CN112467753A - Reactive power replacement method and device - Google Patents
Reactive power replacement method and device Download PDFInfo
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- CN112467753A CN112467753A CN202011379336.5A CN202011379336A CN112467753A CN 112467753 A CN112467753 A CN 112467753A CN 202011379336 A CN202011379336 A CN 202011379336A CN 112467753 A CN112467753 A CN 112467753A
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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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- 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 device. The reactive power replacement method comprises the following steps: when the operation working point of the dynamic reactive power compensation equipment is not at a normal working point, calculating the reactive power replacement amount of the dynamic reactive power compensation equipment; calculating the estimated bus voltage obtained by compensating according to the reactive displacement; judging whether the estimated bus voltage is out of limit or not; and if not, compensating the dynamic reactive compensation equipment through a capacitor or a reactor according to the reactive displacement. 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.
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 a regional power distribution network is seriously urgent, and a large number of phenomena of high voltage and low voltage exist simultaneously. In the water-rich period, a large amount of small water is fully generated, so that the voltage of a line is higher, and the operation safety is threatened. During the peak load period, the low voltage problem at the end is generated in part of the low voltage transformer area, and the high voltage problem is generated in part of the transformer area during the valley load period. The network frame of the regional distribution network is relatively weak, the distribution network lacks a voltage regulation means, and 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 an Automatic Voltage Control (AVC) system. The AVC system is constructed on a power grid energy management system, can utilize real-time operation data of a power transmission network, scientifically decides an optimal reactive voltage regulation scheme from the perspective of global optimization of the power transmission network, and automatically issues the optimal reactive voltage regulation scheme to a power plant, a transformer substation and a subordinate power grid dispatching mechanism for execution. However, the AVC system is regulated and controlled by taking a transformer substation as a unit, and the voltage distribution condition of a line and a transformer area is not considered. Therefore, the existing scheduling 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 quickly responding to the reactive power regulation requirement of a power grid.
In a first aspect, an embodiment of the present invention provides a reactive power replacement method, where the reactive power replacement method includes the following steps:
when the operation working point of dynamic reactive power compensation equipment in the transformer substation is not at a normal working point, calculating reactive power replacement quantity of the dynamic reactive power compensation equipment;
calculating the estimated bus voltage obtained by compensating according to the reactive displacement;
judging whether the estimated bus voltage is out of limit or not;
and if not, compensating the dynamic reactive compensation equipment through static reactive compensation equipment in the transformer substation according to the reactive displacement.
Optionally, the compensating the dynamic reactive power compensation device through a static reactive power compensation device in a substation according to the reactive power replacement amount includes:
if the reactive displacement is larger than zero, inputting capacitive reactive power for compensation by inputting a capacitor or cutting off an electric reactor;
and if the reactive displacement is less than zero, adding inductive reactive power for compensation by cutting off a capacitor or adding a reactor.
Optionally, calculating a reactive replacement 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 demand reaches the reactive regulation step length of the dynamic reactive compensation equipment; if so, setting the reactive displacement amount 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 the system has standby reactive power; and if so, adjusting the initial bus voltage by using the standby reactive power.
Optionally, the condition for predicting the bus voltage out-of-limit includes: the estimated bus voltage is greater than the operation upper limit parameter value, or the estimated bus voltage is less than the operation lower limit parameter value;
the adjusting the initial bus voltage using the standby reactive power comprises:
if the estimated bus voltage is larger than the operation upper limit parameter value, judging whether a reducible reactive power amount exists in the system; if so, reducing the reactive power to reduce the initial bus voltage;
or, if the estimated bus voltage is less than the operation lower limit parameter value, judging whether the system has the amount of reactive power which can be increased; and if so, increasing the reactive power to improve the initial bus voltage.
Optionally, the reducing reactive power comprises: judging whether the reactive power of the low-voltage side of a main transformer in the system is greater than zero or not; if yes, cutting off the low-voltage side capacitor; otherwise, a low-voltage side reactor is put into the reactor;
the increasing the reactive power comprises: judging whether the reactive power of the low-voltage side of a main transformer in the system is less than zero or not; if so, cutting off the low-voltage side reactor; otherwise, a low-side capacitor is switched in.
