CN117578493A - Reactive voltage regulation method for river basin step chain type hydroelectric area - Google Patents

Reactive voltage regulation method for river basin step chain type hydroelectric area Download PDF

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CN117578493A
CN117578493A CN202311389029.9A CN202311389029A CN117578493A CN 117578493 A CN117578493 A CN 117578493A CN 202311389029 A CN202311389029 A CN 202311389029A CN 117578493 A CN117578493 A CN 117578493A
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node
voltage
reactive
power
reactive power
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王乐宁
王军
刘鹤
孙艳景
向青海
赵明
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Guoneng Dadu River Pubugou Power Generation Co ltd
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Guoneng Dadu River Pubugou Power Generation Co ltd
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/12—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
    • 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
    • H02J3/002—Flicker reduction, e.g. compensation of flicker introduced by non-linear load
    • 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
    • H02J3/24—Arrangements for preventing or reducing oscillations of power in networks
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
    • H02J3/50—Controlling the sharing of the out-of-phase component
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
    • H02J2203/10—Power transmission or distribution systems management focussing at grid-level, e.g. load flow analysis, node profile computation, meshed network optimisation, active network management or spinning reserve management
    • 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
    • H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
    • H02J2203/20—Simulating, e g planning, reliability check, modelling or computer assisted design [CAD]
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
    • H02J2300/20—The dispersed energy generation being of renewable origin
    • 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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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • Supply And Distribution Of Alternating Current (AREA)

Abstract

The invention relates to a reactive voltage regulation method for a river basin step chain type hydroelectric area, which comprises the following steps: calculating line voltage gradient deviation between two adjacent nodes, if the line voltage gradient deviation is out of limit, performing reactive power control, otherwise, performing optimization calculation with minimum active network loss as a target; calculating the required total reactive power adjustment quantity, comparing the reactive power compensation power with the total reactive power adjustment quantity, if the reactive power compensation power is larger than the total reactive power adjustment quantity, entering a step 3 to perform joint optimization, otherwise, calling standby reactive power compensation; and carrying out joint optimization by taking the minimum reactive network loss and the minimum voltage deviation difference as targets, so that the line voltage gradient deviation is within a limit value. The invention realizes the distribution of the power stations from downstream to upstream in the direction of the voltage decreasing in turn, and the voltage gradient deviation is reasonable.

Description

Reactive voltage regulation method for river basin step chain type hydroelectric area
Technical Field
The invention relates to the technical field of voltage regulation, in particular to a reactive voltage regulation method for a river basin step chain type hydroelectric area.
Background
With the rapid development of the electric power system in China, the electric power grid is larger in scale and more complex in structure, and Automatic Voltage Control (AVC) is an important foundation for safe system operation, power supply quality and economic operation. At present, research on an AVC control strategy is mainly and intensively applied to a provincial large power grid, french EDF provides a secondary voltage control SVC, and three-layer control modes are provided later, namely coordinated secondary voltage control CSVC is provided on the basis, compared with SVC, coordinated control among all the subareas is comprehensively considered, namely the control strategy of CSVC pursues reactive power output balance among adjustable generator sets in an area on the premise of ensuring that the deviation between central point bus voltage and a set value is as small as possible, so that the adjustable generator sets have enough reactive power regulation margin. Intensive research is carried out on coordination and coordination methods among all levels of scheduling in China, and the focus is on selection of coordination variables and formulation of coordination strategies. In order to realize information interaction between the upper and lower power grids, proper coordination variables should be selected, and the most common practice in the current domestic AVC system is to select operation information of the intersection part network (i.e. boundary gateway) of the upper and lower power grids as the coordination variables, and the operation information is usually gateway voltage or gateway reactive power (power factor). In the aspect of research of coordination strategies, the main focus is on coordination control strategies among all levels of AVC systems of the network, the province and the ground.
