Method and method for realizing island logic judgment

Abstract

The invention relates to a method for realizing island logic judgment, which comprises the following steps of: starting a protection device by judging whether a starting condition of the protection device is met or not, and sequentially judging whether active power, active power sudden drop quantity, positive sequence current sudden drop quantity and any two-phase current of a main transformer side meet requirements or not; and judging whether the positive sequence voltage and the negative sequence voltage of the main transformer side meet requirements or not, judging whether a protection function hard pressing plate is input or not, and if both are met, carrying out delay protection action on the generator tripping. According to the invention, the problem that a stable device cannot change a control strategy or a protection device is unreliable in logic judgment and does not have an island logic realization function can be solved. Meanwhile, zero-power generator tripping protection is additionally adopted to serve as a starting element of an FCB trigger signal. The zero-power generator tripping protection can act to start an FCB function under the condition that the unit is loaded, stabilizes the unit in a split running state with auxiliary power, and can be quickly connected to a grid after a power transmission channel is recovered.

Description

Technical Field

[0001] The invention belongs to the field of electrical control technology, and in particular to a method and method for realizing island logic judgment. Background Art

[0002] Generator Set is a complete set of mechanical equipment that converts other forms of energy into electrical energy. Generator Set consists of power system, control system, silencer system, shock absorption system and exhaust system. The principle is that when the diesel generator set shrinks in size, the temperature rises rapidly to reach the ignition point of diesel. When the diesel is ignited, the mixed gas burns violently, the volume expands rapidly, and the piston is pushed downward, which is called "work". Each cylinder works in a certain order, and the thrust acting on the piston is transformed into a force that drives the crankshaft to rotate through the connecting rod, thereby driving the crankshaft to rotate. Using the principle of "electromagnetic induction", the generator will output an induced electromotive force and generate current through a closed load circuit. The types of generator sets include diesel generator sets, gas generator sets, gasoline generator sets, etc.

[0003] For large generator sets, if they have FCB function, they can also fully or partially restore the power supply of the generator set in a very short time through self-help mode in the case of large-scale power grid failure, further ensuring the safety of the main equipment of the generator set, and at the same time restore external power supply, which brings huge benefits to the rapid recovery of the local power grid. At present, large generator sets should have the ability to operate in an isolated island. Island operation requires the power plant control system to respond quickly and automatically, and the logical judgment of triggering the island is particularly important, and the control logic needs to be carefully considered. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and propose a method and method for realizing island logic judgment, which can overcome the problem of how to judge the island mode according to electrical quantities under the premise that the existing stability device cannot change the strategy, thereby triggering the island FCB action.

[0005] The present invention solves the technical problem by adopting the following technical solutions:

[0006] A method and method for implementing island logic judgment, comprising the following steps:

[0007] Step 1: Determine whether the protection device startup conditions are met. If so, the protection is started after the delay protection and proceed to step 2. Otherwise, the protection device is not started.

[0008] Step 2: Determine whether the active power, active power sudden drop, positive sequence current sudden drop and any two-phase current on the main transformer side meet the requirements. If so, proceed to step 3; otherwise, do not start the delayed protection.

[0009] Step 3: Determine whether the positive sequence voltage and negative sequence voltage on the main transformer side meet the requirements. If they do, proceed to step 4; otherwise, do not start the delayed protection.

[0010] Step 4: Determine whether to activate the protection function hard pressure plate. If so, the machine will be cut off after the delayed protection action. Otherwise, the delayed protection will not be started.

[0011] Moreover, the protection device startup conditions in step 1 include:

[0012] Condition 1, △U t1 >△U t1set With f>50.2Hz;

[0013] Among them, △U t1 is the voltage on the main transformer side, △U t1set The voltage threshold of the main transformer side, f is the frequency of the main transformer side;

[0014] Condition 2, f>f set or △f>△f set ;

[0015] Among them, f is the frequency of the main transformer side, f set The frequency threshold of the main transformer side, △f is the frequency increment of the main transformer side, △f set It is the frequency sudden increase threshold on the main transformer side;

[0016] Condition 3: P G >P set.1 ;

[0017] Among them, P G is the active power on the main transformer side, P set.1 It is the active rated power of the main transformer side.