Optionally, before calculating the reactive power replacement amount of the dynamic reactive power compensation device, the method further includes:
measuring an initial bus voltage;
judging whether the initial bus voltage exceeds the limit or not, if so, finishing compensation; otherwise, judging whether the operation working point of the dynamic reactive power compensation equipment is a normal working point.
Optionally, before calculating the reactive power replacement amount of the dynamic reactive power compensation device, the method further includes:
acquiring an operation working point and a normal working point of the dynamic reactive power compensation equipment, and acquiring the reactive voltage sensitivity of the dynamic reactive power compensation equipment to a bus; and calculating the estimated bus voltage according to the reactive voltage sensitivity.
In a second aspect, an embodiment of the present invention provides a reactive power replacement device, including:
the reactive power displacement calculation module is used for calculating the reactive power displacement of the dynamic reactive power compensation equipment when the operation working point of the dynamic reactive power compensation equipment in the transformer substation is not at a normal working point;
the estimated bus voltage calculation module is used for calculating estimated bus voltage obtained by compensation 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 compensation equipment through static reactive compensation equipment in the transformer substation according to the reactive displacement when the estimated bus voltage is not out of limit.
Optionally, the reactive power replacement device further includes:
the initial bus voltage adjusting module is used for judging whether standby reactive power exists in the system or not after judging whether the estimated bus voltage is out of limit or not and if the estimated bus voltage is out of limit; and if the standby reactive power exists in the system, adjusting the initial bus voltage by using the standby reactive power.
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 under the condition that 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 dynamic reactive power compensation equipment can respond to voltage fluctuation in time, and the bus voltage has sufficient regulation capacity. And moreover, the dynamic reactive power compensation equipment is compensated when the estimated bus voltage is not out of limit, so that the bus voltage is prevented from being out of limit, impact is caused to a power grid, and even faults are caused due to compensation of the dynamic reactive power compensation equipment. Therefore, compared with the prior art, 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.
Drawings
Fig. 1 is a schematic flow chart of a reactive power replacement method according to an embodiment of the present invention;
fig. 2 is a schematic flow chart of another reactive power replacement method provided by the 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 present invention will be described in further detail with reference to the accompanying drawings and examples. 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 of the structures related to the present invention are shown in the drawings, not all of the structures.
In the prior art, the voltage control strategies for the power transmission network mainly include two types of reactive power control strategies for each generator of the power plant and reactive power equipment control strategies for the transformer substation. Wherein, the reactive power control strategy to each generator of power plant is: and after receiving the reactive adjustment quantity of the generator, the AVC substation of the power plant adjusts the reactive power sent by the generator in a stepping mode according to the current running state of each generator in the power plant until the adjustment quantity sent by the AVC main station is reached. The control strategy of the reactive equipment of the transformer substation is a switching instruction of the reactive compensation equipment, the reactive equipment mainly comprises a capacitor and a reactor, and when the capacitor is put into the reactive equipment 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. And the AVC master station issues an instruction for putting in or cutting off the reactive equipment, and an automatic monitoring system in the transformer substation finds the circuit breaker connected with the reactive equipment and switches on or off the circuit breaker according to the received instruction so as to complete the putting in or cutting off of the reactive equipment.
However, the grid of the regional power distribution network is weak, the reactive voltage operation problem of the regional power distribution network is seriously urgent, and a large number of phenomena of high voltage and low voltage exist simultaneously. In the water-rich period, a large amount of small water is fully generated, so that the voltage of a line is higher, and the operation safety is threatened. During the peak load period, the low voltage problem at the end is generated in part of the low voltage transformer area, and the high voltage problem is generated in part of the transformer area during the valley load period. Because the reactive power can not be balanced on the spot, the reactive current increases the line loss and reduces the economical efficiency of the operation of the distribution network. The distribution network is lack of voltage regulation means, the problem of local low (high) voltage caused by power generation and load dynamic change cannot be solved, and the existing transformer substation, line and transformer area reactive power regulation devices respectively operate independently and lack of global coordination. AVC is regulated and controlled by taking a transformer substation as a unit, and the voltage distribution condition of a line and a transformer area is not considered; the autonomous operation and scheduling of small hydropower stations, distributed photovoltaics and the like cannot be remotely and automatically adjusted, so that high voltage occurs during power generation and low voltage occurs during outage; the transformer area capacitor bank only carries out automatic switching according to the voltage of the head end of the transformer area and cannot carry out cooperative adjustment according to the voltage requirements of a line and a user.
