CN111969636A - Method and device for determining coupling relation of extra-high voltage alternating current and direct current transmission capacity of receiving end system - Google Patents
Method and device for determining coupling relation of extra-high voltage alternating current and direct current transmission capacity of receiving end system Download PDFInfo
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Abstract
The invention discloses a method and a device for determining an ultra-high voltage alternating current and direct current transmission capacity coupling relation of a receiving end system, and solves the problem of requirements on a method for calculating the ultra-high voltage alternating current and direct current transmission capacity coupling relation of the receiving end system limited by direct current faults. When an extra-high voltage alternating current and direct current receiving end system is restricted by direct current faults, the alternating current and direct current transmission capacity coupling relation is calculated, and therefore the alternating current and direct current transmission power can be determined, the calculation efficiency can be remarkably improved, manpower and material resources are saved, and obvious economic benefits are created.
Description
Technical Field
The application relates to the field of safe and stable operation of a power grid, in particular to a method for determining the coupling relation of extra-high voltage alternating current and direct current transmission capacity of a receiving end system, and also relates to a device for determining the coupling relation of the extra-high voltage alternating current and direct current transmission capacity of the receiving end system.
Background
With the large-scale development of extra-high voltage direct current, power impact caused by direct current faults becomes a key factor influencing the safe and stable operation of a power system. With the continuous improvement of the extra-high voltage direct current power, after the extra-high voltage direct current is disturbed or has a locking fault, large-scale power is transferred through an extra-high voltage alternating current section, so that a tidal current heavy load phenomenon is generated on an extra-high voltage alternating current line, and even exceeds a static stability limit or a thermal stability limit of an alternating current line, so that the alternating current line is disconnected. The large-range tidal current transfer may cause steady-state low voltage of an extra-high voltage alternating-current bus and a receiving end trunk net rack alternating-current bus, and may cause problems of power angle instability, frequency oscillation and the like of an extra-high voltage alternating-current and direct-current system.
In order to avoid the safety and stability problems of extra-high voltage alternating current line disconnection or extra-high voltage alternating current buses, receiving end backbone net rack alternating current buses, stable low voltage and the like caused by direct current faults, the limitation of direct current transmission power and alternating current section transmission power needs to be set. However, in the simulation calculation of the actual power grid, a unified calculation method suitable for the coupling relationship of the alternating current and direct current transmission capacity of the large-scale extra-high voltage alternating current and direct current hybrid power grid under the direct current fault is not formed, and research on the calculation method of the coupling relationship of the extra-high voltage alternating current and direct current transmission capacity of the receiving-end system constrained by the direct current fault is urgently needed.
Disclosure of Invention
The method aims to solve the problem of the requirement of a method for calculating the coupling relation of the ultra-high voltage alternating current and direct current transmission capacity of a receiving end system restricted by direct current faults. The application provides a method for determining a coupling relation of ultra-high voltage alternating current and direct current transmission capacities of a receiving end system, which comprises the following steps:
determining the extra-high voltage alternating current and direct current power of an alternating current and direct current series-parallel connection receiving end power grid under an initial operation mode of the power grid;
calculating the coupling relation of the AC/DC power transmission capacity and the extra-high voltage AC/DC power limit when the power grid meets the safety and stability constraint conditions of different extra-high voltage DC systems under any DC fault;
and calculating the coupling relation of the AC/DC transmission capacity and the extra-high voltage AC/DC power of the power grid under different DC faults when the safety and stability constraint conditions of the extra-high voltage AC/DC system are met.
Preferably, determining the extra-high voltage ac/dc power of the grid in the initial operation mode of the ac/dc series-parallel receiving-end grid includes:
analyzing the sensitivity of an alternating current-direct current series-parallel receiving end power grid to determine that the power grid adopts a conservative operation mode;
under the conservative operation mode, determining that the extra-high voltage alternating current power of the power grid is PAC0The extra-high voltage direct current power is PDC0。
Preferably, the calculating the coupling relation of the ac/dc power transmission capacity and the extra-high voltage ac/dc power limit when the power grid meets the constraint conditions of safety and stability of different extra-high voltage dc systems under any dc fault includes:
under any direct current fault, when an alternating current and direct current safety and stability constraint condition i (i is 1, 2, 3, … …, n) is met, the extra-high voltage alternating current and direct current is in a non-coupling constraint power transmission capacity relation; at the moment, the extra-high voltage alternating current power of the power grid is PAC0The extra-high voltage direct current power is PDC0；