[0018] Moreover, in step 1, under the premise that condition 3 must be met, if either condition 1 or condition 2 is met, the protection is activated after a delay of 0 to T2.

[0019] Moreover, the specific implementation method of step 2 is: G <P set.2 ,△P>△P set , △I t1 >I t1。set When any two phase currents on the main transformer side are less than the threshold,

[0020] Among them, P G is the active power on the main transformer side, P set.2 The maximum active power of the main transformer side is 8%, △P is the sudden drop of active power on the main transformer side, △P set The threshold of the sudden drop in active power on the main transformer side, △I t1 The positive sequence current sudden drop on the main transformer side, I t1。setIt is the threshold of the sudden drop of positive sequence current on the main transformer side.

[0021] Moreover, the specific implementation method of the step 2 is that any two-phase current on the main transformer side is less than the threshold value. ta <I φset or I tb <I φset or I tc <I φset , where I ta is the phase a current on the main transformer side, I tb is the phase b current on the main transformer side, I tc is the phase c current on the main transformer side, I φset Current threshold on the main transformer side.

[0022] Moreover, the specific implementation method of step 3 is: t1 >U 1set with U t2 >U 2set ;

[0023] Among them, U t1 is the positive sequence voltage on the main transformer side, U 1set is the positive sequence voltage threshold on the main transformer side, U t2 is the negative sequence voltage on the main transformer side, U 2set It is the negative sequence voltage threshold on the main transformer side.

[0024] Moreover, the specific implementation method of the time-delay protection action in step 4 is: after the time period from t1 to T3, the t1 time limit action is performed, and after the time period from t2 to T3, the t2 time limit action is performed.

[0025] The advantages and positive effects of the present invention are:

[0026] The present invention starts the protection device by judging whether the starting conditions of the protection device are met, and judges in turn whether the active power, the sudden drop in active power, the sudden drop in positive-sequence current and any two-phase current on the main transformer side meet the requirements, judges whether the positive-sequence voltage and the negative-sequence voltage on the main transformer side meet the requirements, and judges whether to put the protection function hard pressure plate into operation. If all conditions are met, the machine is cut off after the delayed protection. The present invention can make up for the fact that the stability device cannot change the control strategy, or the logical judgment of the protection device is unreliable, and does not have the function of realizing the island logic. At the same time, the present invention adopts the addition of zero-power machine-cutting protection as the starting element of the FCB trigger signal. The zero-power machine-cutting protection can act to start the FCB function when the unit is loaded, stabilize the unit in the decoupling operation state with plant power, and can be quickly connected to the grid after the transmission channel is restored. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a logic diagram of the present invention;

[0028] Figure 2 This is the logic diagram for starting the protection device of the present invention. DETAILED DESCRIPTION

[0029] The present invention is further described in detail below with reference to the accompanying drawings.

[0030] A method and method for implementing island logic judgment, such as Figure 1 As shown, the following steps are included:

[0031] Step 1: Determine whether the protection device startup conditions are met. If so, the protection is started after the delay protection and proceed to step 2. Otherwise, the protection device is not started.

[0032] like Figure 1 As shown, the protection device startup conditions in step 1 include:

[0033] Condition 1, △U t1 >△U t1set With f>50.2Hz;

[0034] Among them, △U t1 is the voltage on the main transformer side, △U t1set The voltage threshold of the main transformer side, f is the frequency of the main transformer side;

[0035] Condition 2, f>f set or △f>△f set ;

[0036] Among them, f is the frequency of the main transformer side, f set The frequency threshold of the main transformer side, △f is the frequency increment of the main transformer side, △f set It is the frequency sudden increase threshold on the main transformer side;

[0037] Condition 3: P G >P set.1 ;

[0038] Among them, P G is the active power on the main transformer side, P set.1 It is the active rated power of the main transformer side.

[0039] Under the premise that condition 3 must be met, if either condition 1 or condition 2 is met, the protection will be activated after a delay of 0 to T2.

