Background technology
The operational mode of current conversion station is divided into two kinds, and a kind of is islet operation, and a kind of is networking operation.The decoupled mode of current conversion station, referring to the power supply that inserts the sending end current conversion station directly sends by DC line after rectification, power supply, current conversion station all are not electrically connected with AC system, and the networking operation of current conversion station means the current conversion station or the power station of access current conversion station and the transformer station of major network and is electrically connected.
In the prior art, general high-capacity direct current current conversion station takes the isolated island mode to move, and can avoid shifting to AC system on a large scale after the direct current fault, avoid because not controlled trend shifts the stabilization of power grids malicious event that may bring, and be a kind of more excellent electric network composition.The high voltage DC engineering particularly sending end current conversion station employing decoupled mode of high-capacity direct current engineering is present a kind of development trend.After current conversion station adopts decoupled mode, the isolated island system will present a series of characteristics different during with networking operation, different control strategy in the time of need taking with networking operation:
(1) current conversion station islet operation has reduced isolated island system direct current fault effects degree.Direct current generation bipolar locking during networking operation except the needs excision inserts the unit of current conversion station, may also need to excise the major network part of generating units; Current conversion station is taked islet operation, direct current generation bipolar locking, the general unit that only needs excision access current conversion station;
(2) current conversion station islet operation, the horizontal 1.3pu that overvoltage level after the DC bipolar locking generally allows considerably beyond conventional substation, can reach 1.4 ~ 1.7 pu, excise again after generally requiring the change of current to become time-delay 60 ~ 100ms, utilizing the change of current to become inhibitory action to power-frequency overvoltage, this point is different during with the current conversion station networking operation;
(3) the isolated island system take place to exchange or DC line fault, and system frequency, voltage fluctuation are more serious than networking mode.When therefore current conversion station is in islet operation, isolated island system generation unit fault, exchange or DC line fault, the transient frequency fluctuation that current conversion station isolated island system allows is bigger, generally reach ± 1Hz, when changing, isolated island or networking operation mode need switch frequency limitation device (FLC) parameter in the DC control system, to obtain best FREQUENCY CONTROL effect;
(4) the isolated island system is when the locking of direct current generation one pole, allows current conversion station to restart unsuccessful number of times and reaches (being generally 1 ~ 2 time), directly locking fault one pole behind the limit value.During the networking operation of current conversion station stream, more when allowing to restart unsuccessful number of times after the locking of direct current one pole generally than islet operation.
At the problems referred to above, the current conversion station islet operation need be taked a series of operation control strategies different during with networking operation.But, also there are not a kind of checkout gear or method to detect the operational mode of current conversion station at present, the switching that moves control strategy for current conversion station provides foundation.
The current conversion station operational mode detects, be very different with the islet operation detected state tool of the microgrid that is used for distributed energy (as wind-powered electricity generation, solar energy), the latter is usually by active or passive detection method, as the variation of the voltage of passive detection and site, electric current, frequency, phase place and island state is detected, or by in the output of distributed power source, adding specific harmonic signal, by contrast power supply near region with major network in the having or not of this harmonic signal, amplitude size, phase change, impedance magnitude variation wait and judge whether current conversion station is in islet operation.
The islet operation tool of the islet operation of current conversion station and microgrid is very different:
(1) islet operation of current conversion station, the isolated island system has identical voltage, electric current, frequency or phase place with may having with the major network system, therefore, judges that by the variation of above-mentioned amount whether current conversion station is in islet operation is insecure.
(2) because the transmission power of high voltage direct current is bigger, routine can arrive 3000MW ~ 7200MW, the installation scale that inserts the power supply place is bigger, employing adds the modulation harmonic wave at the power supply place method judges whether to be in island state, reliably detect as needs, harmonic current or voltage magnitude need reach certain value, and prior art can't realize, even realize that investment is also higher, the harmonic wave that injects at the power supply place might worsen the quality of power supply of isolated island system.Side's one side in addition also needs and compares from the detected harmonic wave of major network, and therefore, detection speed can't meet the demands.
(3) owing to different control strategies is taked in isolated island, networking operation, it is for the islet operation state that the island detection of current conversion station not only needs to detect current conversion station, also needs to detect current conversion station and whether is in the networking operation state; Conventional piconet island detection method is promptly moved with the system splitting termination routine after detecting island state, and the island detection of current conversion station also needs to continue detection system and whether returns to networking operation after detecting island state.Therefore, it is higher that the current conversion station island state detects requirement.This method is not only applicable to unplanned islet operation, also is applicable to the plan islet operation.
