This paper introduces the Particle-added Element Connectivity Parametrization (P-ECP), a new numerical framework for internal contact problems within structural topology optimization. The present method incorporates a penalty-based node-to-surface contact formulation by leveraging a recently developed particle contact approach [1] and the Element Connectivity Parametrization (ECP) method [2], the latter of which is specifically designed to handle geometric nonlinearities in topology optimization. Within the P-ECP framework, the density-based design is represented as a smoothed wall, and the penetration depth is utilized to define the contact potential. By employing the ECP method, contact analysis can be performed without element inversion throughout the optimization process. The contact potential derived from P-ECP is differentiated for both the nonlinear analysis and the sensitivity analysis for optimization. Several numerical examples are provided to validate the accuracy of the contact analysis as shown in Fig. 1 and demonstrate the efficacy of the method. The results show that P-ECP can effectively and directly consider contact interactions between structural components during topology optimization.