[0040] Step 2: Determine whether the active power, active power sudden drop, positive sequence current sudden drop and any two-phase current on the main transformer side meet the requirements. If so, proceed to step 3; otherwise, do not start the delayed protection.

[0041] P G <P set.2 ,△P>△P set , △I t1 >It1。set Any two-phase current on the main transformer side is less than the threshold;

[0042] Among them, P G is the active power on the main transformer side, P set.2 The maximum active power of the main transformer side is 8%, △P is the sudden drop of active power on the main transformer side, △P set The threshold of the sudden drop in active power on the main transformer side, △I t1 The positive sequence current sudden drop on the main transformer side, I t1。set It is the threshold of the sudden drop of positive sequence current on the main transformer side.

[0043] The specific implementation method of the current of any two phases on the main transformer side is less than the threshold value is I ta <I φset or I tb <I φset or I tc <I φset , where I ta is the phase a current on the main transformer side, I tb is the phase b current on the main transformer side, I tc is the phase c current on the main transformer side, I φset Current threshold on the main transformer side.

[0044] Step 3: Determine whether the positive sequence voltage and negative sequence voltage on the main transformer side meet the requirements. If they do, proceed to step 4; otherwise, do not start the delayed protection.

[0045] U t1 >U 1set with U t2 >U 2set ;

[0046] Among them, U t1 is the positive sequence voltage on the main transformer side, U 1set is the positive sequence voltage threshold on the main transformer side, U t2 is the negative sequence voltage on the main transformer side, U 2set It is the negative sequence voltage threshold on the main transformer side.

[0047] Step 4: Determine whether to activate the protection function hard pressure plate. If so, the machine will be cut off after the delayed protection action. Otherwise, the delayed protection will not be started.

[0048] The specific implementation method of the time-delay protection action and the machine cutting is: after the time period from t1 to T3, the t1 time limit action is performed, and after the time period from t2 to T3, the t2 time limit action is performed.

[0049] According to the above method and method for realizing island logic judgment, a 100% load shedding island is tested, and the required analog quantity is connected according to the principle of the zero power protection device; the zero power protection setting value and the zero power protection action outlet are set; the combination logic is used as the trigger logic of the island FCB. The specific test process is as follows:

[0050] Step 1: Determine whether the protection device startup conditions are met. If so, the protection is started after the delay protection and proceed to step 2. Otherwise, the protection device is not started.

[0051] The protection device activation conditions include:

[0052] Condition 1: The positive sequence voltage on the main transformer side increases by more than 1.5V and the frequency is greater than 50.2HZ;

[0053] Condition 2: The frequency on the main transformer side is greater than 51HZ or the sudden increase in the frequency on the main transformer side is greater than 0.3HZ;

[0054] Condition 3: The active power on the main transformer side is greater than 20% of the rated active power and has been delayed.

[0055] Under the premise that condition three must be met, if either condition one or condition two is met, the delayed protection will be activated.

[0056] Step 2: Determine whether the active power, active power sudden drop, positive sequence current sudden drop and any two-phase current on the main transformer side meet the requirements. If so, proceed to step 3; otherwise, do not start the delayed protection.

[0057] The active power on the main transformer side is less than 8%, the active power sudden drop on the main transformer side is greater than the active power sudden drop threshold on the main transformer side, the positive sequence current sudden drop on the main transformer side is greater than 0.1A, and the current of any two phases on the main transformer side is less than 0.6A.

[0058] Step 3: Determine whether the positive sequence voltage and negative sequence voltage on the main transformer side meet the requirements. If they do, proceed to step 4; otherwise, do not start the delayed protection.

[0059] The positive sequence voltage on the main transformer side is greater than 50V, while the negative sequence voltage is less than 6V.

[0060] Step 4: Determine whether to activate the protection function hard pressure plate. If so, the machine will be cut off after the delayed protection action. Otherwise, the delayed protection will not be started.

[0061] The specific implementation method of the time-delay protection action and the machine cutting is: after the time period from t1 to T3, the t1 time limit action is performed, and after the time period from t2 to T3, the t2 time limit action is performed.