The proposal and application of CSVC promote the solution of the problem of coordination control of reactive voltage among areas to a certain extent, but the problem of coordination control among power plants in the areas is still a direction which needs to be focused. The specific bit is to make corresponding control strategies for specific analysis of specific structures of specific power grid structures in some areas. At present, AVC application research on chained hydropower is blank, chained hydropower refers to hydropower with close adjacent connection, obvious mutual influence and upstream and downstream relation in geographic position. Due to the structural specificity of the automatic voltage regulation and control system, when multiple stations participate in automatic voltage regulation and control, the voltage shaving problem among stations is needed to be considered, the reactive power pulling problem among stations is easy to occur in actual operation, the voltage fluctuation is frequent during the reactive power pulling, the loss is increased, the economic and stable operation of a power station is not facilitated, and the power generation power of a hydropower station is also influenced by the crossing power among stations.
Therefore, when the chained hydropower is put into AVC voltage regulation, in order to track and respond to the change of the busbar voltage set value of each station, the reactive power output of the power station is correspondingly increased or reduced, so that the situation that a part of the power stations send reactive power and a part of the power stations absorb reactive power appears in the three-station area, the problem of reactive power pulling in the area is caused (namely, the reactive power sent by a part of the power stations is absorbed by other adjacent power stations in the area, and the problem of reactive power pulling between stations is caused), the positive effect on the quality of the maintained voltage is not generated, and the influence of power factor reduction, power generation efficiency reduction and the like of the power stations is further caused, so that the safe, stable and economic operation of each power station is not facilitated.
Disclosure of Invention
The invention aims to solve the problems that the power stations from downstream to upstream show voltage distribution in the direction of descending in sequence and the voltage gradient deviation is reasonable, and provides a reactive voltage regulation method for a river basin step chain type hydroelectric area.
In order to achieve the above object, the embodiment of the present invention provides the following technical solutions:
the reactive voltage regulation method for the river basin step chain type hydroelectric area comprises the following steps:
step 1, calculating line voltage gradient deviation between two adjacent nodes, if the line voltage gradient deviation is out of limit, performing reactive power control, otherwise, performing optimization calculation with minimum active network loss as a target;
step 2, calculating the required total reactive power adjustment quantity Q ref To generate reactive power Q max And the total reactive power adjustment quantity Q ref Comparing, if the reactive power compensation power Q max Compared with the total reactive power adjustment quantity Q ref If the number is large, the process enters step 3 to be carried outJoint optimization, otherwise, calling standby reactive compensation;
and 3, carrying out joint optimization by taking the minimum reactive network loss and the minimum voltage deviation difference as targets, so that the line voltage gradient deviation is within a limit value.
Further, in the step 1, the step of calculating the line voltage gradient deviation between two adjacent nodes includes:
calculating line voltage gradient deviation between two adjacent nodes:
wherein, the node i and the node j are two adjacent nodes; deltaU ij Line voltage gradient bias from node i to node j; p (P) ij Active power for the line; q (Q) ij Reactive power for the line; r is R ij The equivalent resistance of the circuit; x is X ij Is the equivalent reactance of the circuit; u (U) ij Is the rated voltage of the line.
Further, in the step 3, the step of performing joint optimization with the minimum reactive power loss and the minimum voltage offset difference as targets includes:
and (3) performing joint optimization by using the constructed model, wherein the minimum reactive network loss and the minimum voltage offset difference value are taken as objective functions, and the objective functions are as follows:
min F＝ΔQ d +ΔU i
ΔQ d ＝Q 1 +Q 2 +...+Q n -Q load
ΔU i ＝|U seti -U i |
wherein DeltaQ d Is reactive loss; q (Q) i For reactive power of node i, i=1, 2,..n, n is the total number of nodes; q (Q) load Reactive power for the load; deltaU i The voltage offset difference value of the node i; u (U) seti A voltage set point for node i; u (U) i Is the actual value of the voltage at node i.
Further, bus voltage constraints of the objective function include a tide equation constraint, a line power constraint and a voltage constraint of each node;
the constraint of the tide equation is as follows:
wherein node i is the adjacent upstream node of node j; p (P) i Representing active power injected by a node i in the tide process; q (Q) i Representing reactive power injected by a node i in the tide process; u (U) i Representing the actual value of the voltage at node i; u (U) j Representing the actual value of the voltage at node j; θ ij Is the voltage phase angle difference between node i and node j; g ij Representing the conductance of node i to node j; b (B) ij Representing susceptances of nodes i through j;
the line power constraint is:
wherein k is a line between the node i and the node j; p (P) k (t) is the active power of line k during period t; q (Q) k (t) is the reactive work of line k during period t;the minimum value and the maximum value are allowed by the active power of the line k respectively; />The minimum value and the maximum value are allowed for the reactive power of the line k respectively;
each node voltage constraint:
wherein U is i The current voltage of node i;the lower voltage limit and the upper voltage limit of the node i are respectively defined.