Under any direct current fault, when an alternating current and direct current safety and stability constraint condition i (i is 1, 2, 3, … …, n) is not met, the extra-high voltage alternating current and direct current have a coupling constraint power transmission capacity relation; under the condition that the extra-high voltage alternating current and direct current are coupled to restrict the power transmission capacity, the extra-high voltage alternating current power is unchanged, the extra-high voltage direct current power is reduced, and the constraint condition of safety and stability of the alternating current and the direct current is metWhen i (i is 1, 2, 3, … …, n), determining the extra-high voltage alternating current power of the alternating current-direct current series-parallel receiving end grid as PAC0The extra-high voltage direct current power is PDCi(ii) a Under the condition that extra-high voltage alternating current and direct current are in a coupling constraint transmission capacity relation, extra-high voltage direct current power is unchanged, extra-high voltage alternating current power is reduced, and when the constraint condition i (i is 1, 2, 3, … …, n) of safety and stability of alternating current and direct current is met, the extra-high voltage alternating current power of an alternating current and direct current series-parallel connection receiving end power grid is determined to be PACiThe extra-high voltage direct current power is PDC0。
Preferably, the method further comprises the following steps:
under any direct current fault, if the mode power flow meets the constraint condition i (i is 1, 2, 3, … …, n) of safety and stability of alternating current and direct current, the extra-high voltage alternating current and direct current are not coupled to restrict the relation of power transmission capacity; at the moment, the extra-high voltage alternating current power of the power grid is PAC0The extra-high voltage direct current power is PDC0；
Under any direct current fault, if the mode power flow does not meet the constraint condition i (i is 1, 2, 3, … …, n) of safety and stability of alternating current and direct current, the extra-high voltage alternating current and direct current power is P when the extra-high voltage direct current power is pre-controlledAC0,min{PDC1,PDC2,…,PDCnThe extra-high voltage AC/DC power is min { P } when the extra-high voltage AC power is pre-controlledAC1,PAC2,…,PACn},PDC0(ii) a Under any direct current fault, if the 1 st to i th safety and stability constraint conditions are met and the i +1 st to n th safety and stability constraint conditions are not met, the i +1 st to n th safety and stability constraint conditions cause the coupling constraint power transmission capacity relation of the extra-high voltage alternating current and direct current, and the extra-high voltage alternating current and direct current power is P when the extra-high voltage direct current power is pre-controlledAC0,min{PDCi+1,PDCi+2,…,PDCnThe extra-high voltage AC/DC power is min { P } when the extra-high voltage AC power is pre-controlledACi+1,PACi+2,…,PACn},PDC0。
Preferably, the method further comprises the following steps:
under any DC fault, when an AC/DC safety and stability constraint condition i (i is 1, 2, 3, … …, n) is met, if the extra-high voltage AC/DC does not have the coupling constraint transmission capacity relation, the extra-high voltage AC/DC power is PAC0、PDC0；
If the extra-high voltage alternating current and direct current have the relation of coupling restricting transmission capacity, the alternating current power PAC0When not changed, set PDCj＝min{PDC1,PDC2,…,PDCnIs } or PDCj＝min{PDCi+1,PDCi+2,…,PDCnReduce DC power to PDCjThe extra-high voltage AC/DC power is PAC0、PDCj(ii) a DC power PDCWhen not changed, set PACj＝min{PAC1,PAC2,…,PACnIs } or PACj＝min{PACi+1,PACi+2,…,PACnThe AC power needs to be reduced to PACjThe extra-high voltage AC/DC power is PACj、PDC0。
Preferably, the calculating the coupling relation of the ac/dc power transmission capacity and the extra-high voltage ac/dc power when the power grid meets the constraint condition of the safety and stability of the extra-high voltage ac/dc system under different dc faults includes:
calculating that mode power flow of the power grid meets the extra-high voltage alternating current and direct current safety and stability constraint condition i (i is 1, 2, 3, … …, n) under different direct current faults, and when m direct current faults exist, if the extra-high voltage alternating current and direct current do not have the relation of coupling constraint on transmission capacity, the extra-high voltage alternating current and direct current power is PAC0、PDC0；
If the extra-high voltage alternating current and direct current have the relation of coupling restricting transmission capacity, the alternating current power PAC0When not changed, the DC power is reduced to
The extra-high voltage AC/DC power is PAC0、
DC power PDC0When not changed, the AC power is reduced to
Ultra-high voltage AC/DC power is
PDC0。
This application provides an extra-high voltage alternating current-direct current transmission capacity coupling relation determining means simultaneously of receiving end system, includes:
the system comprises an initial operation mode determining unit, a control unit and a control unit, wherein the initial operation mode determining unit is used for determining the extra-high voltage alternating current and direct current power of an alternating current and direct current series-parallel connection receiving end power grid under the initial operation mode of the power grid;
the coupling relation and quota calculation unit is used for calculating the coupling relation of the AC/DC power transmission capacity and the extra-high voltage AC/DC power quota when the power grid meets the safety and stability constraint conditions of different extra-high voltage DC systems under any DC fault;
and the coupling relation and quota calculating unit is used for calculating the coupling relation of the AC/DC transmission capacity and the extra-high voltage AC/DC power when the power grid meets the constraint condition of safety and stability of the extra-high voltage AC/DC system under different DC faults.