[0062] The present invention can make up for the inability of the stabilization device to change the control strategy, or the unreliable logic judgment of the protection device, and the lack of the function of realizing the island logic. At the same time, the present invention adopts the addition of zero-power cutting protection as the starting element of the FCB trigger signal. The zero-power cutting protection can act to start the FCB function when the unit is loaded, stabilize the unit in the decoupling operation state with factory power, and can be quickly connected to the grid after the transmission channel is restored. This method sets three tripping output contacts and sends them to the control system for two out of three to meet the reliability requirements.

[0063] It should be emphasized that the embodiments described in the present invention are illustrative rather than restrictive. Therefore, the present invention includes but is not limited to the embodiments described in the specific implementation manner. Any other implementation manners derived by those skilled in the art based on the technical solution of the present invention also fall within the scope of protection of the present invention.

Claims

1. A method and method for realizing island logic judgment, characterized in that: The following steps are involved: Step 1: Determine whether the protection device startup conditions are met. If so, the protection is started after the delay protection and proceed to step 2. Otherwise, the protection device is not started. Step 2: Determine whether the active power, active power sudden drop, positive sequence current sudden drop and any two-phase current on the main transformer side meet the requirements. If so, proceed to step 3; otherwise, do not start the delayed protection. Step 3: Determine whether the positive sequence voltage and negative sequence voltage on the main transformer side meet the requirements. If they do, proceed to step 4; otherwise, do not start the delayed protection. Step 4: Determine whether to activate the protection function hard pressure plate. If so, the machine will be cut off after the delayed protection action. Otherwise, the delayed protection will not be started.

2. A method and method for realizing island logic judgment according to claim 1, characterized in that: The protection device startup conditions in step 1 include: Condition 1, △U t1 >△U t1set With f>50.2Hz; Among them, △U t1 is the voltage on the main transformer side, △U t1set The voltage threshold of the main transformer side, f is the frequency of the main transformer side; Condition 2, f>f set or △f>△f set ; Among them, f is the frequency of the main transformer side, f set The frequency threshold of the main transformer side, △f is the frequency increment of the main transformer side, △f set It is the frequency sudden increase threshold on the main transformer side; Condition 3: P G >P set.1 ; Among them, P G is the active power on the main transformer side, P set.1 It is the active rated power of the main transformer side.

3. A method and method for realizing island logic judgment according to claim 2, characterized in that: In step 1, under the premise that condition 3 must be met, if either condition 1 or condition 2 is met, the protection is activated after a delay of 0 to T2.

4. The method and method for realizing island logic judgment according to claim 1, characterized in that: The specific implementation method of step 2 is: G <P set.2 ,△P>△P set , △I t1 >I t1。set When any two phase currents on the main transformer side are less than the threshold, Among them, P G is the active power on the main transformer side, P set.2 The maximum active power of the main transformer side is 8%, △P is the sudden drop of active power on the main transformer side, △P set The threshold of active power sudden drop on the main transformer side, △I t1 The positive sequence current sudden drop on the main transformer side, I t1。set It is the threshold of the sudden drop of positive sequence current on the main transformer side.

5. The method and method for realizing island logic judgment according to claim 1, characterized in that: The specific implementation method of step 2 in which the current of any two phases on the main transformer side is less than the threshold is: ta <I φset or I tb <I φset or I tc <I φset , where I ta is the phase a current on the main transformer side, I tb is the phase b current on the main transformer side, I tc is the phase c current on the main transformer side, I φset Current threshold on the main transformer side.

6. A method and method for realizing island logic judgment according to claim 1, characterized in that: The specific implementation method of step 3 is: t1 >U 1set with U t2 >U 2set ; Among them, U t1 is the positive sequence voltage on the main transformer side, U 1set is the positive sequence voltage threshold on the main transformer side, U t2 is the negative sequence voltage on the main transformer side, U 2set It is the negative sequence voltage threshold on the main transformer side.

7. A method and method for realizing island logic judgment according to claim 1, characterized in that: The specific implementation method of the time-delay protection action in step 4 is: after the time period from t1 to T3, the t1 time limit action is performed, and after the time period from t2 to T3, the t2 time limit action is performed.

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