In summary, the existing reactive power regulation method has the problems of small margin and slow response of the dynamic reactive power compensation equipment.
In order to solve the above problem, an embodiment of the present invention provides a reactive power replacement method, which may be implemented based on a reactive power replacement device, and the method may be applicable to adjustment of coordination between reactive power adjusting devices in a regional power grid substation. Fig. 1 is a schematic flow chart of a reactive power replacement method according to an embodiment of the present invention. Referring to fig. 1, the reactive replacement method includes the steps of:
and 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 replacement amount of the dynamic reactive power compensation equipment.
The embodiment is suitable for reactive power replacement between dynamic reactive power compensation equipment and static reactive power compensation equipment in a regional power grid transformer substation so as to improve the reactive power margin of the dynamic reactive power compensation equipment. The dynamic reactive power compensation equipment is also called as a static reactive power compensator, and the compensation capacity of the dynamic reactive power compensation equipment can be adjusted at will. The dynamic reactive compensation equipment can be a thyristor phase control reactor, a thyristor switched capacitor, a static reactive generator and the like. Preferably, the dynamic reactive compensation device is a Static synchronous compensator (STATCOM) to ensure fast response and complete reactive power regulation tasks. The static synchronous compensator is a dynamic reactive power compensation device based on a voltage source converter, and a reactive power dynamic compensation device for generating and absorbing reactive power is carried out by a self-phase-changing power semiconductor bridge type converter. The AC link is connected with the system, firstly, the AC electric energy of the system is converted into DC through a converter and is stored in an energy storage device at the DC side, and meanwhile, the voltage current at the DC side is converted into AC voltage current through the converter and is transmitted to the system.
When the dynamic reactive power compensation equipment runs at a normal working point, the compensation capacity is the best, and the reactive margin is the highest. Therefore, when the dynamic reactive power compensation device is not operated at the normal operating point (for example, in order to adjust the bus voltage, the dynamic reactive power compensation device has performed reactive power compensation), it is necessary to control other standby reactive power devices (for example, static reactive power compensation devices) to perform reactive power replacement with the dynamic reactive power compensation device, so that the operating point of the dynamic reactive power compensation device is returned to the vicinity of the normal operating point, so as to ensure the reactive power margin thereof.
Alternatively, the reactive displacement amount may be a positive value or a negative value; the operation working point of the dynamic reactive power compensation equipment can be determined, for example, the difference value between the operation working point and the normal working point is used as the reactive power replacement amount; or the reactive replacement quantity is determined by integrating the operation working point of the dynamic reactive compensation equipment and the spare reactive quantity in the system. For example, when the switched capacitor is used for performing reactive power replacement, the capacity and the number of the capacitors can be considered, and the combination of the capacity and the number of the capacitors closest to the difference value between the operating point and the normal operating point can be used as the reactive power replacement amount.
And S120, calculating the estimated bus voltage obtained by compensation according to the reactive displacement.
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 (referred to as estimated bus voltage) is calculated on the basis of the current bus voltage and if the compensation is carried out according to the reactive displacement. When the estimated bus voltage is within the normal operation range of the bus voltage, compensation can be performed according to the reactive displacement quantity, so that impact on a system caused by the fact that the bus voltage is out of limit after compensation is prevented.
S130, judging whether the estimated bus voltage is out of limit or not; if not, go to S140.
The bus voltage generally has a normal operating range in which the bus voltage can operate relative to a rated voltage, for example, the allowable voltage fluctuation is +/-10%; or allow voltage fluctuations of + 10%, -5%, etc. The normal working range is determined according to factors such as bus length, rated voltage class and operating environment. Generally, 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 allowable voltage fluctuation range, the estimated bus voltage is considered to be out of limit.