Summary of the invention
Consider the importance of the operational mode detection of current conversion station, and still there are not a kind of checkout gear or method of effective current conversion station operational mode in the prior art, the detection of current conversion station operational mode also can't be applied in the various island detection methods that microgrid proposes, and therefore needs to propose a kind of detection method and checkout gear of current conversion station operational mode.
The invention discloses a kind of detection method of current conversion station operational mode, it comprises following steps:
Step 1: checkout gear is gathered the state value S of the circuit breaker of power station, current conversion station, transformer station
1~ S
n
Step 2: the value of checkout gear computational logic expression formula:
Step 3: checkout gear exports value of logical expression to the control of current conversion station station, current conversion station stability control device, power station stability control device.
Preferably, adopt two cover checkout gears and B-CII loop line road to detect, its logical expression is:
F in the following formula
A, f
BThe output signal of representing two cover island detection devices respectively;
Logical variable for B-CII loop line road power rating; "
" be the negate symbol; "
" be the logical AND symbol.
Preferably, said method also comprises:
Step 4: obtain current time T1; And obtaining step 1 time T 0 when carrying out, judge T1-T0 whether greater than
, be then to go to step 1, otherwise repeated execution of steps 4;
Wherein
Be the time that is provided with according to the time-delay situation of installing.
Preferably, the logical expression of above-mentioned steps 2 is:
Preferably, inconsistent will the warning of above-mentioned two cover island detection device outputs, whether detect stream oriented device output by following formula consistent:
The invention also discloses a kind of checkout gear of current conversion station operational mode, comprise power station, current conversion station, transformer station and circuit breaker thereof; Above-mentioned detection device also comprises breaker signal harvester, checkout gear logical calculated module;
Above-mentioned breaker signal harvester is connected with each killer switch auxiliary contact, is used to gather the state value S of the circuit breaker of power station, current conversion station, transformer station
1~ S
n
Checkout gear logical calculated module: be used for the computational logic expression formula
Value;
Above-mentioned detection device logical calculated module is connected with current conversion station station control device, current conversion station stability control device, is used to send detected value;
Above-mentioned detection device logical calculated module is connected by optical fiber with the power station stability control device.
Preferably, the checkout gear of above-mentioned current conversion station operational mode also comprises:
Time detection device and judge module are used for detection time and storage and relatively judgement.
Preferably, the checkout gear of above-mentioned current conversion station operational mode is two covers, and every covering device is independently gathered the relative breaker state information of power station, current conversion station, transformer station.
Preferably, the checkout gear of above-mentioned current conversion station operational mode also comprises warning device, and above-mentioned warning device is exported when inconsistent at two island detection devices and started.
Beneficial effect of the present invention is: by method disclosed by the invention and device, by differentiation current conversion station and access power supply the circuit-breaker status of sending interconnection outside being differentiated current conversion station is for isolated island or networking operation mode, do not need to gather, detect the information such as voltage, frequency, phase place, impedance of current conversion station, do not need to inject disturbing signal to electrical network yet, noiseless to electrical network, differentiate fast, accuracy is high, especially is fit to the differentiation to the very high big capacity high DC converter station decoupled mode of speed and reliability requirement.
Embodiment
Object lesson below in conjunction with Figure of description and one ± 800kV/6400MW current conversion station specifies embodiments of the present invention.
Current conversion station wiring schematic diagram during as shown in Figure 1 networking operation.A 9 * the 700MW that installs in power station goes out the 500kV line access system altogether 4 times, wherein directly inserts current conversion station B 3 times, and other 1 tieback is to the C of transformer station, and current conversion station B links by 2 times 500kV circuits and the C of transformer station.The power of power station A is mainly sent for the high voltage direct current of ± 800kV/6400MW by 1 time rated power.
Because the direct current transmission power is big, the direct current fault is very big to system safety stabilizing influence, and from simplifying stable setting, current conversion station B can realize following two kinds of decoupled mode wiring:
(1) decoupled mode as shown in Figure 2,6 units of power station A insert current conversion station B by 4 times 500kV circuits, two limit circuit breakers disconnections of going here and there to power station A, to this place, loop line road of current conversion station B among the current conversion station B move, change of current B is out of service to another time of the C of transformer station 500kV circuit, has realized power station A, current conversion station B and electrical isolation major network.
