阅读说明：本技术 一种解决直流闭锁后送端稳态过电压的电压协调控制方法 (Voltage coordination control method for solving steady-state overvoltage of direct-current locked sending end ) 是由 蔡绍荣 魏明奎 周泓 江栗 路亮 陶宇轩 沈力 梁文举 文一宇 张鹏 王庆 杨 于 2021-08-26 设计创作，主要内容包括：本发明属于电力系统及其自动化技术领域,尤其涉及一种解决直流闭锁后送端稳态过电压的电压协调控制方法,本发明基于直流闭锁信号,启动电压协调控制系统,根据离线整定策略,选取关键节点最高电压,匹配离线控制策略,下发执行站依次让风机吸无功、调相机吸无功、切电容、投电抗,该系统可有效缓解直流闭锁的送端系统的过电压问题。(The invention belongs to the technical field of power systems and automation thereof, and particularly relates to a voltage coordination control method for solving steady-state overvoltage of a sending end after direct-current blocking.)

1. A voltage coordination control method for solving the steady-state overvoltage of a sending end after direct current blocking is characterized by comprising the following steps: the method comprises the following steps:

step 1: when the direct current is locked, the direct current control protection system sends direct current locking information to the voltage coordination control system;

step 2: after receiving the direct current blocking information, the voltage coordination control system acquires the bus voltage of the key node of the power grid, judges whether to start the voltage coordination control logic according to the direct current blocking information, and if the starting condition P is met_{Loss of power}≥P₁And V is_max＞V_SETGo to step 3, otherwise keep step 2, where P_{Loss of power}For blocking the actual loss of power, P, of DC₁For setting threshold value, V_maxTo select the highest voltage value, V, of the key node_SETIs set between 1.0p.u and 1.05 p.u;

and step 3: the voltage coordination control system matches the off-line policy table according to the bus voltage of the detected key node, and executes a corresponding control measure if the logic action fixed value is met;

and 4, step 4: and the execution station absorbs reactive power from the system according to the instruction issued by the voltage coordination control system until the system voltage is restored to be within the set range or the control measures are used up.

2. The voltage coordination control method for solving the steady-state overvoltage of the sending end after the direct current blocking according to claim 1 is characterized in that: the DC blocking information comprises the name of the blocking DC and the loss power.

3. The voltage coordination control method for solving the steady-state overvoltage of the sending end after the direct current blocking according to claim 1 is characterized in that: p of the starting condition constant value in the step 2₁And determining that the current direct current power is a starting set value, wherein the steady state overvoltage is obtained based on off-line time domain simulation calculation, the steady state overvoltage under different power direct current locks is simulated based on different operation modes of a power grid, and if a certain direct current power is locked, the steady state overvoltage of a corresponding system key node is mostly higher than 1.05 p.u.

4. The voltage coordination control method for solving the steady-state overvoltage of the sending end after the direct current blocking according to claim 1 is characterized in that: v of constant value of starting condition in step 2_maxDetermining that the voltage coordination control system adopts several set key node voltages and compares the maximum V_max＝max(V₁,V₂,V₃,…,V_n) Wherein: v₁,V₂,V₃… is the voltage of the key node corresponding to the DC setting, and n is the number of the key nodes.

5. The voltage coordination control method for solving the steady-state overvoltage of the sending end after the direct current blocking according to claim 4 is characterized in that: the key nodes are selected to comprise direct current converter stations and buses of main networks adjacent to the converter stations.

6. The voltage coordination control method for solving the steady-state overvoltage of the sending end after the direct current blocking according to claim 1 is characterized in that: the offline policy table in the step 3:

wherein: v₁、V₂、V₃、V₄For voltage criterion logic constant, T₁、T₂、T₃、T₄For setting the delay value, Q, for each round₁、Q₂、Q₃、Q₄The fixed value can be set according to the power grid for each round of action reactive value.

7. The voltage coordination control method for solving the steady-state overvoltage of the sending end after the direct current blocking according to claim 6 is characterized in that: and the reactive control measure action object is sequentially executed by absorbing reactive power from a fan, absorbing reactive power from a phase modulator, cutting a capacitor and throwing a reactor.

8. The voltage coordination control method for solving the steady-state overvoltage of the sending end after the direct current blocking according to claim 7 is characterized in that: selecting a reactive control measure action object wind power plant, selecting the wind power plant with high control sensitivity as a voltage coordination control object after corresponding direct current blocking according to different wind power plants and different blocking direct current distances, and calculating the sensitivity:

recording the initial voltage u of each direct current key bus under the steady state working condition of the system_bus1,L,u_busnAnd initial voltage u_bus ⁰Wherein n is the number of key nodes;

recording the candidate new energy station as r₁,r₂L r_kAll candidate new energy stations cannot absorbSame reactive power delta q_kUnder the condition, the voltage of a key bus of the system is u_bus ¹,u_bus ²L u_bus ^kSeparately calculating a voltage variation value k is the number of the selected new energy stations;

respectively calculating the voltage-output sensitivity of each new energy station to a system key bus, wherein the calculation formulas are as follows:

selecting new energy key bus sensitivity eta_kAnd the larger than zeta is taken as a control measure object of a corresponding direct-current voltage coordination control system.