Preferably, the initial operation mode determining unit includes:
the operation mode determining subunit is used for determining that the power grid adopts a conservative operation mode by analyzing the sensitivity of the alternating current-direct current series-parallel connection receiving end power grid;
the alternating current and direct current power determining subunit determines that the extra-high voltage alternating current power of the power grid is P in the conservative operation modeAC0The extra-high voltage direct current power is PDC0。
Preferably, the coupling relation and quota calculating unit includes:
the alternating current and direct current power determining subunit is used for determining the relation of the extra-high voltage alternating current and direct current no-coupling constraint power transmission capacity when the alternating current and direct current safety and stability constraint condition i (i is 1, 2, 3, … …, n) is met under any direct current fault; at the moment, the extra-high voltage alternating current power of the power grid is PAC0The extra-high voltage direct current power is PDC0；
The alternating current and direct current power determining subunit is used for determining the relation of the extra-high voltage alternating current and direct current coupling restricting power transmission capacity when the alternating current and direct current safety and stability restricting condition i (i is 1, 2, 3, … …, n) is not met under any direct current fault; at extra highThe method comprises the steps that under the condition that voltage alternating current and direct current are coupled and the power transmission capacity is restricted, the extra-high voltage alternating current power is unchanged, the extra-high voltage direct current power is reduced, and when the constraint condition i (i is 1, 2, 3, … …, n) of the safety and stability of the alternating current and the direct current is met, the extra-high voltage alternating current power of an alternating current and direct current series-parallel receiving end power grid is determined to be PAC0The extra-high voltage direct current power is PDCi(ii) a Under the condition that extra-high voltage alternating current and direct current are in a coupling constraint transmission capacity relation, extra-high voltage direct current power is unchanged, extra-high voltage alternating current power is reduced, and when the constraint condition i (i is 1, 2, 3, … …, n) of safety and stability of alternating current and direct current is met, the extra-high voltage alternating current power of an alternating current and direct current series-parallel connection receiving end power grid is determined to be PACiThe extra-high voltage direct current power is PDC0。
Preferably, the coupling relation and quota calculating unit includes:
and the alternating current and direct current power determining subunit calculates that mode power flow of the power grid meets an extra-high voltage alternating current and direct current safety and stability constraint condition i (i is 1, 2, 3, … …, n) under different direct current faults, and when m direct current faults exist, if the extra-high voltage alternating current and direct current do not have a relation of restricting transmission capacity by coupling, the extra-high voltage alternating current and direct current power is PAC0、PDC0；
An AC/DC power determining subunit, wherein if the extra-high voltage AC/DC has a relation of coupling restricting transmission capacity, the AC power PAC0When not changed, the DC power is reduced to
Ultra-high voltage AC/DC power is
DC power PDC0When not changed, the AC power is reduced to
Ultra-high voltage AC/DC power is
PDC0。
Drawings
Fig. 1 is a schematic flow chart of a method for determining an extra-high voltage alternating current/direct current transmission capacity coupling relationship of a receiving end system according to the application;
FIG. 2 is a schematic diagram of a process for calculating the coupling relationship of the ultra-high voltage AC/DC power transmission capability of a receiving end system under the constraint of ultra-high voltage AC/DC safety and stability under the constraint of a certain DC fault;
fig. 3 is a schematic diagram of a passive dc receiving end system provided in the present application;
fig. 4 is a schematic diagram of a device for determining the coupling relationship between the extra-high voltage alternating current and direct current transmission capacities of a receiving end system provided by the application.
Detailed Description
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. This application is capable of implementation in many different ways than those herein set forth and of similar import by those skilled in the art without departing from the spirit of this application and is therefore not limited to the specific implementations disclosed below.
Fig. 1 is a schematic flow chart of a method for determining an extra-high voltage ac/dc power transmission capacity coupling relationship of a receiving end system, and the method provided by the present application is described in detail below with reference to fig. 1.
Step S101, determining the extra-high voltage alternating current and direct current power of the power grid under the initial operation mode of the alternating current and direct current series-parallel connection receiving end power grid.
Problems of ultrahigh voltage alternating current and direct current line power flow transfer, ultrahigh voltage alternating current bus and direct current receiving end main net rack alternating current bus steady-state low voltage and the like after direct current fault are related to various factors, such as direct current power level, reactive compensation mode, near-region line power flow, unit running state, safety control tripping strategy and the like. The sensitivity of the alternating current-direct current series-parallel connection receiving end power grid is analyzed, the power grid is determined to adopt a conservative operation mode, and various possibilities are guaranteed to be covered.
In an initial operation mode, the load level of a direct current receiving end, the power level of the section of an extra-high voltage alternating current line, the power level of the section of the direct current receiving end alternating current line and the power level of the section of the direct current line to be researched and the like are mainly considered;
considering the aversionIn the inferior mode, after the static stability limit of the extra-high voltage alternating current bus is determined, the static stability reserve coefficient K is calculated according to the power angle criterionpThe lower limit should be taken to be 15%;
considering a severe mode, the bus voltage of a key node of an extra-high voltage alternating-current bus 500kV voltage class (the reference voltage is 525kV, the same below) is reduced to 0.95-0.96p.u., and the voltage of the key node alternating-current bus of the 500kV after a direct-current fault is kept above 0.9 p.u.;
the direct current faults comprise bipolar locking, commutation failure accelerated section checking, bipolar restart failure and the like, and the safety control strategy comprises measures of modulating other direct current power related to a receiving end, switching direct current receiving end loads and the like.
Under the conservative operation mode, determining that the extra-high voltage alternating current power of the power grid is PAC0The extra-high voltage direct current power is PDC0。
And S102, calculating the coupling relation of the alternating current and direct current transmission capacity and the extra-high voltage alternating current and direct current power limit when the power grid meets the safety and stability constraint conditions of different extra-high voltage direct current systems under any direct current fault.