Still further, the in-station constraints of the objective function include generating active, generating reactive, reactive compensation, active ramp rate and reactive ramp rate constraints of the generator set;
the generating active power and generating reactive power constraint of the generating set is as follows:
wherein P is g The current active power of the generator set g in the station is used;the minimum allowable value and the maximum allowable value of the active power of the generator set g are respectively; q (Q) g The current reactive power of the generator set g in the station is used; />The reactive power of the generator set g is respectively the minimum value and the maximum value allowed by reactive power;
reactive compensation constraint is as follows:
Q SR ＝m×Q R
wherein Q is SR Representing the total capacity input by the reactive compensation device; m represents the number of reactive power compensation devices put into, and is an integer of 0,1, 2; q (Q) R Representing the capacity of a single reactive compensation device;
the constraint of the active climbing rate and the reactive climbing rate is as follows:
wherein P is i (t) is the active power output of the generator set at node i at time t; p (P) i (t-1) is the active power output of the generator set at node i at time t-1;the lower limit and the upper limit of the active power ramp rate of the generator set at the node i are respectively set; q (Q) i (t) is the reactive power output of the generator set at node i at time t; q (Q) i (t-1) is the reactive power output of the generator set at node i at time t-1; />The lower limit and the upper limit of the reactive power ramp rate of the generator set at the node i are respectively set.
Further, in the step 3, the step of making the line voltage gradient deviation within the limit value includes: and (3) sequentially judging whether the line voltage gradient deviation between every two adjacent nodes is within the limit value from upstream to downstream, and repeating the steps (1) to (3) until the line voltage gradient deviation between all the adjacent nodes is within the limit value.
Further, the limits of the line voltage gradient deviation between any two adjacent nodes are equal or unequal.
Further, step 4 is included, after the joint optimization, determining whether the voltage set value of the power station changes from upstream to downstream, and if the change exceeds the dead zone, resetting the voltage set value of the downstream power station.
Further, the specific steps of the step 4 include:
node i is the adjacent upstream node of node j, and after joint optimization, if the voltage set value U of node i is reset seti Based on the voltage setpoint U at this time seti Changing the total reactive power Q of node i i If the total reactive power Q i If the variation exceeds the dead zone, according to the line voltage gradient deviation delta U between the node i and the node j after the joint optimization ij Voltage set point of meter node j: u (U) setj ＝U seti +ΔU ij And judge the voltage offset delta U of the node j j If the dead zone is exceeded, the power generation pressure set value U is re-lowered to the node j setj 。
Further, in the step 4, the line voltage gradient deviation Δu between the node i and the node j after the joint optimization is performed ij Voltage set point of meter node j: u (U) setj ＝U seti +ΔU ij Instead, the voltage set point for node j is calculated from the set limit Δu between node i and node j: u (U) setj ＝U seti +ΔU。
Compared with the prior art, the invention has the beneficial effects that:
the invention provides a reactive voltage abnormality problem of a step chain type hydropower transmission end network in AVC operation, and provides an effective regulation strategy, so that the problems of inter-station reactive power pulling, unreasonable actual operation voltage gradient direction and magnitude and the like in chain type hydropower AVC regulation are solved.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of three-station connection of a waterfall ditch, a deep stream ditch and a pillow dam according to the embodiment;
fig. 2 is a schematic diagram of voltage and reactive power change of three stations when the waterfall ditch power station is put into AVC in this embodiment, where (a) in fig. 2 is a schematic diagram of voltage change, and (b) in fig. 2 is a schematic diagram of reactive power change;
fig. 3 is a schematic diagram of voltage and reactive power variation when three stations are put into AVC in this embodiment, where (a) in fig. 3 is a schematic diagram of voltage variation, and (b) in fig. 3 is a schematic diagram of reactive power variation;
FIG. 4 is a flow chart of steps 1 to 3 of the method of the present invention;
fig. 5 is a flow chart of step 4 of the method of the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. The components of the embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the invention, as presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be made by a person skilled in the art without making any inventive effort, are intended to be within the scope of the present invention.