(2) decoupled mode as shown in Figure 3, power station A 4 machines 3 lines insert current conversion station B, power station A disconnects to two limit circuit breakers in this 4/3 string of transformer station B place, 7 remaining units of power station insert current conversion station B by 3 times 500kV circuits, and current conversion station B is all out of service to twice 500kV circuits of the C of transformer station.The wiring schematic diagram of decoupled mode B as shown in Figure 3.
The electrical main connecting wire at each station, extremely shown in Figure 6 as Fig. 4.As shown in Figure 4, power station A is 3/2,4/3 mixing wiring.As Fig. 5, shown in Figure 6, current conversion station B, the C of transformer station are 3/2 wiring.The electrical main connecting wire design at each station can realize satisfying the requirement that current conversion station B carries out the flexible conversion of isolated island and networking operation mode flexibly, and wherein the wherein loop line road of power station A to this loop line road of the C of transformer station and the C of transformer station to current conversion station B fits over on a string at the C of transformer station.
The detection method of a kind of current conversion station operational mode disclosed by the invention, as shown in Figure 7, it comprises following steps:
Step 1: the state value S that gathers the circuit breaker of power station A, current conversion station B, the C of transformer station
1~ S
n, (corresponding this example is S
1~ S
14);
Step 2: computational logic expression formula
Value; The expression formula of asking for can be set, and to this example then is:
Step 3: export value of logical expression to the control of current conversion station station, stability control device, power station stability control device;
Preferably, the detection method of above-mentioned current conversion station operational mode also further comprises:
Step 4: obtain current time T
1And the obtaining step 1 current time T when carrying out
0, and judge T
1-T
0Whether greater than
, be then to go to step 1, otherwise repeated execution of steps 4.
Wherein
Be the time that is provided with according to the time-delay situation of installing.
Preferably, the island detection device is realized the isolated island of current conversion station B, networking status detection by the circuit breaker opening and closing state that detects power station A, current conversion station B, the C of transformer station.The island detection device only provides the logic detection of isolated island, networking, by calculating power station A, current conversion station B, the C of transformer station circuit breaker S
1To S
14(the state logic variable expression as Fig. 4-Fig. 6) is realized each circuit breaker S
1To S
14All use " 1 " expression " is opened ", " 0 " expression " closure ", and value of logical expression is in decoupled mode for " 1 " expression current conversion station, for " 0 " expression is in the networking operation mode.Based on above-mentioned supposition, there is following logical expression in the island detection:
(1) to return current conversion station B side connection status be S to B-C I
1(S
2+ S
3); Be S
1Open (logical variable is " 1 "), S
2With S
3One of them must be opened, S
1(S
2+ S
3) value of logical expression be 1;
(2) to return the C of transformer station side connection status be S to B-C I
7(S
8+ S
9);
(3) to return current conversion station B side connection status be S to B-C II
4(S
5+ S
6);
(4) to return the C of transformer station side connection status be S to B-C II
10S
11
(5) C of the transformer station side connection status of A-C line is
Wherein
Expression and S
8The negate symbol;
(6) to return connection status be S to B-C I
1(S
2+ S
3)+S
7S
8
(7) to return connection status be S to B-C II
4(S
5+ S
6)+S
10S
11
(8) power station A and major network electrical isolation state are S
13S
14
The logic determines relational expression of decoupled mode A is
The logic determines relational expression of decoupled mode B is
Decoupled mode A, B logical relation are got " or " the logic island detection logical relation that can get step 2 always is:
This transition formula evaluation result is that 1 detection is an isolated island, is that 0 detection is networking.
By above-mentioned flow process, can realize cycle detection, according to the time-delay situation of device to island state
Can be set to 5 ~ 10ms, i.e. the temporal resolution of island state detection can reach 5 ~ 10ms.
For improving the reliability of island detection device, can install two cover island detection devices at current conversion station, every covering device is all independently gathered the relative breaker state information of power station A, current conversion station B, the C of transformer station.After the trend information of the relative breaker state information of current conversion station B, the C of transformer station, current conversion station and major network interconnector all reaches current conversion station B, carry out logic determines by the island detection device that is located at current conversion station B, the result of judgement is expressed as respectively
For avoiding failing to judge, as long as two cover island detection devices have 1 cover to be output as " 1 ", promptly there is 1 covering device to detect current conversion station and is in the islet operation state, think that promptly current conversion station is in the islet operation state.
