CN113224763B - Control method based on multistage fast switch and reactor power flow control device - Google Patents
Control method based on multistage fast switch and reactor power flow control device Download PDFInfo
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- CN113224763B CN113224763B CN202110628151.1A CN202110628151A CN113224763B CN 113224763 B CN113224763 B CN 113224763B CN 202110628151 A CN202110628151 A CN 202110628151A CN 113224763 B CN113224763 B CN 113224763B
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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
- H02J3/04—Circuit arrangements for ac mains or ac distribution networks for connecting networks of the same frequency but supplied from different sources
- H02J3/06—Controlling transfer of power between connected networks; Controlling sharing of load between connected networks
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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
- H02J3/001—Methods to deal with contingencies, e.g. abnormalities, faults or failures
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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
Abstract
The invention relates to the technical field of control of power transmission equipment, in particular to a control method based on a multistage fast switch and a reactanceThe control method of the device power flow control device mainly comprises the following steps: s11, when the power flow controller operates normally, the fast switch is switched on, and the reactor is in a bypass state; s12, detecting the line power in real time, and adjusting the reactor until the line power flow is reduced to a threshold value P N The following; s13, when the line power is reduced to P NS When the electric reactor is started, the parallel switches of the electric reactors are adjusted until all the electric reactors are withdrawn; s21, when the power grid fails, the line overload exceeds a threshold value P OL Then, a primary reactor with the largest reactance value is put into the reactor; s22, adjusting the reactor until the line tide is below a threshold value; s23, when the line current is reduced to P ON When the voltage is lower than the preset voltage, adjusting the parallel switches of the reactors until all the reactors are gradually withdrawn; according to the invention, by assigning a reasonable control strategy to the multistage fast switch and the reactor connected in series on the line, the reasonable tidal current regulation of the tidal current controller during normal operation is ensured, the tidal current is quickly regulated after a fault, and the overload is eliminated.
Description
Technical Field
The invention relates to the technical field of power transmission equipment control, in particular to a control method based on a multistage fast switch and a reactor power flow control device.
Background
With the continuous development of the power load, the mechanism of the power grid becomes stronger and stronger, but in some large-scale urban power grids, as the urban development tends to be saturated, the structure of the power grid becomes stable gradually, but with the continuous increase of the power load, the demand on the power transmission capacity of the power grid still increases, the power grid power flow distribution presents the characteristic of natural power flow distribution, and the problem that the power transmission capacity is limited due to the uneven power flow distribution exists in a local area, so that the power transmission potential of the power grid is exploited, and the improvement of the power transmission capacity of the power grid becomes one of the key points of research in recent years. Under the requirement, advanced equipment such as a unified power flow controller and distributed power flow control can be put into operation in a power grid, and great promotion effects are achieved on the aspects of improving the power transmission capacity of the power grid and flexibly adjusting the power flow of the power grid, but the equipment is mainly a fully-controlled power electronic device, so that the equipment is high in manufacturing cost, and is difficult to bear large investment in areas with weak investment capacity of the power grid; therefore, a relatively low technical scheme for solving the problem of uneven section tidal current is found and can be more suitable for the requirement of a large range of a power grid.
In principle, the problem of uneven power flow distribution is solved, one is to change the phase angle difference of the head end and the tail end of a line to change the power flow of a power grid, such as a unified power flow controller technology, and the other is to change the impedance of the line, such as connecting a reactance in series on a heavy-load line and forcing the power flow to be transferred to other lines, but the series impedance has the problem of large loss in normal operation, namely if the series impedance is always through-current, the impedance loss of a system is always existed, and the overload problem of the power grid is that the line is overloaded after N-1 occurs, namely the line is not overloaded in normal operation, and the line is overloaded after N-1 and needs to be adjusted in real time. Therefore, the power flow controller can be applied by connecting the multistage fast switch and the reactor in parallel and then connecting the multistage fast switch and the reactor in series, and the switching of the reactors of several stages can be realized by flexibly controlling the switching of the switch, so that the flexible control of the power flow is realized. When the basic invention is researched by a control strategy, the head on-off sequence and logic of the reactor under different operating conditions need to be considered, and the control method is important for the engineering application of the power flow controller based on the multistage fast switch and the reactor in a power grid.
Disclosure of Invention
In order to solve the problems, the invention aims to disclose the technical field of power transmission equipment control, in particular to a control method based on a multistage fast switch and a reactor power flow control device.