It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further definition or explanation thereof is necessary in the following figures. Also, in the description of the present invention, the terms "first," "second," and the like are used merely to distinguish one from another, and are not to be construed as indicating or implying a relative importance or implying any actual such relationship or order between such entities or operations. In addition, the terms "connected," "coupled," and the like may be used to denote a direct connection between elements, or an indirect connection via other elements.
The three-station chained water-electricity transmission end network system architecture, operation mode, AVC operation condition, tide distribution and the like of the large river basin 'waterfall ditch-deep stream ditch-pillow dam' are used for analysis. Referring to fig. 1, the three-station chained water delivery network from upstream to downstream is a waterfall ditch, a deep stream ditch, a pillow dam in sequence, and the voltage at downstream should be higher than the voltage at upstream. The waterfall ditch hydropower station (P station for short) is a 17 th cascade power station for cascade planning of the main flow of the large river, 6 single-machine capacity 600WM mixed-flow hydroelectric generating sets are adopted, and a 500kV voltage class access system is adopted in the power station; the hydropower station of the channel of the stream (S station for short) is an 18 th cascade hydropower station for cascade planning of the main flow of the large-river, wherein the upper cascade is the hydropower station of the channel of the stream, the lower cascade is the hydropower station of the pillow dam, 4 single-machine capacity 165WM mixed-flow hydroelectric generating sets are adopted, and a 500kV voltage class access system is adopted in the power station; the pillow dam hydropower station (Z station for short) is a 19 th step hydropower station for large-river main flow step planning, the last step is a deep-channel hydropower station, 4 single-machine axial-flow rotating-paddle generator sets with 180WM capacity are adopted, and the power station adopts a 500kV voltage class access system.
From the operation mode of three stations, the three stations are in typical chained water delivery, the power stations of the deep stream ditch and the waterfall ditch all have passing through power, the three stations should meet gradient direction distribution of 'pillow dam-deep stream ditch-waterfall ditch theoretical voltage drop' in sequence, and voltage gradient deviation is reasonable. Referring to fig. 2, when only the P station is put into an AVC scene, the voltage gradient of the bus of the three stations in most of the time period presents unreasonable distribution of the "Z station > S station < P station", and although the reactive pulling phenomenon does not exist in the whole, the key of unreasonable distribution is also the problem of cooperative coordination of the reactive voltage regulation in the three-station chained water power end network. Referring to fig. 3, in the case of three stations all throw AVC, although the three-station bus voltage gradient maintains or presents reasonable distribution of "Z station > S station > P station" in a partial period, reactive pulling phenomenon between stations occurs, and the voltage gradient deviation is unreasonable. Therefore, research solutions from the control level of cooperative coordination in a three-station chained water-electricity transmission-end network are needed.
In a power system, the voltage loss at the end of a line connecting two nodes (node represents a site) can be expressed as:
wherein, the node i and the node j are two adjacent nodes, and k is a line between the node i and the node j; deltaU k Deviation of voltage gradient of the line k; p (P) k Active power for the line; q (Q) k Reactive power for the line; r is R k The equivalent resistance of the circuit; x is X k Is the equivalent reactance of the circuit; u (U) k Is the rated voltage of the line. In general, in a high voltage power transmission network, X k Far greater than R k Therefore, in the formula Q k X k The term has a larger influence on voltage loss, P k R k The effect of the term is negligible, i.e. reactive power Q k The value of (2) has a large influence on the voltage. As shown in FIG. 3, in the three-station AVC scenario, when the bus voltage of each station is given a given value of voltageThe gradient deviation is not reasonable, i.e. DeltaU k When the power supply is too large, larger power flow can be caused between stations correspondingly, so that reactive power pulling phenomenon is aggravated.