Technical Field

The invention belongs to the technical field of power systems and automation thereof, and particularly relates to a voltage coordination control method for solving the steady overvoltage of a direct-current locked sending end.

Background

The primary energy and the load in China are distributed reversely, so that urgent requirements on aspects such as large-scale clean energy delivery, load center power supply, energy conservation and emission reduction of southwest hydropower stations and the like are met, the national power grid is vigorously developed to be suitable for extra-high voltage alternating current and direct current technologies of long-distance and large-capacity power transmission, and the large-range resource optimizing and allocating capacity of the power grid is remarkably improved. Meanwhile, the integration characteristics of the power grid are continuously enhanced, the coupling between the power grid transmitting and receiving end and the alternating current and direct current becomes tighter and tighter, and the power grid has many new characteristics in operation. Along with the rapid development of the extra-high voltage alternating current and direct current, particularly the step-type promotion of the extra-high voltage direct current transmission scale, the operation characteristics of a power grid are deeply changed, and the contradiction of strong direct current and weak direct current is prominent. Particularly, large-scale power transfer caused by the extra-high voltage direct current blocking fault can cause large-area power flow backspacing of part of extra-high voltage direct current sending ends, so that the problem of steady-state overvoltage in the near area of a bus of the direct current converter station is caused.

At present, the problem of steady overvoltage after direct current fault is solved by cutting off a matched conventional unit according to the allowable power unbalance amount of a power grid through a large amount of off-line calculation, giving a bus voltage pre-control value of a key node, and adjusting direct current near-zone voltage by adjusting a near-zone conventional unit, a transformer tap, reactive compensation equipment and the like through a dispatcher to reach the pre-control value. However, with continuous production of extra-high voltage direct current mainly based on new energy, the direct current near-zone voltage regulation capability is continuously reduced, and the steady-state overvoltage problem after direct current locking is more and more prominent. The invention aims at an extra-high voltage direct current transmission end system, and the long-time overvoltage suspension of a transmission end is caused by the power flow transfer after the large direct current is locked.

Disclosure of Invention

The invention provides a voltage coordination control method for solving the steady overvoltage of a sending end after direct current locking, aiming at solving the problem that the sending end is suspended for a long time due to power flow transfer after large direct current locking in an ultrahigh-voltage direct current sending end system.

The technical scheme is adopted to solve the technical problems;

a voltage coordination control method for solving the steady-state overvoltage of a sending end after direct-current blocking comprises the following steps:

step 1: when the direct current is locked, the direct current control protection system sends direct current locking information to the voltage coordination control system;

step 2: after receiving the direct current blocking information, the voltage coordination control system acquires the bus voltage of the key node of the power grid, judges whether to start the voltage coordination control logic according to the direct current blocking information, and if the starting condition (P) is met_{Loss of power}≥P₁And V is_max＞V_SET) Go to step 3, otherwise keep step 2, where P_{Loss of power}For blocking the actual loss of power, P, of DC₁For setting threshold value, V_maxTo select the highest voltage value, V, of the key node_SETGenerally set between 1.0p.u and 1.05 p.u;

and step 3: the voltage coordination control system matches the off-line control strategy table according to the bus voltage of the detected key node, and if the bus voltage meets the logic action fixed value, corresponding control measures are executed;

and 4, step 4: and the execution station absorbs reactive power from the system according to the instruction issued by the voltage coordination control system until the system voltage is restored to be within the set range or the control measures are used up.

Preferably, the dc blocking information includes a name of the blocking dc and a loss power.

Preferably, the starting condition in step 2 is constant value of P₁And determining that the current direct current power is a starting set value, wherein the steady state overvoltage is obtained based on off-line time domain simulation calculation, the steady state overvoltage under different power direct current locks is simulated based on different operation modes of a power grid, and if a certain direct current power is locked, the steady state overvoltage of a corresponding system key node is mostly higher than 1.05 p.u. Preliminary simulation calculation, general P₁Slightly be greater than 4000MW, guarantee that direct current single valve or monopole after shutting, voltage coordinated control system does not start, greatly reduced the risk that the device frequently starts.

Preferably, the starting condition in step 2 is constant V_maxDetermining that the voltage coordination control system adopts several set key node voltages and compares the maximum V_max＝max(V₁,V₂,V₃,…,V_n) Wherein: v₁,V₂,V₃… is the voltage of the key node corresponding to the DC setting, and n is the number of the key nodes.

