- Detail

Electric safety and stability analysis and measures

1, electric stability analysis

1, n-1 static Enron analysis. In the analysis, we should pay attention to the overload environment of components, the voltage environment of key points, the weak link of electricity, etc

2. Static power angle stability analysis (analysis of static power angle stability sharing algorithm). In the analysis, we should pay attention to whether the process and processing method of adding and subtracting line or section power are different from the actual situation, and whether the voltage level is appropriate and practical

3. Time domain stability analysis. Attention should be paid to when using the time domain stability analysis method to stop the analysis of power angle, voltage and frequency stability:

(1) the calculation premise should reflect the hapless environment that can be presented by fragments

(2) the fault type should meet the requirements of stability guidelines, and the fault address should cover the most serious fault address that can be presented

(3) pay attention to the representativeness of the selected physical quantities (unit, bus and line angle, voltage, etc.)

(4) it is necessary to explain the environment and fairness of DC transmission fragmentation, various active assembly, and unit shelter measures

(5) attention should be paid to distinguishing the nature and form of stability loss, such as voltage stability (continuous drop of load intermediate voltage) and power angle stability (periodic change or continuous drop of tie line voltage)

(6) attention should be paid to generator coherence and piecemeal oscillation

(7) we should pay attention to the fragmentary damping environment and evaluate the need to stop detailed static stability analysis

(8) pay attention to the recovery environment of voltage and frequency after the accident

(9) the primary factors that affect the stability of piecemeal power angle, voltage and frequency, and the methods to improve piecemeal stability

4. Static stability frequency domain analysis. When using frequency domain analysis to improve performance stability analysis, we should pay attention to:

(1) the premise of calculation should reflect the hapless environment that can be presented in pieces

(2) focus on the analysis of the oscillation frequency, damping ratio and strong coherent units of interregional oscillation forms, piecemeal coherent oscillation forms sent by remote power sources and other weakly damped oscillation forms

(3) pay attention to the primary relevant unit working conditions of the oscillation form concerned, and the fairness and accuracy of the unit and its excitation piecemeal (including PSS) model parameters

(4) the primary factors that affect the static stability of fragments and the methods to improve the static stability of fragments

5. Short circuit current calculation. In the calculation, we should pay attention to whether the initial power flow considers the maximum startup mode and the most complete rack layout, and whether the voltage level is normal high value; When calculating asymmetric short circuit, attention should be paid to the completeness of zero sequence collection, including the zero sequence parameters of lines, main transformers, high reactance and other components and the zero sequence mutual inductance parameters of lines. The zero sequence parameters of main transformers should consider the connection style of transformer windings and the neutral point grounding mode, and the zero sequence parameters of high reactance should consider the small reactance of high reactance neutral point

6. Comprehensive analysis. On the basis of the above analysis, affirm the nature of piecemeal stability performance, the primary factors affecting piecemeal stability, find out the weak links of piecemeal stability, discuss the methods and control requirements for improving piecemeal stability and ensuring the safe and stable operation of electricity in the field of lithium-ion battery consumption in China in 2017, and discuss ways to improve the overall safety and stability of piecemeal stability, such as improving the electrical layout

2. Implement the methods of electrical stability

1. In view of the safety and stability results of electricity found in the calculation and analysis, and the requirements for the electrical layout, put forward the methods of perfect electrical layout, optimizing the layout of active and reactive power sources, saving, and unlocking the electromagnetic ring, so as to complete the reasonable layered division of electricity, increase the dependence of fragmentary stability on Enron's active assembly, and reduce the probability of serious electrical disturbance. And coated with a mixture of high-purity graphite and salt free butter

2. According to the safe and stable calculation results and the ability of relevant equipment, put forward the control limit of relevant lines/sections and the operation control scheme of the style (including the statement of control premise)

3. Follow the level 2 and level 3 safety and stability standards specified in the guidelines for safety and stability of electric power (DL), and formulate electric stability control methods according to the calculation results of safety and stability and the ability of related equipment that we will grow faster in this way. The corresponding methods of the second level safety and stability standard include interlocking machine cut-off, interlocking load cut-off, quick closing of steam valve and other methods; The third level safety and stability standard the corresponding methods of safety and stability standard include step out splitting, fast splitting, low-frequency load shedding, high-voltage load shedding, high-frequency machine cutting and other methods

4. For the environment where the short-circuit current exceeds the standard, measures must be taken to reduce it to below the switching breaking current

the methods that can be adopted in the planning stage include: selecting switchgear with large breaking current, layered and partitioned electrical justice, reasonable access to power supply, adopting high impedance transformer, adding small reactance to the neutral point of transformer, adopting old techniques such as short-circuit current limiter, etc

the methods that can be adopted in the operation stage include: Unlocking the electromagnetic ring for operation, disconnecting part of the lines, bus arrangement for operation, line out of series operation, limiting the starting mode of the unit, etc

when selecting the above methods, we should comprehensively consider the implementability of the methods and the factors such as fragmentary stability, equipment safety, power supply and transmission ability, power supply reliability, flexibility of style placement, etc

5. Next, the enterprise will face the sense of further steps and urgency. When definitely exchanging the piecemeal control limit value, it should consider the calculation error caused by the difference between the operation style and model parameters adopted in the calculation and the actual situation, and deduct 5% - 8% from the calculation limit value to obtain the control limit value. Calculation error is not considered for DC fragmentary

in the environment where the operation style and model parameters adopted in the calculation can have large errors (such as stopping the durability calculation, etc.), the value should be taken according to the lower limit of the above range

in the environment where the operation mode is relatively certain (such as the calculation of short-term operation mode, etc.), the value can be taken according to the lower limit of the above range. In the calculation of power plant delivery ability, if the coherent model parameters are more accurate, the value of calculation error can be appropriately reduced

6. When placing the power transmission plan of the tie line, it should also properly consider the fluctuation of the normal power flow, so as to prevent the fluctuation of the normal power flow from causing the power to run beyond the control limit

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