The invention provides a reactive voltage regulation method for a river basin step chain type hydroelectric area, which aims to solve the problem that power stations from downstream to upstream show voltage distribution in a direction of descending in sequence, and has reasonable voltage gradient deviation, namely line offset voltage between two adjacent power stations is within a limit value, for example, the line offset voltage value is within 0.5kV-1kV, and is realized by the following technical scheme, as shown in fig. 4, and comprises the following steps:
step 1, calculating line voltage gradient deviation between two adjacent nodes, if the line voltage gradient deviation is out of limit, performing reactive power control, otherwise, performing optimization calculation with the minimum active network loss as a target.
In the present embodiment, the three stations are taken as an example to describe the technical scheme, and when the number of stations in the chained hydropower station is greater than three, the same calculation is performed. First, calculating the line voltage gradient deviation DeltaU between P station and S station PS ：
Wherein DeltaU PS Voltage gradient deviation from P-station to S-station; p (P) PS Active power for the line; q (Q) PS Reactive power for the line; r is R PS The equivalent resistance of the circuit; x is X PS Is the equivalent reactance of the circuit; u (U) PS Is the rated voltage of the line.
Preset limit value DeltaU 1 When DeltaU PS Greater than DeltaU 1 And (3) if yes, entering a step (2) to perform reactive power control, otherwise, directly performing optimization calculation with the minimum active network loss as a target.
Step 2, calculating the required total reactive power adjustment quantity Q ref To generate reactive power Q max And the total reactive power adjustment quantity Q ref Comparing, if the reactive power compensation power Q max Compared with the total reactive power adjustment quantity Q ref If the number is large, the method enters step 3 to carry out the combinationAnd optimizing, otherwise, calling standby reactive compensation.
And 3, carrying out joint optimization by taking the minimum reactive network loss and the minimum voltage deviation difference as targets, so that the line voltage gradient deviation is within a limit value.
In order to realize voltage control and adjustment of a power grid, a regional network with a plurality of power stations as a center can be established, a scattered voltage adjustment and centralized control mode is adopted, and the voltage of a local region is automatically maintained within a specified range under unified coordination of a dispatching center according to a reactive power in-situ balancing principle.
Based on reactive power implementation layering, partitioning and on-site balancing principles in the power system, the RVCS of the cascade hydropower station is mainly used for implementing reactive power output decision of each power station after the load of the power system is adjusted in real time, and real-time distribution of reactive load among the cascade hydropower stations is realized.
And (3) performing joint optimization by using the constructed model, wherein the minimum reactive network loss and the minimum voltage offset difference value are taken as objective functions, and the objective functions are as follows:
min F＝ΔQ d +ΔU P
ΔQ d ＝Q P +Q S +Q Z -Q load
ΔU P ＝|U setP -U P |
wherein DeltaQ d Is reactive loss; q (Q) P Reactive power for the P station; q (Q) S Reactive power for the S station; q (Q) Z Reactive power for Z station; q (Q) load Reactive power for the load; deltaU P Is the voltage offset difference for the P-station; u (U) setP For a P-station voltage setpoint; u (U) P Is the actual value of the P-station voltage.
The optimal power flow optimizes reactive power and network loss in addition to active power and loss. In addition, the optimal power flow also considers the constraint of bus voltage and the safety constraint of line power flow.
Restraint of bus voltage
(1) Network constraints
The network constraint mainly comprises a tide equation constraint, a line power constraint and a voltage constraint of each node. The constraint of the tide equation is as follows:
wherein, the node i and the node j are two adjacent nodes; p (P) i Representing active power injected by a node i in the tide process; q (Q) i Representing reactive power injected by a node i in the tide process; u (U) i Representing the actual value of the voltage at node i; u (U) j Representing the actual value of the voltage at node j; θ ij Is the voltage phase angle difference between node i and node j; g ij Representing the conductance of node i to node j; b (B) ij Representing susceptances of nodes i through j.
The line power constraint is:
wherein k is a line between the node i and the node j; p (P) k (t) is the active power of line k during period t; q (Q) k (t) is the reactive work of line k during period t;the minimum value and the maximum value are allowed by the active power of the line k respectively; />The reactive power of the line k allows a minimum value, a maximum value, respectively.
Each node voltage constraint:
wherein U is j The current voltage of node j;the lower voltage limit and the upper voltage limit of the node j are respectively defined.