In order to achieve the purpose, the invention adopts the technical scheme that: a control method based on a multistage fast switch and a reactor power flow control device is characterized in that the control device mainly comprises a multistage series reactor, a fast switch and a control system of the multistage fast switch, and the control method comprises the following steps:
when the device normally operates without failure, the control method of the device comprises the following steps:
s11, when the power flow controller operates normally, the fast switch is switched on, and the electric reactor is in a bypass state;
s12, detecting the line power in real time, and when the line power flow of the installation point reaches a threshold value P N And then, turning on a reactor parallel switch, putting in a minimum first-stage reactor, after delaying for T seconds, putting in a first-stage reactor with a minimum residual reactance value if the line tide exceeds the threshold value again until the line tide is reduced to a threshold value P N The following;
s13, when the line power is reduced to P NS And when the current is detected, closing the parallel switch of the reactor with the largest reactance value to enable the shunt switch to exit, and continuously monitoring whether the line current is P NS Then, all the reactors are withdrawn;
after the fault occurs, the control method of the device comprises the following steps:
s21, when the power grid fails, the overload of the line exceeds a threshold value P OL Then, a primary reactor with the maximum reactance value is put into the reactor;
s22, time delay T 1 After second, continuing to detect the line power flow if the line power flow still exceeds the threshold value P OL Then, the reactor with the largest residual reactance value is put into the reactor; continued delay T 1 Second detection circuit power flow exceeds threshold value P OL Until the line tide is below a threshold value;
s23, when the line current is reduced to P ON When the current is lower than the preset value, the parallel switch of the reactor with the maximum reactance value is closed, the reactor bypass is withdrawn, and whether the line current is in P or not is continuously monitored ON And then, until all reactors are gradually withdrawn.
Preferably, the control device is connected to a power transmission section with limited power transmission capacity caused by uneven power flow distribution and connected to a heavy-duty circuit to achieve balanced improvement of power transmission capacity of a power grid; the control device is connected to achieve the purpose of balancing the tide and is mainly installed on a tide heavy-load circuit which does not meet the requirement of N-1 checking.
Preferably, the reactance value of each stage of the multistage series reactor is distributed according to the number of series-connected stages; when 2-stage reactors are connected in series, the reactance value of each stage is determined according to 1/3,2/3 of the total impedance; when 3 stages of reactors are connected in series, reactance values of all stages are determined according to 1/7,2/7,4/7 of total impedance; when 4 stages of reactors are connected in series, the reactance value of each stage is determined according to 1/11,2/11,4/11,7/11 of the total impedance; the reactors connected in series preferably do not exceed 3 stages.
Preferably, the smallest primary reactor in step 12 is a one-pole reactor with the smallest reactance value, and when 2-4 reactors are connected in series, the smallest reactance value is 1/3, 1/7 and 1/11 of the total impedance respectively.
Preferably, the largest primary reactor in step 21 is a one-pole reactor with the largest reactance value, and when 2-4 reactors are connected in series, the largest reactance values are 2/3, 4/7 and 7/11 of the total impedance respectively.
The invention has the beneficial effects that: according to the invention, through assigning a reasonable control strategy for the serial connection of the multistage fast switch and the reactor on the line, the reasonable adjustment of the power flow controller during normal operation is ensured, the power flow is quickly adjusted after a fault, and the overload is eliminated.
The control method can adapt to the overload problem of the adjusting line under various operation modes or after the fault, the loss during normal operation is reduced as much as possible in consideration of the sequence of putting the reactors, and meanwhile, the overload problem of the line after the fault is quickly solved.
Drawings
Fig. 1 is a basic structural view of the present invention.
Fig. 2 is a structural view of a control device of the present invention installed on a cross section.
FIG. 3 is a logic operation step diagram of the control method of the present invention.
