ABSTRACT
With the development of China's social life, the deepening of housing reform,
the continuous improvement of living standards, rapid development of urban
construction, but also on a higher infrastructure demands，
The construction of urban water supply system is one important aspect of water
supply reliability, stability, economy directly affect the user's normal work
and life, but also directly reflects the level of water supply management，
Traditional water supply plant, in particular small and medium water plant widely
used by the constant speed pump pressure there is less efficient water supply,
reliability is not high, low automation shortcomings, can not meet the current
needs of economic life，
This paper highlights the energy supply system frequency control theory,
detailed analysis of the principle of variable frequency and constant pressure
water supply system, the composition of the structure and proposed a different
control scheme, through research and comparison, concluded that: a kind of
frequency control is better than surge speed, mechanical speed governor means
other programs, is also a benefit of today's international, highest performance,
most widely, the most promising of motor control technology ， It combines
computer control technology, electric power electronics and motor drive
technology, and implementation of industrial variable speed AC motors with high
efficiency, wide range and high precision characteristics of the conclusions，
This article in combinations with frequency converter and PLC system step by step
to clarify how to achieve a constant water pressure was achieved，
Keywords: Constant pressure water supply, Frequency conversion speed,PLC
