1. The asymmetric voltage and current flow rate generated after an asymmetric failure in the power system can be decomposed into three sequential networks by applying the symmetrical component method, analyzed according to the sequential voltage and current symmetry in each sequence network, and then synthesized into the actual ABC quantity, so that the asymmetric failure The calculation is greatly simplified.
2. The damage to the normal operation of the power system is mainly related to asymmetric failure or asymmetric operation of circuit breakers. Since only a few points in the whole power system have unequal three-phase impedance, the method of directly solving complex three-phase asymmetric circuits is generally not used, but a simpler symmetric component method is used for analysis.
3. The method of analyzing asymmetric short circuit is the symmetrical component method. Asymmetric short circuit. Simply put, single-phase grounded short circuit, two-phase grounded short circuit, two-phase short circuit, etc. in the short circuit type are asymmetric short circuits.Three-phase short circuit belongs to symmetrical short circuit. However, for three-phase short-circuits that occur at different points, short circuits are also asymmetric short circuits.
1. Causes of power grid asymmetry, ultra-high-voltage overhead transmission lines The road does not change. The structure of the transformer is asymmetrical. The existence of AC and DC transformers, the system load is unbalanced, and there are nonlinear components in the system.
2. Power system short-circuit faults can be divided into three types: three relative faults, asymmetric faults and single-phase ground faults. Asymmetric fault refers to the different size and polarity of the three-phase current, and there may be two or more combinations; single-phase ground fault refers to the grounding phenomenon in one phase, and measures need to be taken to ensure personal safety.
3. Asymmetric short-circuit failure, according to different short-circuit causes, the calculation method is as follows: single-phase grounded short-circuit Single-phase grounded short-circuit current is less than the three-phase short-circuit current at the same fault point, and vice versa, the single-phase short-circuit current is greater than the three-phase short-circuit current.
4. Symmetric fault: three-phase balance fault Asymmetric fault: single-line ground fault, double-line ground fault, line-to-line fault The cause of symmetry failure is a short circuit fault between the three phases at the same time, at which time the fault current and phase difference of the three phases are equal;The magnitude of the current and the phase angle between the three phases of asymmetric faults are not equal.
5. Borrow the existing answer to the first question: asymmetric failure will produce negative sequence current and voltage. Asymmetric grounding faults or disconnection faults will produce zero-sequence voltage, and whether to generate zero-sequence current depends on the grounding operation mode of the system.
Asymmetric faults of power systems are mainly divided into two categories: transverse asymmetrical faults and longitudinal asymmetrical faults. Horizontal asymmetry failure Two-phase short circuit This refers to the short circuit between the two phases in the power system. In this case, the two-phase current of the short circuit will increase, while the other phase current will decrease or be zero.
Zero-sequence impedance = positive-sequence impedance: the non-fault phase voltage is the pre-fault voltage, and the short-circuit current is equal to the three-phase short-circuit current. Zero-sequence impedance is infinite: the non-fault phase voltage is 5 times the voltage before the failure, and the short-circuit current is the three-phase short-circuit current √3/2.
Asymmetric operation of the power grid, including short-circuit faults and disconnection faults. Short-circuit faults include single-phase grounding, interphase short-circuit and interphase short-circuit grounding faults. In the neutral point grounding system, grounding faults and disconnection faults will generate zero-sequence current, and of course there is also negative-sequence current. Interphase short circuit does not produce negative sequence components.
OKX Wallet extension-APP, download it now, new users will receive a novice gift pack.
1. The asymmetric voltage and current flow rate generated after an asymmetric failure in the power system can be decomposed into three sequential networks by applying the symmetrical component method, analyzed according to the sequential voltage and current symmetry in each sequence network, and then synthesized into the actual ABC quantity, so that the asymmetric failure The calculation is greatly simplified.
2. The damage to the normal operation of the power system is mainly related to asymmetric failure or asymmetric operation of circuit breakers. Since only a few points in the whole power system have unequal three-phase impedance, the method of directly solving complex three-phase asymmetric circuits is generally not used, but a simpler symmetric component method is used for analysis.