Preferably, the selection of the key node is that the steady-state voltage rise caused by general direct current blocking is sequentially reduced from the direct current converter station to the power flow conveying channel, and a bus comprising the direct current converter station and a main network adjacent to the converter station is selected.

Preferably, the offline control policy table in step 3:

wherein: v₁、V₂、V₃、V₄For voltage criterion logicConstant value, T₁、T₂、T₃、T₄For setting the delay value, Q, for each round₁、Q₂、Q₃、Q₄The fixed value can be set according to the power grid for each round of action reactive value.

Preferably, the reactive control measure action object is executed by a fan to absorb reactive power, a phase modulator to absorb reactive power, a cut capacitor and a throw reactor in sequence.

Preferably, the selection of the reactive control measure action object wind farm selects a wind farm with high control sensitivity as a voltage coordination control object after corresponding direct current blocking according to different wind farms and different blocking direct current distances, and the sensitivity calculation step includes:

recording the initial voltage u of each direct current key bus under the steady state working condition of the system_bus1,L,u_busnAnd initial voltage u_bus ⁰Wherein n is the number of key nodes;

recording the candidate new energy station as r₁,r₂L r_kEach candidate new energy station absorbs different reactive power delta q_kUnder the condition, the voltage of a key bus of the system is u_bus ¹,u_bus ²L u_bus ^kSeparately calculating a voltage variation value k is the number of the selected new energy stations;

respectively calculating the voltage-output sensitivity of each new energy station to a system key bus, wherein the calculation formulas are as follows:

selecting new energy key bus sensitivity eta_kAnd the larger than zeta is taken as a control measure object of a corresponding direct-current voltage coordination control system.

Compared with the prior art, the invention has the beneficial effects that: the system starts a voltage coordination control system based on a direct current blocking signal, divides four rounds according to an offline setting strategy to carry out reactive power support on the system, selects the highest voltage of a key node, matches the offline control strategy, and issues an execution station to sequentially enable a fan to absorb reactive power, a phase modulator to absorb reactive power, a capacitor to be cut and a reactor to be switched on.

Drawings

FIG. 1 is a flow chart of a voltage coordination control method for solving the steady-state overvoltage of the sending end after DC blocking according to the present invention;

FIG. 2 is a system diagram of a voltage coordination control method for solving the steady-state overvoltage of the DC blocking rear end according to the present invention;

fig. 3 is a schematic diagram of an example grid structure of a voltage coordination control method for solving the steady-state overvoltage of the sending end after dc blocking according to the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to FIGS. 1 to 3, preferred embodiments of the present invention will be further described;

a voltage coordination control method for solving the steady-state overvoltage of a sending end after direct-current blocking comprises the following steps:

step 1: when the direct current is locked, the direct current control protection system sends direct current locking information to the voltage coordination control system; the DC blocking information comprises the name of the blocking DC and the loss power.

Step 2: after receiving the direct current blocking information, the voltage coordination control system acquires the bus voltage of the key node of the power grid, judges whether to start the voltage coordination control logic according to the direct current blocking information, and if the starting condition (P) is met_{Loss of power}≥P₁And V is_max＞V_SET) Go to step 3, otherwise keep step 2, where P_{Loss of power}For blocking the actual loss of power, P, of DC₁For setting threshold value, V_maxTo select the highest voltage value, V, of the key node_SETGenerally set between 1.0p.u and 1.05 p.u;

p of the starting condition constant value₁And determining that the current direct current power is a starting set value, wherein the steady state overvoltage is obtained based on off-line time domain simulation calculation, the steady state overvoltage under different power direct current locks is simulated based on different operation modes of a power grid, and if a certain direct current power is locked, the steady state overvoltage of a corresponding system key node is mostly higher than 1.05 p.u. Preliminary simulation calculation, general P₁Slightly more than 4000MW, the voltage coordination control system is not started after the direct current single valve or the single pole is locked, and the risk of frequent starting of the device is greatly reduced;

v of constant value of the starting condition_maxDetermining that the voltage coordination control system adopts several set key node voltages and compares the maximum V_max＝max(V₁,V₂,V₃,…,V_n) Wherein: v₁,V₂,V₃… is the voltage of the key node set corresponding to the direct current, and n is the number of the key nodes;

and selecting key nodes, wherein the steady-state voltage rise caused by the general direct current locking is sequentially reduced from the direct current converter station to the power flow conveying channel, and selecting a bus comprising the direct current converter station and a main network adjacent to the converter station.

And step 3: the voltage coordination control system matches the off-line policy table according to the bus voltage of the detected key node, and executes a corresponding control measure if the logic action fixed value is met;

the offline policy table is as follows:

wherein: v₁、V₂、V₃、V₄For voltage criterion logic constant, T₁、T₂、T₃、T₄For setting the delay value, Q, for each round₁、Q₂、Q₃、Q₄The fixed value can be set according to the power grid for each round of action reactive value;

and 4, step 4: and the execution station absorbs reactive power from the system according to the instruction issued by the voltage coordination control system until the system voltage is restored to be within the set range or the control measures are used up.