Under any direct current fault, when an alternating current and direct current safety and stability constraint condition i (i is 1, 2, 3, … …, n) is met, the extra-high voltage alternating current and direct current is in a non-coupling constraint power transmission capacity relation; at the moment, the extra-high voltage alternating current power of the power grid is PAC0The extra-high voltage direct current power is PDC0。
Under any direct current fault, when an alternating current and direct current safety and stability constraint condition i (i is 1, 2, 3, … …, n) is not met, the extra-high voltage alternating current and direct current have a coupling constraint transmission capacity relation, and extra-high voltage direct current power or extra-high voltage alternating current power needs to be pre-controlled in the case.
Pre-controlling the extra-high voltage direct current power: in an initial operation mode, the extra-high voltage alternating current power is unchanged, the extra-high voltage direct current power is reduced, transient stability calculation under the direct current fault is carried out again after the new mode power flow is converged, whether a simulation result meets a safety and stability constraint condition i or not is judged, the extra-high voltage direct current power is continuously reduced until the safety and stability constraint condition i is met, and the extra-high voltage alternating current power and the extra-high voltage direct current power are determined to be P at the momentAC0、PDCi；
Pre-controlling the extra-high voltage alternating current power: in an initial operation mode, the extra-high voltage direct current power is unchanged, the extra-high voltage alternating current power is reduced, transient stability calculation under the direct current fault is carried out again after the new mode power flow is converged, whether a simulation result meets a safety and stability constraint condition i or not is judged, the extra-high voltage alternating current power is continuously reduced until the safety and stability constraint condition i is met, and the extra-high voltage alternating current power is determined to be P at the momentACi、PDC0。
Under any direct current fault, whether the mode power flow meets all safety and stability constraint conditions or not is considered, and the method can be divided into three conditions:
(a) when all safety and stability constraint conditions are met, the relation that the extra-high voltage alternating current and direct current have no coupling constraint on the transmission capacity under the direct current fault is shown, and the extra-high voltage alternating current and direct current power is PAC0、PDC0；
(b) When all the safety and stability constraint conditions are not met, the fact that each safety and stability constraint condition can cause that the extra-high voltage alternating current and direct current have the relation of coupling constraint transmission capacity under the direct current fault is shown, and the extra-high voltage alternating current and direct current power is P when the extra-high voltage direct current power is pre-controlled at the momentAC0,min{PDC1,PDC2,…,PDCnThe extra-high voltage AC/DC power is min { P } when the extra-high voltage AC power is pre-controlledAC1,PAC2,…,PACn},PDC0。
(c) When the 1 st to i th safety and stability constraint conditions are met and the i +1 th to n th safety and stability constraint conditions are not met, the fact that the i +1 th to n th safety and stability constraint conditions can cause the extra-high voltage alternating current and direct current to have a coupling constraint power transmission capacity relation under the direct current fault is shown, and the extra-high voltage alternating current and direct current power is P when the extra-high voltage direct current power is pre-controlled at the momentAC0,min{PDCi+1,PDCi+2,…,PDCnThe extra-high voltage AC/DC power is min { P } when the extra-high voltage AC power is pre-controlledACi+1,PACi+2,…,PACn},PDC0。
Under any DC fault, when the AC/DC safety and stability constraint condition i (i is 1, 2, 3, … …, n) is satisfied, if the extra-high voltage AC/DC does not have the coupling constraint power transmission capacity relationWhen the extra-high voltage AC/DC power is PAC0、PDC0；
If the extra-high voltage alternating current and direct current have the relation of coupling restricting transmission capacity, the alternating current power PAC0When not changed, set PDCj＝min{PDC1,PDC2,…,PDCnIs } or PDCj＝min{PDCi+1,PDCi+2,…,PDCnReduce DC power to PDCjThe extra-high voltage AC/DC power is PAC0、PDCj(ii) a DC power PDCWhen not changed, set PACj＝min{PAC1,PAC2,…,PACnIs } or PACj＝min{PACi+1,PACi+2,…,PACnThe AC power needs to be reduced to PACjThe extra-high voltage AC/DC power is PACj、PDC0。
And S103, calculating the coupling relation of the alternating current and direct current transmission capacity and the extra-high voltage alternating current and direct current power when the power grid meets the constraint conditions of safety and stability of the extra-high voltage alternating current and direct current system under different direct current faults.
According to whether the relation of coupling restriction transmission capacity exists when the extra-high voltage alternating current and direct current meet the safety and stability constraint condition under the direct current fault, the method can be divided into the following two conditions:
(a) when the relation of coupling restricting transmission capacity does not exist, the extra-high voltage AC/DC power is PAC0、PDC0。
(b) When there is a coupling-limited transmission capacity relationship, the AC power PAC0When not changed, set PDCj＝min{PDC1,PDC2,…,PDCnIs } or PDCj＝min{PDCi+1,PDCi+2,…,PDCnReduce DC power to PDCjThe extra-high voltage AC/DC power is PAC0、PDCj(ii) a DC power PDCWhen not changed, set PACj＝min{PAC1,PAC2,…,PACnIs } or PACj＝min{PACi+1,PACi+2,…,PACnThe AC power needs to be reduced to PACjThe extra-high voltage AC/DC power is PACj、PDC0。
Under the safety control measure, the coupling relation of the alternating current and direct current transmission capacities under the safety control measure can be calculated according to the step S102 and the step S103, and the extra-high voltage alternating current and direct current power is determined. And further analyzing the effects of different safety control measures and giving an optimal safety control strategy.