Detailed Description
The following detailed description of embodiments of the invention refers to the accompanying drawings:
a control method based on a multistage fast switch and a reactor power flow control device is disclosed, the control device mainly comprises a multistage series reactor, a fast switch and a control system of the multistage fast switch, the control device is connected to a power transmission section with limited power transmission capacity caused by uneven power flow distribution and is connected to a heavy load circuit to realize balanced improvement of the power transmission capacity of a power grid; the control device is connected to achieve the purpose of balancing the tide and is mainly installed on a tide heavy-load circuit which does not meet the requirement of N-1 checking; each stage of reactance value of the multistage series reactor is distributed according to the series stage number; when a 2-stage reactor is connected in series, reactance values of all stages are determined according to 1/3 and 2/3 of total impedance; when 3 stages of reactors are connected in series, the reactance value of each stage is determined according to 1/7,2/7,4/7 of the total impedance; when 4 stages of reactors are connected in series, the reactance value of each stage is determined according to 1/11,2/11,4/11,7/11 of the total impedance; the series reactor is preferably not more than 3 stages;
the control method mainly comprises the steps that the power flow control device is put into, the control device adjusts the control method to each stage that the control device quits in real time, and the putting into of the power flow control device is provided with two layers of normal operation heavy load control and power flow control after failure, and the control method comprises the following specific steps:
when the device normally operates without failure, the control method of the device comprises the following steps:
s11, when the power flow controller operates normally, the fast switch is switched on, and the electric reactor is in a bypass state;
s12, detecting the line power in real time, and when the line power flow of the installation point reaches a threshold value P N And then, turning on a reactor parallel switch, putting in the minimum first-stage reactor, after delaying T seconds, if the line tide exceeds the threshold value again, putting in the first-stage reactor with the minimum residual reactance value until the line tide is reduced to the threshold value P N The following; the minimum first-stage reactor is a one-pole reactor with the minimum reactance value, and when 2-4 stages of reactors are connected in series, the minimum reactance values are respectively 1/3, 1/7 and 1/11 of the total impedance
S13, when the line power is reduced to P NS And when the current is detected, closing the parallel switch of the reactor with the largest reactance value to enable the shunt switch to exit, and continuously monitoring whether the line current is P NS Then, all the reactors are withdrawn;
after the fault occurs, the control method of the device comprises the following steps:
s21, when the power grid fails, the overload of the line exceeds a threshold value P OL Then, the reactance value is put into the maximum levelA reactor; the largest first-stage reactor is a one-pole reactor with the largest reactance value, and when the 2-4-stage reactor is connected in series, the largest reactance values are 2/3, 4/7 and 7/11 of the total impedance respectively;
s22, time delay T 1 After second, continuing to detect the line power flow if the line power flow still exceeds the threshold value P OL Then, the reactor with the largest residual reactance value is put into the reactor; continued delay T 1 Second detection circuit power flow exceeds threshold value P OL Until the line tide is below a threshold value;
s23, when the line current is reduced to P ON When the current is below the preset value, the parallel switch of the reactor with the maximum reactance value is closed, the reactor bypass is withdrawn, and whether the line current is P or not is continuously monitored ON And then, until all reactors are gradually withdrawn.
Referring to fig. 1, a basic structure diagram of a device for dynamically adjusting power flow of a power grid based on a multi-stage fast switch and a reactor is shown, and a basic connection structure can be realized. As shown in fig. 2, a certain power grid is taken as an embodiment, and a device for dynamically adjusting power flow of the power grid based on a multi-stage fast switch and a reactor is described, a power grid in a certain area and a main grid are connected with a channel B through a 220kV line a channel, each channel is a double-circuit line, and receives the influence of natural distribution of power flow, the power flow of the channel B is heavier, the rated current of the line of the channel B is 1.3kA, and the maximum allowable power is 445MW according to the consideration of the power factor of 0.9; during the peak load period of the regional power grid B, a large amount of power needs to be input from the main grid, the flow of the channel A is light and is 320MW; the channel B is overloaded, the maximum power of the line is 630MW, the power of the other circuit after the channel B line N-1 is 520MW, and the other circuit is overloaded (overloaded by 16.9%); in order to prevent the B channel line N-1 from being overloaded, the maximum transmission capacity of a section formed by the A channel and the B channel is limited to 730MW; 540MW for a B-channel double loop (another loop just full load after N-1), 290MW for an A-channel double loop; the existing channel power transmission capacity is difficult to meet the demand of load increase, so that the device for dynamically adjusting the power flow of the power grid based on the multistage fast switch and the reactor is considered to be adopted, and the reactance needing to be connected in series to the maximum extent is obtained by calculating in various modes; adjustment of power flow due to more frequent load changes from region to regionThe requirements need to be relatively fine, so a class 3 reactor is considered; reactance values of the three-stage reactors are set to 1 ohm, 2 ohm and 4 ohm, respectively. By adopting the scheme of the grading reactor, the reactance values of 7 levels such as 1 ohm, 2 ohm, 3 ohm, 4 ohm, 5 ohm, 6 ohm and 7 ohm can be input into the system, and the control on the power flow of the power grid can be more fine; the voltage withstand level of the fast switch in parallel with the three-stage reactor may be selected in direct proportion to the selected reactance value. As shown in fig. 3, which is a flow chart of a control method of power flow control, in this embodiment, when the power flow controller is installed in a channel B, and when the power flow controller runs without a fault, a set running threshold value is 500MW, that is, when the power of a double-circuit line reaches 500MW, a series reactor is considered to be put into use, and the reactor is put into use from small to large, so that the power of the line is considered to be limited to below 500 MW; firstly, opening switches CB11 and CB21, and putting in 1 ohm reactance, wherein the delay time can be 10s, and if the line power is still more than 500MW, continuing opening switches CB12 and CB22, and putting in 2 ohm reactance; until the line power is lower than 500 MW; when the line power is lower than 470MW, the put-in maximum reactor shunt switch is closed, for example, the CB12 switch and the CB22 switch are closed, and the 2 ohm series reactance is withdrawn; if still lower than 470MW, the remaining 1 ohm reactance is also dropped; the above is the control strategy in normal operation. If the I loop of the B channel has a fault, the power flow controller enters an accident control mode, and the threshold value of the II loop of the B channel is the single-loop power 445MW (the set threshold value P) NS ) If the reactance value is larger than the threshold value, the CB23 switch is opened to input the reactance with the maximum reactance value; 3-ohm reactors are put in, if the reactor is still high in 445MW after time delay of 10s, the rest maximum reactors which are not put in operation are put in, namely, the reactor with CB22 and 2-ohm input is opened; until the power flow of the II loop is lower than 445MW; when the line power is lower than 430MW (the set threshold value P) N ) If the maximum reactor shunt switch is closed, the maximum reactor shunt switch which is already put into use is closed, for example, the CB22 switch is closed, and the 2 ohm series reactance is withdrawn; if still lower than 430MW, the CB23 switch is continuously closed, and the residual 3 ohm reactance is also withdrawn; the above is the control strategy in abnormal operation.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the technical scope of the present invention, and those skilled in the art may make modifications and variations within the spirit of the present invention, and all modifications, equivalents and modifications of the above embodiments according to the technical spirit of the present invention are within the scope of the present invention.
