Substation Voltage And Reactive Power Integrated Control System Design

The scale of modern power system becomes larger and larger, the balance of reactive power and voltage stabilize is very important. So reactive power and voltage control in modern power system is a very important problem that need to solve well.First, the analysis of present situation is given for the voltage and reactive power control of modern power system in this paper. Nowadays, the major method of voltage and reactive power control is based on region and voltage level in our country. Effective and reasonably control of reactive power and voltage in power system is for realization of balance of reactive power on stratification and region, can extensively reduce reactive power flow in power system ,and can decrease reactive power loss , it can extensively improve economic benefit of electrical network operation.Today, the major adjust methods of voltage and reactive power in power system are follows: 1. by use synchronous alternators; 2. by use series compensation capacitors; 3. by use parallel compensation condensers; 4. by use synchronous condensers ; 5. by use SVC; 6. by use transformer with on-load-tap-changer. In these adjust methods of voltage and reactive power, synchronous generators are merely used in power plant, series compensation capacitors are only used in transmission network, only 4 methods can be used in substation. method 3 and 6 are adopted in this design.In these control policies, traditional nine-zone control policy must be adjust voltage and reactive power frequently in some conditions; Improved nine-zone diagram( seventeen-zone diagram ) make voltage and reactive power control become more complex, five-zone control policy is relatively advanced in idea, but must to practice. On project applications, nine-zone control policy is more mature, but improved nine-zone fuzzy boundary control policy has solved the problem of voltage and reactive power that is frequently adjusted in some zone. It can make regulating times of tap changing switch of on-load-tap-changer-transformer reduce to least at qualified voltage and reactive balance, thus the service life of tap changing switch of transformer is greatly improved, the line loss may decrease 20% also. So, improved nine-zone fuzzy boundary control policy is adopted in this design. The performance of substation voltage and reactive control device must be better meet the needs of operation in a substation for a long time, its performance should accord with the requirement concerning national standard and occupation standard, this device can control two double-coil transformers or two three-coil transformers that can work on parallel or separation manner, it may make voltage and power factor keeping in normal scope.With the parallel compensation condensers and with on-load -lap-changer transformers as control means, and nine-zone voltage and reactive power fuzzy boundary criterion as control strategy, with single-chip computer as key controller, main circuit and control device of control system have been designed, the process of single-chip computer is also made. For better communicating with other communication device, convenient operation, improving control effect, upper computer and VQC software is adopted, it make man-machine interface more friendly.