When the estimated bus voltage is out of limit, the dynamic reactive power compensation equipment is not compensated; or increasing the constraint condition that the estimated bus voltage is not out of limit, recalculating the reactive displacement, and then compensating according to the new reactive displacement; or, the current bus voltage is reversely adjusted to ensure that the bus voltage cannot exceed the limit after compensation is carried out according to the reactive displacement. In a word, on the basis that the estimated bus voltage is not out of limit, the dynamic reactive power compensation equipment is compensated to return to the vicinity of a normal working point.
And S140, compensating the dynamic reactive compensation equipment through the static reactive compensation equipment in the transformer substation according to the reactive displacement.
The regulating equipment in the power grid system is often provided with redundancy, and spare margins exist. The static reactive compensation device may be a capacitor and a reactor. When the dynamic reactive power compensation equipment is compensated, optionally, capacitive reactive power can be input by inputting a capacitor or cutting off a reactor; or by cutting capacitors or by putting reactors to put in inductive reactive power. The compensation mode can be selected according to actual requirements, and is not limited here.
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 under the condition that 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 dynamic reactive power compensation equipment can respond to voltage fluctuation in time, and the bus voltage has sufficient regulation capacity. And moreover, the dynamic reactive power compensation equipment is compensated when the estimated bus voltage is not out of limit, so that the bus voltage is prevented from being out of limit, impact is caused to a power grid, and even faults are caused due to compensation of the dynamic reactive power compensation equipment. The embodiment of the invention defines the replacement logic among different reactive power devices and improves the reactive power reserve of the dynamic reactive power compensation device, 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, on the basis of the foregoing embodiments, optionally, after determining whether the estimated bus voltage exceeds the limit (S130), the reactive power replacement method further includes:
if the estimated bus voltage is out of limit, S150 is executed;
s150, judging whether a system has standby reactive power; if yes, go to S160; if not, go to S170.
After the reactive compensation of the dynamic reactive compensation equipment according to the reactive displacement is judged, when the bus voltage is estimated to be out of limit, the initial bus voltage (namely the current uncompensated bus voltage) is firstly reversely adjusted, so that the adjusted bus voltage cannot be out of limit after the compensation of the reactive displacement.
And S160, adjusting the initial bus voltage by using the standby reactive power.
The standby reactive power may be, for example, a redundantly provided reactive device (such as a capacitor or a reactor) in the system; or a redundant part of the dynamic reactive power compensation equipment without output power. The adjusting 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 exceeds the lower limit, the initial bus voltage is adjusted upwards. The adjustment amount of the initial bus voltage can be set according to the estimated out-of-limit condition of the bus voltage. For example, the setting adjustment amount is proportional to the amount of overrun.
And S170, finishing compensation.
If there is no spare reactive power 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 displacement by taking the estimated bus voltage as the limit not to exceed the limit.
In this embodiment, by increasing the judgment whether there is standby reactive power in the system, the conditions and steps of reactive power replacement are further defined.
On the basis of the above embodiments, the embodiment of the present invention further describes a manner of compensating for the dynamic reactive power compensation device. Optionally, according to the reactive power replacement amount, compensating the dynamic reactive power compensation device by using a static reactive power compensation device in the substation, including the following steps:
and if the reactive displacement is larger than zero, inputting capacitive reactive power for compensation by inputting a capacitor or a cut-off reactor.
And if the reactive displacement is less than zero, adding inductive reactive power for compensation by cutting off the capacitor or adding the reactor.
The reactive power of the electric line is not consumed, inductive equipment (a reactor) can only generate inductive reactive power (voltage lead current), a capacitor can only generate capacitive reactive power (current lead voltage), and the inductive equipment (the reactor) and the capacitor are 180 degrees apart in phase and can compensate each other. When the reactive displacement is larger than zero, the system lacks capacitive reactive power; when the reactive displacement is less than zero, the content reactive power of the system is excessive, and inductive reactive power needs to be added for compensation. The embodiment is arranged like this, and can carry out reactive power replacement according to the system requirement to under each condition, all can select to compensate with capacitor or reactor or the combination of the two, can realize more nimble compensation, reach better replacement effect.