(2) In-station constraints
The in-station constraint mainly comprises the constraints of generating active power, generating reactive power, reactive power compensation, active climbing rate, reactive climbing rate and the like of the generating set.
Generating active power and generating reactive power constraint:
wherein P is g The current active power of the generator set g in the station is used;the minimum allowable value and the maximum allowable value of the active power of the generator set g are respectively; q (Q) g The current reactive power of the generator set g in the station is used; /> The reactive power of the generator set g is allowed to be minimum and maximum respectively.
Reactive compensation constraint is as follows:
Q SR ＝m×Q R
wherein Q is SR Representing the total capacity input by the reactive compensation device; m represents the number of reactive power compensation devices put into, and is an integer of 0,1, 2; q (Q) R Representing the capacity of a single reactive compensation device.
The active climbing rate constraint and the reactive climbing rate constraint are as follows:
wherein P is i (t) is the active power output of the generator set at node i at time t; p (P) i (t-1) is the active power output of the generator set at node i at time t-1;the lower limit and the upper limit of the active power ramp rate of the generator set at the node i are respectively set; q (Q) i (t) is the reactive power output of the generator set at node i at time t; q (Q) i (t-1) is the reactive power output of the generator set at node i at time t-1; />The lower limit and the upper limit of the reactive power ramp rate of the generator set at the node i are respectively set.
After the combined optimization, the line voltage gradient deviation delta U between the P station and the S station PS Restoring to the limit value DeltaU 1 In the step, the line voltage gradient deviation delta U between the S station and the Z station is judged SZ Whether or not to be within the limit value DeltaU 2 In, deltaU 1 And DeltaU 2 Repeating the steps 1-3, when there are multiple power stations (more than three stations), until all line voltage gradient deviations DeltaU ij Are within the limits and step 4 is entered again.
And step 4, after the joint optimization, judging whether the voltage set value of the power station changes from upstream to downstream, and resetting the voltage set value of the downstream power station if the change exceeds a dead zone.
Referring to FIG. 5, if the line voltage gradient deviation between the P station and the S station is out of limit, the voltage set point U of the P station is reset after the joint optimization setP (voltage setpoint, i.e. voltage setpoint), now based on voltage setpoint U setP Changing the total reactive power Q of a P station P If the total reactive power Q P The variation exceeds the dead zone, and the variation delta U is based on the line voltage gradient deviation between the P station and the S station after the joint optimization PS (or the limit DeltaU between the P station and the S station is set 1 ) Calculating a voltage set point of the S station: u (U) setS ＝U setP +ΔU PS (or U) setS ＝U setP +ΔU 1 ) And judges the voltage deviation difference delta U of the S station S (i.e. voltage set point U) setS And the actual value U of the voltage S The absolute value of the difference value of (a) exceeds the dead zone, and if the dead zone is exceeded, the power generation voltage set value U is returned to the S station setS 。
It should be noted that determining whether the total reactive power variation exceeds the dead zone refers to presetting a variation as the dead zone, and performing subsequent policy adjustment when the total reactive power variation exceeds the preset dead zone to avoid frequent adjustment of the system and accommodate variation of the variation within an acceptable range. The same is true for determining whether the voltage offset difference exceeds the dead zone.
With continued reference to FIG. 5, the S-station voltage set point U is then reset setP It is necessary to base on the voltage set point U setP Changing the total reactive power Q of S station S If the total reactive power Q S The variation exceeds the dead zone, and the variation delta U is based on the line voltage gradient deviation between the S station and the Z station after the combined optimization SZ (or a set limit DeltaU between S-station and Z-station) 2 ) Calculating a voltage set point of the Z station: u (U) setZ ＝U setS +ΔU SZ (or U) setZ ＝U setS +ΔU 2 ) And judges the voltage deviation difference delta U of the Z station Z (i.e. voltage set point U) setZ And the actual value U of the voltage Z The absolute value of the difference value of (a) exceeds the dead zone, and if the dead zone is exceeded, the power generation voltage set value U is lowered to the Z station again setZ 。
When more than three power stations are arranged on the line, the method continues to judge whether to update the voltage value of the power station downstream of the Z station from upstream to downstream.
