Particle swarm optimization（PSO）has been used widely in the reactive power optimization of distribution networks.However

the basic PSO algorithm takes long time to solve the voltage and reactive power optimization problem of low voltage distribution network with multiple constraints.For solving this problem

a scheme of voltage reactive power optimization for low-voltage distribution network using dynamic multi-population particle swarm optimization is proposed.The dynamic multi-swarm particle swarm optimization algorithm is dynamically classified in accordance with the constraints that voltage of each node is qualified

the reactive power compensation capacity of each node does not exceed the preset value and the total reactive power of the system is compensated rationally by roulette.The particles are searched in accordance with the updated particle velocity position updating formula.Finally

the optimal solution of the voltage reactive power optimization problem satisfying the above constraints can be obtained.The voltage reactive power optimization scheme proposed in this paper combines the decentralized parallel capacitor bank with the voltage regulation of the distribution transformer.And compared with the centralized reactive power compensation mode

the node voltage deviation of the scheme proposed is smaller and the grid loss is lower.The constrained optimization algorithm

compared to the basic particle swarm optimization algorithm

improves greatly the operation speed and optimizes the calculation results.