In addition to the above embodiments, an automatic control period (denoted as T) may be optionally setc) AVC system automatically controlling period TcThe 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 automation of the replacement process are ensured. Wherein the period T is automatically controlledcCan be set according to actual requirements, for example, the period T can be automatically controlled when the electricity utilization condition is more complicatedcThe setting ground is short; when distributed sub-networks with larger access uncertainty in the system are less, the period T is automatically controlledcLonger in arrangement, etc. At a time, for each automatic control period TcThe steps of the reactive replacement method will be explained.
Fig. 2 is a schematic flow chart of another reactive power replacement method according to an embodiment of the present invention. Referring to fig. 2, the reactive replacement steps are further supplemented in this embodiment, so that the whole replacement logic is more definite, and the system is favorable for making a quick and accurate response to the reactive replacement requirement. Optionally, the reactive replacement method comprises the following steps:
s210, obtaining an operation working point and a normal working point of the dynamic reactive power compensation equipment, and obtaining the reactive voltage sensitivity of the dynamic reactive power compensation equipment to the bus.
Wherein, in each automatic control period TcWhen the current comes, the operation working points (real-time reactive power measurement values Q) of dynamic reactive power compensation equipment (such as static synchronous compensators) in regional power grid substations are respectively read from the automatic voltage control system of the power gridr-s) Normal operating point (reactive normal operating point parameter Q)nom-s) Reactive replacement threshold parameter (denoted as Q)maxUpper limit value for reactive replacement) and reactiveStep length of adjustment QstepAnd reading the reactive voltage sensitivity (marked as C) of the static synchronous compensator in the regional power grid transformer substation to a regional power grid transformer substation bus (such as a 220kV bus)s-m). The sensitivity of the dynamic reactive power compensation equipment to each bus can be the same or different. Reactive voltage sensitivity Cs-mFor calculating the estimated bus voltage, the calculation method is explained in the following steps.
S220, judging whether the initial bus voltage is out of limit or not; if yes, ending compensation; if not, go to S230.
First, an initial bus voltage is measured, for example, a voltage measurement value (denoted as V) of a bus in a regional power grid substation is read from a power grid dispatching systemmI.e. the initial bus voltage), the upper operating limit parameter value (denoted V) of the bus is read from the grid automatic voltage control systemm-max) And a lower operating limit parameter value (denoted as V)m-min) For the initial bus voltage VmAnd (4) judging: when the initial bus voltage VmSatisfy Vm-min<Vm<Vm-maxWhen it is considered that the initial bus voltage VmThe limit is not out of limit; when the initial bus voltage VmConform to Vm-min>VmOr Vm>Vm-maxIn one of them, the initial bus voltage V is judgedmAnd (4) out-of-limit. When the initial bus voltage VmThe initial bus voltage V should be immediately exceeded when the time is exceededmAnd (4) processing to prevent accidents and not performing compensation of the dynamic reactive compensation equipment any more.
The sequence given in the embodiment of the present invention is only an example of the reactive power replacement method, and is not a limitation to the present application. The order of the steps can be adjusted or combined according to actual conditions.
S230, judging whether the operation working point of the dynamic reactive power compensation equipment is a normal working point or not; if yes, ending compensation; if not, go to S240.
And S240, calculating the reactive power demand of the dynamic reactive power compensation equipment according to the operation working point and the normal working point.
The embodiment is used for the reactive displacement quantity (recorded as delta Q)s) Meter (2)The calculations are further illustrated. Alternatively, the operating point Q may be usedr-sMinus the normal operating point Qnom-sAnd the absolute value of the obtained reactive difference value is used as the reactive demand (recorded as delta Q) of the dynamic reactive compensation equipment.
S250, judging whether the reactive demand reaches the reactive regulation step length of the dynamic reactive compensation equipment; if yes, go to S260; if not, finishing the compensation.
Wherein, when the reactive demand delta Q does not reach the reactive regulation step length QstepIn time, the dynamic reactive power compensation equipment can be considered to be currently operated at a normal working point Qnom-sNearby, it does not need to be compensated.