The calculation flow shown in the attached figure 2 is applied to engineering practice of calculating the coupling relation of the ultra-high voltage alternating current and direct current transmission capacity of the receiving-end system restricted by the direct current fault, and the best embodiment of the specific application can be formed.
Taking the relaxed dc receiving end system shown in fig. 3 as an example, the method for calculating the ultra-high voltage ac/dc power transmission capability coupling relationship of the receiving end system constrained by the dc fault provided by the invention is explained.
The method comprises the following steps: determining an initial operation mode: the load of Henan is 4000 ten thousand kilowatts, the direct current of Henan is 400 thousand kilowatts, the direct current of Tianzhong is 650 thousand kilowatts, the direct current of Channan is 420 thousand kilowatts, and the direct current of Hunan is 30 thousand kilowatts.
In an initial mode, the south power transmission of the long south line is 420 ten thousand kilowatts, the 500 kV-level bus voltages of the long south, south sun and Jingmen are respectively 500kV, 505kV and 505kV, and the 500 kV-level bus voltages of the long south, south sun and Jingmen under the direct current fault are not lower than 0.9 p.u..
Step two: and calculating the coupling relation between the Janus DC and the Long south line under the constraint conditions that the Long south line is not disconnected and the Long south line is not low in voltage under the direct current bipolar latching fault.
In the initial operation mode, the long south line is not disconnected; considering that the steady state voltage of a Changzhi, Nanyang and Jingmen 500kV bus is not lower than 0.9p.u., the direct current of the Chengyu is 400 ten thousand kilowatts, and the south power of the Changzhou line is not more than 350 ten thousand kilowatts; the south power transmission of the south of the Changnan line is 420 ten thousand kilowatts, and the direct current transmission power of the south of the Changnan line needs to be pre-controlled to be 350 ten thousand kilowatts.
To sum up: considering that under the bipolar latch-up fault, when two constraint conditions of no disconnection of the south-length line and no low voltage of the south-length line are met, the coupled relation exists between the direct current of the Henan and the south-length line: the direct current of the qingyu is 400 ten thousand kilowatts, and the south power of the southern line is required to be controlled not to exceed 350 ten thousand kilowatts; the south power transmission of the south of the Changnan line is 420 ten thousand kilowatts, and the direct current transmission power of the south of the Changnan line needs to be pre-controlled to be 350 ten thousand kilowatts.
Step three: and calculating the coupling relation between the Qingyu direct current and the Long south line under the constraint conditions that the Long south line is not disconnected and the Long south line is not low voltage under the failure of locking after 4 continuous commutation failures of the Qingyu direct current and the failure of bipolar 2 times full voltage reduction and 1 time voltage reduction and restarting.
Considering that when two constraint conditions of no-train of south-bound-length line and no-low voltage of south-bound-length line are met under the condition of latch-up fault after 4 continuous commutation failures of the direct current of the Qingyu province, the direct current of the Qingyu province and the south-bound-length line have a coupling relation: the direct current of the qingyu is 400 ten thousand kilowatts, and the south power transmission of the southern line is required to be controlled to be not more than 400 ten thousand kilowatts; the south power transmission of the south of the Changnan line is 420 ten thousand kilowatts, and the direct current transmission power of the south of the Changnan line needs to be pre-controlled to be 350 ten thousand kilowatts.
Considering that under the failure fault of 2 times of full voltage reduction and 1 time of voltage reduction restarting of the Janus DC bipolar, when two constraint conditions of no train disconnection of the southern long line and no low voltage of the southern long line are met, the Janus DC and the southern long line have a coupling relation: the direct current of the qingyu is 400 ten thousand kilowatts, and the south power transmission of the southern line is required to be controlled to be not more than 390 ten thousand kilowatts; the south power transmission of the south of the Changnan line is 420 ten thousand kilowatts, and the south power transmission of the south needs to be pre-controlled to be 360 ten thousand kilowatts.
To sum up: considering the faults of bipolar latch, latch after 4 continuous commutation failures and bipolar 2 full-voltage 1 step-down restart, when two constraint conditions of no train disconnection of south-length line and no low voltage of south-length line are met, the coupling relation exists between the celiac direct current and the south-length line: the direct current of the qingyu is 400 ten thousand kilowatts, and the south power of the southern line is required to be controlled not to exceed 350 ten thousand kilowatts; the south power transmission of the south of the Changnan line is 420 ten thousand kilowatts, and the direct current transmission power of the south of the Changnan line needs to be pre-controlled to be 350 ten thousand kilowatts.
Step four: under the regulation measure of modulation of the three gorges direct current 100 ten thousand kilowatts, under the failure faults of calculating the dead direct current bipolar latch, latch after 4 continuous commutation failures and bipolar 2 full voltage reduction 1 voltage reduction restart, the dead direct current and the long south line are in a coupling relation under the constraint conditions that the long south line is not disconnected and the long south line is not low in voltage.