Preferably, the reactive control measure action object is executed by a fan to absorb reactive power, a phase modulator to absorb reactive power, a cut capacitor and a throw reactor in sequence. The reactive control measure is the four-wheel action quantity Q in the voltage coordination system offline control strategy table in the step 3₁、Q₂、Q₃、Q₄If the direct current is locked and the system voltage meets the starting fixed value of the voltage coordination system, and the system voltage meets the action fixed value of each round, the voltage coordination system issues according to the support reactive power of each round of setting, and the phase modulator absorbs reactive power, cuts the system capacitor and throws the reactor to act in sequence according to the wind power station of the controlled object.

Preferably, the selection of the reactive control measure action object wind farm selects a wind farm with high control sensitivity as a voltage coordination control object after corresponding direct current blocking according to different wind farms and different blocking direct current distances, and the sensitivity calculation step includes:

recording the initial voltage u of each direct current key bus under the steady state working condition of the system_bus1,L,u_busnAnd initial average voltage u_bus ⁰Wherein n is the number of key nodes;

recording the candidate new energy station as r₁,r₂L r_kEach candidate new energy farmStanding to absorb different reactive power quantities delta q_kUnder the condition, the voltage of a key bus of the system is u_bus ¹,u_bus ²L u_bus ^kSeparately calculating a voltage variation value k is the number of the selected new energy stations;

respectively calculating the voltage-output sensitivity of each new energy station to a system key bus, wherein the calculation formulas are as follows:

selecting new energy key bus sensitivity eta_kAnd the larger than zeta is taken as a control measure object of a corresponding direct-current voltage coordination control system.

u_bus1,L,u_busnThe method is characterized in that a plurality of key bus initial voltages are selected when a system is in a steady state (under the condition of no power disturbance), and a certain key node voltage is selected to judge different absorbed reactive powers delta q of different wind power plants_kIt is certainly inappropriate to reduce the sensitivity of the system voltage, and the initial voltage of all key buses is selected as an average u_bus ⁰As a measure of the different absorbed reactive powers Δ q of different wind farms_kThe sensitivity of the system voltage can be reduced, and each wind power plant absorbs different reactive power so that the reduction degree of the system voltage is equal to the average voltage u_bus ⁰Compared with one key node voltage.

An embodiment of the present invention is shown in fig. 1, and step 1-2 in fig. 1 describes that after the voltage coordination control system receives the dc blocking information sent by the dc control protection system, and after determining that the blocking dc is blocked, the voltage of the bus of the key node corresponding to the blocking dc is obtained to determine whether the voltage is higher than the set value V_max＞V_SETIn this text V_SET1.05 p.u. Further judging whether the blocking DC loss power is larger than a set value P_{Loss of power}≥P₁If both are satisfied, the voltage coordination control device is started. Wherein: the direct current locking form is many, has single valve, monopole, 3/4 shutting, bipolar shutting etc. and direct current accuse is protected and all will be sent the shutting signal, does not adopt the control principle based on calculation guiding direct current monopole system after shutting, and is 8000MW for current extra-high voltage direct current majority, P in this publication₁Slightly be greater than 4000MW, guarantee that direct current single valve or monopole after shutting, voltage coordinated control system does not start, greatly reduced the risk that the device frequently starts.

The offline control strategy table described in step 3 in fig. 1 is obtained by determining an action constant value and a delay constant value through a large number of offline simulations according to the voltage recovery characteristics after the dc blocking of the power grid, setting each round of reactive action quantity according to the sensitivity of control measures in the operation size mode and considering the capability of reducing the system voltage after each round of action, and sequentially acting according to the sequence of the reactive power absorption, phase modulation and capacitor reactance switching of the wind farm until the system voltage is recovered to a preset value or the reactive measures are used up, and ending the action of the voltage coordination control system.

Taking a northwest extra-high voltage QiShao direct current sending end as an example, as shown in fig. 3, at the moment, the direct current running power is 8000MW, two phase modulators of a converter station are not absorbed in an initial state, the unbalance amount of the flow after the QiShao direct current locking is 2400MW, the steady state voltage of the converter station is raised to 65kV, after a wind power plant 1+ a wind power plant 2+ a wind power plant 3+ a wind power plant 4 are adopted to absorb the reactive power of 200Mvar together, the steady state voltage of the converter station is raised to 45kV, and after the phase modulators are continuously adopted to absorb the reactive power of 200Mvar, the steady state voltage of the system can be raised to about 20kV, so that the operation of a power grid is met.

Table 1 comparison of the control effect of coordination of voltage

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.

Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.