And S260, setting the reactive displacement as a reactive adjustment step size.
Wherein, when the reactive difference value in the above steps is a positive value, the reactive displacement quantity delta Q is converted into the reactive displacement quantity delta QsSet to a positive adjustment step size Qstep(ii) a When the reactive difference value is a negative value, the reactive displacement quantity delta Q is converted into a reactive displacement quantitysSetting to a negative adjustment step-Qstep。
And S270, calculating the estimated bus voltage obtained by compensation according to the reactive displacement.
According to the reactive voltage sensitivity C read in S210s-mCalculating the estimated bus voltage (marked as V) of the reactive compensation device in the regional power grid transformer substation adjusted according to the reactive displacementm') the calculation is as follows: vm’＝Vm+Cs-m*ΔQs。
S280, judging whether the estimated bus voltage is out of limit or not; if yes, go to S290; if not, then S2C0 is performed.
The condition for predicting the bus voltage out-of-limit comprises the following steps: the estimated bus voltage is larger than the upper limit of operation parameter value (V)m’>Vm-max) Or predicting that the bus voltage is less than the lower limit of operation parameter value (V)m-min>Vm’)。
S290, judging whether the estimated bus voltage is larger than an operation upper limit parameter value; if yes, go to S2a 0; if not, then S2B0 is performed.
Wherein, when the bus voltage V is estimatedm' greater than upper running limit parameter value Vm-maxIn time, the reactive power (marked as Q) at the low-voltage side of the main transformer in the transformer substation is read from the power grid dispatching systemj) And the amount of reactive power (denoted as Q)dec-j). And judging whether the reducible reactive power Q exists in the systemdec-j(ii) a If yes, reducing the idle work to reduce the initial bus voltage Vm(ii) a Otherwise, no work Q can be reduceddec-jTo reduce the initial bus voltage VmWill make the amount of reactive substitution Δ QsAfter compensation, the bus voltage is out of limit, and impacts the power grid, so that no reducible reactive power Q is availabledec-jOr the reactive Q can be reduceddec-jAnd when the voltage is insufficient, ending the compensation.
When the bus voltage V is estimatedm' less than lower operation limit parameter value Vm-minReading the reactive power Q at the low-voltage side of the main transformer in the transformer substation from the power grid dispatching systemjAnd the amount of reactive power (denoted as Q)add-j). And judging whether the system has the increasable reactive power Qadd-j(ii) a If yes, increasing the reactive power to increase the initial bus voltage Vm. Otherwise, the compensation is ended.
And S2A0, reducing the reactive power so as to reduce the initial bus voltage.
Wherein reducing reactive power comprises: judging the reactive Q of the low-voltage side of the main transformer in the systemjWhether it is greater than zero; if yes, cutting off the low-voltage side capacitor; otherwise, the low-voltage side reactor is put into use.
And S2B0, adding reactive power to improve the initial bus voltage.
Wherein, increasing the reactive power comprises: judging the reactive Q of the low-voltage side of the main transformer in the systemjWhether less than zero; if so, cutting off the low-voltage side reactor; otherwise, a low-side capacitor is switched in.
And S2C0, compensating the dynamic reactive power compensation equipment through a capacitor or a reactor according to the reactive power replacement quantity.
Wherein, when the reactive displacement amount is Delta Qs>When 0, putting inductive reactive power into the dynamic reactive power compensation equipment through a capacitor or a reactor; when the reactive displacement amount is delta Qs<When 0, the power is dynamically idle through a capacitor or a reactorThe compensation equipment inputs inductive reactive power; the reactive value of the dynamic reactive compensation equipment in the regional power grid transformer substation is a reactive normal operating point Qnom-sThe range of the method can realize the reactive replacement of the dynamic reactive compensation equipment and the capacitor (reactor) in the regional power grid transformer substation.