Under the initial operation mode, after modulation of the three gorges direct current 100 ten thousand kilowatt safety control measures, after bipolar latching of the dead direct current, latching after 4 continuous commutation failures, and bipolar 2 full-voltage 1-time voltage reduction and restart failure faults, the simulation result is as follows: the long south line is not disconnected, and the long south thorn is not low in voltage. In this case, there is no coupling relationship between the Janus DC and the south-Long line.
Based on the same inventive concept, the present application also provides a device for determining the coupling relationship between the ultra-high voltage ac/dc transmission capabilities of a receiving end system, as shown in fig. 4, including:
an initial operation mode determining unit 410, configured to determine an extra-high voltage ac/dc power of an ac/dc series-parallel receiving end power grid in an initial operation mode of the power grid;
the coupling relation and quota calculating unit 420 is used for calculating the coupling relation of the alternating current and direct current transmission capacity and the extra-high voltage alternating current and direct current power quota when the power grid meets the safety and stability constraint conditions of different extra-high voltage direct current systems under any direct current fault;
and the coupling relation and quota calculating unit 430 is used for calculating the coupling relation of the alternating current and direct current transmission capacity and the extra-high voltage alternating current and direct current power when the extra-high voltage alternating current and direct current system safety and stability constraint conditions are met under different direct current faults of the power grid.
Preferably, the initial operation mode determining unit includes:
the operation mode determining subunit is used for determining that the power grid adopts a conservative operation mode by analyzing the sensitivity of the alternating current-direct current series-parallel connection receiving end power grid;
the alternating current and direct current power determining subunit determines that the extra-high voltage alternating current power of the power grid is P in the conservative operation modeAC0The extra-high voltage direct current power is PDC0。
Preferably, the coupling relation and quota calculating unit includes:
the alternating current and direct current power determining subunit is used for determining the relation of the extra-high voltage alternating current and direct current no-coupling constraint power transmission capacity when the alternating current and direct current safety and stability constraint condition i (i is 1, 2, 3, … …, n) is met under any direct current fault; at the moment, the extra-high voltage alternating current power of the power grid is PAC0The extra-high voltage direct current power is PDC0；
Under any direct current fault, when the direct current safety and stability constraint condition i (i is 1, 2, 3, … …, n) is not met, the extra-high voltage alternating current and direct current have the relation of coupling constraint transmission capacity(ii) a Under the condition that extra-high voltage alternating current and direct current are in a coupling constraint transmission capacity relation, extra-high voltage alternating current power is unchanged, extra-high voltage direct current power is reduced, and when the constraint condition i (i is 1, 2, 3, … …, n) of safety and stability of alternating current and direct current is met, the extra-high voltage alternating current power of an alternating current and direct current series-parallel connection receiving end power grid is determined to be PAC0The extra-high voltage direct current power is PDCi(ii) a Under the condition that extra-high voltage alternating current and direct current are in a coupling constraint transmission capacity relation, extra-high voltage direct current power is unchanged, extra-high voltage alternating current power is reduced, and when the constraint condition i (i is 1, 2, 3, … …, n) of safety and stability of alternating current and direct current is met, the extra-high voltage alternating current power of an alternating current and direct current series-parallel connection receiving end power grid is determined to be PACiThe extra-high voltage direct current power is PDC0。
Preferably, the coupling relation and quota calculating unit includes:
and the alternating current and direct current power determining subunit calculates that mode power flow of the power grid meets an extra-high voltage alternating current and direct current safety and stability constraint condition i (i is 1, 2, 3, … …, n) under different direct current faults, and when m direct current faults exist, if the extra-high voltage alternating current and direct current do not have a relation of restricting transmission capacity by coupling, the extra-high voltage alternating current and direct current power is PAC0、PDC0；
An AC/DC power determining subunit, wherein if the extra-high voltage AC/DC has a relation of coupling restricting transmission capacity, the AC power PAC0When not changed, the DC power is reduced to
Ultra-high voltage AC/DC power is
DC power PDC0When not changed, the AC power is reduced to
Ultra-high voltage AC/DC power is
PDC0。
The method and the device for determining the coupling relation of the ultra-high voltage alternating current and direct current transmission capacity of the receiving end system solve the problem of requirements on a method for calculating the coupling relation of the ultra-high voltage alternating current and direct current transmission capacity of the receiving end system restricted by direct current faults. When an extra-high voltage alternating current and direct current receiving end system is restricted by direct current faults, the alternating current and direct current transmission capacity coupling relation is calculated, and therefore the alternating current and direct current transmission power can be determined, the calculation efficiency can be remarkably improved, manpower and material resources are saved, and obvious economic benefits are created.
The foregoing is a more detailed description of the invention in connection with specific preferred embodiments and it is not intended that the invention be limited to these specific details. For those skilled in the art to which the invention pertains, several simple deductions or substitutions can be made without departing from the spirit of the invention, and all shall be considered as belonging to the protection scope of the invention.