In summary, the invention provides the problem of abnormal reactive voltage of the step chain type water power transmission end network in AVC operation, and provides an effective regulation strategy, thereby solving the problems of inter-station reactive power pulling, unreasonable actual operation voltage gradient direction and magnitude and the like in chain type water power AVC regulation. In the three-station chained water power transmission end network of the large river, after analysis and processing by the scheme, the busbar voltage values of the Z station and the S station are corrected, the line offset voltage values from downstream to upstream are all positive values, the line offset voltage values of the Z station-S station and the S station-P station are smaller than 1kV, and the voltage gradient distribution of the three stations is reasonable.
The foregoing is merely illustrative of the present invention, and the present invention is not limited thereto, and any person skilled in the art will readily recognize that variations or substitutions are within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims (10)

1. The reactive voltage regulation method for the river basin step chain type hydroelectric area is characterized by comprising the following steps of: the method comprises the following steps:
step 1, calculating line voltage gradient deviation between two adjacent nodes, if the line voltage gradient deviation is out of limit, performing reactive power control, otherwise, performing optimization calculation with minimum active network loss as a target;
step 2, calculating the required total reactive power adjustment quantity Q ref To generate reactive power Q max And the total reactive power adjustment quantity Q ref Comparing, if the reactive power compensation power Q max Compared with the total reactive power adjustment quantity Q ref If the reactive power compensation is large, the step 3 is entered to carry out joint optimization, otherwise, standby reactive power compensation is invoked;
and 3, carrying out joint optimization by taking the minimum reactive network loss and the minimum voltage deviation difference as targets, so that the line voltage gradient deviation is within a limit value.
2. The watershed step chain type hydroelectric area reactive voltage regulation method according to claim 1, wherein the method comprises the following steps: in the step 1, the step of calculating the line voltage gradient deviation between two adjacent nodes includes:
calculating line voltage gradient deviation between two adjacent nodes:
wherein, the node i and the node j are two adjacent nodes; deltaU ij Line voltage gradient bias from node i to node j; p (P) ij Active power for the line; q (Q) ij Reactive power for the line; r is R ij The equivalent resistance of the circuit; x is X ij Is the equivalent reactance of the circuit; u (U) ij Is the rated voltage of the line.
3. The watershed step chain type hydroelectric area reactive voltage regulation method according to claim 1, wherein the method comprises the following steps: in the step 3, the step of performing joint optimization with the minimum reactive power loss and the minimum voltage offset difference as targets includes:
and (3) performing joint optimization by using the constructed model, wherein the minimum reactive network loss and the minimum voltage offset difference value are taken as objective functions, and the objective functions are as follows:
min F＝ΔQ d +ΔU i
ΔQ d ＝Q 1 +Q 2 +...+Q n -Q load
ΔU i ＝|U seti -U i |
wherein DeltaQ d Is reactive loss; q (Q) i For reactive power of node i, i=1, 2,..n, n is the total number of nodes; q (Q) load Reactive power for the load; deltaU i The voltage offset difference value of the node i; u (U) seti A voltage set point for node i; u (U) i Is the actual value of the voltage at node i.
4. A watershed step chain type hydroelectric area reactive voltage regulation method according to claim 3, characterized in that: the bus voltage constraint of the objective function comprises a tide equation constraint, a line power constraint and a node voltage constraint;
the constraint of the tide equation is as follows:
wherein node i is the adjacent upstream node of node j; p (P) i Representing active power injected by a node i in the tide process; q (Q) i Representing reactive power injected by a node i in the tide process; u (U) i Representing the actual value of the voltage at node i; u (U) j Representing the actual value of the voltage at node j; θ ij Is the voltage phase angle difference between node i and node j; g ij Representing the conductance of node i to node j; b (B) ij Representing susceptances of nodes i through j;
the line power constraint is:
wherein k is a line between the node i and the node j; p (P) k (t) is the active power of line k during period t; q (Q) k (t) is the reactive work of line k during period t;the minimum value and the maximum value are allowed by the active power of the line k respectively; />The minimum value and the maximum value are allowed for the reactive power of the line k respectively;
each node voltage constraint:
wherein U is i The current voltage of node i;the lower voltage limit and the upper voltage limit of the node i are respectively defined.