The reactive power replacement method provided by the embodiment of the invention utilizes conventional capacitor (reactor) equipment and dynamic reactive power compensation equipment in the transformer substation to perform reactive power replacement, is used for quickly responding to the regional power grid fluctuation problem caused by the large access of small hydropower plants and new energy plants to the regional power grid, and reduces the voltage fluctuation of the regional power grid, thereby improving the voltage quality of the regional power grid. The embodiment of the invention defines the reactive power replacement logic among different reactive power 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 the embodiments 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 system comprises a reactive displacement calculation module 110, a pre-estimated bus voltage calculation module 120, an out-of-limit judgment module 130 and a compensation module 140.
The reactive power replacement amount calculation module 110 is configured to calculate a reactive power replacement amount of the dynamic reactive power compensation device when an operation operating point of the dynamic reactive power compensation device in the substation is not a normal operating point; the estimated bus voltage calculation module 120 is configured to calculate an estimated bus voltage obtained by performing compensation according to the reactive displacement; the out-of-limit judging module 130 is used for judging whether the estimated bus voltage is out-of-limit; the compensation module 140 is configured to compensate the dynamic reactive compensation device through the static reactive compensation device in the substation according to the reactive displacement amount when the bus voltage is not out of limit in prediction.
On the basis of the foregoing embodiments, optionally, the reactive power replacement amount calculation module 110 includes: the device comprises a reactive demand calculation unit, a reactive demand judgment unit and a reactive displacement setting unit. The reactive power demand calculation unit is used for calculating the reactive power demand of the dynamic reactive power compensation equipment according to the operation working point and the normal working point; the reactive demand judging unit is used for judging whether the reactive demand reaches the reactive regulation step length of the dynamic reactive compensation equipment; the reactive displacement setting unit is used for setting the reactive displacement to the reactive adjustment step length when the reactive demand reaches the reactive adjustment step length 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 displacement is larger than zero; and the inductive compensation unit is used for inputting inductive reactive power for compensation by cutting off the capacitor or inputting the reactor when the reactive displacement is less than zero.
On the basis of the foregoing embodiments, optionally, the reactive power replacement device further includes: the initial bus voltage adjusting module is used for judging whether standby reactive power exists in the system or not after judging whether the estimated bus voltage is out of limit or not and if the estimated bus voltage is out of limit; and if the system has spare reactive power, adjusting the initial bus voltage by using the spare reactive power.
On the basis of the above embodiments, optionally, the initial bus voltage adjustment module includes a decrease reactive unit and an increase reactive unit. The condition for predicting the bus voltage out-of-limit comprises the following steps: and predicting that the bus voltage is greater than the operation upper limit parameter value or predicting that the bus voltage is less than the operation lower limit parameter value. The reactive power reduction unit is used for judging whether reducible reactive power exists in the system when the estimated bus voltage is larger than the operation upper limit parameter value; if so, reducing the reactive power to reduce the initial bus voltage. The reactive power unit is added for judging whether the increasable reactive power quantity exists in the system when the estimated bus voltage is smaller than the operation lower limit parameter value; if yes, increasing the reactive power to improve the initial bus voltage.
On the basis of the foregoing embodiments, optionally, the reactive power reduction unit is further configured to determine whether a reactive power at a low-voltage side 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 use. The added reactive unit is also used for judging whether the reactive power of the low-voltage side of the main transformer in the system is less than zero; if so, cutting off the low-voltage side reactor; otherwise, a low-side capacitor is switched in.
On the basis of the foregoing embodiments, optionally, the reactive power replacement device further includes: the device comprises 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 power replacement amount of the dynamic reactive power compensation equipment. The initial bus voltage judging unit is used for judging whether the initial bus voltage exceeds the limit or not, and if so, finishing the compensation; otherwise, judging whether the operation working point of the dynamic reactive power compensation equipment is a normal working point.
On the basis of the foregoing embodiments, optionally, the reactive power replacement device further includes: the dynamic reactive compensation device comprises an acquisition unit, a calculation unit and a control unit, wherein the acquisition unit is used for acquiring an operation working point and a normal working point of the dynamic reactive compensation device and acquiring the reactive voltage sensitivity of the dynamic reactive compensation device to a bus before calculating the reactive displacement of the dynamic reactive compensation device; and the reactive voltage sensitivity is used for calculating the estimated bus voltage.