Preferably, for fear of cause two covering device island detection difference as a result because of switch changed position, wiring or interior communication reason, except that constituting the main criterion by above-mentioned logical relation, also adopt B-CII loop line road (can choose the circuit that needs monitor) power to constitute anti-error criterion, avoid the higher mistiming of this meeting circuit to be judged to corresponding isolated island wiring according to actual conditions.Anti-erroneous judgement, the anti-logical expression of failing to judge of two cover island detection devices are:
F in the following formula
A, f
BThe output signal of representing two cover island detection devices respectively;
Be the logical variable of B-CII loop line road power rating, be when power is arranged " 1 " during inactivity to be " 0 ", "
" be the negate symbol.
Two cover island detection devices inconsistently will send voice and image alarm signal as exporting, and this function mainly detects whether unanimity of two covering devices output by following formula:
F wherein
A, f
BThe output signal of representing two island detection devices respectively,
Be XOR operation, f
A, f
BAll identically be output as 1, be output as 0 when opposite, "
" be the negate symbol.K is logical expression result, i.e. f
A, f
BNot not simultaneously, K is output as 1, starts voice and image alarm device, reminds the operator on duty to make inspection by buzz, flicker demonstration on alarm window " lonely detection conflict " literal.
The island detection device is also accepted manual command, and when personnel on duty pressed " isolated island " button, the island detection device was promptly exported the control of island state signalisation current conversion station station and entered the islet operation state with steady control.This function is applicable to plan islet operation situation, this moment, the operations staff was by the corresponding circuit breaker of stabilized control system tripping, enter the corresponding islet operation mode of connection, because current conversion station is in isolated island or networking mode, the control strategy that current conversion station is taked is different with mode, but so long as be in the isolated island mode, control strategy and parameter then are on all four, and to need not to differentiate be to enter any islet operation state to checkout gear when manually entering isolated island.
The island detection device generally is installed in current conversion station, the circuit-breaker status signal that need read current conversion station, power station and the major network transformer station of electrical link is arranged.The offside station of current conversion station (power station of access or continuous major network transformer station) mainly is to gather the circuit-breaker status signal, need not carry out logic judging function, and coherent signal carries out logic determines after passing to the island detection device of current conversion station again.Circuit-breaker status signal from this current conversion station can read from corresponding killer switch auxiliary contact, after then the measure and control device at this station reads from the circuit-breaker status signal of power station, a distant place, transformer station, transfers to current conversion station by professional optical fiber or multiplex channel.The input interface of isolated island discriminating gear is shown in Figure 9.
For improving reliability and transmission speed, the result of island detection device sends to the stability control device of current conversion station B and the control system of standing by hard connect (as lead or control cable); And power station A only need obtain the island state signal, need not to carry out the switching of control strategy, so the output result of isolated island device delivers to power station A by the optical fiber connection.
The invention also discloses a kind of checkout gear of current conversion station operational mode, it is characterized in that comprising power station, current conversion station, transformer station and circuit breaker thereof as shown in Figure 8, the checkout gear of above-mentioned current conversion station operational mode is connected with each circuit breaker, is used to detect the status signal with power station, current conversion station, circuit breaker that transformer station is relevant;
The breaker signal harvester is used to gather the state value S of the circuit breaker of power station A, current conversion station B, the C of transformer station
1~ S
n, (corresponding this example is S
1~ S
14);
Checkout gear logical calculated module: be used for the computational logic expression formula
Value;
The checkout gear of above-mentioned current conversion station operational mode is connected with current conversion station station control device, current conversion station stability control device, is used to send detected value;
The checkout gear of above-mentioned current conversion station operational mode is connected by optical fiber with the power station stability control device.
Preferably, the checkout gear of above-mentioned current conversion station operational mode also comprises time detection device and judge module, is used to detect current time and storage and relatively judgement.
Preferably, the checkout gear of above-mentioned current conversion station operational mode is two covers, two covering devices are all independently gathered the relative breaker state information of power station A, current conversion station B, the C of transformer station, as long as the island detection device has 1 cover to be output as " 1 ", promptly have 1 covering device to detect current conversion station and are in the islet operation state.
Preferably, the checkout gear of above-mentioned current conversion station operational mode also comprises warning device, and above-mentioned warning device is exported under the inconsistent situation at the checkout gear of two cover current conversion station operational modes and started.Remind the lifting operator on duty to make inspection.
The present invention is not limited to aforesaid embodiment.The present invention expands to any new feature or any new combination that discloses in this manual, and the arbitrary new method that discloses or step or any new combination of process.