1. First, find out the impact of single-section battery damage on the operation of the entire set of batteries.
The load of the DC system is basically stable at the normal operation of the substation, powered by the charger, and the battery pack is a spare power supply. The characteristics of the entire set of battery charging are, such as one or more internal resistance of an internal resistance, the capacity is inevitable, and when the charger is charged to the battery pack, the aging battery is small due to small capacity, which will be full. The charger will be mistaken to convert to the battery pack with a constant voltage and small current. Good stocks are not possible. The battery pack will charge and discharge with the capacity of aging batteries. Multiple floating-discharge-equal charge-discharge-floating malignant circulation, resulting in a very low activation frequency, battery The polar active substance is gradually solidified, so that the capacity of the battery is gradually decreased, and the battery backup time is shortened.
Since the battery operation is in a long time in a floating charge, it will cause a decrease in the activity of battery chemical energy and electrical energy. During operation, as the use time will inevitably have individual or part of the battery due to the internal resistance, with a degenerative aging, the capacity of the "battery capacity is short) Board, when the actual capacity of the battery drops below 90% of its own rated capacity, the battery enters the recession period, when the battery capacity drops to the original 80% or less, the battery enters a sharp recession, the recession is very short, and The battery pack is connected in series. If there is a problem, the whole group will fail. At this time, there is a great accident hidden danger, accelerate aging and shorten the service life. At the same time, due to the principle defects present in the current monitoring method, the battery pack damage cannot be found in time, the Eastern Change, the city has changed the DC abnormal disappearance or switch refusal due to the large decline in the battery pack. .
Therefore, if the battery is not detected, it is not possible to find the processing of aging batteries. The capacity of the battery pack will become smaller, the battery life is shortened, which affects the efficient and safe operation of the system.
2. Second, analyze the defects of the current substation battery capacity detection method
General Substation is reliable to ensure that the DC system is reliable, and does not allow the battery pack to interrupt from the DC system. At present, there are two ways to monitor the battery monitoring of the Central District:
1) Measure the end voltage of the battery pack (including a single battery). The structure is composed of a master module and a plurality of acquisition modules, and the main module receives the monitor's command, and transmits battery data to the DC device monitor. Each module acquires the voltage of the 18-stricken battery, and can display each single battery voltage to determine the number of the fault battery and give alarm through the monitor of the DC charging device. Such battery patrol monitors are generally provided by DC equipment manufacturers. It is an optional device when ordering. Due to single function, it cannot test capacity, and the measurement accuracy is poor. Test diagram is shown in Figure 1:
Although the duty person can reflect the end voltage of the battery by the monitor, the battery-side voltage cannot reflect the actual capacity of the battery, and cannot find a failure battery, and the city, Huajian and other substations use artificial measurement voltage. The installation space is limited, half of the battery does not measure normal, run the real-time nature, operational risk is large, and it cannot be found in time, it is found to be charged, over-discharge.
2) Determine the capacity of the battery through the verification of the apparent discharge (around a year);
At present, the battery capacity detection method is to perform the entire set of verified discharge, that is, connect the battery pack to the load box, and then discharge, to verify the capacity of the battery, but this method has many hidden dangers and disadvantages:
A, long discharge time, large risk, battery pack must be separated from the system, the chemical energy stored in the battery pack is consumed in thermal energy, which is wasteful and cost-effective and low efficiency.
B, check-in test, must have a certain condition to be carried out under the conditions of alternating current fundamental guarantees of substation. It also needs to be relieved, and there is a hidden danger to security power supply. If there is a power outage during the battery test, it may cause the system to be paralyzed.
C. Check discharge can only test the capacity of the entire set of battery, and cannot test each of the unit cell capacity. Since the maximum internal resistance has reached the amount of electricity, it has caused other batteries due to insufficient discharge depth, it is still not fully exposed.
D, there is a capacity of the battery. Since the internal chemical reaction of the battery is not completely reversible. The number of times the full depth cycle discharge is limited, so it is not suitable for the ultra-discharge of the lead-acid battery. However, the state of the battery between the interval is too long, the battery status between the two checks is uncertain. After the capacity of the battery drops below 80%, the battery has entered a sharp decline. The recession is very short, which may fail after a check of discharge, and in the remaining time, there is a great accident hidden danger .
By analyzing the analysis of 7 substation battery failure, it is understood that the internal resistance value of the battery increases, that is, when the battery is constantly aging, the capacity is constantly decreased, the internal resistance of the battery is constantly increasing . Contrasting the internal resistance of the entire group of battery or the inner resistance of the unit cell, you can find a single battery in the entire group. By tracking the degree of resistance of the single-cell cell, master the degree of aging battery of the single-section battery reaches the purpose of maintaining the battery.
3. Measure the battery charge status and connect the resistance parameters, and determine the health state of the battery.
We measure an important parameters such as the voltage, internal resistance, capacity of single and multi-set batteries. Reporting the status of the battery (excellent, good, medium, change, abnormality), can track the decay trend of the battery, providing reasonable advice to the operation and maintenance of the battery, and compensate for the shortcomings of the discharge detection.
Article from: http://www.brcpower.com/
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