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 changes, rearrangements 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 (10)
1. A reactive power replacement method, comprising the steps of:
when the operation working point of dynamic reactive power compensation equipment in the transformer substation is not at a normal working point, calculating reactive power replacement quantity of the dynamic reactive power compensation equipment;
calculating the estimated bus voltage obtained by compensating according to the reactive displacement;
judging whether the estimated bus voltage is out of limit or not;
and if not, compensating the dynamic reactive compensation equipment through static reactive compensation equipment in the transformer substation according to the reactive displacement.
2. The reactive power replacement method according to claim 1, wherein the compensating the dynamic reactive power compensation equipment through static reactive power compensation equipment in a substation according to the reactive power replacement amount comprises:
if the reactive displacement is larger than zero, inputting capacitive reactive power for compensation by inputting a capacitor or cutting off an electric reactor;
and if the reactive displacement is less than zero, adding inductive reactive power for compensation by cutting off a capacitor or adding a reactor.
3. The reactive power replacement method of claim 1, wherein calculating the reactive power replacement amount of the dynamic reactive power 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 demand reaches the reactive regulation step length of the dynamic reactive compensation equipment; if so, setting the reactive displacement amount as the reactive adjustment step length; otherwise, the compensation is ended.
4. The reactive replacement method of claim 1, further comprising, after said determining whether the estimated bus voltage is out-of-limit:
if yes, judging whether the system has standby reactive power; and if so, adjusting the initial bus voltage by using the standby reactive power.
5. The reactive replacement method of claim 4, wherein the condition that the bus voltage is estimated to be out of limit comprises: the estimated bus voltage is greater than the operation upper limit parameter value, or the estimated bus voltage is less than the operation lower limit parameter value;
the adjusting the initial bus voltage using the standby reactive power comprises:
if the estimated bus voltage is larger than the operation upper limit parameter value, judging whether a reducible reactive power amount exists in the system; if so, reducing the reactive power to reduce the initial bus voltage;
or, if the estimated bus voltage is less than the operation lower limit parameter value, judging whether the system has the amount of reactive power which can be increased; and if so, increasing the reactive power to improve the initial bus voltage.
6. The reactive power replacement method of claim 5, wherein the reducing reactive power comprises: judging whether the reactive power of the low-voltage side of a main transformer in the system is greater than zero or not; if yes, cutting off the low-voltage side capacitor; otherwise, a low-voltage side reactor is put into the reactor;
the increasing the reactive power comprises: judging whether the reactive power of the low-voltage side of a main transformer in the system is less than zero or not; if so, cutting off the low-voltage side reactor; otherwise, a low-side capacitor is switched in.
7. The reactive power replacement method according to claim 1, further comprising, before calculating the reactive power replacement amount of the dynamic reactive power compensation device:
measuring an initial bus voltage;
judging whether the initial bus voltage exceeds the limit or not, if so, finishing compensation; otherwise, judging whether the operation working point of the dynamic reactive power compensation equipment is a normal working point.
8. The reactive power replacement method according to claim 1, further comprising, before calculating the reactive power replacement amount of the dynamic reactive power compensation device:
acquiring an operation working point and a normal working point of the dynamic reactive power compensation equipment, and acquiring the reactive voltage sensitivity of the dynamic reactive power compensation equipment to a bus; and calculating the estimated bus voltage according to the reactive voltage sensitivity.
9. A reactive replacement device, comprising:
the reactive power displacement calculation module is used for calculating the reactive power displacement of the dynamic reactive power compensation equipment when the operation working point of the dynamic reactive power compensation equipment in the transformer substation is not at a normal working point;
the estimated bus voltage calculation module is used for calculating estimated bus voltage obtained by compensation 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 compensation equipment through static reactive compensation equipment in the transformer substation according to the reactive displacement when the estimated bus voltage is not out of limit.
10. The reactive replacement device of claim 9, further comprising:
the initial bus voltage adjusting module is used for judging whether standby reactive power exists in the system or not after judging whether the estimated bus voltage is out of limit or not and if the estimated bus voltage is out of limit; and if the standby reactive power exists in the system, adjusting the initial bus voltage by using the standby reactive power.
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