5. The watershed step chain type hydroelectric area reactive voltage regulation method according to claim 4, wherein the method comprises the following steps: the in-station constraint of the objective function comprises the generation active power, the generation reactive power, the reactive power compensation, the active climbing rate and the reactive climbing rate constraint of the generator set;
the generating active power and generating reactive power constraint of the generating set is as follows:
wherein P is g The current active power of the generator set g in the station is used;the minimum allowable value and the maximum allowable value of the active power of the generator set g are respectively; q (Q) g The current reactive power of the generator set g in the station is used; />The reactive power of the generator set g is respectively the minimum value and the maximum value allowed by reactive power;
reactive compensation constraint is as follows:
Q SR ＝m×Q R
wherein Q is SR Representing the total capacity input by the reactive compensation device; m represents the number of reactive power compensation devices put into, and is an integer of 0,1, 2; q (Q) R Representing the capacity of a single reactive compensation device;
the constraint of the active climbing rate and the reactive climbing rate is as follows:
wherein P is i (t) is the active power output of the generator set at node i at time t; p (P) i (t-1) is the active power output of the generator set at node i at time t-1;the lower limit and the upper limit of the active power ramp rate of the generator set at the node i are respectively set; q (Q) i (t) is the reactive power output of the generator set at node i at time t; q (Q) i (t-1) is the reactive power output of the generator set at node i at time t-1; />Reactive power of generator set at node i respectivelyLower and upper power ramp rate limits.
6. The watershed step chain type hydroelectric area reactive voltage regulation method according to claim 1, wherein the method comprises the following steps: in the step 3, the step of making the line voltage gradient deviation within the limit value includes: and (3) sequentially judging whether the line voltage gradient deviation between every two adjacent nodes is within the limit value from upstream to downstream, and repeating the steps (1) to (3) until the line voltage gradient deviation between all the adjacent nodes is within the limit value.
7. The watershed step chain type hydroelectric area reactive voltage regulation method according to claim 6, wherein the method comprises the following steps: the limits of line voltage gradient deviation between any two adjacent nodes are equal or unequal.
8. The watershed step chain type hydroelectric area reactive voltage regulation method according to claim 1, wherein the method comprises the following steps: and step 4, after the combined optimization, judging whether the voltage set value of the power station is changed from upstream to downstream, and if the change exceeds the dead zone, resetting the voltage set value of the downstream power station.
9. The watershed step chain type hydroelectric area reactive voltage regulation method according to claim 8, wherein: the specific steps of the step 4 include:
node i is the adjacent upstream node of node j, and after joint optimization, if the voltage set value U of node i is reset seti Based on the voltage setpoint U at this time seti Changing the total reactive power Q of node i i If the total reactive power Q i If the variation exceeds the dead zone, according to the line voltage gradient deviation delta U between the node i and the node j after the joint optimization ij Voltage set point of meter node j: u (U) setj ＝U seti +ΔU ij And judge the voltage offset delta U of the node j j If the dead zone is exceeded, the power generation pressure set value U is re-lowered to the node j setj 。
10. The watershed step chain type hydroelectric area reactive voltage regulation method according to claim 9, wherein: in the step 4, the line voltage gradient deviation DeltaU between the node i and the node j after the joint optimization is performed ij Voltage set point of meter node j: u (U) setj ＝U seti +ΔU ij Instead, the voltage set point for node j is calculated from the set limit Δu between node i and node j: u (U) setj ＝U seti +ΔU。
CN202311389029.9A 2023-10-25 2023-10-25 Reactive voltage regulation method for river basin step chain type hydroelectric area Pending CN117578493A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117543589A (en) * 2024-01-10 2024-02-09 四川能投云电科技有限公司 Scheduling method of cascade hydropower safety centralized control system

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117543589A (en) * 2024-01-10 2024-02-09 四川能投云电科技有限公司 Scheduling method of cascade hydropower safety centralized control system
CN117543589B (en) * 2024-01-10 2024-05-07 四川能投云电科技有限公司 Scheduling method of cascade hydropower safety centralized control system

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