Claims (3)
1. A control method based on a multistage fast switch and a reactor power flow control device is characterized in that the control device mainly comprises a multistage series reactor, a fast switch and a control system of the multistage fast switch, the control device is connected to a power transmission section with limited power transmission capacity caused by uneven power flow distribution and connected to a heavy load circuit to achieve balanced improvement of power transmission capacity of a power grid; each stage of reactance value of the multistage series reactor is distributed according to the series stage; when a 2-stage reactor is connected in series, reactance values of all stages are determined according to 1/3 and 2/3 of total impedance; when 3 stages of reactors are connected in series, the reactance value of each stage is determined according to 1/7,2/7,4/7 of the total impedance; when 4 stages of reactors are connected in series, the reactance value of each stage is determined according to 1/11,2/11,4/11,7/11 of the total impedance; the control method comprises the following steps:
when the device normally runs without faults, the control method of the device comprises the following steps:
s11, when the rapid switch is closed when the power flow controller operates normally, the reactor is in a bypass state;
s12, detecting the line power in real time, and when the line tide of the installation point reaches a threshold valueP N And then, turning on a reactor parallel switch, putting in the minimum first-stage reactor, after delaying T seconds, if the line tide exceeds the threshold value again, putting in the first-stage reactor with the minimum residual reactance value until the line tide is reduced to the threshold valueP N The following;
s13, when the line power is reduced toP NS And then closing the parallel switch of the reactor with the maximum reactance value to withdraw the bypass, and continuously monitoring whether the line tide is inP NS Then, all the reactors are withdrawn;
after the fault occurs, the control method of the device comprises the following steps:
s21, when the power grid fails, the overload of the line exceeds a threshold valueP OL When the current is measured, a primary reactor with the largest reactance value is put into the reactor;
s22, time delayT 1 After second, continuing to detect line power flow, if the line power flow still exceeds the threshold valueP OL Then, the reactor with the maximum residual reactance value is put into the reactor; continuing to delayT 1 Second detection of whether line power flow exceeds threshold valueP OL Until the line tide is below a threshold value;
s23, when the line current is reduced toP ON When the current is below the predetermined value, the parallel switch of the reactor with the largest reactance value is closed to withdraw the bypass of the reactor, and the monitoring of whether the line current is in the current state or not is continuedP ON And then, until all reactors are gradually withdrawn.
2. The control method based on the multistage fast switching and reactor power flow control device is characterized in that the smallest reactor in the step 12 is a reactor with the smallest reactance value, and when 2-4 reactors are connected in series, the smallest reactance value is 1/3, 1/7 and 1/11 of the total impedance respectively.
3. The control method based on the multistage fast switching and reactor power flow control device as claimed in claim 1, characterized in that the largest reactor in step 21 is a reactor with the largest reactance value, and when 2-4 reactors are connected in series, the largest reactance values are 2/3, 4/7 and 7/11 of the total impedance respectively.
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| JP2004350337A (en) * | 2003-05-20 | 2004-12-09 | National Institute Of Advanced Industrial & Technology | Power flow controller with current limiting function |
| EP1847001B1 (en) * | 2005-01-31 | 2013-01-09 | Georgia Tech Research Corporation | Active current surge limiters |
| CN104319765B (en) * | 2014-10-29 | 2017-01-11 | 国家电网公司 | Control method of distributed in-series coupling power flow controller |
| CN112054491B (en) * | 2020-09-07 | 2022-11-04 | 国电南瑞科技股份有限公司 | Unified power flow controller closing failure protection method and system based on current discrimination |
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