Claims (10)
1. A method for determining a coupling relation of ultra-high voltage alternating current and direct current transmission capacities of a receiving end system is characterized by comprising the following steps:
determining the extra-high voltage alternating current and direct current power of an alternating current and direct current series-parallel connection receiving end power grid under an initial operation mode of the power grid;
calculating the coupling relation of the AC/DC power transmission capacity and the extra-high voltage AC/DC power limit when the power grid meets the safety and stability constraint conditions of different extra-high voltage DC systems under any DC fault;
and calculating the coupling relation of the AC/DC transmission capacity and the extra-high voltage AC/DC power of the power grid under different DC faults when the safety and stability constraint conditions of the extra-high voltage AC/DC system are met.
2. The method according to claim 1, wherein determining the extra-high voltage AC/DC power of the grid in the initial operation mode of the AC/DC series-parallel receiving end grid comprises:
analyzing the sensitivity of an alternating current-direct current series-parallel receiving end power grid to determine that the power grid adopts a conservative operation mode;
under the conservative operation mode, determining that the extra-high voltage alternating current power of the power grid is PAC0The extra-high voltage direct current power is PDC0。
3. The method according to claim 1, wherein the step of calculating the coupling relation of the AC/DC power transmission capacity and the extra-high voltage AC/DC power limit when the power grid meets the safety and stability constraint conditions of different extra-high voltage DC systems under any DC fault comprises the following steps:
under any direct current fault, when an alternating current and direct current safety and stability constraint condition i (i is 1, 2, 3, … …, n) is met, the extra-high voltage alternating current and direct current is in a non-coupling constraint power transmission capacity relation; at the moment, the extra-high voltage alternating current power of the power grid is PAC0The extra-high voltage direct current power is PDC0；
Under any direct current fault, when an alternating current and direct current safety and stability constraint condition i (i is 1, 2, 3, … …, n) is not met, the extra-high voltage alternating current and direct current have a coupling constraint power transmission capacity relation; under the condition that extra-high voltage alternating current and direct current are in a coupling constraint transmission capacity relation, extra-high voltage alternating current power is unchanged, extra-high voltage direct current power is reduced, and when the constraint condition i (i is 1, 2, 3, … …, n) of safety and stability of alternating current and direct current is met, the extra-high voltage alternating current power of an alternating current and direct current series-parallel connection receiving end power grid is determined to be PAC0The extra-high voltage direct current power is PDCi(ii) a Under the condition that extra-high voltage alternating current and direct current are in a coupling constraint transmission capacity relation, extra-high voltage direct current power is unchanged, extra-high voltage alternating current power is reduced, and when the constraint condition i (i is 1, 2, 3, … …, n) of safety and stability of alternating current and direct current is met, the extra-high voltage alternating current power of an alternating current and direct current series-parallel connection receiving end power grid is determined to be PACiThe extra-high voltage direct current power is PDC0。
4. The method of claim 3, further comprising:
under any direct current fault, if the mode power flow meets the constraint condition i (i is 1, 2, 3, … …, n) of safety and stability of alternating current and direct current, the extra-high voltage alternating current and direct current are not coupled to restrict the relation of power transmission capacity; at the moment, the extra-high voltage alternating current power of the power grid is PAC0The extra-high voltage direct current power is PDC0；
Under any DC fault, if the mode is tidal currentWhen the constraint condition i (i is 1, 2, 3, … …, n) of safety and stability of alternating current and direct current is not satisfied, when the extra-high voltage direct current power is pre-controlled, the extra-high voltage alternating current and direct current power is PAC0,min{PDC1,PDC2,…,PDCnThe extra-high voltage AC/DC power is min { P } when the extra-high voltage AC power is pre-controlledAC1,PAC2,…,PACn},PDC0(ii) a Under any direct current fault, if the 1 st to i th safety and stability constraint conditions are met and the i +1 st to n th safety and stability constraint conditions are not met, the i +1 st to n th safety and stability constraint conditions cause the coupling constraint power transmission capacity relation of the extra-high voltage alternating current and direct current, and the extra-high voltage alternating current and direct current power is P when the extra-high voltage direct current power is pre-controlledAC0,min{PDCi+1,PDCi+2,…,PDCnThe extra-high voltage AC/DC power is min { P } when the extra-high voltage AC power is pre-controlledACi+1,PACi+2,…,PACn},PDC0。
5. The method of claim 3 or 4, further comprising:
under any DC fault, when an AC/DC safety and stability constraint condition i (i is 1, 2, 3, … …, n) is met, if the extra-high voltage AC/DC does not have the coupling constraint transmission capacity relation, the extra-high voltage AC/DC power is PAC0、PDC0；
If the extra-high voltage alternating current and direct current have the relation of coupling restricting transmission capacity, the alternating current power PAC0When not changed, set PDCj＝min{PDC1,PDC2,…,PDCnIs } or PDCj＝min{PDCi+1,PDCi+2,…,PDCnReduce DC power to PDCjThe extra-high voltage AC/DC power is PAC0、PDCj(ii) a DC power PDC0When not changed, set PACj＝min{PAC1,PAC2,…,PACnIs } or PACj＝min{PACi+1,PACi+2,…,PACnThe AC power needs to be reduced to PACjThe extra-high voltage AC/DC power is PACj、PDC0。
6. The method according to claim 1, wherein the step of calculating the coupling relation of the AC/DC transmission capacity and the extra-high voltage AC/DC power when the extra-high voltage AC/DC system safety and stability constraint conditions are met under different DC faults of the power grid comprises the following steps:
