normal operating point Q nom-s The reactive replacement of the dynamic reactive compensation equipment and the capacitor (reactance) in the regional power grid transformer substation is realized.
The reactive power replacement method provided by the embodiment of the invention utilizes the conventional capacitor (reactor) equipment and dynamic reactive power compensation equipment in the transformer substation to perform reactive power replacement, is used for rapidly responding to the problem of regional power grid fluctuation caused by massive access of small hydropower and new energy factories, reduces the voltage fluctuation of the regional power grid, and improves the voltage quality of the regional power grid. The embodiment of the invention defines reactive replacement logic among different reactive devices, improves the voltage stability of the power grid and improves the voltage quality of the power grid.
The embodiment of the invention also provides a reactive power replacement device which can realize the reactive power replacement method provided by each embodiment and has corresponding beneficial effects.
Fig. 3 is a schematic structural diagram of a reactive power replacement device according to an embodiment of the present invention. Referring to fig. 3, the reactive replacement device includes: the reactive displacement amount calculation module 110, the estimated bus voltage calculation module 120, the out-of-limit judgment module 130 and the compensation module 140.
The reactive displacement calculation module 110 is configured to calculate a reactive displacement of the dynamic reactive compensation device when an operation operating point of the dynamic reactive compensation device in the substation is not at a normal operating point; the estimated bus voltage calculation module 120 is used for calculating the estimated bus voltage obtained by compensation according to the reactive displacement; the out-of-limit judging module 130 is configured to judge whether the estimated bus voltage is out of limit; and the compensation module 140 is used for compensating the dynamic reactive power compensation equipment through the static reactive power compensation equipment in the transformer substation according to the reactive power displacement when the estimated bus voltage is not limited.
On the basis of the above embodiments, optionally, the reactive displacement amount calculation module 110 includes: a reactive demand amount calculating unit, a reactive demand amount judging unit and a reactive replacement amount setting unit. The reactive power demand calculation unit is used for calculating reactive power demand of the dynamic reactive power compensation equipment according to the operation working point and the normal working point; the reactive power demand judging unit is used for judging whether the reactive power demand reaches the reactive power adjustment step length of the dynamic reactive power compensation equipment; the reactive displacement setting unit is used for setting the reactive displacement as the reactive adjustment step when the reactive demand reaches the reactive adjustment step of the dynamic reactive compensation equipment.
On the basis of the above embodiments, the compensation module 140 optionally includes a capacitive compensation unit and an inductive compensation unit. The capacitive compensation unit is used for inputting capacitive reactive power for compensation by inputting a capacitor or cutting off a reactor when the reactive replacement amount is larger than zero; the inductive compensation unit is used for switching in inductive reactive power to compensate by cutting off a capacitor or switching in a reactor when the reactive replacement amount is smaller than zero.
On the basis of the above embodiments, optionally, the reactive replacement device further includes: the initial bus voltage adjusting module is used for judging whether the system has standby reactive power or not if the estimated bus voltage is out of limit after judging whether the estimated bus voltage is out of limit; and if the standby reactive power exists in the system, the standby reactive power is used for adjusting the voltage of the initial bus.
Optionally, the initial bus voltage adjustment module includes a decreasing reactive unit and an increasing reactive unit based on the embodiments described above. The condition for predicting bus voltage out-of-limit comprises the following steps: the estimated bus voltage is greater than the upper operating limit parameter value or the estimated bus voltage is less than the lower operating limit parameter value. The reactive power reduction unit is used for judging whether the reducible no-work amount exists in the system when the estimated bus voltage is larger than the operation upper limit parameter value; if yes, reactive power is reduced to reduce the initial bus voltage. The reactive power adding unit is used for judging whether the system has the added variable quantity or not when the estimated bus voltage is smaller than the operation lower limit parameter value; if yes, reactive power is increased to increase the initial bus voltage.
On the basis of the above embodiments, optionally, the reactive power reduction unit is further configured to determine whether the low-voltage side dead load of the main transformer in the system is greater than zero; if yes, cutting off the low-voltage side capacitor; otherwise, the low-voltage side reactor is put into operation. The reactive power unit is further used for judging whether the low-voltage side non-work amount of the main transformer in the system is smaller than zero; if yes, cutting off the low-voltage side reactor; otherwise, a low-side capacitor is put in.
On the basis of the above embodiments, optionally, the reactive replacement device further includes: an initial bus voltage measuring unit and an initial bus voltage judging unit. The initial bus voltage measuring unit is used for measuring the initial bus voltage before calculating the reactive displacement of the dynamic reactive compensation equipment. The initial bus voltage judging unit is used for judging whether the initial bus voltage is out of limit, if so, the compensation is ended; otherwise, judging whether the running working point of the dynamic reactive compensation equipment is a normal working point.