3. The method of analyzing asymmetric short circuit is the symmetrical component method. Asymmetric short circuit. Simply put, single-phase grounded short circuit, two-phase grounded short circuit, two-phase short circuit, etc. in the short circuit type are asymmetric short circuits.Three-phase short circuit belongs to symmetrical short circuit. However, for three-phase short-circuits that occur at different points, short circuits are also asymmetric short circuits.
1. Causes of power grid asymmetry, ultra-high-voltage overhead transmission lines The road does not change. The structure of the transformer is asymmetrical. The existence of AC and DC transformers, the system load is unbalanced, and there are nonlinear components in the system.
2. Power system short-circuit faults can be divided into three types: three relative faults, asymmetric faults and single-phase ground faults. Asymmetric fault refers to the different size and polarity of the three-phase current, and there may be two or more combinations; single-phase ground fault refers to the grounding phenomenon in one phase, and measures need to be taken to ensure personal safety.
3. Asymmetric short-circuit failure, according to different short-circuit causes, the calculation method is as follows: single-phase grounded short-circuit Single-phase grounded short-circuit current is less than the three-phase short-circuit current at the same fault point, and vice versa, the single-phase short-circuit current is greater than the three-phase short-circuit current.
4. Symmetric fault: three-phase balance fault Asymmetric fault: single-line ground fault, double-line ground fault, line-to-line fault The cause of symmetry failure is a short circuit fault between the three phases at the same time, at which time the fault current and phase difference of the three phases are equal;The magnitude of the current and the phase angle between the three phases of asymmetric faults are not equal.
5. Borrow the existing answer to the first question: asymmetric failure will produce negative sequence current and voltage. Asymmetric grounding faults or disconnection faults will produce zero-sequence voltage, and whether to generate zero-sequence current depends on the grounding operation mode of the system.
Asymmetric faults of power systems are mainly divided into two categories: transverse asymmetrical faults and longitudinal asymmetrical faults. Horizontal asymmetry failure Two-phase short circuit This refers to the short circuit between the two phases in the power system. In this case, the two-phase current of the short circuit will increase, while the other phase current will decrease or be zero.
Zero-sequence impedance = positive-sequence impedance: the non-fault phase voltage is the pre-fault voltage, and the short-circuit current is equal to the three-phase short-circuit current. Zero-sequence impedance is infinite: the non-fault phase voltage is 5 times the voltage before the failure, and the short-circuit current is the three-phase short-circuit current √3/2.
Asymmetric operation of the power grid, including short-circuit faults and disconnection faults. Short-circuit faults include single-phase grounding, interphase short-circuit and interphase short-circuit grounding faults. In the neutral point grounding system, grounding faults and disconnection faults will generate zero-sequence current, and of course there is also negative-sequence current. Interphase short circuit does not produce negative sequence components.
Binance app download Play Store
author: 2025-02-01 05:06998.38MB
Check966.85MB
Check424.87MB
Check674.84MB
Check755.72MB
Check445.77MB
Check648.85MB
Check987.24MB
Check692.84MB
Check823.97MB
Check711.14MB
Check453.16MB
Check387.59MB
Check347.14MB
Check715.19MB
Check568.31MB
Check888.84MB
Check378.17MB
Check736.56MB
Check895.88MB
Check483.82MB
Check375.53MB
Check628.94MB
Check667.77MB
Check233.37MB
Check962.24MB
Check926.66MB
Check417.34MB
Check114.61MB
Check831.31MB
Check838.44MB
Check941.52MB
Check754.74MB
Check779.34MB
Check813.22MB
Check189.23MB
CheckScan to install
OKX Wallet extension to discover more
Netizen comments More
1831 古今中外网
2025-02-01 05:30 recommend
1893 安如太山网
2025-02-01 05:27 recommend
831 饿虎擒羊网
2025-02-01 05:18 recommend
459 扪心自问网
2025-02-01 03:55 recommend
213 千载一时网
2025-02-01 03:02 recommend