calculating that mode power flow of the power grid meets the extra-high voltage alternating current and direct current safety and stability constraint condition i (i is 1, 2, 3, … …, n) under different direct current faults, and when m direct current faults exist, if the extra-high voltage alternating current and direct current do not have the relation of coupling constraint on transmission capacity, the extra-high voltage alternating current and direct current power is PAC0、PDC0；
If the extra-high voltage alternating current and direct current have the relation of coupling restricting transmission capacity, the alternating current power PAC0When not changed, the DC power is reduced to
The extra-high voltage AC/DC power is PAC0、
DC power PDC0When not changed, the AC power is reduced to
Ultra-high voltage AC/DC power is
PDC0。
7. The utility model provides a receive end system extra-high voltage alternating current-direct current transmission capacity coupling relation determination device which characterized in that includes:
the system comprises an initial operation mode determining unit, a control unit and a control unit, wherein the initial operation mode determining unit is used for determining the extra-high voltage alternating current and direct current power of an alternating current and direct current series-parallel connection receiving end power grid under the initial operation mode of the power grid;
the coupling relation and quota calculation unit is used for calculating the coupling relation of the AC/DC power transmission capacity and the extra-high voltage AC/DC power quota when the power grid meets the safety and stability constraint conditions of different extra-high voltage DC systems under any DC fault;
and the coupling relation and quota calculating unit is used for calculating the coupling relation of the AC/DC transmission capacity and the extra-high voltage AC/DC power when the power grid meets the constraint condition of safety and stability of the extra-high voltage AC/DC system under different DC faults.
8. The apparatus of claim 7, wherein the initial operation mode determining unit comprises:
the operation mode determining subunit is used for determining that the power grid adopts a conservative operation mode by analyzing the sensitivity of the alternating current-direct current series-parallel connection receiving end power grid;
the alternating current and direct current power determining subunit determines that the extra-high voltage alternating current power of the power grid is P in the conservative operation modeAC0The extra-high voltage direct current power is PDC0。
9. The apparatus of claim 7, wherein the coupling relation and quota calculating unit comprises:
the alternating current and direct current power determining subunit is used for determining the relation of the extra-high voltage alternating current and direct current no-coupling constraint power transmission capacity when the alternating current and direct current safety and stability constraint condition i (i is 1, 2, 3, … …, n) is met under any direct current fault; at the moment, the extra-high voltage alternating current power of the power grid is PAC0The extra-high voltage direct current power is PDC0；
The alternating current and direct current power determining subunit is used for determining the relation of the extra-high voltage alternating current and direct current coupling restricting power transmission capacity when the alternating current and direct current safety and stability restricting condition i (i is 1, 2, 3, … …, n) is not met under any direct current fault; under the condition that extra-high voltage alternating current and direct current are in a coupling constraint transmission capacity relation, extra-high voltage alternating current power is unchanged, extra-high voltage direct current power is reduced, and when the constraint condition i (i is 1, 2, 3, … …, n) of safety and stability of alternating current and direct current is met, the extra-high voltage alternating current power of an alternating current and direct current series-parallel connection receiving end power grid is determined to be PAC0The extra-high voltage direct current power is PDCi(ii) a Under the condition that the extra-high voltage alternating current and direct current are coupled to restrict the power transmission capacity, the extra-high voltage direct current power is unchanged, the extra-high voltage alternating current power is reduced, and the safety of alternating current and direct current is metWhen the constraint condition i (i is 1, 2, 3, … …, n), determining the extra-high voltage alternating current power of the alternating current-direct current series-parallel connection receiving end power grid as PACiThe extra-high voltage direct current power is PDC0。
10. The apparatus of claim 7, wherein the coupling relation and quota calculating unit comprises:
and the alternating current and direct current power determining subunit calculates that mode power flow of the power grid meets an extra-high voltage alternating current and direct current safety and stability constraint condition i (i is 1, 2, 3, … …, n) under different direct current faults, and when m direct current faults exist, if the extra-high voltage alternating current and direct current do not have a relation of restricting transmission capacity by coupling, the extra-high voltage alternating current and direct current power is PAC0、PDC0；
An AC/DC power determining subunit, wherein if the extra-high voltage AC/DC has a relation of coupling restricting transmission capacity, the AC power PAC0When not changed, the DC power is reduced to
The extra-high voltage AC/DC power is PAC0、
DC power PDC0When not changed, the AC power is reduced to
Ultra-high voltage AC/DC power is
PDC0。
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| CN112713620A (en) * | 2020-11-23 | 2021-04-27 | 中国电力科学研究院有限公司 | Method and system for analyzing transmission capacity of extra-high voltage alternating current-direct current coupling system |
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| CN112713620A (en) * | 2020-11-23 | 2021-04-27 | 中国电力科学研究院有限公司 | Method and system for analyzing transmission capacity of extra-high voltage alternating current-direct current coupling system |
| CN112713620B (en) * | 2020-11-23 | 2022-11-25 | 中国电力科学研究院有限公司 | Method and system for analyzing power transmission capacity of extra-high voltage alternating current-direct current coupling system |
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