On the basis of the above embodiments, optionally, the reactive replacement device further includes: the system comprises an acquisition unit, a control unit and a control unit, wherein the acquisition unit is used for acquiring an operation working point and a normal working point of dynamic reactive power compensation equipment and acquiring reactive voltage sensitivity of the dynamic reactive power compensation equipment to a bus before calculating reactive power displacement of the dynamic reactive power compensation equipment; the reactive voltage sensitivity is used for calculating the estimated bus voltage.
Note that the above is only a preferred embodiment of the present invention and the technical principle applied. 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 changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, while the invention has been described in connection with the above embodiments, the invention is not limited to the embodiments, but may be embodied in many other equivalent forms without departing from the spirit or scope of the invention, which is set forth in the following claims.
Claims (8)
1. A reactive replacement method, comprising the steps of:
when the operation working point of the dynamic reactive power compensation equipment in the transformer substation is not at the normal working point, calculating the reactive power displacement of the dynamic reactive power compensation equipment;
calculating the estimated bus voltage obtained by compensation according to the reactive displacement;
judging whether the estimated bus voltage is out of limit;
if not, compensating the dynamic reactive power compensation equipment through static reactive power compensation equipment in the transformer substation according to the reactive power displacement;
after the judging whether the estimated bus voltage is out of limit, the method further comprises:
if yes, judging whether a standby reactive power exists in the system; if yes, the standby reactive power is used for adjusting the voltage of the initial bus.
2. The reactive replacement method according to claim 1, wherein the compensating the dynamic reactive compensation device by a static reactive compensation device in a substation according to the reactive replacement amount comprises:
if the reactive replacement amount is larger than zero, adding capacitive reactive power for compensation by adding a capacitor or cutting off a reactor;
and if the reactive replacement amount is smaller than zero, switching inductive reactive power into the capacitor or the reactor for compensation.
3. The reactive replacement method according to claim 1, wherein calculating the reactive replacement amount of the dynamic reactive compensation device comprises:
calculating reactive power demand of the dynamic reactive power compensation equipment according to the operation working point and the normal working point;
judging whether the reactive power demand reaches the reactive power adjustment step length of the dynamic reactive power compensation equipment; if yes, setting the reactive displacement as the reactive adjustment step length; otherwise, the compensation is ended.
4. The reactive replacement method according to claim 1, wherein the condition of predicting bus voltage out-of-limit comprises: the estimated bus voltage is larger than an upper operation limit parameter value or smaller than a lower operation limit parameter value;
the adjusting the initial bus voltage using the backup reactive power includes:
if the estimated bus voltage is larger than the operation upper limit parameter value, judging whether the reducible work load exists in the system or not; if yes, reducing reactive power to reduce the initial bus voltage;
or if the estimated bus voltage is smaller than the operation lower limit parameter value, judging whether the system has the variable work or not; if yes, reactive power is increased to increase the initial bus voltage.
5. The reactive replacement method of claim 4, wherein the reducing reactive power comprises: judging whether the low-voltage side non-work amount of the main transformer in the system is larger than zero; if yes, cutting off the low-voltage side capacitor; otherwise, putting into a low-voltage side reactor;
the increasing reactive power includes: judging whether the low-voltage side non-work amount of the main transformer in the system is less than zero; if yes, cutting off the low-voltage side reactor; otherwise, a low-side capacitor is put in.
6. The reactive replacement method according to claim 1, further comprising, before calculating the reactive replacement amount of the dynamic reactive compensation apparatus:
measuring an initial bus voltage;
judging whether the initial bus voltage is out of limit, if so, ending compensation; otherwise, judging whether the running working point of the dynamic reactive compensation equipment is a normal working point.
7. The reactive replacement method according to claim 1, further comprising, before calculating the reactive replacement amount of the dynamic reactive compensation apparatus:
acquiring an operation working point and a normal working point of the dynamic reactive power compensation equipment, and acquiring reactive voltage sensitivity of the dynamic reactive power compensation equipment to a bus; the reactive voltage sensitivity is used for calculating the estimated bus voltage.
8. A reactive power replacement device, comprising:
the reactive displacement amount calculating module is used for calculating reactive displacement amount of the dynamic reactive compensation equipment when the operation working point of the dynamic reactive compensation equipment in the transformer substation is not at a normal working point;
the estimated bus voltage calculation module is used for calculating the estimated bus voltage obtained by compensating according to the reactive displacement;
the out-of-limit judging module is used for judging whether the estimated bus voltage is out-of-limit or not;
the compensation module is used for compensating the dynamic reactive power compensation equipment through the static reactive power compensation equipment in the transformer substation according to the reactive power displacement when the estimated bus voltage is not beyond the limit;
the initial bus voltage adjusting module is used for judging whether the pre-estimated bus voltage is out of limit or not, and judging whether standby reactive power exists in the system or not if the pre-estimated bus voltage is out of limit; and if the standby reactive power exists in the system, the standby reactive power is used for adjusting the voltage of the initial bus.
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